Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 03/15/07

AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
200 PM PDT TUE MAR 13 2007 .SYNOPSIS... HIGH PRESSURE ALOFT WILL WEAKEN AND THE MARINE LAYER WILL RETURN PROMISING A COOLING TREND AND COASTAL FOG WEDNESDAY AND THURSDAY. HIGH PRESSURE AND WEAK OFFSHORE FLOW WILL REBUILD FRIDAY FOR FAIR AND WARMER WEATHER. WEAK LOW PRESSURE WILL BRING A COOLING TREND NEXT WEEK AND ALLOW THE MARINE AIR TO RETURN. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES. AN EDDY CIRCULATION IS HELPING THE FOG ADVANCE FROM THE WEST THROUGH THE ISLANDS AND FROM THE SOUTH ALONG THE COAST. THIS FOG WILL TOUCH THE COAST THIS AFTERNOON AND EVE IN MANY AREAS AND WILL BE DENSE AT LEAST INITIALLY...HENCE THE DENSE FOG ADVISORY. THE COOLING TREND HAS BEGUN EVERYWHERE...BUT ESPECIALLY AT THE COAST. THE COOLER AIR WILL MOVE FARTHER INLAND WED AND THU AS A WEAK SHORTWAVE PASSES THROUGH THE RIDGE TO THE NORTH. TEMPS AWAY FROM THE MARINE INFLUENCE WILL ALSO COME DOWN SOME. THE MARINE LAYER WILL REMAIN VERY SHALLOW WED AND LIFT SLIGHTLY THU...SO ON THU FOG WILL NOT BE AS DENSE AT THE COAST BUT EXTEND A LITTLE FARTHER INLAND AND WILL BE DENSE ON THAT LEADING EDGE. THE RIDGE REBUILDS FRI AND CONTINUES SAT FOR MORE HOT DRY WEATHER WITH A DASH OF OFFSHORE FLOW...AND THE HIGHER FIRE POTENTIAL THAT GOES WITH IT. A LARGE TROUGH OF LOW PRESSURE DEVELOPS OVER THE EASTERN PACIFIC OVER THE WEEKEND. ON SUN A VERY WEAK SHORTWAVE EXTENDING FROM THE LONGWAVE TROUGH WILL SLIDE THROUGH SOCAL AND BRING BACK THE MARINE LAYER. THIS ADVANCE WAVE SEEMS TO SOFTEN THE RIDGE AND OPEN THE DOOR FOR ANOTHER LOW PRESSURE SYSTEM TO MOVE INTO SOCAL BY TUE OR WED...BUT IT HAS A LONG WAY TO GO BEFORE WE CAN CONSIDER RAIN. && 131930Z...FOG BANK ALONG THE COAST HAS PUSHED NORTHWARD ALONG THE COAST AND SHOULD REACH COASTAL ORANGE COUNTY NEAR KSNA BY LATE THIS AFTERNOON. IT DOES NOT APPEAR TO BE MAKING MUCH EASTWARD PROGRESS AT THIS TIME. A MODERATE COASTAL EDDY IS HELPING WITH THE NORTHWARD PROGESSION OF THE FOG BANK. ANOTHER AREA OF STRATUS FURTHER OFF THE COAST IS ALSO PUSHING EASTWARD TOWARDS THE COAST. BASED ON A RECENT TOP REPORT FROM AN AIRCRAFT ARRIVING KNZY...TOP OF 500 FEET...FOG BANK NEAR THE COAST IS VERY SHALLOW. EXPECT IT TO BEGIN TO PUSH ONSHORE LATER THIS EVENING WITH A CEILING REACHING KSAN BY 06Z AND KSNA BY 08Z WITH LIFR CONDITIONS REACHING BOTH AIRPORTS AT THAT TIME OR WITHIN AN HOUR OR TWO AFTER IT ARRIVES. FOG SHOULD REMAIN OVER THE AIRPORTS THROUGH THE NIGHT BEFORE LIFTING OUT AFTER SUNRISE ON WEDNESDAY. ABOVE THE MARINE LAYER...CONTINUED VFR WITH A MOSTLY CLEAR SKY AND UNRESTRICTED VISIBILITIES THROUGH WEDNESDAY. && .SGX WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY ALONG THE COAST...SEE LAXNPWSGX. HIGH RIP CURRENT RISK AT THE BEACHES...SEE LAXSRFSGX. && $$ PUBLIC...MM AVIATION/MARINE...HORTON
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
100 PM EDT WED MAR 14 2007 .AVIATION (18Z TAFS)... ISOLATED SHOWERS WILL BECOME MORE WIDESPREAD BY 18 TO 19Z FOR SDF AND BWG. SCATTERED SHOWERS WILL PROBABLY HOLD OFF UNTIL AFTER 20Z FOR LEX. SOME THUNDERSTORMS ARE ALSO POSSIBLE. CEILINGS WILL REMAIN VFR EXCEPT FOR BRIEF MVFR ASSOCIATED WITH SHOWER ACTIVITY. SHOWER ACTIVITY WILL BECOME MORE WIDESPREAD AFTER MIDNIGHT. EXPECT SEVERAL HOURS OF SHOWERS WITH EMBEDDED THUNDER DURING THE EARLY MORNING HOURS AS SDF...LEX AND BWG. A COLD FRONT WILL MOVE SOUTH OF SDF AND LEX BY 14Z THURSDAY. EXPECT WINDS TO SHIFT TO THE NORTH AND MVFR CEILINGS OF 1 TO 2 THOUSAND FEET BEHIND THE FRONT. RAIN WILL LIKELY CONTINUE INTO EARLY AFTERNOON ACROSS BWG. JSD && .SHORT TERM (TODAY AND TONIGHT)... UPPER VORT PRODUCING SCATTERED SHOWERS ACROSS THE LOUISVILLE FORECAST AREA AT 06Z WILL CONTINUE ITS MARCH TO THE NORTHEAST AND WILL TAKE ITS SHOWERS OUT OF OUR AREA EARLY THIS MORNING. WE SHOULD THEN HAVE SEVERAL MOSTLY DRY HOURS FROM MID MORNING INTO EARLY AFTERNOON. UPPER LOW OVER TEXAS WILL CONTINUE TO EDGE SLOWLY EAST...CROSSING TEXAS TODAY AND ENTERING THE LOWER MISSISSIPPI VALLEY TONIGHT. IT WILL SEND ANOTHER SMALL VORT MAX NORTHEAST TODAY...CROSSING CENTRAL KENTUCKY LATE THIS AFTERNOON AND THIS EVENING. THIS FEATURE WILL HELP TO SPARK OFF SHOWERS AND THUNDERSTORMS. IN ADDITION...TONIGHT AN EAST-WEST COLD FRONT WILL DROP SOUTH OUT OF THE MIDWEST AND GREAT LAKES INTO THE OHIO VALLEY. TIMING DIFFERENCES NOTED BY THE DAY SHIFT YESTERDAY CONTINUE...WITH THE NAM12 ABOUT 8 HOURS SLOWER THAN THE GFS. MREF IS ALSO SLOWER THAN THE OPERATIONAL GFS. USING A MREF/SREF BLEND PUTS THE COLD FRONT ALONG OR JUST ON THE INDIANA SIDE OF THE OHIO RIVER BY 12Z THURSDAY MORNING. AS A RESULT WILL LEAN TOWARDS THE WARMER MET NUMBERS FOR LOWS TONIGHT. BETWEEN THE UPPER SYSTEM MOVING OVERHEAD LATER TODAY AND THE COLD FRONT APPROACHING TONIGHT SHOWERS AND THUNDERSTORMS ARE A GOOD BET. THE STORM PREDICTION CENTER HAS PLACED LOCATIONS ALONG AND NORTH OF THE OHIO RIVER IN A SLIGHT RISK FOR SEVERE STORMS. IT APPEARS HOWEVER TO BE A RATHER MARGINAL SET-UP FOR SEVERE WEATHER. LIFTED INDICES AND SHOWALTER INDEX NUMBERS BOTTOMING OUT AROUND -1 OR -2 THIS AFTERNOON WITH TOTAL TOTALS OF 45 TO 50...WEAK CAPE...AND SHALLOW MID-LEVEL LAPSE RATES SUGGEST THUNDERSTORMS ARE A POSSIBILITY BUT THE CHANCE FOR SEVERE SEEMS SMALL. BEST TIME FOR THUNDERSTORMS WILL BE LATE THIS AFTERNOON AS SHEAR PEAKS. CHANCES SHOULD THEN DIMINISH FURTHER ONCE THE SUN SETS. LOW LEVEL JET DOES CRANK UP THIS AFTERNOON AND THE WET BULB ZERO HEIGHT WILL BE AROUND 9000 FEET SO THE STRONGEST STORMS MAY BE ABLE TO PRODUCE SOME GUSTY WINDS AND HAIL. TEMPERATURES TODAY WILL BE TRICKY. LOUISVILLE WAS STILL 70 DEGREES AT 100 AM BEFORE SHOWERS MOVED IN AND DROPPED THE TEMPERATURE TO 63...WITH MIDDLE 60S REPORTED THROUGHOUT THE REST OF THE FORECAST AREA AS WELL. AS OPPOSED TO YESTERDAY...TODAY WILL HAVE COPIOUS AMOUNTS OF CLOUD COVER. HOWEVER A FEW BREAKS WILL BE POSSIBLE BETWEEN THIS MORNING/S AND THIS AFTERNOON/S SHOWERS. WILL ALLOW READINGS TO CLIMB ABOUT TEN DEGREES...INTO THE MIDDLE 70S. 13 .LONG TERM (THURSDAY THROUGH TUESDAY)... THURSDAY THROUGH FRIDAY NIGHT... THIS PERIOD WILL BE THE MAIN FOCUS OF THE EXTENDED FORECAST AS DECENT COLD FRONT WILL DROP SOUTH AND BRING A PERIOD OF SHOWERS AND STORMS TO THE OHIO VALLEY. 00Z GFS AND NAM-WRF RUNS CONTINUE TO HAVE TIMING DIFFERENCES WITH THE ACTUAL FRONTAL PASSAGE. GFS SOLUTIONS CONTINUE TO BE CONSISTENT WITH PREVIOUS RUNS ON A THURSDAY MORNING FRONTAL PASSAGE WHILE THE NAM-WRF IS SOME 12 HOURS LATER. 21Z SREF SOLUTIONS ARE FAIRLY CONSISTENT WITH THE YESTERDAYS 09Z SOLUTION WHICH IS DOWN THE MIDDLE OF BOTH THE OP GFS AND NAM RUNS. THEREFORE WILL CONTINUE TO LEAN THE TOWARD THIS SOLUTION FOR THE FORECAST. USING THE 21Z SREF SOLUTION SFC FRONTAL BOUNDARY LOOKS TO CROSS THROUGH THE AREA DURING THE DAY ON THURSDAY. EXTENSIVE CLOUDINESS AND SCATTERED PRECIPITATION ARE EXPECTED THURSDAY MORNING AND WILL LIKELY LIMIT SFC BASED INSTABILITY. ADDITIONALLY...LAPSE RATES ARE NOT ALL THAT GREAT AS COOLER AIR ALOFT IS DISPLACED FURTHER NW OF THE AREA. LOW-LEVEL FLOW AHEAD OF THE FRONT STILL LOOKS TO BE IN THE AREA OF 35-40 KTS...THEREFORE SOME GUSTY WINDS WILL BE POSSIBLE WITH ANY CONVECTION THAT CAN GET GOING. HOWEVER...OVERALL THREAT OF ORGANIZED SEVERE APPEARS QUITE DIMINISHED AS OF THIS TIME. BEST FORCING WILL BE ALONG SAID FRONTAL BOUNDARY AND BASED ON 21Z SREF HAVE GONE AHEAD AND BUMPED POPS UP TO THE HIGH END OF THE LIKELY CATEGORY. TEMPERATURES FOR THURSDAY WILL BE A CHALLENGE DUE TO CLOUD COVER AND PRECIPITATION. I HAVE LOWERED TEMPS BY A DEGREE OR TWO WITH LOWER 60S ACROSS SOUTHERN INDIANA AND MID TO UPPER 60S ACROSS CENTRAL AND SOUTHERN KENTUCKY. I ANTICIPATE FALLING TEMPERATURES QUICKLY AFTER FRONTAL PASSAGE. LOWS THURSDAY NIGHT WILL DROP INTO THE UPPER 30S ACROSS SOUTHERN INDIANA AND PORTIONS OF NORTH CENTRAL KY. WARMER READINGS WILL BE FURTHER SOUTH ALONG THE KY/TN BORDER WITH MID TO UPPER 40S. FOR FRIDAY...POST FRONTAL PRECIPITATION WILL CONTINUE TO MOVE EAST AND OUT OF THE AREA. WILL MAINTAIN A SMALL CHANCE OF PRECIPITATION FOR FRIDAY MORNING ACROSS THE EASTERN SECTIONS. MOSTLY CLOUDY SKIES ARE EXPECTED THROUGH MUCH OF THE DAY WITH SOME PARTIAL CLEARING POSSIBLE BY LATE AFTERNOON. CLOUDS WILL KEEP TEMPS DOWN WITH HIGHS ONLY WARMING INTO THE UPPER 40S TO AROUND 50. A RETURN TO COLDER TEMPS IS EXPECTED FRIDAY NIGHT WITH OVERNIGHT LOWS DIPPING INTO THE UPPER 20S TO AROUND 30. SATURDAY THROUGH SUNDAY... MODEL CONSENSUS SOLUTION SUGGESTS DRY CONDITIONS THROUGH THIS PORTION OF THE FORECAST PERIOD. OHIO VALLEY TO REMAIN IN GENERAL NORTHWEST FLOW PATTERN. LAST FEW RUNS OF THE GFS HAVE BEEN SUGGESTING THAT WEAK VORT WITHIN THE FLOW MAY TRIGGER SOME LIGHT PRECIPITATION JUST TO OUR NORTHEAST DURING THE DAY ON SATURDAY. A STRONGER SYSTEM MAY DROP DOWN INTO THE REGION BY SUNDAY BRINGING LIGHT PRECIP. THERMAL PROFILES SUPPORT LIQUID PRECIPITATION AT THIS TIME. FOR NOW WILL HOLD OFF ON MAKING MAJOR ADJUSTMENTS TO THE FORECAST PERIOD AND WAIT TO SEE WHAT THE ENSEMBLES RUNS REVEAL. CURRENT FORECAST TEMPS LOOK OK FOR NOW...WITH HIGHS IN THE MID 40S IN THE NORTHEAST SECTIONS TO THE UPPER 40S AND LOWER 50S ACROSS THE SOUTHWEST. TEMPERATURES FOR SUNDAY MAY NEED TO BE TRENDED DOWN SOME AS 00Z GFS RAW NUMBERS SUPPORT COOLER TEMP TRENDS. -MJ SUNDAY NIGHT THROUGH TUESDAY... NO CHANGES MADE FOR THIS PART OF THE FORECAST PERIOD. PREVIOUS DISCUSSION FOLLOWS... BASING THE LAST TWO DAYS OF THE FCST PRIMARILY ON BLEND OF 0Z NCEP ENS MEAN AND ECMWF...WHICH SHOW UPPER TROF LIFTING NE WITH STRONG SW LOW LEVEL FLOW DEVELOPING OVER THE OHIO VALLEY. THIS WILL HELP TEMPS RISE QUICKLY BACK INTO THE 60S (ABOVE NORMAL) FOR MON AND TUES. A SFC FRONT DEPICTED BY BOTH MODEL SOLNS IS EXPECTED TO DROP S INTO THE OHIO VALLEY SOMETIME LATE MONDAY...PROVIDING A CHANCE FOR SHOWERS...SLIGHT CHANCES MONDAY...BETTER CHANCES INTO TUESDAY. THERE COULD BE SOME THUNDER INVOLVED AS WELL BUT AMT OF INSTABILITY THAT CAN DEVELOP IS QUESTIONABLE AT THIS TIME. CS && .AVIATION (12Z TAFS)... 40 KNOT WINDS SHOWING UP ON VWP AT FORT KNOX AT 2000 FEET AT 10Z. RECENT ACARS SOUNDING SHOWING 35 KNOTS AT THAT LEVEL. AS THE WINDS ALOFT DECREASE A BIT AND SURFACE WINDS INCREASE THE LLWS OVER THE REGION EARLY THIS MORNING WILL DIMINISH. WE WILL HAVE SEVERAL DRY HOURS BEFORE THE NEXT UPPER LEVEL DISTURBANCE COMES IN FROM THE SOUTHWEST AND BRINGS ANOTHER ROUND OF SHOWERS WITH IT. EXPECT SHOWERS AND THUNDERSTORMS NEAR THE TAF SITES LATE THIS AFTERNOON INTO EARLY THIS EVENING. THE BEST CHANCE FOR THUNDER WILL BE AFTER 21Z AND THIS IS REFLECTED IN THE TAFS BY INCLUDING A CB CLOUD TYPE. BEST CHANCES FOR SHOWERY WEATHER WILL BE AT SDF AND LEX AS THOSE LOCATIONS ARE INFLUENCED BY BOTH THE UPPER LEVEL DISTURBANCE AND A SURFACE COLD FRONT THAT WILL BE DROPPING SOUTHWARD INTO THE OHIO VALLEY. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$
