Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 222122
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
322 PM CST Mon Jan 22 2018

.SHORT TERM...

Tonight and Tuesday...Forecast Confidence is Medium...

An occluding low pressure system will progress across the lower
Great Lakes through Tuesday. The associated warm frontal zone
should hold steady along the Wisconsin/Illinois border, with some
warmer temperatures sneaking into the far south. With the frontal
zone in this vicinity, we`ll need to keep an eye on our far south
into this evening as thunderstorms now developing over central
Illinois push north into southern Wisconsin this evening. While
convective allowing mesoscale models suggest these storms will
weaken over time (the most likely scenario as instability is
quite meager), there is a large amount of (largely unidirectional)
shear present. We`ll need to watch for a very small severe
potential along our southern border, but this appears to be a
rather small risk.

Our attention then turns towards tonight, as the low pressure
system pulls away to our east. Precipitation will transition from
rain to snow as temperatures cool aloft, with a TROWAL and
frontogenesis band contributing to a burst of wet snow generally
after midnight tonight. Current model solutions place the highest
QPF across our southeast, where a Winter Weather Advisory for
impacts was issued. It`s important to note that the placement of
mesoscale banding features such as this are tough for the synoptic
forecast models to nail down. As such, it`s possible that the
location of this band may change. The key message is that
travelers late tonight into tomorrow morning should prepare for
the possibility of slippery/slushy roads resulting from the snow.
Reduced visibility is also possible late tonight/early tomorrow
morning in bursts of moderate snow.

Temperatures will fall below freezing late tonight, and will
remain there tomorrow. Lows tomorrow night will drop into the
teens.

.LONG TERM...

Tuesday night through Thursday...Forecast confidence is high:

High pressure will bring quiet weather Tuesday night through
Thursday. Temperatures will be near normal Wednesday, but will
quickly return to above normal conditions Thursday as southerly
winds develop on the back side of the departing high.

Friday through Monday...Forecast confidence is medium:

Low pressure is expected to pass by well to the north on Friday.
Southerly winds ahead of the surface trough will continue to pull
milder air into the region. Temperatures Friday will likely hit at
least the mid-40s, with 50 possible per some of the milder model
solutions.

Could see a little rain and a few snowflakes Friday night as the
trough passes through, though models overall look fairly dry with
the passage. The latest ECMWF is slower with the trough and
develops a surface low in the area, which would keep rain chances
going into Saturday. This is a new solution and is currently an
outlier, so kept the forecast dry for Saturday.

Milder temps will probably linger Saturday, with highs back to
near normal Sunday into Monday.

&&

.AVIATION(21Z TAFS)...

Rain showers and drizzle will continue into this evening with low
ceilings mostly persisting. The exception is in the far south and
southeast, where ceilings may rise for a time into early evening,
before falling once again tonight. Visibility will bounce around
some, with lower periods occurring in between rain showers. There
remains a small chance for thunder into this evening, but
confidence is too low to include it in the TAFs.

A period of wet snow is expected late tonight into early Tuesday
morning. Accumulations of 1 to 3 inches are possible, with the
higher amounts possible in the Milwaukee, Kenosha, and Waukesha
areas.

&&

.MARINE...

Extended the small craft advisory into Tuesday night, with high
winds and waves likely to persist until this time. While
visibility has improved some in the nearshore waters this
afternoon, will keep the marine dense fog advisory in effect until
this evening, as poorer visibility may return. Mariners should
exercise caution.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory from 11 PM this evening to 10 AM CST
     Tuesday for WIZ065-066-069>072.

LM...Dense Fog Advisory until 9 PM CST this evening for LMZ643>646.

     Small Craft Advisory until 12 AM CST Wednesday for LMZ643>646.

&&

$$

Tonight/Tuesday and Aviation/Marine...SPM
Tuesday Night through Monday...DDV



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