Green Bay, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

412
FXUS63 KGRB 030033
AFDGRB

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

Updated aviation portion for 00Z TAF 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 00Z TAF Issuance
Issued at 719 PM CDT Wed Apr 2 2025

Poor flying conditions will continue this evening and into early
Thursday as low pressure lifts northeast across the region. A few
showers, some drizzle and fog (locally dense) will continue this
evening, with some lighter snow showers possible over north
central WI overnight into Thursday morning. A few spots over the
far south could sneak into VFR conditions for a time this evening,
but this looks to be short-lived as clouds will spread back into
or redevelop in any areas of clearing. Some improvement to
ceilings are expected on Thursday, especially in the later morning
and afternoon. East to southeast winds will shift to the west
overnight and become gusty, with gusts to 30-35 kts into early
Thursday morning.

Gusty winds aloft will continue to produce LLWS into tonight,
especially when winds at the surface die off a little. The LLWS
threat will end Thursday morning.

&&

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

&&

$$

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