Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 192103

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
303 PM CST Fri Jan 19 2018


Tonight and Saturday - Confidence...Medium
Surface low and 500 millibar energy passes to our north this
period. A frontal boundary sags into the area and then essentially
washes out. Overall the surface pressure pattern becomes rather
diffuse. This much less wind on Saturday. Temps remain mild.

Sunday - Confidence...Medium
Warm front starts setting up to our south with some 850 waa taking
hold. Stratus likely to evolve and could set the stage for at
least a brief window for some freezing drizzle Sunday morning.
Models expand the 0.01 qpf across the area most likely reflective
of an expansive area of stratus/fog and possibly some drizzle.
Should see temps modify above freezing as the morning wears along
to reduce the threat of the FZDZ.

Sunday night through Tuesday - Confidence...Medium
Forecast focus continues to be on the low pressure system moving
northeast into the Great Lakes this period. Still looking like a
warm system for us here. The ECMWF is the furthest south solution
and thus the coldest for us. Meanwhile the GEM and GFS continue
to show a solidly warm solution. For now will stay the course on
the warm idea for the bulk of this system. Do think we need to
keep an eye on our northern counties for Sunday night as a
lingering critical thermal field may result in some mixed precip
there for a time. This is most noticeable on the ECMWF and NAM.
Once the cold air sweeps in Monday night there will be a changeover
to snow cwa-wide but accums look to be in the light side.

Wednesday through Friday - Confidence...Medium
Colder air lingers into Wednesday with cold advection in the wake
of the departed low setting up a low level thermal trough. The
high shifts east for Thursday and Friday setting up a return waa
regime. At this time the bulk any waa forcing remains to our
north per GFS/ECMWF with the GEM being the outlier at this point.
All models show an overall mild return flow setting up Thursday
and especially for Friday.


.AVIATION(18Z TAFS)...Main concerns will be LLWS tonight. Mid and
high level moisture continues to stream across the area. Decent
pressure gradient has ramped up the southwest winds. Departing
850 speed max combined with some evening dropoff in winds may
result in some LLWS through about 06z or so. As for any stratus or
fog on Saturday have elected to go with the more VFR looking
approach of the GFS rather than the NAM weighted ceiling
solutions. Think stratus and some fog will eventually become an
issue but banking on that arriving more in the Saturday
night/Sunday timeframe as the storm system and better low level
moisture push arrives.


.MARINE...The small craft advisory remains in effect until 09z and
this looks reasonable to account for the lingering pressure
gradient ahead of the approaching frontal boundary.


LM...Small Craft Advisory until 3 AM CST Saturday for LMZ643>646.


Tonight/Saturday and Aviation/Marine...Collar
Saturday Night through Friday...Collar is the U.S. government's official web portal to all federal, state and local government web resources and services.