Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 131538
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
938 AM CST Mon Feb 13 2017

.UPDATE...
The current forecast is on track. Look for the southwest winds to
steadily increase today pushing highs into the mid 40s across the
south where there is no snow and the ground is drying out. A bit
cooler across the northern part of the forecast area where
satellite imagery still shows the snowpack persisting.

&&

.AVIATION/18Z TAFS/...

VFR conditions will persist through the TAF period. An increasing
low level jet will bring the threat of Low Level Wind Shear this
evening when surface winds begin to decouple.

&&

.MARINE...

West winds will back to the south to southwest as high
pressure passes by to the south of Lake Michigan today. Wind gusts
likely to remain below 22 knots through late afternoon. Tightening
pressure gradient associated with passing low pressure trof tonight
will cause south to southwest winds to increase. These south winds
will pull slightly warmer low level air across the lake tonight.
Forecast soundings show low level inversion setting up as Lake MI
surface temps in the mid 30s to around 40 toward the open waters.
This inversion should prevent stronger gusts from mixing down to
the lake surface across most of the near shore waters tonight.
However closer to mid-lake, occasional gusts may reach Small Craft
Advisory levels. For now, wl hold off on posting advy due to
uncertainty and borderline event at this time.

Much more likely for West to northwest winds reaching advy levels on
Tuesday into Tuesday night as several surges of cold air slide
rapidly southward across the Great lakes as strong low pressure
passes by to the north.

&&

.PREV DISCUSSION... /Issued 300 AM CST Mon Feb 13 2017/

TODAY AND TONIGHT...Forecast Confidence - High.

Low level thermal trof continued to slide off to the east overnight
as steering winds briefly become more west to northwest for today
into tonight ahead of mid-level short wave and eventual weak surge
of colder air later tonight into early Tuesday.  Upstream short wave
over western Canadian provinces takes a turn southeast today and
sweeps across WI overnight.  Trend in short term guidance has been
to show slightly more strengthening of this feature tonight as it
passes through and grazes parts of southern WI.  However atmospheric
moisture through 10k feet wl remain sparse as the forcing with this
wave passes through.  Hence wl continue dry forecast but do expect
some increase in higher level clouds later today and tonight.

Strengthening southwest winds ahead of this feature will usher 925h
temperatures to around and a little above 0C today.  Dry southwest
flow and sunshine will combine to push temperatures in snow free
areas into the mid to upper 40s.

TUESDAY AND TUESDAY EVENING - Confidence...Medium
A strong shortwave trough will arrive later in the afternoon into
the evening with a period of DCVA. Some timing differences on this.
Bufkit show impressively steep low level lapse rates. Will be
quite windy in wake of sfc/850 cold front with temps taking a
tumble Tuesday evening. So have introduced slight chance pops for
now trending a bit more towards mos and what qpf panels are
showing given the frontal forcing, steep lapse rates and
shortwave.

WEDNESDAY - Confidence...Medium
Cyclonic flow aloft will persist on western side of circulation in
ne US. Mostly sheared vort here with low level thermal trough in
place. 925 temps down to -8c to -11c. LLVL RH progs show a good deal
of stratocu/stratus likely to be in place. Temps will be at or
slightly below seasonal normals though the sustained nw winds will
make it feel quite a bit chillier.

THURSDAY THROUGH SUNDAY - Confidence...Medium
Rising heights with warming temps this period. On Thursday the GFS
is a little quicker with the return waa regime getting underway. But
by Friday 925 temps are in the 8-10c range which may necessitate
further bumping over Superblend guidance though for now have trended
warmer with a blend of the Euro and Superblend. Pretty much
carried that trend through the weekend as 500 millibar ridge
continues to bump up across the western Great Lakes. Temps in the
east may get tricky with onshore cooling tempering the otherwise
unseasonably mild regime.

AVIATION/12Z TAFS/...VFR conditions for this forecast period.  Low
level jet will develop over the area late this afternoon and evening.
Forecast soundings show the potential for several hours of low
level wind shear across southern WI during this period.

MARINE...West winds will back to the south to southwest as high
pressure passes by to the south of Lake Michigan today. Wind gusts
likely to remain below 22 knots through late afternoon. Tightening
pressure gradient associated with passing low pressure trof tonight
will cause south to southwest winds to increase. These south winds
will pull slightly warmer low level air across the lake tonight.
Forecast soundings show low level inversion setting up as Lake MI
surface temps in the mid 30s to around 40 toward the open waters.
This inversion should prevent stronger gusts from mixing down to
the lake surface across most of the near shore waters tonight.
However closer to mid-lake, occasional gusts may reach Small Craft
Advisory levels. For now, wl hold off on posting advy due to
uncertainty and borderline event at this time.

Much more likely for West to northwest winds reaching advy levels on
Tuesday into Tuesday night as several surges of cold air slide
rapidly southward across the Great lakes as strong low pressure
passes by to the north.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$

UPDATE...Davis
TODAY/TONIGHT AND AVIATION/MARINE...Collar
Tuesday THROUGH Sunday...MBK



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