Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 110303
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
903 PM CST Tue Jan 10 2017

.UPDATE...

Winds beginning to subside. Will drop the wind advisory at 10 pm
west of a Dells to madison to Janesville line. Still high gusts
especially near Sheboygan til midnight.

Brief clearing behind the departing shortwave. High clouds will
stream in late.

&&

.AVIATION/06Z TAFS/...

Main story will be the strong, gusty west winds gradually
subsiding as the strong surface low exits the eastern Lake
Superior region. Brief clearing behind the departing shortwave.
Just a few areas of lingering MVFR clouds. Then high/mid level clouds
will increase by morning.

850 baroclinic zone will serve as focus for more precip on
Wednesday as low pressure rides east northeast along secondary
surface front shifting to our south. Precip type will be tricky
with NAM soundings supportive of either ra/fzra/sleet in the aftn
though expect many area temps to be at or above freezing.

&&

MARINE...

A GALE WARNING IS IN EFFECT UNTIL MIDNIGHT TONIGHT SOUTH OF NORTH
POINT LIGHTHOUSE...AND UNTIL 3 AM WEDNESDAY TO THE NORTH. WEST
GALES UP TO 45 KNOTS ARE EXPECTED. HIGH WAVES WILL OCCUR INTO THE
EVENING IN ICE FREE AREAS.

A SMALL CRAFT ADVISORY WILL MAY BE NEEDED AFTER THE GALE WARNING
EXPIRES LATER TONIGHT...FOR THE GUSTY WEST WINDS SLOWLY
WEAKENING.

&&

.PREV DISCUSSION... /Issued 319 PM CST Tue Jan 10 2017/

TONIGHT...Forecast Confidence Is Medium.

Low pressure lifting east northeast with nice rise/fall couplet.
Impressive comma cloud structure on water vapor animation. Main
story will be the strong west winds this evening. Wind Advisory
still looks solid with the intensifying low lifting to our north
and increased subsidence behind mid level wave. Pondered a High
Wind Warning as Bufkit was showing some conditions getting pretty
close to that but will leave the advisory in place for now as
higher end advisory winds look more likely.

Lingering def zone precip is wrapping up pretty quick late this
afternoon/evening with a brief changeover but progs and radar
animation suggests this will be on the move and out of the area
pretty quick. With the dropping temps below freezing and the
moisture on road surfaces from the rains, will go with an SPS for
the refreeze idea. Temps back into the teens to low 20s later on.

WEDNESDAY...Forecast Confidence Is Medium.

Surface front will shift to our south with 850 baroclinic ribbon
across srn and cntrl WI. Another shortwave will be moving ene into
srn WI as the day wears on and a left front quad jet core will aid
in upper divergence acrs the cwa. Precip type will be tricky as a
warm layer will be present. Surface temps likely to be above
freezing in the southeast and prior to fropa. Temp profile gets
tricky in the afternoon. Based on the thermal profile we may have
a scenario where we see some light snow in the nw cwa with a band
of mixed pcpn in the cntrl and mainly rain se.

WEDNESDAY NIGHT THROUGH FRIDAY...Forecast Confidence Is Medium.

Models seems to have shifted the best upward vertical motion
fields a little further to the southeast for Wednesday night into
Thursday morning. Still, there is robust low level frontogenesis
response that slides just southeast of the area Wednesday evening.
The models have light QPF across the area Wednesday night.
However, the mesoscale models do not have much of any
precipitation sliding through.

The NAM forecast soundings are more favorable for freezing rain
across the southeastern half of the area than the GFS. The GFS is
colder through the column, and favors more of a sleet or snow
setup in this area. They both favor light snow elsewhere across
the area. Given the uncertainty here, went with mainly chance PoPs
except in the far southeast Wednesday evening, and chance PoPs
later Wednesday night. Light ice accumulations remain possible in
the southeast half of the area during this time, with light snow
under an inch elsewhere.

There is also a 500 mb vorticity maximum that slides either
through or just south of the area Thursday morning. The NAM
forecast soundings still show the possibility for light freezing
rain into Thursday morning in the southeast counties, with the GFS
mainly light snow. There is light QPF on most of the models
Thursday morning across the area, so kept PoPs going here as well.
Could see light glazing into Thursday morning in the southeast
counties, which may affect the Thursday morning commute.

Strong cold air advection should help scour out any precipitation
by Thursday afternoon. Should then see quiet weather into Thursday
night, as well as much colder temperatures and wind chills. Lows
Thursday night should drop into the single digits above zero in
most areas, except a little below zero north of Madison. Wind
chills should be in the 5 below to 15 below zero range, coldest
in the north counties. High pressure will keep Friday quiet as
well, with continued cold temperatures.

FRIDAY NIGHT THROUGH TUESDAY...Forecast Confidence Is Medium.

ECMWF/GFS show a 500 mb vorticity maximum sliding east through the
area Friday night into Saturday morning, though have some
differences with placement of the best upward vertical motion with
it. There is light QPF across the area during this period. Kept
PoPs going for this period, with temperature profiles supporting
light snow.

High pressure then should bring quiet weather later Saturday into
Sunday, before the next low pressure system slides northeast
toward the region Sunday night into Tuesday. There still remains
quite a bit of uncertainty here with the evolution of the surface
and 500 mb features, so kept close to the consensus blended PoPs
and temperatures. This system bears watching, as it has decent
amounts of Gulf moisture with it.

AVIATION/00Z TAFS/...

Def zone rain shield shifting ene with a changeover on the far
back side. Meso progs show much of the precip wrapping up aft 22z
with only spotty light precip after that. Main story will be the
strong, gusty west winds as the surface low continues to intensify
as it lifts to our north and pressure gradient tightens. Strongest
winds through 06z then gradient slackens.

850 baroclinic zone will serve as focus for more precip on
Wednesday as low pressure rides ene along secondary surface front
shifting to our south. Precip type will be tricky with NAM
soundings supportive of either ra/fzra/sleet in the aftn though
expect many area temps to be at or above freezing.

MARINE...

A Gale Warning continues into the evening due to initially strong
southwest then west winds on southern side of departing and
intensifying low pressure. May need a ramp down small craft a bit
later in the night as gradient slackens somewhat resulting in
winds dropping below gales though remaining elevated.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...WIND ADVISORY until 10 PM CST this evening for WIZ056-062-063-
     067>069.

     WIND ADVISORY until midnight CST tonight for WIZ046-047-051-052-
     057>060-064>066-070>072.

LM...GALE WARNING until midnight CST tonight for LMZ645-646.

     GALE WARNING until 3 AM CST Wednesday for LMZ643-644.

&&

$$

UPDATE...Hentz
TONIGHT/Wednesday AND AVIATION/MARINE...Wood
Wednesday NIGHT THROUGH Tuesday...Collar



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