AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
930 PM PST THU FEB 8 2007
.SYNOPSIS...
UPPER LEVEL LOW PRESSURE APPROACHING THE COAST WILL BRING INCREASING
CLOUDS FRIDAY AND SATURDAY. A WARM FRONT WILL BRING THE BEST CHANCE
OF RAIN LATE SATURDAY AFTERNOON THROUGH SUNDAY. COOL WEATHER WITH
SHOWERS AND MOUNTAIN SNOW ARE EXPECTED TUESDAY WHEN A COLD FRONT
COMES THROUGH. COOL AND PARTLY CLOUDY THE SECOND HALF OF NEXT WEEK.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES.
LOTS OF HAZE AND MID-HIGH CLOUDS THIS EVE. WE ARE STILL UNDER 576
SW FLOW TONIGHT THROUGH FRIDAY. LOTS OF MOISTURE AT HIGH LEVELS
FOR PARTLY CLOUDY SKIES...BUT PRECIP CHANCES LOOK MINOR AS PLUME OF
CLOUDS AND RAIN IS DIRECTED INTO CENTRAL CALIF. THE PACIFIC TROUGH
FINALLY EDGES INTO THE AREA BY SAT PM. WARM FRONT RAIN IS EXPECTED
SAT NIGHT THROUGH SUN MORNING...WITH LINGERING SHOWERS SUN PM.
THE 160 KT JET WILL BE TO FAR SOUTH TO ENHANCE RAIN. NOT A WHOLE
LOT OF PRESSURE GRAIDENT OR 850 MB SW WINDS TO GET OROGRAPHIC
ENHANCEMENT...SO WE ARE KEEPING PRECIP TOTALS MODERATE FOR THE
WEEKEND STORM. TOTALS ENDING SUNDAY NIGHT SHOULD RANGE FROM 1/4
TO 1/2 INCH ON THE FLATS AND 1/2 TO 1 INCH ON SW FACING MOUNTAIN
SLOPES. SNOW LEVELS WILL BE HIGH...ABOVE 8000 FT. GUSTY WEST
WINDS ARE EXPECTED IN THE MOUNTAINS AHEAD OF THE FRONT SAT PM.
THE FIRST TROUGH IS EAST OF US BY SUNDAY NIGHT. A WEAK 564 RIDGE
SHOULD KEEP US COOL...DRY AND PARTLY CLOUDY MONDAY.
A SECOND TROUGH COMES THROUGH TUESDAY WITH A DECENT COLD FRONT.
WITH 550 CLCONIC WEST FLOW ALOFT AND 6 MB ONSHORE FLOW...THIS
FRONT COULD BRING A GOOD SNOW STORM TO THE MOUNTAINS ABOVE 4000 FT.
VALLEY TEMPS ONLY IN MID-UPR 50S TUE. TOTALS WITH THIS STORM SHOULD
BE AROUND 1/4 INCH ON THE FLATS AND UP TO 3/4 INCH MTS. LINGERING
SHOWERS TUESDAY NIGHT.
PARTLY CLOUDY AND COOL WED THRU FRI UNDER 560 CYCLONIC NW FLOW.
&&
.AVIATION...
EARLY EVENING ACARS SOUNDINGS FROM KSAN...KSNA AND KLGB INDICATE THE
MARINE LAYER REMAINS VERY SHALLOW...AROUND 700 FEET NEAR KSNA AND
500 FEET NEAR KSAN. BASED ON METAR REPORTS FROM OFFSHORE
ISLANDS...THERE ARE AREAS OF STRATUS OFFSHORE BUT MOST OF THIS IS
OBSCURED ON SATELLITE IMAGERY BY THE HIGHER CLOUDS. EXPECTING
STRATUS TO PUSH ONTO THE COAST LATER THIS EVENING WITH BROKEN TO
OVERCAST CONDITIONS EXPECTED. BASES SHOULD BE AROUND 1000 FEET MSL
WITH TOPS AROUND 1500 FEET MSL. CONFIDENCE IS LOW ON EXTENT AND
TIMING OF THE STRATUS IS LOW BUT PROBABLY BEFORE MIDNIGHT. THERE IS
A SIGNIFICANT AMOUNT OF HIGH LEVEL CLOUDS WHICH COULD HELP MINIMIZE
THE STRATUS OVERNIGHT. EXPECT ANY STRATUS TO SCATTER OUT DURING THE
MORNING ON FRIDAY. VISIBILITIES SHOULD REMAIN MVFR OR BETTER EXCEPT
BELOW 3 MILES IS POSSIBLE OVER THE MESAS OVERNIGHT TONIGHT.
