782
FXUS63 KGRB 081659
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1159 AM CDT Tue Jul 8 2025

.KEY MESSAGES...

- A few showers and thunderstorms are possible across the area
  today, with the best window for any convection in the afternoon.

- Additional shower and thunderstorm chances possible late Friday
  into Saturday. Heavy rainfall possible with this second system.

&&

.DISCUSSION...
Issued at 355 AM CDT Tue Jul 8 2025

Precipitation Trends Today...
Overnight shower activity has largely missed our corner of
Wisconsin for the late overnight period. The more organized
clusters to our north have largely tracked along the upper
shortwave and 700mb moisture axis, while the more scattered shower
activity to our south remains oriented along the weak WAA and
moisture influx to our south. Lowered the pops through the mid
to late morning as a result, as virga and satellite do show
lingering potential for a stray shower, but not as widespread as
previously forecast. As moisture and warm air aloft continue to
push into the region through the morning, would expect some
spotty showers and storms to develop over the region by the late
morning and early afternoon. An uptick in any convection is
then anticipated for the mid to late afternoon as the tail end
of weak shortwave trough crosses into the region. Daytime
instability remains modest due to cloud cover, around 800-1200
J/kg,and shear remains relatively weak so the threat for severe
weather remains low. Some brief heavy rainfall will be possible
and storms will be relatively slow moving, but limited
thunderstorm coverage should help mitigate hydro concerns.
Probabilistic guidance keeps the probability of exceeding half
an inch of rain to around 20-30%, with only far north-central
getting to around 40%.

End of the Week System...
The next shot of active weather in the region will be around the
end of the week as a negatively tilted trough crosses into the
region Friday afternoon and evening. A surge of warmth and
moisture ahead of the trough will push PWATs above 2 inches, which
will certainly allow for another heavy rain threat. Initial looks
at severe potential for our area are unimpressive, with most model
soundings showing a lack of instability, likely due to an earlier
arrival of both rain and clouds which will limit reaching better
surface convective temperatures. How long the rain lasts into
Saturday is uncertain at this point, as the trough is expected to
promote the development of a low pressure system that then slides
off to our northeast. How far this gets during the overnight
period will dictate how much wrap around moisture we see as the
CAA follows on Saturday. Retained the pops from the previous
forecast cycle for now.

Temperature-wise we will run fairly close to normal through the
week, with a weak warming trend into Friday that could bring us
into the middle 80s.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1159 AM CDT Tue Jul 8 2025

Scattered storms (30-60% chance) will develop by mid-afternoon
before weakening in the evening. Some uncertainty in coverage
exists, although the highest chances appear to be focused across
far northeast Wisconsin. Updates likely will be needed, based
on afternoon trends.

Otherwise, a weak front will slide through this afternoon and
evening with winds becoming light overnight. As low-level flow
shifts northerly overnight, some guidance suggests MVFR/IFR
stratus developing for a period overnight into Wednesday
morning, so have trended that direction for this issuance.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
WI...None.
MARINE...None.

&&

$$

DISCUSSION...Uhlmann
AVIATION...JM