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fxus63 kgrb 182350 
afdgrb

Area forecast discussion
National Weather Service Green Bay WI
550 PM CST Mon Nov 18 2019

Updated aviation portion for 00z taf issuance

Short term...tonight and Tuesday
issued at 241 PM CST Mon Nov 18 2019

The latest rap analysis and satellite/radar imagery show a weak
surface ridge axis moving across the western half of Wisconsin
early this afternoon. Widespread low overcast remains in place
across the region and the clearing line over Minnesota has made
little progress eastward so far today. Visibilities in mist and
drizzle have gradually improved through midday, and Road
conditions have improved as well. Looking to the west, weak
shortwave energy is moving to the southeast over the eastern
Dakotas with mainly light right and temps in the 40s and 50s. As
this shortwave tracks towards the region late tonight into
Tuesday, forecast concerns mainly revolve around potential and
timing of light wintry weather.

Tonight...weak high pressure will shift east of the region, while
a warm front and shortwave energy approach from the west. With a
Stout inversion, overcast skies have little potential of
clearing. Meanwhile, the shortwave and associated warm front have
slowed down somewhat, and will approach central WI in the 3 to 6
am time period. Guidance generally keeps the heaviest precip over
western WI, but it appears that light snow will clip western
Marathon, wood, Portage, and Waushara counties where up to a half
inch of snow could fall by 6 am. Otherwise, clouds should limit
the nocturnal fall of temperatures, so trended heavily towards
last nights lows for lows tonight.

Tuesday...shortwave energy will continue to slide southeast across
the region. Light snow will likely be diminishing in the morning
over parts of central WI, where there may be an additional tenth
or two of accumulations. Although most models have precip
weakening by late morning, forecast soundings remain relatively
saturated through the rest of the day from the Fox Valley to
north-central WI. So wonder if the area will see occasional
freezing drizzle/drizzle/flurries once the more widespread precip
ends in the morning. With little change to the low overcast,
temps shouldnt warm much, and stayed with highs in the middle to
upper 30s.

Long term...Tuesday night through Monday
issued at 241 PM CST Mon Nov 18 2019

Mostly cloudy skies and generally dry conditions are anticipated
as a weak ridge of high pressure moves through Tuesday night into
Wednesday.

A strong low pressure system is expected to arrive Wednesday
night into Thursday, and the GFS/European model (ecmwf) are in decent agreement on
timing and a track through southeast/east central Wisconsin. Low-
level thermal profiles and thicknesses suggest rain across all but
the far northwest part of grb County Warning Area by early Thursday, where
pockets of snow or freezing rain may mix in. The rain/snow line is
expected to gradually shift southeast across north central WI
during the day, but the heavier precipitation should be tapering
off as this occurs. Could see 1 to 3 inches of accumulation in our
northwest counties before the system pulls out Thursday
afternoon. Farther southeast, a good slug of moisture, with pwats
exceeding 1 inch, will lead to moderate rainfall late Wednesday
night into Thursday morning, with rainfall totals likely reaching
a half inch to an inch. With frost depths of 4+ inches over the
forecast area, runoff from the rain could cause minor flooding
issues.

As the low pressure system exits, there will be potential for a
brief period of light lake effect snow showers over north central
WI Thursday night.

The weekend looks quiet, with systems tracking north and south of
the forecast area. Looks like a generally dry weekend, with
temperatures near seasonal normals.
&&

Aviation...for 00z taf issuance
issued at 550 PM CST Mon Nov 18 2019

The solid deck of IFR/MVFR ceilings will continue into Tuesday, with
vsbys possibly falling from VFR to MVFR this evening. Fog should
not get much worse due to the thick stratus deck in place. Ceilings
might lower slightly overnight into Tuesday as a weak weather
system pushes South/West of the area. Some light snow is possible
at kauw/kcwa/krhi, reducing vsbys for a time, but little to no
accumulation is expected. Some flurries, sprinkles, or drizzle is
possible Tuesday afternoon across the entire area, but confidence
not high enough to include in the tafs and not expecting any
impacts. Winds will remain very light through the taf period.
&&

Grb watches/warnings/advisories...
none.
&&

$$

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