FXUS63 KGRB 182349

Area Forecast Discussion
National Weather Service Green Bay WI
549 PM CST Mon Feb 18 2019

Updated aviation portion for 00Z TAF issuance

.SHORT TERM...Tonight and Tuesday
Issued at 258 PM CST Mon Feb 18 2019

There were some clouds across eastern and far northern Wisconsin
today but few clouds remained by 20Z, mainly across far northern
Door County. High pressure that was centered over the Plains early
this afternoon is expected to reach the Great Lakes by Tuesday

Winds will be light and there should be few clouds as the high
passes. These conditions are expected to allow temperatures to
fall below zero tonight, except in the Fox Valley and Lakeshore
area where lows should be around or a little above zero.

Return flow behind the departing high will result in an increase
in clouds, but even with the cold start and increasing clouds
there should be enough warm advection for temperatures to reach
the lower to mid 20s for highs on Tuesday.

.LONG TERM...Tuesday Night Through Monday
Issued at 258 PM CST Mon Feb 18 2019

An upper trough moving from the central Plains towards
the western Great lakes is forecast to produce a period of strong
vertical motion across Wisconsin Wednesday. Moisture is not very
abundant, but should be enough to produce a moderate snowfall. Four
to six inches of snow appear likely in central and north central
Wisconsin, where the best upper support and low level warm advection
is expected. Two to four inches should fall in the Fox valley and
Lakeshore areas, where the snow could end as freezing drizzle
Wednesday night.

Dry weather should follow for Thursday through Friday night with
seasonable temperatures as upper flow becomes zonal.

The medium range models then forecast a strong upper low lifting
northeast from the southwestern United States to produce an
intensifying surface low that tracks from the panhandles of
Oklahoma and Texas Saturday morning towards southern Lake
Michigan Sunday afternoon. There are significant differences in
the models regarding the type and amount of precipitation, so an
accurate forecast is not likely at this point. It does appear that
there would be moisture available from the Gulf of Mexico, and a
strong temperature contrast across the front. That could make for
a big winter storm somewhere in the Midwest or Great Lakes.

.AVIATION...for 00Z TAF Issuance
Issued at 542 PM CST Mon Feb 18 2019

VFR conditions will prevail across the region through the TAF
period, with the possible exception of patchy MVFR/IFR fog in
central and north central WI late tonight/early Tuesday. Given
the dryness of the air mass, confidence in fog development is
low, so will not mention it with this set of TAFs.

A band of mid-level clouds is expected to move through the
northwest part of the forecast area during the late evening
and overnight hours.

Light west winds should become south-southwest during the mid to
late afternoon on Tuesday.




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