Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Milwaukee/Sullivan WI
526 am CST Sat Dec 16 2017
Light snow showers are beginning to taper off across the far
northeastern corner of the County Warning Area. This trend will continue, with
precip ending by mid morning at the latest.
Light easterly winds are expected today and tonight across the
area. Ceilings will initially be VFR this morning, but will lower
as the day GOES on as moisture increases. MVFR is expected by
afternoon or evening, then IFR is expected overnight for most
Previous discussion... (issued 205 am CST Sat Dec 16 2017)
Early this morning through tonight...forecast confidence is
medium to high...
A band of light snow continues across the northeastern corner of
the forecast area early this morning. This snow remains very
light, with just minor additional accumulations expected through
As the precipitation ends this morning, a very brief period of
freezing drizzle is possible, at least in pockets across the Fond
Du Lac and Sheboygan areas as cloud ice begins to dissipate.
Right now, it doesn't look like any freezing drizzle would be
widespread enough to cause significant impacts, but it'll be
something to keep an eye on this morning.
A few peeks of sun will be possible in counties adjacent to the
Illinois state line today, but everywhere to the north will remain
cloudy. Temperatures will reflect the range in sunshine, with
readings near 40 along the state line, to just the low to mid 30s
across the Highway 23 corridor.
Skies will remain overcast tonight, with temperatures falling back
into the 20s area-wide.
Sunday and Sunday night - confidence...medium
broad mid level wave passes to our south. Surface low proggd to
near or into srn WI midday into the afternoon. Another mild day
though cloud cover expected to be stubborn. Models trending precip
to our south and blended guidance just clips our far southeast.
Surface trough passes with nearly neutral or even positive thermal
advection. Any clearing Sunday night could set up a fog scenario
though low level moisture for now is keeping the stratus in check with
progd MOS surface vsbys not reflective of fog at this time.
Monday through Tuesday night - confidence...medium
mild west/southwest flow will maintain mild conditions into at
least early Tuesday. A cold front will pass Monday night though
and start to pull in some cooler air as Tuesday wears along. The
GFS collapses the 925 thermal pattern a bit more quickly during
the day than the European model (ecmwf). It will be on the brisk side as well with
a tight gradient in the wake of the cold front. High pressure
along with a chillier airmass takes hold for Tuesday night with
high pressure nudging closer.
Wednesday - confidence...medium
the high and cold airmass lingers into early before a developing
warm air advection regime takes hold. The progs are showing the bulk of this lift
would be focused across northern/central WI though our northern
County Warning Area could end up being on the southern fringe. So may have to
consider some pops as we draw closer but for now blended guidance
is keeping this north of our area so will leave it dry for now.
Thursday and Friday - confidence...medium
progs continue to show an unsettled period with surface/850 low
to our west on Thursday morning and then slowly shifting east
along a rather tight baroclinic zone. Influence of a milder
airmass out ahead of the low at least into the morning. Colder air
starts to arrive Thursday afternoon with cold advection
continuing into Friday in blustery fashion. The European model (ecmwf) and Gem have
a more interesting surface low evolution and more favorable track
for decent snows than does the GFS. Pops are on the high side and
best consensus on the window for steadiest/heaviest snowfall
being Thursday night. The northern and western County Warning Area could end up
seeing a longer period of snow being in the colder airmass
longest. Potential there for several inches of accumulation County Warning Area
wide from this system.
Marine...easterly flow will continue across the nearshore waters
today and tonight. Waves will approach Small Craft Advisory levels
(4 ft) at times, but right now are expected to remain just below
at 2-3 ft.
Winds will become easterly again Sunday night, with waves
decreasing in response.