Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 220246
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
846 PM CST Tue Feb 21 2017

.UPDATE...

Warm advection mid clouds are clipping across southern Wisconsin
this evening and will exit the east by midnight. Fog has been
pesky along the lake and has drifted far enough inland to impact
parts the cities of Racine and Kenosha and right at the shore in
Milwaukee county. Some guidance is keeping this fog around through
early Wednesday morning, others push it out with a slightly
increasing offshore wind. Given the uncertainty, decided to post a
dense fog advisory, but will cancel it early if it looks like it
decidedly pushes offshore. A mild February night for sure with
record warmth again on Wednesday.

&&

.AVIATION/06Z TAFS/...

Fog over Lake Michigan is wavering along the shore and drifting
farther inland at times. This could impact KMKE and KENW with some
IFR conditions. It may become dominant late tonight into early
Wednesday morning. But, increasing off shore winds...out of the
southwest...by mid morning should bring VFR conditions back for
the remainder of the TAF period.

&&

.MARINE...
A moist airmass and light onshore winds has brought widespread
dense fog to the nearshore waters and this should persist through
mid morning on Wednesday. A marine dense fog advisory is in
effect.

South to southwest winds may gust to 20 knots Wednesday, but
should stay below Small Craft Advisory levels.

Strong low pressure passing through the region will likely result in
Small Craft Advisory conditions at times Thursday night through
Saturday night. Could even see winds approach gale force on
Saturday.

&&

.PREV DISCUSSION... /Issued 331 PM CST Tue Feb 21 2017/

SHORT TERM...

TONIGHT AND WEDNESDAY...Forecast Confidence...High

High pressure well to the east will continue to depart tonight ahead
of an advancing trough of low pressure. This will result in the
development of stronger southwest low level winds, which will bring
in even milder temperatures for Wednesday. Didn`t make much change
to the forecast for tomorrow, with record highs expected. Still
looks like the all time February records of 64 at Madison and 68 at
Milwaukee have a good chance of falling. 925 mb temps should be in
the 13-15C range tomorrow and with the expected winds, mixing to
925mb seems reasonable. This would yield highs pushing or evening
hitting 70! Does look like the trough could bring some late morning
and afternoon clouds in the north, which might hold back temps a tad
there.

Models are showing a chance for fog near Lake Michigan tonight, but
window of opportunity looks fairly small before winds shift back
offshore. Webcams do show a soupy look toward open waters, so
something to keep an eye on tonight.

Wednesday night through Saturday...Forecast confidence medium.

Low pressure and a shortwave trough will track across the nrn
Great Lakes Wed night with a trailing cold front to move sewd
across srn WI. Nely winds in the wake of the cold front and
increasing clouds will cool the high temps into the 40s for
Thu.

A large polar trough will move into the wrn USA on Wed and
eventually induce strong cyclogenesis over KS on Thu. The strong
low will then track to IA Thu night and across srn WI for Fri or
Fri night. The timing and evolution is in question as the GFS
occludes the low over se MN on Fri with the low and cold front to
pass Fri night into Sat AM. Chances for rain begin Thu afternoon
as 850-700 mb warm advection and frontogenesis ensues. The
strongest push of warm advection, moisture transport and
frontogenesis will then occur Thu night. Widespread showers and
isolated tstorms are forecast with rain amounts of 0.60-0.80
through Fri AM. The dry slot will bring a period of dry weather
for a portion of Fri but the upper trough passage or occlusion
passage will bring a round of light snow for late Fri night into
Sat. Seasonal temps will return on Sat via nwly winds and cold
advection.

LONG TERM...Sunday through Tuesday...Forecast confidence medium.

A shortwave trough will be passing to the south for Sun and Sun
night with slight chances of rain or snow for srn WI. Another
upper trough will move from the wrn USA into the Great Plains for
early in the week. Low pressure will develop and pass either over
srn WI or to the south with rain and snow expected.

AVIATION/00Z TAFS/...

VFR conditions are likely to persist through Wednesday. Will have to
keep an eye on fog near Lake michigan for a time this evening into
tonight, but window of opportunity seemed to small to mention in
forecast. Low level wind shear values will approach 30 knots after
midnight tonight into early Wednesday morning. Looks too borderline
though for mention in forecast.

MARINE...

Onshore winds may bring some fog into the nearshore waters for a
time this evening into early tonight before winds shift back
offshore. Not high confidence in this, so left out of forecast for
now.

South to southwest winds may gust to 20 knots at times tonight and
Wednesday, but should stay below Small Craft Advisory levels.

Strong low pressure passing through the region will likely result in
Small Craft Advisory conditions at times Thursday night through
Saturday night. Could even see winds approach gale force on
Saturday.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Dense Fog Advisory until 9 AM CST Wednesday for WIZ066-071-072.

LM...Dense Fog Advisory until 9 AM CST Wednesday for LMZ643>646.

&&

$$

UPDATE...Davis
TONIGHT/Wednesday AND AVIATION/MARINE...DDV
Wednesday NIGHT THROUGH Tuesday...Gehring


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