AREA FORECAST DISCUSSION...CORRECTED TIME STAMP
NWS LOUISVILLE KY
1133 AM EDT WED MAR 14 2007 .MORNING UPDATE... INITIAL SHORTWAVE THAT BROUGHT RAIN EARLIER THIS MORNING ACROSS KENTUCKY HAS MOVED INTO OHIO. IN ITS WAKE...WEAK SUBSIDENCE HAS PRODUCED PARTLY CLOUDY SKIES AND MILD TEMPERATURES. LOCAL SOUNDINGS AND SATELLITE IMAGERY SHOW THAT ALTHOUGH SOME INSTABILITY WILL DEVELOP THIS AFTERNOON...A LACK OF ANY UPPER LEVEL SUPPORT MAY DELAY ANY THUNDERSTORM DEVELOPMENT UNTIL LATE THIS AFTERNOON OR EVENING. HAVE DELAYED LIKELY THUNDERSTORM DEVELOPMENT UNTIL THIS EVENING...AND TRENDED SKIES TOWARDS PARTLY CLOUDY. JSD .SHORT TERM (TODAY AND TONIGHT)... UPPER VORT PRODUCING SCATTERED SHOWERS ACROSS THE LOUISVILLE FORECAST AREA AT 06Z WILL CONTINUE ITS MARCH TO THE NORTHEAST AND WILL TAKE ITS SHOWERS OUT OF OUR AREA EARLY THIS MORNING. WE SHOULD THEN HAVE SEVERAL MOSTLY DRY HOURS FROM MID MORNING INTO EARLY AFTERNOON. UPPER LOW OVER TEXAS WILL CONTINUE TO EDGE SLOWLY EAST...CROSSING TEXAS TODAY AND ENTERING THE LOWER MISSISSIPPI VALLEY TONIGHT. IT WILL SEND ANOTHER SMALL VORT MAX NORTHEAST TODAY...CROSSING CENTRAL KENTUCKY LATE THIS AFTERNOON AND THIS EVENING. THIS FEATURE WILL HELP TO SPARK OFF SHOWERS AND THUNDERSTORMS. IN ADDITION...TONIGHT AN EAST-WEST COLD FRONT WILL DROP SOUTH OUT OF THE MIDWEST AND GREAT LAKES INTO THE OHIO VALLEY. TIMING DIFFERENCES NOTED BY THE DAY SHIFT YESTERDAY CONTINUE...WITH THE NAM12 ABOUT 8 HOURS SLOWER THAN THE GFS. MREF IS ALSO SLOWER THAN THE OPERATIONAL GFS. USING A MREF/SREF BLEND PUTS THE COLD FRONT ALONG OR JUST ON THE INDIANA SIDE OF THE OHIO RIVER BY 12Z THURSDAY MORNING. AS A RESULT WILL LEAN TOWARDS THE WARMER MET NUMBERS FOR LOWS TONIGHT. BETWEEN THE UPPER SYSTEM MOVING OVERHEAD LATER TODAY AND THE COLD FRONT APPROACHING TONIGHT SHOWERS AND THUNDERSTORMS ARE A GOOD BET. THE STORM PREDICTION CENTER HAS PLACED LOCATIONS ALONG AND NORTH OF THE OHIO RIVER IN A SLIGHT RISK FOR SEVERE STORMS. IT APPEARS HOWEVER TO BE A RATHER MARGINAL SET-UP FOR SEVERE WEATHER. LIFTED INDICES AND SHOWALTER INDEX NUMBERS BOTTOMING OUT AROUND -1 OR -2 THIS AFTERNOON WITH TOTAL TOTALS OF 45 TO 50...WEAK CAPE...AND SHALLOW MID-LEVEL LAPSE RATES SUGGEST THUNDERSTORMS ARE A POSSIBILITY BUT THE CHANCE FOR SEVERE SEEMS SMALL. BEST TIME FOR THUNDERSTORMS WILL BE LATE THIS AFTERNOON AS SHEAR PEAKS. CHANCES SHOULD THEN DIMINISH FURTHER ONCE THE SUN SETS. LOW LEVEL JET DOES CRANK UP THIS AFTERNOON AND THE WET BULB ZERO HEIGHT WILL BE AROUND 9000 FEET SO THE STRONGEST STORMS MAY BE ABLE TO PRODUCE SOME GUSTY WINDS AND HAIL. TEMPERATURES TODAY WILL BE TRICKY. LOUISVILLE WAS STILL 70 DEGREES AT 100 AM BEFORE SHOWERS MOVED IN AND DROPPED THE TEMPERATURE TO 63...WITH MIDDLE 60S REPORTED THROUGHOUT THE REST OF THE FORECAST AREA AS WELL. AS OPPOSED TO YESTERDAY...TODAY WILL HAVE COPIOUS AMOUNTS OF CLOUD COVER. HOWEVER A FEW BREAKS WILL BE POSSIBLE BETWEEN THIS MORNING/S AND THIS AFTERNOON/S SHOWERS. WILL ALLOW READINGS TO CLIMB ABOUT TEN DEGREES...INTO THE MIDDLE 70S. 13 .LONG TERM (THURSDAY THROUGH TUESDAY)... THURSDAY THROUGH FRIDAY NIGHT... THIS PERIOD WILL BE THE MAIN FOCUS OF THE EXTENDED FORECAST AS DECENT COLD FRONT WILL DROP SOUTH AND BRING A PERIOD OF SHOWERS AND STORMS TO THE OHIO VALLEY. 00Z GFS AND NAM-WRF RUNS CONTINUE TO HAVE TIMING DIFFERENCES WITH THE ACTUAL FRONTAL PASSAGE. GFS SOLUTIONS CONTINUE TO BE CONSISTENT WITH PREVIOUS RUNS ON A THURSDAY MORNING FRONTAL PASSAGE WHILE THE NAM-WRF IS SOME 12 HOURS LATER. 21Z SREF SOLUTIONS ARE FAIRLY CONSISTENT WITH THE YESTERDAYS 09Z SOLUTION WHICH IS DOWN THE MIDDLE OF BOTH THE OP GFS AND NAM RUNS. THEREFORE WILL CONTINUE TO LEAN THE TOWARD THIS SOLUTION FOR THE FORECAST. USING THE 21Z SREF SOLUTION SFC FRONTAL BOUNDARY LOOKS TO CROSS THROUGH THE AREA DURING THE DAY ON THURSDAY. EXTENSIVE CLOUDINESS AND SCATTERED PRECIPITATION ARE EXPECTED THURSDAY MORNING AND WILL LIKELY LIMIT SFC BASED INSTABILITY. ADDITIONALLY...LAPSE RATES ARE NOT ALL THAT GREAT AS COOLER AIR ALOFT IS DISPLACED FURTHER NW OF THE AREA. LOW-LEVEL FLOW AHEAD OF THE FRONT STILL LOOKS TO BE IN THE AREA OF 35-40 KTS...THEREFORE SOME GUSTY WINDS WILL BE POSSIBLE WITH ANY CONVECTION THAT CAN GET GOING. HOWEVER...OVERALL THREAT OF ORGANIZED SEVERE APPEARS QUITE DIMINISHED AS OF THIS TIME. BEST FORCING WILL BE ALONG SAID FRONTAL BOUNDARY AND BASED ON 21Z SREF HAVE GONE AHEAD AND BUMPED POPS UP TO THE HIGH END OF THE LIKELY CATEGORY. TEMPERATURES FOR THURSDAY WILL BE A CHALLENGE DUE TO CLOUD COVER AND PRECIPITATION. I HAVE LOWERED TEMPS BY A DEGREE OR TWO WITH LOWER 60S ACROSS SOUTHERN INDIANA AND MID TO UPPER 60S ACROSS CENTRAL AND SOUTHERN KENTUCKY. I ANTICIPATE FALLING TEMPERATURES QUICKLY AFTER FRONTAL PASSAGE. LOWS THURSDAY NIGHT WILL DROP INTO THE UPPER 30S ACROSS SOUTHERN INDIANA AND PORTIONS OF NORTH CENTRAL KY. WARMER READINGS WILL BE FURTHER SOUTH ALONG THE KY/TN BORDER WITH MID TO UPPER 40S. FOR FRIDAY...POST FRONTAL PRECIPITATION WILL CONTINUE TO MOVE EAST AND OUT OF THE AREA. WILL MAINTAIN A SMALL CHANCE OF PRECIPITATION FOR FRIDAY MORNING ACROSS THE EASTERN SECTIONS. MOSTLY CLOUDY SKIES ARE EXPECTED THROUGH MUCH OF THE DAY WITH SOME PARTIAL CLEARING POSSIBLE BY LATE AFTERNOON. CLOUDS WILL KEEP TEMPS DOWN WITH HIGHS ONLY WARMING INTO THE UPPER 40S TO AROUND 50. A RETURN TO COLDER TEMPS IS EXPECTED FRIDAY NIGHT WITH OVERNIGHT LOWS DIPPING INTO THE UPPER 20S TO AROUND 30. SATURDAY THROUGH SUNDAY... MODEL CONSENSUS SOLUTION SUGGESTS DRY CONDITIONS THROUGH THIS PORTION OF THE FORECAST PERIOD. OHIO VALLEY TO REMAIN IN GENERAL NORTHWEST FLOW PATTERN. LAST FEW RUNS OF THE GFS HAVE BEEN SUGGESTING THAT WEAK VORT WITHIN THE FLOW MAY TRIGGER SOME LIGHT PRECIPITATION JUST TO OUR NORTHEAST DURING THE DAY ON SATURDAY. A STRONGER SYSTEM MAY DROP DOWN INTO THE REGION BY SUNDAY BRINGING LIGHT PRECIP. THERMAL PROFILES SUPPORT LIQUID PRECIPITATION AT THIS TIME. FOR NOW WILL HOLD OFF ON MAKING MAJOR ADJUSTMENTS TO THE FORECAST PERIOD AND WAIT TO SEE WHAT THE ENSEMBLES RUNS REVEAL. CURRENT FORECAST TEMPS LOOK OK FOR NOW...WITH HIGHS IN THE MID 40S IN THE NORTHEAST SECTIONS TO THE UPPER 40S AND LOWER 50S ACROSS THE SOUTHWEST. TEMPERATURES FOR SUNDAY MAY NEED TO BE TRENDED DOWN SOME AS 00Z GFS RAW NUMBERS SUPPORT COOLER TEMP TRENDS. -MJ SUNDAY NIGHT THROUGH TUESDAY... NO CHANGES MADE FOR THIS PART OF THE FORECAST PERIOD. PREVIOUS DISCUSSION FOLLOWS... BASING THE LAST TWO DAYS OF THE FCST PRIMARILY ON BLEND OF 0Z NCEP ENS MEAN AND ECMWF...WHICH SHOW UPPER TROF LIFTING NE WITH STRONG SW LOW LEVEL FLOW DEVELOPING OVER THE OHIO VALLEY. THIS WILL HELP TEMPS RISE QUICKLY BACK INTO THE 60S (ABOVE NORMAL) FOR MON AND TUES. A SFC FRONT DEPICTED BY BOTH MODEL SOLNS IS EXPECTED TO DROP S INTO THE OHIO VALLEY SOMETIME LATE MONDAY...PROVIDING A CHANCE FOR SHOWERS...SLIGHT CHANCES MONDAY...BETTER CHANCES INTO TUESDAY. THERE COULD BE SOME THUNDER INVOLVED AS WELL BUT AMT OF INSTABILITY THAT CAN DEVELOP IS QUESTIONABLE AT THIS TIME. CS && .AVIATION (12Z TAFS)... 40 KNOT WINDS SHOWING UP ON VWP AT FORT KNOX AT 2000 FEET AT 10Z. RECENT ACARS SOUNDING SHOWING 35 KNOTS AT THAT LEVEL. AS THE WINDS ALOFT DECREASE A BIT AND SURFACE WINDS INCREASE THE LLWS OVER THE REGION EARLY THIS MORNING WILL DIMINISH. WE WILL HAVE SEVERAL DRY HOURS BEFORE THE NEXT UPPER LEVEL DISTURBANCE COMES IN FROM THE SOUTHWEST AND BRINGS ANOTHER ROUND OF SHOWERS WITH IT. EXPECT SHOWERS AND THUNDERSTORMS NEAR THE TAF SITES LATE THIS AFTERNOON INTO EARLY THIS EVENING. THE BEST CHANCE FOR THUNDER WILL BE AFTER 21Z AND THIS IS REFLECTED IN THE TAFS BY INCLUDING A CB CLOUD TYPE. BEST CHANCES FOR SHOWERY WEATHER WILL BE AT SDF AND LEX AS THOSE LOCATIONS ARE INFLUENCED BY BOTH THE UPPER LEVEL DISTURBANCE AND A SURFACE COLD FRONT THAT WILL BE DROPPING SOUTHWARD INTO THE OHIO VALLEY. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
