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Area Forecast Discussion
Issued by NWS Twin Cities, MN
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FXUS63 KMPX 010306
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
906 PM CST Tue Jan 31 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 408 PM CST Tue Jan 31 2017

This afternoon, a 150+ kt jet streak stretches from NW Montana
southeast to the Quad Cities. This places us in the left exit
region of this jet. We are also within a strong shear region
around h5 on the poleward side of the mid-level jet, with a strip
of vorticity moving across the area. These features are providing
a background of favorable lift. Within this lift back ground, we
warmed again into the mid/upper 30s within a weak CAA regime all
day. These warm temps beneath a winter airmass has resulted little
in the way of an inversion and deep mixing. BUFKIT soundings show
steep lapse rates and even 50-70 j/kg of CAPE, all of this is
adding up to an environment supportive of upright convection. We
have seen this all come together within about a 15 mile wide band
of snow just northeast of the Twin Cities. The 12/15z runs of the
HopWRF actually picked up on this band pretty good, so followed it
for dropping a narrow band of higher PoPs across eastern
MN/western WI. Looking at MNdot plow cameras from within the band,
snowfall rates are easily up around an inch per hour and we
expect that we will see about a 15 mile wide NW to SE oriented
band that picks up 2-3" of snow in under 2 hours.

Outside of this band, we will continue to see scattered snow
showers drop across areas north of the MN River into the evening
until a strong cold front currently crossing the international
border sweeps all of this activity out of the area. Was cautious
with going too low with temperatures overnight given expected
cloud cover and the fact we are up in the 30s this afternoon, so
lows in the teens/single digits should be about all we can muster,
which would represent modest 20 to 30 degree temperature drops in
a windy (mixed) and cloudy environment.

Not much expected with the weather tomorrow as we get mostly
sunny skies. However, those mostly cloudy skies will come with the
coldest air we have seen since the 13th/14th of January, so look
for the highs for the first calendar day of February to come
around midnight, with temperatures in the afternoon remaining
steady or slowly falling.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 408 PM CST Tue Jan 31 2017

The longer term concerns remain the snow threat for Saturday and
development of significant storm possible Tue/Wed period of next
week.

Fairly quiet weather into Saturday as a band of snow is forecast
to travel southwest of the CWA. We retained the slight chance pop
for the southwest for the moment on Friday. Trend of the GFS has
been drier with the 12z ECMWF continuing to show some potential
into the far southwest.

The Saturday system appears to be better organized as some short
wave energy moves through the western conus trough toward the
area. Strong isentropic lift indicated with the system with about
the eastern half of the cwa vulnerable for at least a couple
inches of snow. The GFS is painting a similar scenario which was
seen on Monday/Monday night. We will mention categorical pops
developing to the eastern cwa Saturday afternoon.

Then the focus turns to the possible storm developing next week
as the significant easter Pacific trough moves inland. It develops
lee side cyclogenesis and lifts the storm northeast toward the
western Great Lakes into Wednesday. Most deterministic models and
the GFS ensemble mean are in good agreement with this overall
trend at the moment...but which has been the case much of the
winter...phasing of the northern and southern stream energy has
not been handled well by the models. This has lead to considerable
variability in the longer term models. The 12z ECMWF is much
warmer than the GFS with the system...drawing H850 temepratures of
+5C into southeast MN on Tuesday. This would most likely generate
freezing rain/rain sleet potential into the southeast early in
the event...with a heavier snow band into central MN. We will
continue the overall high level pop trend spreading east over the
are for Tuesday for now. We will continue to monitor model trends
for overall impacts for the event.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 906 PM CST Tue Jan 31 2017

There could be a brief period (1-3 hours) of MVFR ceilings
tonight, but generally VFR is expected with the vast majority of
snow showers now to the southeast of the TAF sites.

KMSP...
No much to add to the above discussion. A band of MVFR ceilings
could drop south across the area between 06z-12z, but the band
will not be continuous and might not impact KMSP at all. Should be
clearing skies for the morning commute.

/OUTLOOK FOR KMSP/
THU...VFR. Winds WNW 10-15 kts.
FRI...VFR. Winds W 5-10 kts.
SAT...MVFR/IFR. -SN Likely. Winds SSE 10-15 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&

$$

SHORT TERM...MPG
LONG TERM...DWE
AVIATION...CLF
National Weather Service Regional Headquarters
