343
FXUS63 KGRB 071938
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
238 PM CDT Mon Jul 7 2025

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Seasonal summer weather is expected this week. Shower and
  thunderstorm chances expected late tonight through Tuesday
  evening, and Friday into Saturday. Heavy rainfall possible
  with the late week system.

&&

.DISCUSSION...
Issued at 238 PM CDT Mon Jul 7 2025

High pressure dominated our weather this afternoon, with SCT-BKN
stratocumulus, light winds and comfortable temperatures in the
70s.

Forecast concerns include shower/thunderstorm chances late tonight
through Tuesday evening, and again Friday into Saturday.

Precipitation Trends Late Tonight through Tuesday Evening...based
on the latest CAMs, will have the highest pops (Likely category)
impacting the forecast area late tonight through Tuesday morning.
The forcing during this period will be provided by the RRQ of a
weak jet streak, weak WAA and a modest influx of moisture (PWATs
1.2-1.7 inches) and elevated instability. Convection looks to be
more scattered during the afternoon and evening, as a short-wave
trough brushes through northern WI and a weak surface low/front
moves through. Daytime instability will be on the marginal side
(CAPE 800-1300 j/kg) due to extensive cloud cover, so the threat
of severe storms looks to be low.

Precipitation Trends Late Friday into Saturday... The late week
system appears to have a bit more dynamic forcing, with a
negatively-tilted short-wave moving through Friday afternoon and
night. In addition, PWATs will increase to around 2 inches in C/EC
WI, so at least locally heavy rainfall is expected. Current
probabilistic guidance is not too excited about heavy rainfall,
with only around a 10 percent chance of 1+ inches of rain. Suspect
these probabilities will come up a bit as we get closer to the
event. Have extended pops into Saturday, as an upper trough
crosses the region.

Seasonal temperatures are expected through next weekend, with
highs hovering a few degrees below to a few degrees above normal.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1226 PM CDT Mon Jul 7 2025

SCT-BKN stratocumulus clouds (VFR) were observed across much of
the forecast area at issuance time, along with light and variable
winds. No precipitation was reported regionwide, though a line of
showers and storms was moving into NW MN.

VFR conditions will persist through this evening. A round of
showers and storms will arrive at the western TAF sites by
09z-10z/Tue, and the eastern TAF sites by 12z-13z/Tue. Have added
TEMPO groups for thunderstorms at each site, with the most
favorable 4-hour time period for occurrence. MVFR conditions may
accompany storms, and some low clouds (MVFR/local IFR) will
probably impact RHI/AUW/CWA after the main band of showers moves
through. Light and variable winds will become SE-S tonight into
Tuesday morning.

&&

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

&&

$$

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