ABOVE THE MARINE LAYER...VFR CONDITIONS WILL CONTINUE WITH VARIABLE
AMOUNTS OF ALTOCU AROUND FL150 AND CIRRUS ABOVE FL200 THROUGH FRIDAY.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
PUBLIC...MACKECHNIE
AVIATION/MARINE...HORTON
AREA FORECAST DISCUSSION
NWS MIAMI FL
956 AM EST FRI FEB 9 2007
.UPDATE...MADE ONLY MINOR CHANGES TO THE FCST THIS MORNING.
REMOVED SPRINKLES FROM THE FCST FOR TODAY...SINCE SATELLITE
IMAGES SHOW MOSTLY CLEAR TO PARTLY CLOUDY SKIES ACROSS THE AREA AND
THE MIAMI SOUNDING THIS MORNING SHOWS DRY AIR IN PLACE...WITH A
PWAT OF ONLY 0.82 INCHES. SO AM EXPECTING A TRANQUIL DAY WITH PLENTY
OF SUNSHINE AND TEMPERATURES REACHING INTO THE UPPER 70S TO NEAR 80
DEGREES. MADE MINOR CHANGES TO THE WIND FCST...FOLLOWING CLOSELY
WITH THE NAM-WRF SOLUTION...WHICH SHOWS THE EAST COAST SEA BREEZE
NOT DEVELOPING AND PUSHING INLAND UNTIL MID/LATE AFTERNOON. THIS
SEEMS MOST REASONABLE GIVEN THE FACT THAT THE MORNING SOUNDING AND
ACARS DATA SHOW THAT THE SW FLOW THROUGH 5KFT THIS MORNING IS A
FEW KNOTS STRONGER COMPARED TO YESTERDAY...AND IT TOOK AWHILE
YESTERDAY FOR THE SEA BREEZE TO DEVELOP AND PUSH INLAND. UPDATES
ARE ALREADY OUT. /GREGORIA
&&
.PREV DISCUSSION... /ISSUED 403 AM EST FRI FEB 9 2007/
DISCUSSION...
A QUIET NIGHT IS CURRENTLY IN PROGRESS ACROSS SOUTH FLORIDA AND WILL
TRANSLATE INTO A VERY PLEASANT DAY ACROSS THE AREA...WITH TRANQUIL
CONDITIONS EXPECTED TO CONTINUE THROUGHOUT THE SHORT TERM PORTION
OF THIS FORECAST. MODELS ARE IN UNANIMOUS AGREEMENT ON A
CONTINUATION OF WEST-NORTHWEST FLOW ALOFT ACROSS THE SUNSHINE
STATE THROUGH THE FIRST PART OF THE WEEKEND. THIS WILL ALLOW A
WEAK COLD FRONT TO PASS ACROSS THE SOUTHERN PORTION OF THE
PENINSULA FROM FRIDAY EVENING INTO SATURDAY MORNING. SUBSEQUENT
PASSAGE OF A WEAK MID-LEVEL SHEAR AXIS MAY RESULT IN INCREASED MID
AND HIGH LEVEL CLOUD COVER...BUT VERY DRY MOISTURE PROFILES WILL
GENERALLY RESULT IN A DRY FRONTAL PASSAGE FOR ALL AREAS. LIGHT
NORTHERLY WINDS WILL CONTINUE FOR THE REMAINDER OF THE WEEKEND...
BUT RAPIDLY MODIFYING SURFACE HIGH OVER THE MID-ATLANTIC REGION
WILL ENSURE THAT MAXIMUM/MINIMUM TEMPERATURES REMAIN NEAR
CLIMATOLOGICAL NORMALS.
