132
FXUS63 KGRB 021914
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
214 PM CDT Wed Sep 2 2026

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Multiple rounds of thunderstorms are possible late tonight
  through Thursday. A few strong to severe thunderstorms are
  possible with damaging winds and large hail being the main
  threats.

- Above normal temperatures and periodic rain/storm chances will
  continue through the weekend.

&&

.DISCUSSION...
Issued at 213 PM CDT Wed Sep 2 2026

Dry conditions will prevail for the remainder of the day as a weak
ridge builds over the region. Tonight areas of patchy fog will again
be possible with light winds and a moist boundary layer. A round of
showers/thunderstorms is expected to develop overnight/early
Thursday morning across IA and southwest WI along the noise of a
strengthening LLJ. There is still a lot of spread amounts the latest
CAMs as to how morning convection will play out exactly, but a
parameter space of ~1500 J/kg and 40-45kt 0-6km shear along and just
north of I-90 does point to at least a low (10-20% chance) for
strong to severe storms with up to 1 inch hail and 40-60 mph wind
gusts as these storms move northeastward through central and east-
central WI. A second round of thunderstorms is possible Thursday
afternoon/evening as a compact mid-level shortwave moves across the
region. CAMs suggest initially discrete cells develop over ND/MN with
the potential to grow upscale into an eastward propagating MCS
during the afternoon. If an organized MCS is able to develop would
expect it to track along the instability gradient from east central
WI toward northern IL. This would put parts of the forecast area,
south of a Merrill to Green Bay line in play, however, there is still
a lot of uncertainty with how convection will evolve through the
afternoon and evening.

The warm and humid airmass will continue to linger over the area
Friday through this weekend keeping on and off chances for showers
and storms each day. However, confidence in the timing of any
precipitation is low as forcing remains rather nebulous due to the
lack of stronger synoptic features.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1232 PM CDT Wed Sep 2 2026

VFR conditions are expected through the rest of the day. Tonight
light winds and a moist boundary layer may result in areas of
patchy fog across much of the region.

Next chance for thunderstorms arrives early Thursday morning as
scattered to widespread storms are expected to develop across
central WI shortly after sunrise and spread north and east through
the morning. There is uncertainty regarding the timing of storms
impacting any terminals so have framed out the best chance timing
with PROB30 groups at all TAF sites. As storms progress through the
morning there is a low-end ~20% chance that a storms becomes strong
to severe with strong wind gusts and hail being the main impacts
along with brief heavy downpours. There is an additional chance for
storms Thursday afternoon/evening, however, the timing and intensity
of these storms is uncertain and will be impacted by earlier storms.

&&

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

&&

$$

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

NWS GRB Office Area Forecast Discussion