952
FXUS63 KGRB 071853
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
153 PM CDT Tue Jul 7 2026

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- 20-30% chance of showers and thunderstorms this afternoon and
  evening across parts of north-central and far northeast
  Wisconsin.

- There is a 15-30% chance of severe thunderstorms (15-30%
  chance) and heavy rain (15% chance) on Wednesday afternoon and
  evening, primarily across central and east- central Wisconsin.
  Damaging winds and localized flooding will be the main threats,
  but isolated large hail and a tornado are also possible.

- Monitoring the potential for excessive heat early next week as
  high temperatures rise into the low to middle 90s on Monday and
  Tuesday.

&&

.DISCUSSION...
Issued at 152 PM CDT Tue Jul 7 2026

The latest RAP analysis and satellite/radar imagery show a weak
sfc trough across northeast Wisconsin early this afternoon.
Dewpoints have been creeping up this morning and are comfortably
in the low to middle 60s. Meanwhile, a weak cold front is draped
across western Lake Superior and central Minnesota, with upstream
convective clusters developing across the northern Plains that
will eventually influence our weather over the next 24 TO 36
hours.

Scattered Afternoon/Evening Storms: With further daytime heating,
instability is projected to rise into the 1000-1500 j/kg range
this afternoon over north-central and far northeast Wisconsin. Low
level moisture convergence will be favorable for pop up showers
and storms along a weak surface trough, with 3-8 PM being the
most favored time period. Brief wind gusts in excess of 40 mph and
heavy downpours will be possible with any showers today before
dissipating around mid- evening.

Wednesday Afternoon and Evening Severe/Heavy Rain Risk: Attention
turns to late tonight when the upstream cold front sags into
northern Wisconsin, bringing clusters of thunderstorms across
northern Wisconsin late tonight into Wednesday morning. This first
round should exit by late morning, but its evolution (coverage &
timing) will help determine the severe potential for late
afternoon and evening. There is potential for outflow to create an
effective front over central and east-central Wisconsin, but
considerable uncertainty exists how this will evolve. If the
atmosphere can recover, potential instability from 1500-2500 j/kg
and effective shear of 25 to 30 kts will support organized storms
from 3-9 PM. Damaging winds will be the primary threat, but an
organized storm could also produce isolated large hail and an
isolated tornado. Locally heavy rainfall of 2-4 inches is under a
15% chance, with the greatest potential across central and east-
central Wisconsin.

Excessive Heat Potential Early Next Week: After the threat of
strong storms ends Wednesday night, the slow moving front sags
south on Thursday, leaving only light rain potential over central
and east-central Wisconsin. High pressure then moves across the
area on Friday through the weekend. By early next week, we will be
monitoring the potential for excessive heat. A potent sub-tropical
ridge is expected to build over the northern Plains and western
Great Lakes in the 95-100 percentile. There is a 60-80% chance of
850 mb temps greater than 20C on Monday and Tuesday, which would
equate to surface highs in the low to mid 90s.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1155 AM CDT Tue Jul 7 2026

A band of mid and high clouds is passing over northeast Wisconsin
late this morning. Beneath these clouds, fair weather clouds will
develop by early afternoon. Brief MVFR ceilings are possible at
RHI/AUW/CWA prior to 19Z. Widely scattered to scattered showers
and storms are expect to pop between 3 and 8 PM across north-
central and far northeast WI. RHI has highest probability of being
impacted (up to about 25%), but low confidence on coverage and
will monitor for amendments.

After the daytime instability showers dissipate, VFR conditions
are expected until early Wednesday morning. As a cold front slowly
sags into the region, clusters of showers and storms are likely
to impact the region from 09Z-16Z. Added a prob30 or tempo group
at all TAF sites. MVFR ceilings and visibilities (locally IFR) will
be possible within the shower activity.

&&

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

&&

$$

DISCUSSION.....MPC
AVIATION.......MPC

NWS GRB Office Area Forecast Discussion