321 AM EDT TUE MAR 13 2007 .SHORT TERM (TODAY AND TONIGHT)... AN UPPER LOW SWIRLING OVER NORTH TEXAS TODAY WILL SEND A VORT MAX NORTHEAST INTO THE TENNESSEE VALLEY BY AFTERNOON AND ACROSS CENTRAL KENTUCKY OVERNIGHT. AS THIS UPPER SYSTEM AND ITS POOL OF HIGHER ATMOSPHERIC MOISTURE MOVES THROUGH THE AREA SCATTERED SHOWERS CAN BE EXPECTED. THE FIRST FEW ISOLATED SHOWERS SHOULD BREAK OUT OVER FAR WESTERN AND SOUTHWESTERN PORTIONS OF CENTRAL KENTUCKY LATE THIS AFTERNOON. THE BULK OF THE PRECIPITATION HOWEVER WILL TAKE PLACE OVERNIGHT...ESPECIALLY AFTER MIDNIGHT AS A LOW LEVEL JET OF 30 TO 40 KNOTS DEVELOPS AND WE SIT BENEATH THE LEFT EXIT REGION OF A SMALL UPPER JET ASSOCIATED WITH THE AFOREMENTIONED UPPER LOW. A FEW THUNDERSTORMS WILL BE POSSIBLE LATE THIS AFTERNOON AS CAPE INCREASES AND TONIGHT WITH INCREASING JET ENERGY...BUT SHOWERS WILL BE THE MAIN THREAT AS OVERALL INSTABILITY REMAINS SLIGHT. FORECAST HIGHS FOR TODAY IN THE UPPER 70S LOOK GOOD. ACTUALLY WITH ENOUGH SUNSHINE...BRISK SOUTHWEST SURFACE WINDS...AND 850 TEMPS PROGGED TO AROUND 11 DEGREES THIS AFTERNOON...WOULDN/T BE AT ALL SURPRISED TO SEE SOMEONE ATTAIN THEIR FIRST 80 DEGREE DAY OF 2007 TODAY. 13 .LONG TERM (WEDNESDAY THROUGH MONDAY)... MAIN CONCERN IN THE LONGER TERM IS THE SYSTEM THAT WILL BE ACROSS THE AREA WEDNESDAY THROUGH THURSDAY AND FINALLY EXITING THE REGION FRIDAY MORNING. CONCERNS INCLUDE WHEN TO INCLUDE THUNDER...HOW HIGH PROBABILITIES AND TEMPERATURES. WEDNESDAY THROUGH FRIDAY... PRECIPITATION WILL BE ONGOING OVER AT LEAST PART OF THE FORECAST AREA WEDNESDAY MORNING AS MOISTURE IS DRAWN NORTH ON SOUTHWESTERLY BREEZES AROUND HIGH PRESSURE OFF THE ATLANTIC COAST. DEW POINTS WILL BE RISING WELL INTO THE 50S ON WEDNESDAY WHILE POLAR FRONT DROPS SLOWLY SOUTH INTO NORTHERN PARTS OF INDIANA AND OHIO. TIMING AND EVOLUTION OF THIS SYSTEM STILL UNCERTAIN AS SHORT RANGE MODELS CONTINUE TO DIFFER ON THE DETAILS. HOWEVER THE FRONT WILL CONTINUE TO DROP SLOWLY TO THE SOUTH WITH SHOWERS AND THUNDERSTORMS DEVELOPING IN THE WARM AND VERY MOIST AIR SOUTH OF THE FRONT. HIGH CHANCE TO LOW LIKELY PROBABILITIES SEEM BEST AS BOTH NAM AND GFS INDICATE HIGH CHANCE OF SHOWERS. AS FRONT DROPS FARTHER TO THE SOUTH...BETTER CHANCE OF STRONGER THUNDERSTORMS AND THE STORM PREDICTION CENTER HAS SOUTH CENTRAL INDIANA IN A SLIGHT RISK OF SEVERE ON WEDNESDAY AFTERNOON AND NIGHT. CHANCES OF RAIN WILL REMAIN HIGH UNTIL AFTER THE FRONT PUSHES THROUGH WHICH CURRENT INDICATIONS SAY SHOULD BE THURSDAY NIGHT WITH PRECIPITATION ENDING FRIDAY MORNING. TEMPERATURES WILL BE WARM ON WEDNESDAY WITH MORE CLOUDS AND SHOWERS CUTTING TEMPERATURES SOME ON THURSDAY. COOLER AIR WILL SETTLE INTO THE NORTHERN HALF OF THE AREA ON FRIDAY. FRIDAY NIGHT THROUGH MONDAY... HIGH PRESSURE WILL BRING SOME DRYING ON SATURDAY AND SUNDAY WITH ANOTHER PERIOD OF SHOWERS EARLY IN THE WEEK. SCHOLZ .AVIATION (06Z TAFS)... VFR THROUGH THE PERIOD. AC DECK AT LEX WILL CLEAR OUT WITHIN AN HOUR OR SO OF THE BEGINNING OF THE NEW TAF PERIOD SO WILL NOT BOTHER INCLUDING IT. FORT KNOX VWP AND ACARS SOUNDINGS OUT OF LOUISVILLE SINCE 04Z HAVE BEEN INDICATING 30 KNOT SOUTHWEST WINDS AT 2000 FEET...WITH SOUTH WINDS BELOW 10 KNOTS AT THE SURFACE. THUS INCLUDED SOME BORDERLINE WIND SHEAR IN THE TAFS UNTIL 12Z WHEN THE WINDS ALOFT WILL LESSEN. JUST SOME SCATTERED CLOUDS AROUND 5000 TO 7000 FEET EXPECTED FOR THE BULK OF THE DAY. PROBABLY SOME CIRRUS ABOVE THAT. TONIGHT AN UPPER LEVEL DISTURBANCE WILL APPROACH THE TERMINALS FROM THE SOUTHWEST. A FEW SHOWERS MAY BREAK OUT IN THE SDF AND BWG VICINITIES THIS EVENING BUT COVERAGE APPEARS AT THIS TIME TO BE TOO SLIGHT TO WARRANT MENTION IN THE TAFS...ESPECIALLY THAT FAR OUT IN THE FORECAST PERIOD. WILL INCREASE LOW CLOUDS TO CONSTITUTE A CEILING BUT WILL REMAIN VFR. 13 && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
300 AM EDT TUE MAR 13 2007 .SHORT TERM (TODAY AND TONIGHT)... AN UPPER LOW SWIRLING OVER NORTH TEXAS TODAY WILL SEND A VORT MAX NORTHEAST INTO THE TENNESSEE VALLEY BY AFTERNOON AND ACROSS CENTRAL KENTUCKY OVERNIGHT. AS THIS UPPER SYSTEM AND ITS POOL OF HIGHER ATMOSPHERIC MOISTURE MOVES THROUGH THE AREA SCATTERED SHOWERS CAN BE EXPECTED. THE FIRST FEW ISOLATED SHOWERS SHOULD BREAK OUT OVER FAR WESTERN AND SOUTHWESTERN PORTIONS OF CENTRAL KENTUCKY LATE THIS AFTERNOON. THE BULK OF THE PRECIPITATION HOWEVER WILL TAKE PLACE OVERNIGHT...ESPECIALLY AFTER MIDNIGHT AS A LOW LEVEL JET OF 30 TO 40 KNOTS DEVELOPS AND WE SIT BENEATH THE LEFT EXIT REGION OF A SMALL UPPER JET ASSOCIATED WITH THE AFOREMENTIONED UPPER LOW. A FEW THUNDERSTORMS WILL BE POSSIBLE LATE THIS AFTERNOON AS CAPE INCREASES AND TONIGHT WITH INCREASING JET ENERGY...BUT SHOWERS WILL BE THE MAIN THREAT AS OVERALL INSTABILITY REMAINS SLIGHT. FORECAST HIGHS FOR TODAY IN THE UPPER 70S LOOK GOOD. ACTUALLY WITH ENOUGH SUNSHINE...BRISK SOUTHWEST SURFACE WINDS...AND 850 TEMPS PROGGED TO AROUND 11 DEGREES THIS AFTERNOON...WOULDN/T BE AT ALL SURPRISED TO SEE SOMEONE ATTAIN THEIR FIRST 80 DEGREE DAY OF 2007 TODAY. 13 .LONG TERM (WEDNESDAY THROUGH MONDAY)... DISCUSSION OUT SOON. .AVIATION (06Z TAFS)... VFR THROUGH THE PERIOD. AC DECK AT LEX WILL CLEAR OUT WITHIN AN HOUR OR SO OF THE BEGINNING OF THE NEW TAF PERIOD SO WILL NOT BOTHER INCLUDING IT. FORT KNOX VWP AND ACARS SOUNDINGS OUT OF LOUISVILLE SINCE 04Z HAVE BEEN INDICATING 30 KNOT SOUTHWEST WINDS AT 2000 FEET...WITH SOUTH WINDS BELOW 10 KNOTS AT THE SURFACE. THUS INCLUDED SOME BORDERLINE WIND SHEAR IN THE TAFS UNTIL 12Z WHEN THE WINDS ALOFT WILL LESSEN. JUST SOME SCATTERED CLOUDS AROUND 5000 TO 7000 FEET EXPECTED FOR THE BULK OF THE DAY. PROBABLY SOME CIRRUS ABOVE THAT. TONIGHT AN UPPER LEVEL DISTURBANCE WILL APPROACH THE TERMINALS FROM THE SOUTHWEST. A FEW SHOWERS MAY BREAK OUT IN THE SDF AND BWG VICINITIES THIS EVENING BUT COVERAGE APPEARS AT THIS TIME TO BE TOO SLIGHT TO WARRANT MENTION IN THE TAFS...ESPECIALLY THAT FAR OUT IN THE FORECAST PERIOD. WILL INCREASE LOW CLOUDS TO CONSTITUTE A CEILING BUT WILL REMAIN VFR. 13 && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
107 AM EDT TUE MAR 13 2007 .AVIATION (06Z TAFS)... VFR THROUGH THE PERIOD. AC DECK AT LEX WILL CLEAR OUT WITHIN AN HOUR OR SO OF THE BEGINNING OF THE NEW TAF PERIOD SO WILL NOT BOTHER INCLUDING IT. FORT KNOX VWP AND ACARS SOUNDINGS OUT OF LOUISVILLE SINCE 04Z HAVE BEEN INDICATING 30 KNOT SOUTHWEST WINDS AT 2000 FEET...WITH SOUTH WINDS BELOW 10 KNOTS AT THE SURFACE. THUS INCLUDED SOME BORDERLINE WIND SHEAR IN THE TAFS UNTIL 12Z WHEN THE WINDS ALOFT WILL LESSEN. JUST SOME SCATTERED CLOUDS AROUND 5000 TO 7000 FEET EXPECTED FOR THE BULK OF THE DAY. PROBABLY SOME CIRRUS ABOVE THAT. TONIGHT AN UPPER LEVEL DISTURBANCE WILL APPROACH THE TERMINALS FROM THE SOUTHWEST. A FEW SHOWERS MAY BREAK OUT IN THE SDF AND BWG VICINITIES THIS EVENING BUT COVERAGE APPEARS AT THIS TIME TO BE TOO SLIGHT TO WARRANT MENTION IN THE TAFS...ESPECIALLY THAT FAR OUT IN THE FORECAST PERIOD. WILL INCREASE LOW CLOUDS TO CONSTITUTE A CEILING BUT WILL REMAIN VFR. 13 .SHORT TERM (TONIGHT AND TUESDAY)... AREA OF MID/HIGH LEVEL CLOUDS PASSING THROUGH THE CWA ATTM ASSOC WITH WEAK 500MB TROF. ADDITIONAL POCKET OF CLOUDS OVER WRN KY IS FCST BY NAM 800MB RH FIELDS TO TRANSLATE EWD ACROSS THE CWA LATE THIS AFTN INTO THE EVENING HOURS. OVER THE NE 1/2 OF THE CWA...NAM IS SHOWING THAT THESE CLOUDS MAY HANG AROUND UNTIL DAYBREAK TUES... GFS RH PROFILES SHOW SIMILAR SITUATION. OVERALL TONIGHT...SKIES WILL BE CLASSIFIED AS PARTLY CLOUDY...BUT WE WILL HAVE PERIODS OF MOSTLY CLEAR AND MOSTLY CLOUDY SKIES. THESE CLOUDS ALONG WITH INCREASING SW LOW LEVEL FLOW AND WARM ADVECTION WILL HELP KEEP MINS FAIRLY MILD FOR MID MARCH...ALMOST 15 DEGREES ABOVE NORMAL IN SOME LOCATIONS. THAT TREND CONTINUES INTO TUESDAY WHERE WE ARE FORECASTING OUR WARMEST DAY IN SOME TIME. IF MID TO UPPER 70S VERIFIES...THAT WOULD BE THE WARMEST SINCE AROUND NOVEMBER 10TH. THIS WARMING WILL BE HELPED BY CLOUDS LEAVING THE AREA DURING THE MORNING AS MID-LEVEL RIDGING WORKS INTO THE REGION. MAIN FCST DILEMMA FOR TOMORROW IS CHANCE OF PRECIP OVER SRN KY IN THE AFTN HOURS. NAM/GFS BOTH SHOW A WEAK WAVE RIDING NE UP THE RIDGE INTO WRN KY BY LATE TUES...WHICH COULD INCREASE CLOUDS ALONG WITH GENERATING SOME -SHRA TUES AFTN. HAVE INCLUDED A 20% POP OVER SRN KY. THE NAM IS SHOWING SOME MARGINAL SFC BASED INSTABILITY...SO IT`S NOT OUT OF THE QUESTION WE COULD SEE SOME ISLTD -TSRA AS WELL...BUT WILL LEAVE OUT OF THE FCST AT THIS TIME AS NEG LI`S REMAIN W OF THE CWA IN THE NAM SOLN AND GFS IS LESS AMBITIOUS WITH INSTABILITY. CS .LONG TERM (TUESDAY NIGHT THROUGH MONDAY)... TUESDAY NIGHT-SATURDAY... 500MB CUT-OFF LOW OVER TEXAS AND NRN STREAM COLD FRONT/LAGGING TROUGH WILL COMBINE TO BE THE WEATHER MAKERS FOR THIS TIME PERIOD. IN A NUTSHELL...HAVE INCREASED POPS TO LIKELY FOR A MAJORITY OF THIS PERIOD BASED ON NEW MOS GUIDANCE AND GOOD SUPPORT FROM SREF. 12Z SHORT-RANGE MODELS IN BETTER AGREEMENT WITH PRECIP TRENDS. AS UPPER LOW OVER TX MOVES EAST...MODELS PROG THIS TO GENERATE A NEWD PROPAGATING NOCTURNAL MCS. GIVEN WEAK SFC BASED INSTABILITY...COULD PERSIST INTO OUR AREA. FORWARD PROPAGATING CORFIDI VECTORS SHOW THAT THE MCS IF IT HOLDS TOGETHER WOULD MOVE FROM ROUGHLY BWG TO LEX AND THEN HEAD ESE AFTER THAT. NOT SURE IT WILL HOLD TOGETHER THAT LONG...BUT WENT AHEAD AND INCREASED POPS TO 30-40 PERCENT RANGE FOR NOW GIVEN DIFFERENCES IN MOS POP GUIDANCE (MAV SHOWING SLT CHC AND MET SHOWING HIGH CHC-LIKELY). ALSO GIVEN LI`S AROUND ZERO...PUT IN ISLD T-STORM WORDING. AFTER THAT...CONTINUAL SWRLY FLOW WILL PUMP MOISTURE INTO THE REGION ALL DAY WEDNESDAY. SO WITH AFTERNOON HEATING...COULD VERY WELL SEE SHOWERS/ISLD STORMS DEVELOP IN THE WARM SECTOR. HOWEVER WILL LIKELY SEE A BREAK AFTER THE MORNING DYING MCS AND BEFORE ANY LATE AFTERNOON DEVELOPMENT. WILL BUMP UP LATE WEDNESDAY AFTERNOON-EVENING POPS TO HIGH CHC-LIKELY. MOS GUIDANCE CAME IN WITH HIGHER TEMPS WED BUT WILL TREND ON THE COOL SIDE OF THAT JUST IN CASE MCS HOLDS TOGETHER. FRONT WILL SLIDE SEWD TOWARD THE REGION WEDNESDAY NIGHT...BUT NAM AND GFS INDICATE THAT IT SHOULD BE ALIGNED FROM ST. LOUIS TO INDY BY ROUGHLY 12Z THRS...STILL WELL NORTH. THUS WILL CONTINUE 50-60 PERCENT POPS GIVEN CONTINUED MOISTURE POOLING AHEAD OF THE FRONT. FROPA LOOKS TO BE THURSDAY NIGHT IN THE FORM OF A POSSIBLE SQL LINE. THIS FAR OUT...LI`S ARE SLIGHTLY NEGATIVE BUT SHEAR IS NOT THAT IMPRESSIVE. WILL MENTION LIKELY SHWRS/T-STORMS DURING THIS TIME AND WILL TREND TEMPS TOWARD COOLER MOS. BEHIND THE FRONT...LAGGING UPPER TROUGH MOVES SE ACROSS THE GREAT LAKES INTO OHIO LATE FRIDAY NIGHT-SATURDAY NIGHT. THIS ENHANCED NW FLOW COULD GENERATE A FEW RAIN/SNOW SHOWERS ACROSS THE NERN CWA ON SATURDAY. WITH COLD TEMPS ALOFT FROM GFS...PROGGED SOUNDINGS INDICATE STEEP LAPSE RATES SUPPORTIVE OF THE SHOWERS. JUST DEPENDS IF THE GFS VERIFIES OR IF THE MORE FLATTENED AND PREFERRED ECMWF VERIFIES (WHICH WOULD MEAN NO PRECIP). WILL BEEF UP CLOUD COVER FOR NOW...BUT CERTAINLY SOMETHING TO WATCH. SUNDAY-MONDAY... SOME DIFFERENCES IN THE MODELS THIS FAR OUT. SFC HIGH PRESSURE IS PROGGED TO FILTER IN BEHIND THE UPPER TROUGH BY SUNDAY. HOWEVER...WITH AN ACTIVE NW FLOW...A SFC LOW AND ASSOCIATED SHORTWAVE OVER THE NRN PLAINS IS PROGGED TO QUICKLY MOVE SEWD TOWARD THE REGION. 