MOST MEDIUM RANGE GUIDANCE IS FORECASTING A TRANSITION TO A MORE
ZONALLY ORIENTED MID/UPPER LEVEL FLOW PATTERN ACROSS THE CONUS IN
THE EXTENDED PORTION OF THE FORECAST. A WEAK SOUTHERN STREAM VORT
MAX IS FORECAST TO APPROACH THE AREA FROM THE WEST ON MONDAY...
WITH LOW-LEVEL FLOW FORECAST TO VEER TO SOUTHEAST IN RESPONSE TO
THIS FEATURE. MOISTURE WILL RAPIDLY SPREAD BACK ACROSS THE AREA ON
MONDAY NIGHT AND TUESDAY MORNING...WITH ISOLATED SHOWERS RETURNING
AS WELL. AS SOUTHERN EXTENSION OF THE HUDSON BAY VORTEX BEGINS TO
DROP SOUTHWARD ACROSS THE GREAT LAKES TOWARD THE MIDDLE OF THE
WEEK...ANOTHER COLD FRONT WILL PLUNGE SOUTHWARD ACROSS THE EASTERN
TWO-THIRDS OF THE COUNTRY...AND EXPECT HIGHER RAIN CHANCES FOR
SOUTH FLORIDA TO HOLD OFF UNTIL FRONTAL PASSAGE ON WEDNESDAY.
NORTHERLY WINDS AND COOLER-THAN-NORMAL TEMPERATURES WILL LIKELY BE
THE HIGHLIGHT FOR THE REMAINDER OF THE WEEK...ALTHOUGH THERE ARE
SOME HINTS IN THE GUIDANCE THAT DEVELOPING ISENTROPIC ASCENT NORTH
OF THE FRONT WILL BE SUFFICIENT FOR CLOUDY SKIES AND SOME
POSTFRONTAL RAINFALL. AS THIS IS STILL FAR OUT IN THE FUTURE...
WILL HOLD POPS AT 10 PERCENT OR LESS FOR NOW AND REFINE AS THE
EVENT COMES CLOSER.
AVIATION...
VFR CONDITIONS EXPECTED MOST AREAS THROUGH TODAY...WITH THE
EXCEPTION OF SOME MORNING FOG AT KTMB WITH LIGHT WINDS AND CLEAR
SKIES. MID LEVEL MOISTURE IS EVIDENT ACROSS THE SE GULF EARLY THIS
MORNING...AND THE NAM/GFS BOTH BRING THIS MOISTURE ACROSS SOUTH
FLORIDA TODAY...BUT AT DIFFERING LEVELS FROM 8-12K FEET. OPTED TO
INTRODUCE A SCT080 DECK FOR NOW. VERY LIGHT OFFSHORE WINDS DURING
MUCH OF THE MORNING HOURS WILL LIKELY LEAD TO SEA BREEZE FORMATION
ON BOTH COASTS BY MID DAY...AND THE TAFS REFLECT THIS IDEA.
MARINE...
GENERALLY LIGHT WINDS WILL LEAD TO PLEASANT MARINE CONDITIONS
THROUGH EARLY NEXT WEEK...ALTHOUGH A SLIGHT ONSHORE COMPONENT
ALONG THE GULF COAST MAY HEIGHTEN THE THREAT FOR RIP CURRENTS
LATER TODAY. SOUTHWESTERLY WINDS WILL INCREASE FOR ALL AREAS BY
EARLY NEXT WEEK...WITH SEAS GRADUALLY BUILDING AS A RESULT. ANOTHER
EPISODE OF RIP CURRENTS WILL ALSO BE POSSIBLE ALONG THE GULF
COAST. GULF STREAM SEAS WILL BUILD MORE SUBSTANTIALLY AFTER THE
ONSET OF NORTH WINDS FOLLOWING FRONTAL PASSAGE ON WEDNESDAY.
FIRE WEATHER...
GIVEN LOW DEW POINTS IN PLACE...WILL HAVE TO CLOSELY MONITOR RH TRENDS
FOR ANOTHER POTENTIAL RED FLAG EVENT ACROSS THE NORTHWEST INTERIOR
COUNTIES THIS AFTERNOON. OTHERWISE...NO PROBLEMS ARE ANTICIPATED
THROUGH REMAINDER OF THE FORECAST PERIOD.
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
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