371
FXUS63 KGRB 221151
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
651 AM CDT Tue Apr 22 2025

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Periodic chances for rain expected through the work week, with
  dry conditions returning for the weekend. Thunderstorms
  possible Wednesday afternoon and evening.

- Gusty northeast winds possible Thursday night into Friday night,
  especially in the Fox Valley and lakeshore areas.

- Warming temperatures into mid-week, dropping back to normal on
  Friday, then moderating again over the weekend.

&&

.DISCUSSION...
Issued at 503 AM CDT Tue Apr 22 2025

Precipitation Chances: A band of frontogenetic forcing and WAA
will bring an area of showers through the forecast area this
morning and early afternoon. The showers will likely weaken as
they shift into far NE WI, due to the presence of a dry Canadian
high pressure system. Will carry the highest pops over the
western part of the forecast area. Although thunderstorms are
ongoing on the western periphery of the precipitation in eastern
MN, models show the best instability staying to our southwest/
south, so have left any mention of storms out of the forecast.
The weakening showers will lift into Upper MI by mid-afternoon,
followed by dry weather for the rest of the afternoon and tonight.

A cold front will approach the region on Wednesday, and edge into
NC WI later in the afternoon. Ahead of the front, moisture will
increase, with PWATs rising to around an inch in eastern WI during
the afternoon. In addition, modest instability (CAPE of 300-800
j/kg and mid-level lapse rates around 7 C/km) will build ahead of
the front, resulting in a diurnal increase in showers and
scattered thunderstorms during the afternoon/early evening. Deep
layer shear is strong (45-60 knots), so isolated strong storms
could form if enough heating occurs. The showers and storms will
decrease in coverage as the front shifts east later in the
evening, but a few showers may return to the southern part of
forecast area late.

On Thursday and Thursday evening, scattered showers may persist
across central and east central WI, where better moisture will
reside, but overall forcing looks to be weak. Farther north, have
reduced model blended pops, as high pressure over Ontario will
continue to feed dry air into the region. General model concensus
is for showers to increase late Thursday night into Friday morning
as a short-wave tough moves through and low pressure tracks south
of the region. Should see a diminishing trend in the precipitation
Friday afternoon and evening, followed by dry conditions over the
weekend as high pressure builds into the the western Great Lakes.

A strong low pressure system is expected to lift northwest of the
region early next week, and drag a cold front through WI Tuesday
and Tuesday night. The chance of showers and thunderstorms will
increase as the front approaches.

Gusty Winds Thursday Night into Friday Night: Winds will be
light to moderate through Thursday morning. The pressure gradient
will increase between high pressure over Hudson Bay and low
pressure tracking through IL late in the work week. This is a
good setup for gusty NE winds to funnel down the bay of Green Bay.
Gusts to 25 to 35 mph will be possible in the Fox Valley and
lakeshore areas, especially Friday into Friday evening.

Temperatures: A warming trend is expected into mid-week, with
highs reaching into the 60s and lower 70s on Wednesday. A modest
drop in temperatures is expected after the cold front moves
through Wednesday night, and in association with increasing
clouds and precipitation. This should cause temperatures to
settle back to around normal by Friday. Partly cloudy skies will
help boost readings above normal over the weekend, with much
above normal temperatures possible early next week.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 638 AM CDT Tue Apr 22 2025

Mid-level clouds were thickening over the southwest part of the
forecast area early this morning, and a few showers were brushing
through parts of central WI. While the main area of showers and
embedded storms was headed south of the region, another band of
showers was pushing into western WI and tracking toward
CWA/AUW/RHI.

The frontogenetic band of showers will lift NE, impacting mainly
the northwest half of the forecast area this morning and early
afternoon. Ceilings will gradually lower through the day, and drop
to MVFR in many areas near the back edge of the rain. Clearing is
expected to arrive in the very late afternoon and evening, which
will set the stage for patchy IFR fog development late tonight.

SE winds will pick up a bit this afternoon, with gusts to around
15 kts. The winds will diminish early this evening.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION.....Kieckbusch
AVIATION.......Kieckbusch