00Z ECMWF IS QUICKER THAN THE GFS WITH THE APPROACH. EVEN SLOWER WITH THE APPROACH ARE THE GFS MODELS WHICH HAS THE MAJORITY OF PRECIP HOLDING OFF UNTIL MONDAY NIGHT. ECMWF...BASED ON MSLP PATTERN...WOULD BRING POPS INTO THE AREA AS EARLY AS SUNDAY NIGHT. ONLY HAVE SLT TO LOW CHC POPS BEGINNING SUNDAY NIGHT LASTING THROUGH TUESDAY NIGHT AS CONFIDENCE IS LOW ON TIMING THIS FAR OUT. TEMPS PROBABLY WILL REBOUND CLOSE TO NORMALS BY MONDAY. AL && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1014 PM EDT WED MAR 14 2007 .UPDATE... WINDS AND POSSIBLE LES ARE THE MAIN FCST ISSUES OVERNIGHT. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW LOW AMPLITUDE FLOW/BROAD TROFFING ACROSS THE CONUS. SHORTWAVE MOVING ACROSS ERN ONTARIO IS SENDING ITS ASSOCIATED COLD FRONT THRU UPPER MI THIS EVENING. HEALTHY SFC PRES RISES UPWARDS OF 9MB/3HR BEHIND FRONT AND AHEAD OF 1031MB SFC HIGH PRES OVER ERN SASKATCHEWAN HAS STRONGLY ASSISTED IN STRENGTHENING WINDS TO AROUND GALE FORCE OVER LAKE SUPERIOR FROM ISLE ROYALE TOWARD STANNARD ROCK THIS EVENING. AN UPDATE WAS DONE VERY EARLY THIS EVENING TO BUMP WINDS/WAVES UP TO ACCOUNT BETTER FOR THE APPROACHING SHARP PRES RISE MAX. INCOMING AIRMASS ASSOCIATED WITH ARCTIC HIGH PRES OVER SASKATCHEWAN IS DRY AS NOTED BY 00Z KINL/CWPL SOUNDINGS AND THE LACK OF CLOUDS N OF LAKE SUPERIOR FROM ONTARIO TO MANITOBA. SFC DWPTS TO THE N AND NW ARE RUNNING GENERALLY FROM -10 TO -15F...AND ONLY A FEW STRATOCU ARE OCCASIONALLY NOTED BY SFC OBS. EXPECT GALE FORCE WINDS OVER ERN LAKE SUPERIOR UNTIL AROUND 06Z. BY THAT TIME...SFC PRES RISE MAX WILL HAVE SHIFTED E OF LAKE SUPERIOR...ENDING THE ISALLOBARIC ASSISTANCE TO THE SFC WIND. AS FOR LES...THERE IS A CONSIDERABLE DIFFERENCE IN THE DEGREE OF COOLING AT 850MB OVER LAKE SUPERIOR. AT ONE EXTREME...THE 18Z GFS BRINGS 850MB TEMPS DOWN TO -18 TO -20C OVER THE E HALF OF LAKE SUPERIOR DURING THE NIGHT. AT THE OTHER EXTREME...THE 18Z NAM ONLY HAS TEMPS LOWERING TO -14 TO -16C. BASED ON UPSTREAM CWPL SOUNDING WHICH SHOWED A DROP IN 850MB TEMPS FROM -12C AT 12Z TO -25C AT 00Z...GFS IS PROBABLY CLOSER TO THE RIGHT TRACK. IN ANYCASE...NO MATTER HOW COLD IT GETS AT 850MB...THE VERY DRY AIRMASS WILL SEVERELY LIMIT LES DEVELOPMENT. LES WILL BE FURTHER LIMITED BY THE LARGE SCALE ANTICYCLONIC FLOW ASSOCIATED WITH SFC HIGH PRES BUILDING ESE TOWARD LAKE SUPERIOR. GIVEN THE NEGATIVES...WILL CUT BACK SOME ON AREAL COVERAGE OF LES...ESPECIALLY OVER NW UPPER MI AS WINDS VEER NE BY 12Z. WILL ALSO DROP MENTION DOWN TO JUST FLURRIES...EXCEPT FOR A SMALL AREA OF NCNTRL UPPER MI AS UPSLOPE AND FETCH LENGTH ACROSS THE LAKE WILL BE MAXIMIZED THERE. POPS WILL STILL BE KEPT IN THE LWR PART OF THE CHC CATEGORY. && .PREV DISCUSSION (ISSUED AT 415 PM EDT)... SHORT TERM (TONIGHT AND THURSDAY)... THE MAIN FCST CONCERNS FOR TONIGHT ARE LOW TEMPS AND LES CLOUD TIMING...AS WELL AS WINDS OVER THE EASTERN LAKE EARLY TONIGHT. AS OF 19Z...MID LEVEL CLOUD DECK IS EXITING THE CWA TO THE EAST AHEAD OF HIGH PRESSURE RIDGE BUILDING FROM CANADA. THESE CLOUDS LOOK LIKE THEY WILL BE OUT THE FA BY 3Z...AT THE SAME TIME LES CLOUDS LOOK TO MOVE IN. DECIDED TO LOWER TEMPS A BIT ACROSS THE CWA...ESPECIALLY THE WEST. THERE APPEARS TO BE A CHANCE THAT ENOUGH CLEARING MAY OCCUR FOR TEMPS TO DROP INTO THE LOWER TEENS IN THE WEST AND UPPER TEENS EAST. ALSO DEWPTS HAVE REALLY DROPPED IN THE PAST FEW HOURS AS NOTED BY 19Z OBS...10 AT SAW...9 AT EGV...12 AT ISQ...DYT WAS DOWN TO 3 BUT HAS SINCE RISEN TO 12. LAKE EFFECT SNOW POTENTIAL REALLY DOESN/T ARRIVE UNTIL AFTER 6Z AS 850 HPA TEMPS COOL TO -10 DEGREE C BY THAT TIME. WINDS ALSO VEER NORTH AS THE NIGHT GOES ON SO SNOW POTENTIAL MAY BE A BIT BETTER ACROSS THE NORTH CENTRAL AREA. HOWEVER...DRY AIR IN PLACE FROM THE SURFACE TO AROUND 650 HPA...PER 18Z SAW TAMDAR...WILL INHIBIT ANY SNOW FROM REACHING THE GROUND...THOUGH CAN/T RULE IT OUT. WINDS WILL INCREASE TEMPORARILY OVER THE LAKE TONIGHT AS A 7-9HPA 3 HR PRES CHNG RISE MOVES NORTH OF THE LAKE BETWEEN 00Z AND 06Z. DID INCLUDE GALE WARNING FOR EAST HALF AFTER TALKING WITH CANADA. WILL BE A SHORT GALE THOUGH AS PRESSURE RISE MOVES BY LAKE BY 06Z. THEREAFTER LITTLE CHANGE WAS MADE TO THE GOING FCST...DID DECIDE TO REMOVE LES SNOW ACROSS NORTHCENTRAL FOR LATE THU AFTERNOON. THE WIND FIELD REALLY FALLS APART AT THIS TIME AND LAKE INDUCED INSTABILITY IS MARGINAL TO BEGIN WITH. HIGH TEMPS FOR THU LOOK REASONABLE. KEPT SLIGHT CHANCE POPS IN FOR LATE THU AFTN ACROSS THE WEST AS INVERTED TROUGH ENTERS FROM WI THU EVENING. LONG TERM (THU NIGHT THROUGH NEXT WED)... THU NIGHT AND FRI...MODELS INDICATE SHORTWAVE FROM THE NRN PLAINS WILL SHEAR OUT AS IT APPROACHES WITH WEAK INVERTED SFC TROF HANGING ALONG THE WI BDR. WOULD EXPECT ANY LIGHT SNOW FROM THIS SYSTEM TO REMAIN ALONG THE WI BDR. WHILE LIGHT NE FLOW COULD STILL BRING IN SOME LES ALONG LAKE SUPERIOR SHORE...MARGINALLY COLD 850 MB TEMPS OF -12C/-13C AND LARGE SCALE ANTICYCLONIC FLOW/LOW INVERSION HGTS WILL ENSURE LES IS VERY LIGHT. THUS...WILL TRIM BACK POPS TO SLIGHT CHC EXCEPT FOR ALONG THE WI BDR. SFC WINDS BECOMING LIGHT AND ERLY BY LATE THU NIGHT WILL ALSO ALLOW FOR MIN TEMPS TO DROP INTO THE SINGLE DIGITS OVER INLAND LOCATIONS. HAVE FOLLOWED A BLEND OF GFS AND NAM MOS FOR FCST MIN TEMPS. FRI NIGHT...WEAK NRLY FLOW AS NOTED BY GFS AND CANADIAN SOLNS ON BACKSIDE OF INVERTED TROF MAY KEEP SOME LIGHT LES AROUND ALONG LAKE SUPERIOR SHORE...BUT AGAIN WITH MARGINALLY COLD 850 MB TEMPS AND ANTICYCLONIC FLOW COVERAGE WILL BE LIMITED. WILL KEEP IN SLIGHT CHC ALONG THE LAKE SUPERIOR BORDERING COUNTIES. SAT INTO SUN...FLOW BACKS S BY SAT AS RDG AXIS SLIDES E OF AREA. LOOK FOR PERIOD OF DRY WX FROM SAT INTO SUN MORNING. SUNDAY AFTERNOON...12Z GFS STILL GENERATES SHOWS SOME LIGHT PCPN AHEAD OF NEXT APPROACHING WAVE FROM CANADA AND NORTH OF ASSOC SFC WARM FRONT. AM A BIT SKEPTICAL ON THIS HAPPENING AS UPSTREAM 12Z SNDGS LOOK FAIRLY DRY OVER CANADA...BUT GIVEN THAT IT CONTINUES PRINT OUT SOME LIGHT QPF WILL KEEP GOING SLIGHT CHC POPS FOR MIXED RAIN/SNOW ALONG THE WI BDR SUN AFTERNOON. FOLLOWED OPERATIONAL GFS/ECMWF WOULD EXPECT LIGHT WAA MIXED PCPN TO SPREAD ACROSS THE REST OF THE FCST AREA SUN NIGHT. TIMING OF COLD FRONT LOOKS MORE CONSISTENT NOW BTWN GFS AND ECMWF AS MODELS BRING FRONT THROUGH THE WRN FCST AREA MON MORNING AND THEN THROUGH THE ERN FCST IN THE AFTERNOON. 850 MB TEMPS OF -2 TO -4C WILL ALLOW TEMPS TO RISE ENOUGH AT SFC FOR MIXED PCPN TO CHANGE TO RAIN BY LATE MON MORNING. AGAIN GIVEN LIMITED MOISTURE AHEAD OF THIS SYSTEM WILL ONLY KEEP LOW CHC POPS IN FCST FOR SUN NIGHT INTO MON. MON NIGHT THROUGH WED...SFC RDG MOVING IN BEHIND FRONT WILL DRY CONDITIONS OUT INTO MIDWEEK. RETURN FLOW ON BACKSIDE OF RDG BY WED ALONG WITH 850 MB TEMPS RISING TO AROUND 5C PER ECMWF SHOULD ALLOW TEMPS TO REBOUND ONCE AGAIN INTO THE 40S OVER THE WRN INTERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... GALE WARNING EAST HALF OF LAKE SUPERIOR. && $$ ROLFSON (UPDATE) PEARSON (SHORT TERM) VOSS (LONG TERM)
AREA FORECAST DISCUSSION
NWS GAYLORD MI
952 PM EDT WED MAR 14 2007 .UPDATE...FGEN-RELATED PRECIP...NOW MOSTLY SNOW...WILL BE EXITING THE SE ZONES IN THE NEXT HOUR OR SO. SURFACE FRONT IS NOW SOUTH OF MI...AND TIGHTEST 850MB THERMAL GRADIENT IS ALSO MOVING DOWNSTATE. PRECIP IS OCCURRING SOUTH OF 700-500MB 2D FGEN MAXIMUM (AS IT SHOULD)...WHICH EXTENDS FROM GRB TO GAYLORD TO ROGERS CITY. THIS FGEN MAX ACCELERATES EASTWARD TONIGHT...AWAY FROM THE REGION. THERE IS EXCELLENT AGREEMENT AMONGST THE SHORT TERM MODELS THAT THIS WILL END PRECIP IN NORTHERN MI...AND RADAR TRENDS SUPPORT THIS. THUS...WILL UPDATE AS PRECIP IS ENDING IN THE SE ZONES TO GO DRY FOR THE REST OF THE NIGHT. CLOUD COVER IS STILL QUITE EXTENSIVE ACROSS THE AREA. SAT TRENDS SUPPORT EASTERN UPPER MI PERHAPS SEEING SOME BREAKS SOON AFTER MIDNIGHT...BUT FURTHER SOUTH CLOUDS WILL LIKELY HOLD FIRM...OUTSIDE OF SOME BREAKS VERY LATE. WITH THIS IN MIND...WILL BOOST MIN TEMPS A BIT IN MANY LOCALES. && .AVIATION...APN/PLN/TVC WILL REMAIN PRECIP-FREE AND VFR...AS HIGH PRESSURE IN MANITOBA BUILDS SE TOWARD SUPERIOR. SKIES WILL REMAIN LARGELY OVERCAST...BUT WITH CIGS RISING TO AT OR ABOVE 10K FEET. MAY BE A BRIEF BREAK IN THE HIGH CLOUDS LATE TONIGHT/EARLY WEDNESDAY... BUT THAT WAS NOT SIGNIFICANT ENOUGH TO INCLUDE IN THE TAFS. PRECIP THAT HAS DEVELOPED IN THE PAST FEW HOURS JUST SOUTH OF TVC/APN...IS MOVING TO THE SE AND WILL CONTINUE TO DO SO...POSING NO THREAT TO TVC/APN. && .PREV DISCUSSION...ISSUED 740 PM WED MAR 14... UPDATE...FGEN ALOFT INTENSIFIED ENOUGH TO OVERCOME THE LOW TO MID LEVEL DRY AIR...WITH PRECIP BREAKING OUT SOUTH OF A LINE FROM TVC TO APN. ALONG