328
FXUS63 KGRB 151917
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
217 PM CDT Wed Oct 15 2025

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Temperatures will begin to trend warmer Thursday and by Friday
  highs are back in the upper 60s to 70s for most.

- Periodic rain chances and a few thunderstorms expected Thursday
  into Friday morning and Friday night through Sunday.

&&

.DISCUSSION...
Issued at 209 PM CDT Wed Oct 15 2025

Rest of Today through Friday...

An upper ridge continues to build over northern WI this afternoon
with skies clearing out across northern and northeastern WI. Expect
the clearing trend to continue south and west this evening, however,
mid-level clouds may be more stubborn across central WI as winds turn
to the south and begin to usher in additional moisture. Where skies
do clear out across northeast WI tonight isolated areas of patchy fog
may develop early Thursday morning, however, don`t expect the
impacts from fog to be widespread.

Thursday a warm front is progged to lift northward over the region
as a low currently over the four-corners region lifts toward the
northern Plains. Behind the front an increasing LLJ will advect
ample moisture into the region, PWATS up to 1.5" (99th percentile).
This will lead to the chance for multiple rounds of showers and
possible thunderstorms beginning during the mid-morning and
continuing through the night. Don`t expect any thunderstorms to
become strong, as instability is going to be limited ( >150 J/kg
MUCAPE), however, with the strong dynamical forcing related to the
low and the anomalous moisture a few isolated storms will be possible
(20-30%) mainly during the afternoon and evening. Rainfall totals
are forecast generally range from 0.25 to 0.50 inches, however,
there is a 10-15% chance for isolated areas to receive over 1" of
rain if multiple storms pass over the same location.

By daybreak Friday expect much of the precipitation to be out of the
region as another brief period of ridging develops over the
state.

Saturday through middle of next week...

Global ensembles show an upper trough and associated cold front
dropping out of the Canadian Rockies toward the Upper Midwest late
Friday into Saturday. This will bring another chance (50-80%) for
rain and possible thunderstorms to the region Friday night into
Saturday. Anomalous moisture with this airmass (95-99th percentile
PWATS) along with strong dynamical forcing does increase the chance
for some higher rainfall amounts with this system. Uncertainty with
this system increases into Sunday as many ENS ensemble members show
the cold front stalling out across eastern Wisconsin with a surface
low developing behind the front which would cause rain to linger
through much of Sunday, especially east of I-41/US 141. However,
the GEFS is more progressive with when the front pushes off to the
east. QPF probs for greater than 0.50 inches of rain during this
this period are 40-60%. For greater than 1 inch prob are 20-40%,
highest across eastern Wisconsin.

Northwest winds are expected to become breezy Sunday as the
pressure gradient tightens behind the departing low. LREF probs
show 30-40% chance for greater than 30 mph gusts across much of
the region Sunday afternoon.

Cluster analysis of 500mb heights during the first half of next week
show a low predictability pattern as ensembles members diverge with
the placement of upper troughs and ridges.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1215 PM CDT Wed Oct 15 2025

Mix of VFR and MVFR cigs across the region early this afternoon. As
a Canadian high continues to build into the region expected skies to
continue clearing from northeast to southwest this afternoon and
evening. Tonight expect mostly clear skies north and east of a MTW
to RHI line, while scattered mid-level clouds may linger to the
south and west. Where skies clear over northeast WI patchy areas of
fog may develop, but confidence that fog develops at any particular
TAF site is too low to include with this TAF issuances.

Thursday a warm front lifting north will return the chance for
scattered showers and possibly a few isolated thunderstorms during
the late morning through the afternoon and evening. Cigs will also
gradually lower as the front moves north Thursday with MVFR cigs
possibly returning to AUW, CWA, and RHI by the end of the TAF
period.

&&

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

&&

$$

DISCUSSION.....GK
AVIATION.......GK

NWS GRB Office Area Forecast Discussion