002
FXUS63 KGRB 021902
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
202 PM CDT Wed Apr 2 2025

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- There is a chance of thunderstorms through early this evening. A
  few strong storms capable of producing small hail and gusty
  winds are possible, mainly in parts of central and east-central
  Wisconsin.

- Rainfall and runoff will likely lead to rises on area rivers,
  which may lead to minor flooding at a few locations late this
  week.

- The active weather pattern will abate once this system departs by
  Thursday morning across northeast Wisconsin.

&&

.DISCUSSION...
Issued at 201 PM CDT Wed Apr 2 2025

Short Term...Tonight...Thursday...and Thursday Night

The latest RAP analysis and satellite/radar imagery show low
pressure lifting northeast over northern Iowa early this
afternoon. A warm front extends southeast from the low across
central Illinois and Indiana. As the dry slot advances into
southwest Wisconsin, widespread precipitation has exited across
the northeast part of the state. Additional shower activity over
western Wisconsin will likely move into north-central WI where
temperatures in the low to middle 30s. This precip will likely
bring a rain snow mix for the rest of the day. Other widely
scattered showers could pop up at any time as well.

Further south, concern shifts to thunderstorm potential as
elevated instability lifts north into Wisconsin. Thunderstorm
activity has been confined to south of areas from Madison and
Milwaukee so far today. Short range models have backed off on
lifting most unstable capes upwards of 800 j/kg like they were
showing yesterday. Instead, convective allowing models support
most unstable capes around 200-300 j/kg which may be good for
isolated storms late this afternoon into early this evening (from
about 3-8 pm). While storms could produce small hail, the threat
of severe storms is very low.

As low pressure traverses the region, focus of this forecast then
turns to small precip chances along with gusty winds for the rest
of tonight into Thursday.

Precipitation trends tonight: Low pressure will travel from west-
central Wisconsin at 7 pm to western Lake Superior shortly after
midnight. Scattered showers and perhaps a few thunderstorms will
rapidly lift to the northeast across north-central and northeast
Wisconsin this evening. Then light snow will wrap around the
cyclone and return to north-central WI after midnight into
Thursday morning. A dusting of snow will be possible before the
snow showers come to an end by midday Thursday.

Gusty winds: Cold advection moves into the region after midnight
via west winds. Low level lapse rates will take some time to
steepen, so think gusts from 20-30 mph will be possible late
tonight. But both the RAP and the HRRR indicate that there will be
a period of gusty winds 30-40 mph on Thursday morning with help
from surface heating. This gustiness should diminish on Thursday
afternoon, leading up to winds becoming calm on Thursday night.

Temperatures: Near normal on Thursday with highs ranging from the
lower to middle 40s at most locations. With better radiational
cooling conditions, temps to fall into the lower 20s to lower 30s
on Thursday night.

Long Term...Friday Through Wednesday

A quieter pattern is in store for northern Wisconsin over the next
week. A northern stream trough will amplify and dig across the
western Great Lakes this weekend. While this trough will focus the
storm track over the Ohio Valley, light rain and and snow will be
possible at times from Saturday through Monday. Minor
accumulations will be possible, particularly at night. The highest
chances for minor accumulations will be on Friday night and also
Sunday night into Monday.

Thereafter, polar high pressure will build into the region on
Monday and Tuesday before departing on Wednesday. As the high
departs, warmer air will gradually push back into the region.
Monday and Tuesday look to be the coolest days over the next week
(besides today) with highs ranging from the lower 30s to middle
40s.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1111 AM CDT Wed Apr 2 2025

Poor flying conditions are expected to continue through Thursday
morning. Low pressure will be lifting northeast across the region
through the evening hours. While widespread precipitation will be
exiting for a time through early this afternoon, precipitation is
expected to become more widespread this afternoon mainly north and
west of the Fox Valley. Visibilities may fall for a time into MVFR
or briefly IFR within this precipitation.

After precipitation ends around mid to late evening, gusty west
winds will develop overnight into Thursday morning. Gusts from 30
to 35 kts will be possible at times. Some improvement to ceilings
is possible on Thursday morning.

Low level wind shear will also be an issue to flying at times
through Thursday morning.

&&


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

&&

$$

DISCUSSION.....MPC/MPC
AVIATION.......MPC

NWS GRB Office Area Forecast Discussion