MAIN BAND OF PRECIP...RAIN/SNOW/SLEET/GRAUPEL HAVE ALL BEEN REPORTED. MIXED PRECIP IS STEADILY MOVING TO THE SE...IN AGREEMENT WITH MODEL PROGS...AND SHOULD EXIT THE REGION AT OR SOON AFTER MIDNIGHT. BRIEF PERIOD OF MORE INTENSE PRECIP WITHIN THE MAIN BAND (NOW FROM CAD TO OSSINEKE) COULD PRODUCE A HALF INCH OF SNOW/SLEET ACCUMS...ESPECIALLY IN HIGH TERRAIN AREAS. EARLIER UPDATE ACCOUNTED FOR SOME OF THESE TRENDS...WILL FRESHEN GRIDS A BIT BUT DO NOT ANTICIPATE ANOTHER ZFP UPDATE TIL LATER IN THE EVENING. IN ADDITION...RAPID RISE ON RIFLE RIVER AT STERLING...AND INCREASING HIGH WATER REPORTS FROM LAW ENFORCEMENT...PROMPTED A FLOOD WARNING FOR ARENAC EARLIER THIS EVENING. THIS IS A SOMEWHAT FLOOD-PRONE AREA DURING SPRING THAWS. AT THIS POINT DO NOT EXPECT ANY EXTRAORDINARY PROBLEMS...BUT FLOODING IS FLOODING. ZOLTOWSKI LATEST SURFACE MAP PLACES THE FIRST COLD FRONT NOW MOVING ACROSS SOUTHERN LOWER MICHIGAN...WITH A SECONDARY COLD FRONT ON ITS HEELS DROPPING SOUTHWARD INTO UPPER MICHIGAN. NOT MUCH IN THE WAY OF ANY PRECIPITATION ALONG EITHER FRONT AT THE MOMENT. ALL THAT HAS BEEN SEEN ACROSS THE REGION IS MID TO HIGH LEVEL CLOUDINESS WITH CEILINGS AT OR ABOVE 10K FT. ACARS SOUNDINGS SHOW AN ABUNDANCE OF DRY AIR FROM THE SURFACE TO 650MB. THUS...PRECIPITATION CONCERNS HAVE BEEN MINIMAL AT BEST THIS AFTERNOON. FORECAST ISSUES OVER THE NEXT 24 HOURS REVOLVE MAINLY AROUND CLOUD COVER AND TEMPERATURE ISSUES. TONIGHT AND THURSDAY...THE DRY AIR BELOW 650MB WILL HOLD TOUGH OVER THE NEXT 24 HOURS...SO OUTSIDE OF SOME MID LEVEL CLOUDS...THE WEATHER WILL REMAIN TRANQUIL. DEWPOINTS WILL REALLY FALL OFF TONIGHT IN THE WAKE OF THE SECONDARY COLD FRONT...GENERALLY DROPPING INTO THE LOWER TO MIDDLE TEENS. THIS DRIER AIR...AND PARTIAL CLEARING WILL YIELD A MUCH COLDER NIGHT WITH LOWS REACHING THE TEENS TO LOWER 20S. THIS WILL FREEZE UP ANY SLUSHY AREAS OF SNOW TONIGHT. HIGHS ON THURSDAY WILL ONLY RECOVER TO THE UPPER 20S IN EASTERN UPPER...WITH LOWER AND MIDDLE 30S IN NORTHERN LOWER. MOVING ON TO POTENTIAL FLOODING...AFTER MAKING SOME PHONE CALLS DOWN AROUND ARENAC AND GLADWIN COUNTY...WILL MAKE NO CHANGES TO THE FLOOD WATCH AND KEEP IT RUNNING UNTIL 12Z TOMORROW MORNING. AS TEMPERATURES FALL BELOW FREEZING TONIGHT...THE FLOODING THREAT SHOULD GRADUALLY DIMINISH. THE RIFLE RIVER AT STERLING CONTINUES TO RISE AND IS NOW WITHIN A HALF FOOT OF FLOOD STAGE...SO WILL CONTINUE TO MONITOR THAT SITUATION THROUGH THE OVERNIGHT HOURS. KAS REMAINDER OF THE FORECAST (THURSDAY NIGHT THROUGH NEXT WEDNESDAY)...INCREASING RIDGING OUT WEST WILL LEAD TO A MEAN TROUGH BEING CARVED OUT ACROSS THE GREAT LAKES AND EASTERN STATES. THIS WILL RESULT IN CONTINUED COLDER WEATHER INTO THIS WEEKEND WITH MODERATING TEMPERATURES THEN EXPECTED NEXT WEEK. THE MAIN LONG TERM FORECAST CONCERNS REVOLVE AROUND POPS AND TEMPERATURES. THURSDAY NIGHT THROUGH FRIDAY NIGHT...SURFACE HIGH PRESSURE CENTERED ACROSS EASTERN ONTARIO THURSDAY NIGHT WILL SLIDE OFF INTO QUEBEC FRIDAY INTO FRIDAY NIGHT. MEANWHILE...INVERTED SURFACE TROUGH WILL MOVE FROM MINNESOTA INTO WISCONSIN. SHORT TERM MODELS SHEAR THIS FEATURE OUT AS IT MOVES VERY SLOWLY TO THE EAST. MODEL SOUNDINGS/CROSS SECTIONS REMAIN FAIRLY DRY ESPECIALLY AT LOW LEVELS MEAN 900-700 MB RH AROUND 60 PERCENT). THEREFORE...DUE TO THE COMBINATION OF THE WEAKENING SURFACE WAVE AND THE DRY AIR WILL LOWER POPS INTO THE SLIGHT CHANCE CATEGORY. LAKE EFFECT POTENTIAL DURING THIS TIME LOOKS MINIMAL AS WELL WITH A LIGHT NORTHEAST FLOW AND THE LACK OF MOISTURE (NOT TO MENTION THE HIGH MID MARCH SUN DURING THE DAY). GUIDANCE LOWS THURSDAY NIGHT ARE PRETTY COLD (UPPER SINGLE DIGITS AND TEENS) WHICH LOOK GOOD DUE TO LIGHT WINDS AND PARTLY CLOUDY SKIES. HIGHS FRIDAY RANGING FROM AROUND 30 NORTH TO THE MIDDLE 30S SOUTH WITH LOWS FRIDAY NIGHT MAINLY IN THE TEENS. SATURDAY...SURFACE HIGH PRESSURE BUILDS INTO THE AREA FROM THE WEST WHICH SHOULD PROVIDE AT LEAST PARTLY SUNNY CONDITIONS (MEAN 1000-500 MB RH 40 TO 50 PERCENT). AS THE FLOW BACKS INTO THE NORTH AND INCREASES THERE WILL LIKELY BE LAKE CLOUD FORMATION ALONG WITH A CHANCE OF FLURRIES AS OVER LAKE INSTABILITY IS ALRIGHT WITH 850 MB TEMPERATURES AROUND -14C. HIGHS GENERALLY IN THE LOWER AND MIDDLE 30S. SUNDAY...AS SURFACE HIGH PRESSURE MOVES OFF TO THE EAST...WARM ADVECTION WILL INCREASE AS WE GET INTO A MORE SOUTHERLY FLOW AT THE SURFACE. WILL CONTINUE TO KEEP SUNDAY DRY FOR NOW WITH PRECIPITATION EXPECTED TO HOLD OFF UNTIL SUNDAY NIGHT (BUT THIS TIMING MAY TURN OUT TO BE ON THE OPTIMISTIC SIDE). HIGHS IN THE MIDDLE AND UPPER 30S. SUNDAY NIGHT THROUGH WEDNESDAY...EXTENDED MODELS ARE BACKING OFF OF THE SCENARIO OF COLDER AIR WORKING ITS WAY BACK INTO THE REGION NEXT WEEK. WARM ADVECTION LIGHT SNOW IS POSSIBLE SUNDAY NIGHT AND RAIN OR SNOW ON MONDAY AS LOW PRESSURE MOVES BY TO OUR NORTH. A WEAK COLD FRONT WILL THEN MOVE ACROSS THE AREA LATER MONDAY WITH SLIGHTLY COOLER CONDITIONS TUESDAY BEFORE WARMING BACK UP ON WEDNESDAY. A RIDGE OF SURFACE HIGH PRESSURE IS EXPECTED TO LEAD TO NO PRECIPITATION DURING THE TUESDAY AND WEDNESDAY PERIOD. SULLIVAN && .APX WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH THROUGH 8 AM...MIZ041-042. && $$
AREA FORECAST DISCUSSION
NWS GAYLORD MI
740 PM EDT WED MAR 14 2007 .AVIATION...APN/PLN/TVC WILL REMAIN PRECIP-FREE AND VFR...AS HIGH PRESSURE IN MANITOBA BUILDS SE TOWARD SUPERIOR. SKIES WILL REMAIN LARGELY OVERCAST...BUT WITH CIGS RISING TO AT OR ABOVE 10K FEET. MAY BE A BRIEF BREAK IN THE HIGH CLOUDS LATE TONIGHT/EARLY WEDNESDAY... BUT THAT WAS NOT SIGNIFICANT ENOUGH TO INCLUDE IN THE TAFS. PRECIP THAT HAS DEVELOPED IN THE PAST FEW HOURS JUST SOUTH OF TVC/APN...IS MOVING TO THE SE AND WILL CONTINUE TO DO SO...POSING NO THREAT TO TVC/APN. ZOLTOWSKI && .UPDATE...FGEN ALOFT INTENSIFIED ENOUGH TO OVERCOME THE LOW TO MID LEVEL DRY AIR...WITH PRECIP BREAKING OUT SOUTH OF A LINE FROM TVC TO APN. ALONG MAIN BAND OF PRECIP...RAIN/SNOW/SLEET/GRAUPEL HAVE ALL BEEN REPORTED. MIXED PRECIP IS STEADILY MOVING TO THE SE...IN AGREEMENT WITH MODEL PROGS...AND SHOULD EXIT THE REGION AT OR SOON AFTER MIDNIGHT. BRIEF PERIOD OF MORE INTENSE PRECIP WITHIN THE MAIN BAND (NOW FROM CAD TO OSSINEKE) COULD PRODUCE A HALF INCH OF SNOW/SLEET ACCUMS...ESPECIALLY IN HIGH TERRAIN AREAS. EARLIER UPDATE ACCOUNTED FOR SOME OF THESE TRENDS...WILL FRESHEN GRIDS A BIT BUT DO NOT ANTICIPATE ANOTHER ZFP UPDATE TIL LATER IN THE EVENING. IN ADDITION...RAPID RISE ON RIFLE RIVER AT STERLING...AND INCREASING HIGH WATER REPORTS FROM LAW ENFORCEMENT...PROMPTED A FLOOD WARNING FOR ARENAC EARLIER THIS EVENING. THIS IS A SOMEWHAT FLOOD-PRONE AREA DURING SPRING THAWS. AT THIS POINT DO NOT EXPECT ANY EXTRAORDINARY PROBLEMS...BUT FLOODING IS FLOODING. ZOLTOWSKI && .PREV DISCUSSION...ISSUED 355 PM WED MAR 14... LATEST SURFACE MAP PLACES THE FIRST COLD FRONT NOW MOVING ACROSS SOUTHERN LOWER MICHIGAN...WITH A SECONDARY COLD FRONT ON ITS HEELS DROPPING SOUTHWARD INTO UPPER MICHIGAN. NOT MUCH IN THE WAY OF ANY PRECIPITATION ALONG EITHER FRONT AT THE MOMENT. ALL THAT HAS BEEN SEEN ACROSS THE REGION IS MID TO HIGH LEVEL CLOUDINESS WITH CEILINGS AT OR ABOVE 10K FT. ACARS SOUNDINGS SHOW AN ABUNDANCE OF DRY AIR FROM THE SURFACE TO 650MB. THUS...PRECIPITATION CONCERNS HAVE BEEN MINIMAL AT BEST THIS AFTERNOON. FORECAST ISSUES OVER THE NEXT 24 HOURS REVOLVE MAINLY AROUND CLOUD COVER AND TEMPERATURE ISSUES. TONIGHT AND THURSDAY...THE DRY AIR BELOW 650MB WILL HOLD TOUGH OVER THE NEXT 24 HOURS...SO OUTSIDE OF SOME MID LEVEL CLOUDS...THE WEATHER WILL REMAIN TRANQUIL. DEWPOINTS WILL REALLY FALL OFF TONIGHT IN THE WAKE OF THE SECONDARY COLD FRONT...GENERALLY DROPPING INTO THE LOWER TO MIDDLE TEENS. THIS DRIER AIR...AND PARTIAL CLEARING WILL YIELD A MUCH COLDER NIGHT WITH LOWS REACHING THE TEENS TO LOWER 20S. THIS WILL FREEZE UP ANY SLUSHY AREAS OF SNOW TONIGHT. HIGHS ON THURSDAY WILL ONLY RECOVER TO THE UPPER 20S IN EASTERN UPPER...WITH LOWER AND MIDDLE 30S IN NORTHERN LOWER. MOVING ON TO POTENTIAL FLOODING...AFTER MAKING SOME PHONE CALLS DOWN AROUND ARENAC AND GLADWIN COUNTY...WILL MAKE NO CHANGES TO THE FLOOD WATCH AND KEEP IT RUNNING UNTIL 12Z TOMORROW MORNING. AS TEMPERATURES FALL BELOW FREEZING TONIGHT...THE FLOODING THREAT SHOULD GRADUALLY DIMINISH. THE RIFLE RIVER AT STERLING CONTINUES TO RISE AND IS NOW WITHIN A HALF FOOT OF FLOOD STAGE...SO WILL CONTINUE TO MONITOR THAT SITUATION THROUGH THE OVERNIGHT HOURS. KAS REMAINDER OF THE FORECAST (THURSDAY NIGHT THROUGH NEXT WEDNESDAY)...INCREASING RIDGING OUT WEST WILL LEAD TO A MEAN TROUGH BEING CARVED OUT ACROSS THE GREAT LAKES AND EASTERN STATES. THIS WILL RESULT IN CONTINUED COLDER WEATHER INTO THIS WEEKEND WITH MODERATING TEMPERATURES THEN EXPECTED NEXT WEEK. THE MAIN LONG TERM FORECAST CONCERNS REVOLVE AROUND POPS AND TEMPERATURES. THURSDAY NIGHT THROUGH FRIDAY NIGHT...SURFACE HIGH PRESSURE CENTERED ACROSS EASTERN ONTARIO THURSDAY NIGHT WILL SLIDE OFF INTO QUEBEC FRIDAY INTO FRIDAY NIGHT. MEANWHILE...INVERTED SURFACE TROUGH WILL MOVE FROM MINNESOTA INTO WISCONSIN. SHORT TERM MODELS SHEAR THIS FEATURE OUT AS IT MOVES VERY SLOWLY TO THE EAST. MODEL SOUNDINGS/CROSS SECTIONS REMAIN FAIRLY DRY ESPECIALLY AT LOW LEVELS MEAN 900-700 MB RH AROUND 60 PERCENT). THEREFORE...DUE TO THE COMBINATION OF THE WEAKENING SURFACE WAVE AND THE DRY AIR WILL LOWER POPS INTO THE SLIGHT CHANCE CATEGORY. LAKE EFFECT POTENTIAL DURING THIS TIME LOOKS MINIMAL AS WELL WITH A LIGHT NORTHEAST FLOW AND THE LACK OF MOISTURE (NOT TO MENTION THE HIGH MID MARCH SUN DURING THE DAY). GUIDANCE LOWS THURSDAY NIGHT ARE PRETTY COLD (UPPER SINGLE DIGITS AND TEENS) WHICH LOOK GOOD DUE TO LIGHT WINDS AND PARTLY CLOUDY SKIES. HIGHS FRIDAY RANGING FROM AROUND 30 NORTH TO THE MIDDLE 30S SOUTH WITH LOWS FRIDAY NIGHT MAINLY IN THE TEENS. SATURDAY...SURFACE HIGH PRESSURE BUILDS INTO THE AREA FROM THE WEST WHICH SHOULD PROVIDE AT LEAST PARTLY SUNNY CONDITIONS (MEAN 1000-500 MB RH 40 TO 50 PERCENT). AS THE FLOW BACKS INTO THE NORTH AND INCREASES THERE WILL LIKELY BE LAKE CLOUD FORMATION ALONG WITH A CHANCE OF FLURRIES AS OVER LAKE INSTABILITY IS ALRIGHT WITH 850 MB TEMPERATURES AROUND -14C. HIGHS GENERALLY IN THE LOWER AND MIDDLE 30S. SUNDAY...AS SURFACE HIGH PRESSURE MOVES OFF TO THE EAST...WARM ADVECTION WILL INCREASE AS WE GET INTO A MORE SOUTHERLY FLOW AT THE SURFACE. WILL CONTINUE TO KEEP SUNDAY DRY FOR NOW WITH PRECIPITATION EXPECTED TO HOLD OFF UNTIL SUNDAY NIGHT (BUT THIS TIMING MAY TURN OUT TO BE ON THE OPTIMISTIC SIDE). HIGHS IN THE MIDDLE AND UPPER 30S. SUNDAY NIGHT THROUGH WEDNESDAY...EXTENDED MODELS ARE BACKING OFF OF THE SCENARIO OF COLDER AIR WORKING ITS WAY BACK INTO THE REGION NEXT WEEK. WARM ADVECTION LIGHT SNOW IS POSSIBLE SUNDAY NIGHT AND RAIN OR SNOW ON MONDAY AS LOW PRESSURE MOVES BY TO OUR NORTH. A WEAK COLD FRONT WILL THEN MOVE ACROSS THE AREA LATER MONDAY WITH SLIGHTLY COOLER CONDITIONS TUESDAY BEFORE WARMING BACK UP ON WEDNESDAY. A RIDGE OF SURFACE HIGH PRESSURE IS EXPECTED TO LEAD TO NO PRECIPITATION DURING THE TUESDAY AND WEDNESDAY PERIOD. SULLIVAN && .APX WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH THROUGH TONIGHT...MIZ041-042. && $$
AREA FORECAST DISCUSSION...CORRECTED
NWS MARQUETTE MI
415 PM EDT WED MAR 14 2007 .DISCUSSION... .SHORT TERM (TONIGHT AND THURSDAY)... THE MAIN FCST CONCERNS FOR TONIGHT ARE LOW TEMPS AND LES CLOUD TIMING...AS WELL AS WINDS OVER THE EASTERN LAKE EARLY TONIGHT. AS OF 19Z...MID LEVEL CLOUD DECK IS EXITING THE CWA TO THE EAST AHEAD OF HIGH PRESSURE RIDGE BUILDING FROM CANADA. THESE CLOUDS LOOK LIKE THEY WILL BE OUT THE FA BY 3Z...AT THE SAME TIME LES CLOUDS LOOK TO MOVE IN. DECIDED TO LOWER TEMPS A BIT ACROSS THE CWA...ESPECIALLY THE WEST. THERE APPEARS TO BE A CHANCE THAT ENOUGH CLEARING MAY OCCUR FOR TEMPS TO DROP INTO THE LOWER TEENS IN THE WEST AND UPPER TEENS EAST. ALSO DEWPTS HAVE REALLY DROPPED IN THE PAST FEW HOURS AS NOTED BY 19Z OBS...10 AT SAW...9 AT EGV...12 AT ISQ...DYT WAS DOWN TO 3 BUT HAS SINCE RISEN TO 12. LAKE EFFECT SNOW POTENTIAL REALLY DOESN/T ARRIVE UNTIL AFTER 6Z AS 850 HPA TEMPS COOL TO -10 DEGREE C BY THAT TIME. WINDS ALSO VEER NORTH AS THE NIGHT GOES ON SO SNOW POTENTIAL MAY BE A BIT BETTER ACROSS THE NORTH CENTRAL AREA. HOWEVER...DRY AIR IN PLACE FROM THE SURFACE TO AROUND 650 HPA...PER 18Z SAW TAMDAR...WILL INHIBIT ANY SNOW FROM REACHING THE GROUND...THOUGH CAN/T RULE IT OUT. WINDS WILL INCREASE TEMPORARILY OVER THE LAKE TONIGHT AS A 7-9HPA 3 HR PRES CHNG RISE MOVES NORTH OF THE LAKE BETWEEN 00Z AND 06Z. DID INCLUDE GALE WARNING FOR EAST HALF AFTER TALKING WITH CANADA. WILL BE A SHORT GALE THOUGH AS PRESSURE RISE MOVES BY LAKE BY 06Z. THEREAFTER LITTLE CHANGE WAS MADE TO THE GOING FCST...DID DECIDE TO REMOVE LES SNOW ACROSS NORTHCENTRAL FOR LATE THU AFTERNOON. THE WIND FIELD REALLY FALLS APART AT THIS TIME AND LAKE INDUCED INSTABILITY IS MARGINAL TO BEGIN WITH. HIGH TEMPS FOR THU LOOK REASONABLE. KEPT SLIGHT CHANCE POPS IN FOR LATE THU AFTN ACROSS THE WEST AS INVERTED TROUGH ENTERS FROM WI THU EVENING. .LONG TERM (THU NIGHT THROUGH NEXT WED)... THU NIGHT AND FRI...MODELS INDICATE SHORTWAVE FROM THE NRN PLAINS WILL SHEAR OUT AS IT APPROACHES WITH WEAK INVERTED SFC TROF HANGING ALONG THE WI BDR. WOULD EXPECT ANY LIGHT SNOW FROM THIS SYSTEM TO REMAIN ALONG THE WI BDR. WHILE LIGHT NE FLOW COULD STILL BRING IN SOME LES ALONG LAKE SUPERIOR SHORE...MARGINALLY COLD 850 MB TEMPS OF -12C/-13C AND LARGE SCALE ANTICYCLONIC FLOW/LOW INVERSION HGTS WILL ENSURE LES IS VERY LIGHT. THUS...WILL TRIM BACK POPS TO SLIGHT CHC EXCEPT FOR ALONG THE WI BDR. SFC WINDS BECOMING LIGHT AND ERLY BY LATE THU NIGHT WILL ALSO ALLOW FOR MIN TEMPS TO DROP INTO THE SINGLE DIGITS OVER INLAND LOCATIONS. HAVE FOLLOWED A BLEND OF GFS AND NAM MOS FOR FCST MIN TEMPS. FRI NIGHT...WEAK NRLY FLOW AS NOTED BY GFS AND CANADIAN SOLNS ON BACKSIDE OF INVERTED TROF MAY KEEP SOME LIGHT LES AROUND ALONG LAKE SUPERIOR SHORE...BUT AGAIN WITH MARGINALLY COLD 850 MB TEMPS AND ANTICYCLONIC FLOW COVERAGE WILL BE LIMITED. WILL KEEP IN SLIGHT CHC ALONG THE LAKE SUPERIOR BORDERING COUNTIES. SAT INTO SUN...FLOW BACKS S BY SAT AS RDG AXIS SLIDES E OF AREA. LOOK FOR PERIOD OF DRY WX FROM SAT INTO SUN MORNING. SUNDAY AFTERNOON...12Z GFS STILL GENERATES SHOWS SOME LIGHT PCPN AHEAD OF NEXT APPROACHING WAVE FROM CANADA AND NORTH OF ASSOC SFC WARM FRONT. AM A BIT SKEPTICAL ON THIS HAPPENING AS UPSTREAM 12Z SNDGS LOOK FAIRLY DRY OVER CANADA...BUT GIVEN THAT IT CONTINUES PRINT OUT SOME LIGHT QPF WILL KEEP GOING SLIGHT CHC POPS FOR MIXED RAIN/SNOW ALONG THE WI BDR SUN AFTERNOON. FOLLOWED OPERATIONAL GFS/ECMWF WOULD EXPECT LIGHT WAA MIXED PCPN TO SPREAD ACROSS THE REST OF THE FCST AREA SUN NIGHT. TIMING OF COLD FRONT LOOKS MORE CONSISTENT NOW BTWN GFS AND ECMWF AS MODELS BRING FRONT THROUGH THE WRN FCST AREA MON MORNING AND THEN THROUGH THE ERN FCST IN THE AFTERNOON. 850 MB TEMPS OF -2 TO -4C WILL ALLOW TEMPS TO RISE ENOUGH AT SFC FOR MIXED PCPN TO CHANGE TO RAIN BY LATE MON MORNING. AGAIN GIVEN LIMITED MOISTURE AHEAD OF THIS SYSTEM WILL ONLY KEEP LOW CHC POPS IN FCST FOR SUN NIGHT INTO MON. MON NIGHT THROUGH WED...SFC RDG MOVING IN BEHIND FRONT WILL DRY CONDITIONS OUT INTO MIDWEEK. RETURN FLOW ON BACKSIDE OF RDG BY WED ALONG WITH 850 MB TEMPS RISING TO AROUND 5C PER ECMWF SHOULD ALLOW TEMPS TO REBOUND ONCE AGAIN INTO THE 40S OVER THE WRN INTERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... GALE WARNING EAST HALF OF LAKE SUPERIOR. && $$ VOSS
AREA FORECAST DISCUSSION
NWS GAYLORD MI
355 PM EDT WED MAR 14 2007 .DISCUSSION...LATEST SURFACE MAP PLACES THE FIRST COLD FRONT NOW MOVING ACROSS SOUTHERN LOWER MICHIGAN...WITH A SECONDARY COLD FRONT ON ITS HEELS DROPPING SOUTHWARD INTO UPPER MICHIGAN. NOT MUCH IN THE WAY OF ANY PRECIPITATION ALONG EITHER FRONT AT THE MOMENT. ALL THAT HAS BEEN SEEN ACROSS THE REGION IS MID TO HIGH LEVEL CLOUDINESS WITH CEILINGS AT OR ABOVE 10K FT. ACARS SOUNDINGS SHOW AN ABUNDANCE OF DRY AIR FROM THE SURFACE TO 650MB. THUS...PRECIPITATION CONCERNS HAVE BEEN MINIMAL AT BEST THIS AFTERNOON. FORECAST ISSUES OVER THE NEXT 24 HOURS REVOLVE MAINLY AROUND CLOUD COVER AND TEMPERATURE ISSUES. TONIGHT AND THURSDAY...THE DRY AIR BELOW 650MB WILL HOLD TOUGH OVER THE NEXT 24 HOURS...SO OUTSIDE OF SOME MID LEVEL CLOUDS...THE WEATHER WILL REMAIN TRANQUIL. DEWPOINTS WILL REALLY FALL OFF TONIGHT IN THE WAKE OF THE SECONDARY COLD FRONT...GENERALLY DROPPING INTO THE LOWER TO MIDDLE TEENS. THIS DRIER AIR...AND PARTIAL CLEARING WILL YIELD A MUCH COLDER NIGHT WITH LOWS REACHING THE TEENS TO LOWER 20S. THIS WILL FREEZE UP ANY SLUSHY AREAS OF SNOW TONIGHT. HIGHS ON THURSDAY WILL ONLY RECOVER TO THE UPPER 20S IN EASTERN UPPER...WITH LOWER AND MIDDLE 30S IN NORTHERN LOWER. MOVING ON TO POTENTIAL FLOODING...AFTER MAKING SOME PHONE CALLS DOWN AROUND ARENAC AND GLADWIN COUNTY...WILL MAKE NO CHANGES TO THE FLOOD WATCH AND KEEP IT RUNNING UNTIL 12Z TOMORROW MORNING. AS TEMPERATURES FALL BELOW FREEZING TONIGHT...THE FLOODING THREAT SHOULD GRADUALLY DIMINISH. THE RIFLE RIVER AT STERLING CONTINUES TO RISE AND IS NOW WITHIN A HALF FOOT OF FLOOD STAGE...SO WILL CONTINUE TO MONITOR THAT SITUATION THROUGH THE OVERNIGHT HOURS. KAS REMAINDER OF THE FORECAST (THURSDAY NIGHT THROUGH NEXT WEDNESDAY)...INCREASING RIDGING OUT WEST WILL LEAD TO A MEAN TROUGH BEING CARVED OUT ACROSS THE GREAT LAKES AND EASTERN STATES. THIS WILL RESULT IN CONTINUED COLDER WEATHER INTO THIS WEEKEND WITH MODERATING TEMPERATURES THEN EXPECTED NEXT WEEK. THE MAIN LONG TERM FORECAST CONCERNS REVOLVE AROUND POPS AND TEMPERATURES. THURSDAY NIGHT THROUGH FRIDAY NIGHT...SURFACE HIGH PRESSURE CENTERED ACROSS EASTERN ONTARIO THURSDAY NIGHT WILL SLIDE OFF INTO QUEBEC FRIDAY INTO FRIDAY NIGHT. MEANWHILE...INVERTED SURFACE TROUGH WILL MOVE FROM MINNESOTA INTO WISCONSIN. SHORT TERM MODELS SHEAR THIS FEATURE OUT AS IT MOVES VERY SLOWLY TO THE EAST. MODEL SOUNDINGS/CROSS SECTIONS REMAIN FAIRLY DRY ESPECIALLY AT LOW LEVELS MEAN 900-700 MB RH AROUND 60 PERCENT). THEREFORE...DUE TO THE COMBINATION OF THE WEAKENING SURFACE WAVE AND THE DRY AIR WILL LOWER POPS INTO THE SLIGHT CHANCE CATEGORY. LAKE EFFECT POTENTIAL DURING THIS TIME LOOKS MINIMAL AS WELL WITH A LIGHT NORTHEAST FLOW AND THE LACK OF MOISTURE (NOT TO MENTION THE HIGH MID MARCH SUN DURING THE DAY). GUIDANCE LOWS THURSDAY NIGHT ARE PRETTY COLD (UPPER SINGLE DIGITS AND TEENS) WHICH LOOK GOOD DUE TO LIGHT WINDS AND PARTLY CLOUDY SKIES. HIGHS FRIDAY RANGING FROM AROUND 30 NORTH TO THE MIDDLE 30S SOUTH WITH LOWS FRIDAY NIGHT MAINLY IN THE TEENS. SATURDAY...SURFACE HIGH PRESSURE BUILDS INTO THE AREA FROM THE WEST WHICH SHOULD PROVIDE AT LEAST PARTLY SUNNY CONDITIONS (MEAN 1000-500 MB RH 40 TO 50 PERCENT). AS THE FLOW BACKS INTO THE NORTH AND INCREASES THERE WILL LIKELY BE LAKE CLOUD FORMATION ALONG WITH A CHANCE OF FLURRIES AS OVER LAKE INSTABILITY IS ALRIGHT WITH 850 MB TEMPERATURES AROUND -14C. HIGHS GENERALLY IN THE LOWER AND MIDDLE 30S. SUNDAY...AS SURFACE HIGH PRESSURE MOVES OFF TO THE EAST...WARM ADVECTION WILL INCREASE AS WE GET INTO A MORE SOUTHERLY FLOW AT THE SURFACE. WILL CONTINUE TO KEEP SUNDAY DRY FOR NOW WITH PRECIPITATION EXPECTED TO HOLD OFF UNTIL SUNDAY NIGHT (BUT THIS TIMING MAY TURN OUT TO BE ON THE OPTIMISTIC SIDE). HIGHS IN THE MIDDLE AND UPPER 30S. SUNDAY NIGHT THROUGH WEDNESDAY...EXTENDED MODELS ARE BACKING OFF OF THE SCENARIO OF COLDER AIR WORKING ITS WAY BACK INTO THE REGION NEXT WEEK. WARM ADVECTION LIGHT SNOW IS POSSIBLE SUNDAY NIGHT AND RAIN OR SNOW ON MONDAY AS LOW PRESSURE MOVES BY TO OUR NORTH. A WEAK COLD FRONT WILL THEN MOVE ACROSS THE AREA LATER MONDAY WITH SLIGHTLY COOLER CONDITIONS TUESDAY BEFORE WARMING BACK UP ON WEDNESDAY. A RIDGE OF SURFACE HIGH PRESSURE IS EXPECTED TO LEAD TO NO PRECIPITATION DURING THE TUESDAY AND WEDNESDAY PERIOD. SULLIVAN && .AVIATION...ISSUED AT 125 PM A COLD FRONT WILL CONTINUE TO MOVE SOUTH ACROSS SOUTHERN MICHIGAN FOR THE REST OF THE DAY...BUT ABUNDANT MID-LEVEL MOISTURE BEHIND THE FRONT WILL KEEP A BKN-OVC100 DECK PRESENT INTO TOMORROW. HAVE NOT SEEN A SURFACE OBS INDICATING THAT THE LIGHT PRECIPITATION ON RADAR HAS BEEN REACHING THE GROUND ACROSS NORTHERN WISCONSIN AND UPPER MICHIGAN OVER THE COURSE OF THE MORNING. DRY AIR ASSOCIATED WITH A SURFACE HIGH OVER THE NORTHERN PLAINS WILL NUDGE IN TONIGHT ENSURING A FRESH SUPPLY OF DRY AIR TO PREVENT ANY PRECIP FROM REACHING THE GROUND. WILL THEREFORE KEEP PRECIP OUT OF THE TAFS LEAVING VFR CONDITIONS PRESENT THROUGH TOMORROW. MPC && .APX WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH THROUGH TONIGHT...MIZ041-042. && $$
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
240 AM PDT THU MAR 15 2007 .SHORT TERM... WELL ESTABLISHED MARINE LAYER SOUTH OF POINT CONCEPTION. LOW CLOUDS HAVE FORMED OVER THE LAND ALONG THE CENTRAL COAST BUT THE SEAS REMAIN CLEAR. 0800Z ACARS SHOWS A 1400 FOOT MARINE LAYER BUT THE CLOUDS ARE HAVE A DIFFICULT TIME MOVING INTO THE VLYS PROBABLY DUE TO GOOD OFFSHORE TRENDS BOTH N/S AND E/W. STILL SOME PATCHY CLOUDS WILL GET INTO THE VLYS BY SUNRISE. FLOW WILL TURN OFFSHORE TONIGHT AND THIS WILL LIMIT THE MARINE CLOUDS TO PATCHY AT THE COASTS. IT IS A WEAK OFFSHORE EVENT AND NOT MUCH WINDS. FRIDAY WILL BE NICE. MOSTLY SUNNY AND TEMPS WILL JUMP 3 OR 4 DEGREES WITH THE OFFSHORE FLOW. ALL THE MODELS INDICATE A BETTER MARINE LAYER FOR FRIDAY NIGHT AND SATURDAY. ALTHOUGH IT IS NOT READILY APPARENT WHY. MAYBE A LITTLE EDDY SPUN UP BY STRONG WINDS IN THE OUTER WATERS. KEPT THE MARINE CLOUDS IN THE FORECAST BUT AM NOT ENTIRELY CONFIDENT THEY WILL APPEAR. OTHERWISE SATURDAY WILL BE SUNNY AND A LITTLE COOLER WITH ONSHORE TRENDS AND LOW HGTS ABOVE. .LONG TERM... DRY UPPER TROF GOES OVERHEAD SUNDAY ALONG WITH A GOOD RETURN TO ONSHORE FLOW AND THIS SHOULD PRODUCE A BEEFIER MARINE LAYER ALONG WITH A GOOD REDUCTION IN TEMPERATURES. PARTLY CLOUDY SKIES MONDAY AS A TROF APPROACHES. STRENGTHENING ONSHORE FLOW WILL KEPT THE MARINE LAYER IN PLACE. MORE COOLING AS WELL AS HGTS CONTINUE TO FALL ALONG WITH THE COOL MARINE AIR. TUESDAY`S SYSTEM IS LOOKING WEAKER AND WEAKER. DO NOT SEE RAIN WITH THIS SYSTEM AT THIS TIME. COOLER AND PARTLY CLOUDY. PERHAPS A LITTLE BREEZY ALONG THE CENTRAL COAST. CONTINUED PARTLY CLOUDY BREEZY AND COOL ON WEDNESDAY AS THE TROF MOVES ALONG. THE ONE FLY IN THE OINTMENT IS EC SOLN WHICH IS SLOWER AND DEEPER AND MIGHT MAKE WEDNESDAY A RAINY DAY. WILL KEEP THIS IN THE BACK OF MY MIND FOR TOMORROWS SHIFT AND WILL SEE IF ONE MDL TRENDS TO THE OTHER. && .AVIATION... 15/1000Z S OF POINT CONCEPTION...MARINE LAYER NEAR 1500 DEEP. SOUTHERN AIRFIELDS KLAX...KLGB ARE LOW MVFR CATEGORY THIS MORNING...WHILE AIRFIELDS KOXR AND KSBA CONTINUE IN IFR CIG CATEGORY. LOW CLOUDS SHOULD BURNOFF A BIT SOONER THIS MORNING AS SFC GRADIENTS NOT FORECAST TO BE QUITE AS STRONG AS YESTERDAY. ALTHOUGH NOT EXPECTING WIDESPREAD FOG IN LA/VTU VALLEYS THIS MORNING...THERE COULD BE SOME PATCHY DENSE FOG NEAR KBUR AND KVNY BEFORE DAWN...BUT SHOULD BE SHORT LIVED WITH BURNOFF BY 17Z. N OF POINT CONCEPTION...LOOKS LIKE ONLY STRATUS ISSUES WILL BE AT KSMX AND KSBP THIS MORNING WITH IFR VSBYS AND CIGS EARLY. EXPECTING EARLY MORNING BURNOFF BY 17Z. AT THIS POINT...KPRB SHOULD REMAIN CLEAR. LARGE DEWPOINT DEPRESSION INDICATES NOT AS MOIST AND SATELLITE IMAGERY SHOWS NOTHING TO THE NORTH ADVECTING S THROUGH THE SALINAS VALLEY THIS MORNING. KLAX...EXPECT LOW MVFR CATEGORY TO LOC IFR CIGS WITH MVFR VSBYS THROUGH 18Z. WEAKER ONSHORE SFC GRADIENTS SHOULD LEAD TO A QUICKER BURNOFF THEN YESTERDAY. EXPECT VRB WINDS 6 KT OR LESS BECOMING SW TO W WIND 8 TO 12 KT BY 18-19Z. MVFR VSBYS SHOULD BECOME VFR BY 21Z TODAY. && .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXCWFLOX). && $$ PUBLIC...RORKE AVIATION...KAPLAN WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
500 AM EDT THU MAR 15 2007 .DISCUSSION... MAIN FCST CONCERNS ARE LES TRENDS TODAY AND SNOW POTENTIAL WITH CLIPPER SHRTWV LATE TODAY INTO FRI. WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD FLAT TROF OVER THE NRN CONUS. ONE SHRTWV...THAT BROUGHT THE ARCTIC FRONT THROUGH THE AREA...WAS DEPARTING E OF LAKE SUPERIOR WHILE A VIGOROUS UPSTREAM SHRTWV WAS LOCATED OVER SE SASK/ NW ND. OCNL LIGHTNING NOTED WITH THIS FEATURES OVER SRN SASK WAS ASSOCIATED WITH STEEP MID LEVEL LAPSE RATES (700-500 MB LAPSE RATE OF 8.0-8.5 C/KM). RADAR INDICATED THAT THE LES INTO N CNTRL UPPER MI HAD DIMINISHED SINCE 05Z AS BEST LOW LVL CONV WITH THE FRONT MOVED THROUGH. HOWEVER...IR LOOP SHOWED INCREASE IN MULTIPLE WIND PARALLEL BANDS OVER CNTRL LK SUPERIOR. 900-850 MB TEMPS TO AROUND -15C PROVIDED SUFFICIENT INSTABILITY FOR -SHSN BUT VERY DRY AIR UPSTREAM(SFC-850 DEWPOINT DEPRESSION OF 15 TO 20 F NOTED ON CYQT TAMDAR SNDG) WAS UNFAVORABLE FOR MORE THAN LIGHT LES. TODAY...EXPECT THE LIGHT LES...MAINLY OVER N CNTRL UPPER MI...TO GRADUALLY DIMINISH TODAY AS THE SFC RDG BUILDS INTO THE AREA WITH CONTINUE DRY ADVECTION AND LOW LVL DIVERGENT ACYC FLOW. SNOW SHOWERS ASSOCIATED WITH 700-500 QVECTOR CONV WITH THE CLIPPER SHRTWV MAY ALSO MOVE INTO THE WEST BY LATE AFTERNOON. THE ERLY FLOW THIS AFTERNOON COULD BRING SOME LIGHT LES INTO THE KEWEENAW. TONIGHT INTO FRI...THE NAM AND REGIONAL CANADIAN MDLS FOCUS THE BEST QVECTOR CONV JUST TO THE WEST AND SOUTH OF UPPER MI AS THE SHRTWV MOVES THROUGH. HOWEVER...THE MODERATE TO STRONG DYNAMICS COMBINED WITH THE FCST OF CONTINUED STEEP MID LVL LAPSE RATES INTO THE AREA WARRANT MENTION OF CHANCE POPS INTO THE WEST THIS EVENING SPREADING INTO CNTRL UPPER MI OVERNIGHT INTO FRI MORNING. FRI NIGHT INTO SAT...WITH WEAK NRLY FLOW...THE MID LVL TROF AXIS STILL OVER OR JUST EAST OF THE AREA...850 MB MDL CONSENSUS TEMPS AROUND -13C...AND THE POTENTIAL FOR ADDITIONAL WEAK SHRTWVS TO SLIDE IN FROM THE NW...SOME LIGHT SNOW SHOWERS OR FLURRIES WILL STILL BE POSSIBLE OVER NORTH UPPER MI. SUN AND MON...ALTHOUGH THE 00Z GFS SEEMS TO BE A FAST OUTLIER...PER HPC...WITH THE NEXT STRONG SHRTWV MOVING TOWARD THE UPPER GREAT LAKES...THE 00Z ECMWF AND GLBL CANADIAN SUGGEST THAT LIGHT SNOW COULD MOVE IN LATE SUN AND TRANSITION TO SNOW SHOWERS MONDAY AS THE COLD FRONT MOVES THROUGH. TEMPS FROM THE 12Z/00Z ECMWF STILL LOOK WARM ENOUGH FOR THE POTENTIAL OF SOME RAIN EARLY MON OVER THE SOUTH BEFORE THE COLDER AIR MOVES LATE IN THE DAY. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ JLB
AREA FORECAST DISCUSSION
NWS GAYLORD MI
128 AM EDT THU MAR 15 2007 .AVIATION...VFR CONDITIONS WILL PREVAIL AS HIGH PRESSURE PASSES JUST NORTH OF LAKE SUPERIOR OVERNIGHT THROUGH THURSDAY. MID AND HIGH CLOUDS WILL CONTINUE TO IMPACT THE AREA...THANKS TO A FRONTAL ZONE NOW SOUTH OF THE STATE...AND A CLIPPER SYSTEM ADVANCING ACROSS THE NORTHERN PLAINS. JZ && .UPDATE...ISSUED AT 952 PM. FGEN-RELATED PRECIP...NOW MOSTLY SNOW...WILL BE EXITING THE SE ZONES IN THE NEXT HOUR OR SO. SURFACE FRONT IS NOW SOUTH OF MI...AND TIGHTEST 850MB THERMAL GRADIENT IS ALSO MOVING DOWNSTATE. PRECIP IS OCCURRING SOUTH OF 700-500MB 2D FGEN MAXIMUM (AS IT SHOULD)...WHICH EXTENDS FROM GRB TO GAYLORD TO ROGERS CITY. THIS FGEN MAX ACCELERATES EASTWARD TONIGHT...AWAY FROM THE REGION. THERE IS EXCELLENT AGREEMENT AMONGST THE SHORT TERM MODELS THAT THIS WILL END PRECIP IN NORTHERN MI...AND RADAR TRENDS SUPPORT THIS. THUS...WILL UPDATE AS PRECIP IS ENDING IN THE SE ZONES TO GO DRY FOR THE REST OF THE NIGHT. CLOUD COVER IS STILL QUITE EXTENSIVE ACROSS THE AREA. SAT TRENDS SUPPORT EASTERN UPPER MI PERHAPS SEEING SOME BREAKS SOON AFTER MIDNIGHT...BUT FURTHER SOUTH CLOUDS WILL LIKELY HOLD FIRM...OUTSIDE OF SOME BREAKS VERY LATE. WITH THIS IN MIND...WILL BOOST MIN TEMPS A BIT IN MANY LOCALES. && .UPDATE...ISSUED AT 740 PM. FGEN ALOFT INTENSIFIED ENOUGH TO OVERCOME THE LOW TO MID LEVEL DRY AIR...WITH PRECIP BREAKING OUT SOUTH OF A LINE FROM TVC TO APN. ALONG MAIN BAND OF PRECIP... RAIN/SNOW/ SLEET/GRAUPEL HAVE ALL BEEN REPORTED. MIXED PRECIP IS STEADILY MOVING TO THE SE...IN AGREEMENT WITH MODEL PROGS...AND SHOULD EXIT THE REGION AT OR SOON AFTER MIDNIGHT. BRIEF PERIOD OF MORE INTENSE PRECIP WITHIN THE MAIN BAND (NOW FROM CAD TO OSSINEKE) COULD PRODUCE A HALF INCH OF SNOW/SLEET ACCUMS...ESPECIALLY IN HIGH TERRAIN AREAS. EARLIER UPDATE ACCOUNTED FOR SOME OF THESE TRENDS...WILL FRESHEN GRIDS A BIT BUT DO NOT ANTICIPATE ANOTHER ZFP UPDATE TIL LATER IN THE EVENING. IN ADDITION...RAPID RISE ON RIFLE RIVER AT STERLING...AND INCREASING HIGH WATER REPORTS FROM LAW ENFORCEMENT...PROMPTED A FLOOD WARNING FOR ARENAC EARLIER THIS EVENING. THIS IS A SOMEWHAT FLOOD-PRONE AREA DURING SPRING THAWS. AT THIS POINT DO NOT EXPECT ANY EXTRAORDINARY PROBLEMS...BUT FLOODING IS FLOODING. ZOLTOWSKI && .PREV DISCUSSION...ISSUED AT 355 PM. LATEST SURFACE MAP PLACES THE FIRST COLD FRONT NOW MOVING ACROSS SOUTHERN LOWER MICHIGAN...WITH A SECONDARY COLD FRONT ON ITS HEELS DROPPING SOUTHWARD INTO UPPER MICHIGAN. NOT MUCH IN THE WAY OF ANY PRECIPITATION ALONG EITHER FRONT AT THE MOMENT. ALL THAT HAS BEEN SEEN ACROSS THE REGION IS MID TO HIGH LEVEL CLOUDINESS WITH CEILINGS AT OR ABOVE 10K FT. ACARS SOUNDINGS SHOW AN ABUNDANCE OF DRY AIR FROM THE SURFACE TO 650MB. THUS...PRECIPITATION CONCERNS HAVE BEEN MINIMAL AT BEST THIS AFTERNOON. FORECAST ISSUES OVER THE NEXT 24 HOURS REVOLVE MAINLY AROUND CLOUD COVER AND TEMPERATURE ISSUES. TONIGHT AND THURSDAY...THE DRY AIR BELOW 650MB WILL HOLD TOUGH OVER THE NEXT 24 HOURS...SO OUTSIDE OF SOME MID LEVEL CLOUDS...THE WEATHER WILL REMAIN TRANQUIL. DEWPOINTS WILL REALLY FALL OFF TONIGHT IN THE WAKE OF THE SECONDARY COLD FRONT...GENERALLY DROPPING INTO THE LOWER TO MIDDLE TEENS. THIS DRIER AIR...AND PARTIAL CLEARING WILL YIELD A MUCH COLDER NIGHT WITH LOWS REACHING THE TEENS TO LOWER 20S. THIS WILL FREEZE UP ANY SLUSHY AREAS OF SNOW TONIGHT. HIGHS ON THURSDAY WILL ONLY RECOVER TO THE UPPER 20S IN EASTERN UPPER...WITH LOWER AND MIDDLE 30S IN NORTHERN LOWER. MOVING ON TO POTENTIAL FLOODING...AFTER MAKING SOME PHONE CALLS DOWN AROUND ARENAC AND GLADWIN COUNTY...WILL MAKE NO CHANGES TO THE FLOOD WATCH AND KEEP IT RUNNING UNTIL 12Z TOMORROW MORNING. AS TEMPERATURES FALL BELOW FREEZING TONIGHT...THE FLOODING THREAT SHOULD GRADUALLY DIMINISH. THE RIFLE RIVER AT STERLING CONTINUES TO RISE AND IS NOW WITHIN A HALF FOOT OF FLOOD STAGE...SO WILL CONTINUE TO MONITOR THAT SITUATION THROUGH THE OVERNIGHT HOURS. KAS REMAINDER OF THE FORECAST (THURSDAY NIGHT THROUGH NEXT WEDNESDAY)...INCREASING RIDGING OUT WEST WILL LEAD TO A MEAN TROUGH BEING CARVED OUT ACROSS THE GREAT LAKES AND EASTERN STATES. THIS WILL RESULT IN CONTINUED COLDER WEATHER INTO THIS WEEKEND WITH MODERATING TEMPERATURES THEN EXPECTED NEXT WEEK. THE MAIN LONG TERM FORECAST CONCERNS REVOLVE AROUND POPS AND TEMPERATURES. THURSDAY NIGHT THROUGH FRIDAY NIGHT...SURFACE HIGH PRESSURE CENTERED ACROSS EASTERN ONTARIO THURSDAY NIGHT WILL SLIDE OFF INTO QUEBEC FRIDAY INTO FRIDAY NIGHT. MEANWHILE...INVERTED SURFACE TROUGH WILL MOVE FROM MINNESOTA INTO WISCONSIN. SHORT TERM MODELS SHEAR THIS FEATURE OUT AS IT MOVES VERY SLOWLY TO THE EAST. MODEL SOUNDINGS/CROSS SECTIONS REMAIN FAIRLY DRY ESPECIALLY AT LOW LEVELS MEAN 900-700 MB RH AROUND 60 PERCENT). THEREFORE...DUE TO THE COMBINATION OF THE WEAKENING SURFACE WAVE AND THE DRY AIR WILL LOWER POPS INTO THE SLIGHT CHANCE CATEGORY. LAKE EFFECT POTENTIAL DURING THIS TIME LOOKS MINIMAL AS WELL WITH A LIGHT NORTHEAST FLOW AND THE LACK OF MOISTURE (NOT TO MENTION THE HIGH MID MARCH SUN DURING THE DAY). GUIDANCE LOWS THURSDAY NIGHT ARE PRETTY COLD (UPPER SINGLE DIGITS AND TEENS) WHICH LOOK GOOD DUE TO LIGHT WINDS AND PARTLY CLOUDY SKIES. HIGHS FRIDAY RANGING FROM AROUND 30 NORTH TO THE MIDDLE 30S SOUTH WITH LOWS FRIDAY NIGHT MAINLY IN THE TEENS. SATURDAY...SURFACE HIGH PRESSURE BUILDS INTO THE AREA FROM THE WEST WHICH SHOULD PROVIDE AT LEAST PARTLY SUNNY CONDITIONS (MEAN 1000-500 MB RH 40 TO 50 PERCENT). AS THE FLOW BACKS INTO THE NORTH AND INCREASES THERE WILL LIKELY BE LAKE CLOUD FORMATION ALONG WITH A CHANCE OF FLURRIES AS OVER LAKE INSTABILITY IS ALRIGHT WITH 850 MB TEMPERATURES AROUND -14C. HIGHS GENERALLY IN THE LOWER AND MIDDLE 30S. SUNDAY...AS SURFACE HIGH PRESSURE MOVES OFF TO THE EAST...WARM ADVECTION WILL INCREASE AS WE GET INTO A MORE SOUTHERLY FLOW AT THE SURFACE. WILL CONTINUE TO KEEP SUNDAY DRY FOR NOW WITH PRECIPITATION EXPECTED TO HOLD OFF UNTIL SUNDAY NIGHT (BUT THIS TIMING MAY TURN OUT TO BE ON THE OPTIMISTIC SIDE). HIGHS IN THE MIDDLE AND UPPER 30S. SUNDAY NIGHT THROUGH WEDNESDAY...EXTENDED MODELS ARE BACKING OFF OF THE SCENARIO OF COLDER AIR WORKING ITS WAY BACK INTO THE REGION NEXT WEEK. WARM ADVECTION LIGHT SNOW IS POSSIBLE SUNDAY NIGHT AND RAIN OR SNOW ON MONDAY AS LOW PRESSURE MOVES BY TO OUR NORTH. A WEAK COLD FRONT WILL THEN MOVE ACROSS THE AREA LATER MONDAY WITH SLIGHTLY COOLER CONDITIONS TUESDAY BEFORE WARMING BACK UP ON WEDNESDAY. A RIDGE OF SURFACE HIGH PRESSURE IS EXPECTED TO LEAD TO NO PRECIPITATION DURING THE TUESDAY AND WEDNESDAY PERIOD. SULLIVAN && .APX WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH...UNTIL 8 AM THURSDAY...MIZ041-042. FLOOD WARNING...UNTIL 1230 PM THURSDAY...MIZ042. && $$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
915 AM CDT THU MAR 15 2007 .UPDATED AT 925 AM...LOWERED HIGH TEMPERATURES TODAY ABOUT 5 DEGREES AS IT IS QUITE A BIT COLDER BELOW 900MB THAN EXPECTED. TAMDAR SOUNDINGS AT RHINELANDER...APPLETON AND WAUSAU ALL INDICATE HIGHS BETWEEN 25 AND 30F. .SHORT TERM...TODAY THROUGH FRIDAY...MAIN FCST CONCERNS ARE WINDS... TEMPS AND SNOW CHANCES. A SECONDARY COLD FRONT SHIFTED SOUTH THROUGH THE FORECAST AREA OVERNIGHT...BRINGING A REINFORCING SHOT OF COOLER AND DRIER AIR...AND SOME GUSTY NORTHEAST WINDS TO THE FOX VALLEY/LAKESHORE AREAS. AS A RESULT...NEEDED TO ISSUE A SMALL CRAFT ADVISORY. WV IMAGERY SHOWED A POTENT VORT MOVG THROUGH WSTRN ND. THIS SYSTEM AND ITS ASSOCIATED WEAK SFC LOW WAS PRODUCING SOME SNOW OVER THE EASTERN DAKOTAS. AFTER A SUNNY START TO THE DAY...MID/HIGH CLOUDS WILL OVERSPREAD THE AREA DURING THE LATE MORNING AND AFTERNOON. BLUSTERY CONDITIONS WILL CONTINUE IN THE FOX VALLEY/LKSHR AREAS THIS MORNING...BUT STRONGER GRADIENT AND 925 MB WINDS ARE EXPECTED TO SHIFT SOUTH BY AFTERNOON... SO A DIMINISHING TREND SHOULD OCCUR. MIXING THROUGH 900-875 MB SUPPORTS HIGH TEMPS IN THE LOWER TO MIDDLE 30S. TONIGHT...THE S/W TROF WILL APPROACH THE REGION...BRINGING A CHANCE OF SNOW SHOWERS TO ROUGHLY THE NW HALF OF THE FORECAST AREA. THIS SYSTEM IS FCST TO GRADUALLY WEAKEN AS IT MOVES INTO WI ON FRIDAY...SO HAVE CONTINUED SMALL CHC POPS THROUGHOUT THE DAY. IT SHOULD BE NOTED THAT THE NAM IS SHOWING A MORE POTENT SYSTEM THAN THE OTHER MODELS...WITH THE POTENTIAL FOR A FEW INCHES OF SNOW OVER NC WI. GIVEN THE CURRENT APPEARANCE OF THE SYSTEM...CANNOT DISCOUNT THIS SOLUTION. HOWEVER... HAVE LEANED TOWARD A MODEL BLEND ATTM. WENT A BIT WARMER THAN GUIDANCE TONIGHT DUE TO EXPECTED CLOUD COVER. .LONG TERM...FRIDAY NIGHT THROUGH MONDAY NIGHT. PRECIPITATION IS THE MAIN CONCERN DURING THIS PART OF THE FORECAST. MODELS SHOWED MORE CONSISTENT SOLUTIONS FOR LATE THIS WEEK INTO EARLY NEXT WEEK. A TREND TOWARD MORE ZONAL FLOW WAS NOTED AS THE WESTERN CONUS RIDGE BECOMES FLATTER WHILE IT GETS PUSHED EASTWARD BY A DEVELOPING TROUGH OVER THE EASTERN PACIFIC. SURFACE HIGH PRESSURE THAT IS FORECAST TO BUILD INTO THE REGION OVER THE WEEKEND SHOULD KEEP THE AREA DRY THROUGH SATURDAY NIGHT. A LOW PRESSURE SYSTEM AND UPPER LEVEL SHORT WAVE ARE FORECAST TO PASS NORTH OF WISCONSIN...BUT WILL BE CLOSE ENOUGH TO BRING PCPN TO THE AREA SUNDAY AND SUNDAY NIGHT AS THE LOW DRAGS A FRONT THROUGH WISCONSIN. WARM ADVECTION MAY BRING SOME RAIN TO CENTRAL AND EAST CENTRAL WISCONSIN LATE SUNDAY AND SUNDAY NIGHT...OTHERWISE PCPN SHOULD BE IN THE FORM OF SNOW. THERE IS A SLIGHT CHANCE OF SNOW SHOWERS IN THE NORTH ON MONDAY IN CYCLONIC FLOW ON THE BACK SIDE OF THE LOW. HIGH PRESSURE BUILDING INTO THE AREA ON MONDAY NIGHT SHOULD BRING AN END TO ANY PCPN. && .AVIATION...VFR CONDITIONS ARE ANTICIPATED TODAY...WITH ONLY MID/HIGH CLOUDS SPREADING INTO THE RGN AHEAD OF AN APPROACHING UPPER LEVEL TROF. THIS SYSTEM WILL BRING A CHANCE OF SNOW SHOWERS AND POSSIBLE MVFR CONDITIONS TO RHI/AUW/CWA AFTER MIDNIGHT TONIGHT. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ KIECKBUSCH/MG WEATHER.GOV/GREENBAY $$ RDM/ECKBERG WEATHER.GOV/GREENBAY
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
230 PM PDT THU MAR 15 2007 .SYNOPSIS... A DECREASING MARINE WILL CAUSE COASTAL LOW CLOUDS AND FOG IN THE NIGHTS AND MORNINGS...EXTENDING LOCALLY INLAND. OTHERWISE...FAIR THROUGH THE WEEKEND UNDER HIGH PRESSURE. UPPER LEVEL LOW PRESSURE WILL BRING MORE CLOUDS AND COOLING EARLY NEXT WEEK WITH A SLIGHT CHANCE OF LIGHT SHOWERS TUESDAY. WARMER TOWARD THE END OF NEXT WEEK AS HIGH PRESSURE BUILDS. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES. .SHORT TERM (TONIGHT-SUN)... LOW CLOUDS WERE INTO THE WRN INLAND VALLEYS THIS MORNING WITH PATCHY DENSE FOG INLAND...CLEARING TO JUST OFFSHORE BY EARLY AFTERNOON. ACARS SOUNDINGS INDICATE AN INVERSION BASED NEAR 1200 FT. WEAK OFFSHORE GRADIENTS FROM THE N AND ONSHORE TO THE E WITH ABOUT 3 MB SAN-IPL. UPPER LEVEL HIGH PRESSURE WILL BUILD A LITTLE INTO FRI AND THEN SLOWLY WEAKENS SAT. WEAK UPPER TROUGHING WILL MOVE IN FROM THE W LATE SUN. THE ONSHORE GRADIENTS TO THE E WILL WEAKEN SLIGHTLY AND OFFSHORE GRADIENTS FROM THE N WILL REMAIN WEAK. THE MARINE LAYER WILL DECREASE A LITTLE TONIGHT AND REMAIN SHALLOW THROUGH SAT WITH PATCHY DENSE FOG NEAR THE INLAND EXTENT OF THE STRATUS AND ON HIGHER COASTAL TERRAIN. THE MARINE LAYER SHOULD START TO DEEPEN AGAIN SAT NIGHT AND SUN MORNING. A LITTLE WARMER FRI THEN GRADUALLY COOLER SAT AND SUN. .LONG TERM (MON-THU)... HEIGHTS WILL CONTINUE TO LOWER A LITTLE MON FOR MORE COOLING AND THE MARINE LAYER WILL DEEPEN SUN NIGHT INTO MON MORNING. A STRONGER TROUGH WILL MOVE THROUGH TUE FOR MORE CLOUDS...COOLING AND A SLIGHT CHANCE OF LIGHT SHOWERS. DRIER NW FLOW ALOFT WED FOR PARTLY CLOUDY SKIES AND SLIGHT WARMING. LOCALLY WINDY TUE AND WED...MAINLY IN THE MOUNTAINS AND DESERTS. FAIR AND WARMER THU AS HIGH PRESSURE BUILDS. && .AVIATION... 151845Z...LATE MORNING ACARS SOUNDINGS INDICATE THE MARINE LAYER DEPTH WAS AROUND 1300 FEET. STRATUS PULLED BACK TO THE COASTAL WATERS EARLIER THIS MORNING BUT SHOULD BEGIN TO PUSH BACK ONSHORE THIS EVENING. EXPECT A WEAK OFFSHORE FLOW TO KEEP THE STRATUS CONFINED MAINLY TO THE COASTAL AREAS TONIGHT WITH STRATUS/FOG RETURNING TO THE COASTAL AIRPORTS DURING THE LATE EVENING...BETWEEN 04 AND 07Z. STRATUS SHOULD CLEAR OUT BETWEEN 16 AND 17Z ON FRIDAY. ABOVE THE MARINE LAYER...CONTINUED VFR CONDITIONS WITH A MOSTLY CLEAR SKY AND UNRESTRICTED VISIBILITIES THROUGH FRIDAY. && .SGX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...DVA AVIATION...HORTON