378
FXUS63 KGRB 251718
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1218 PM CDT Thu Jun 25 2026

Updated aviation portion for 18Z TAF issuance

.KEY MESSAGES...

- Locally dense fog, with visibilities between one half and one
  quarter mile, possible through late this morning.

- Isolated to scattered showers/storms possible this afternoon.
  Potential for strong or severe storms then increases into early
  next week.

- Below normal temperatures through Friday, rising to above normal
  through the weekend. Potential for heat-related impacts early
  next week.

&&

.DISCUSSION...
Issued at 1231 AM CDT Thu Jun 25 2026

Fog... As showers and storms continue to diminish overnight,
remnant moisture near the surface has resulted in patchy fog
development across the region. CAMs continue to show the greatest
signal for locally dense fog, with visibilities between one half
and one quarter mile, along the lakeshore through late this
morning. Signal for fog becomes less clear further west, with
equal chances for manifesting as low stratus.

Rain/storm chances... Additional chances for diurnal showers and
storms will be possible Thursday afternoon as mid-level shortwave
pivots through the Great Lakes and cyclonic flow persists.
Instability remains meager (500 to 700 J/kg MUCAPE), so storm
coverage should remain isolated to scattered. No severe weather is
expected.

Long-range ensemble/ML guidance remains locked in for a ring of
fire pattern developing over the eastern CONUS early next week,
bringing us our first true taste of summer thus far. Influx of
moisture from a wide open Gulf will result in potential for ridge
rider activity at times, with severe weather on the table as said
moisture interacts with instability reservoir under the ridge.
Hard to pinpoint exact timing of any stronger storms this far out,
as this will hinge on how the upper pattern evolves. Timing of
frontal passages will also play a role in strong or severe storm
development. As of right now, biggest hindrance to the forecast
looks to be substantial capping in place Sunday and Monday, with
models showing 700 mb temperatures between 14 and 16C. Regardless,
expect a period of active weather late this weekend into early
next week, with finer details to come within the next few days.

Temperatures... Below normal temperatures continue through Friday,
with highs gradually warming into the weekend as heat ridge
builds. Temperatures peak in the low to mid 90s across the area
Monday and Tuesday, with little to no overnight recovery as lows
only fall into the 70s. Dewpoints will also rise into the low to
mid 70s during this time, resulting in potential for several days
of heat-related impacts. Major (level 3 out of 4) to extreme
(level 4 out of 4) risk for heat-related impacts are already being
highlighted for Monday and Tuesday, which would necessitate
headlines at some point this weekend if trends hold. Only factor
that would potentially mitigate higher end temperatures would be
any storm complexes or associated cloud shields that pass over
the area.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1214 PM CDT Thu Jun 25 2026

Scattered showers and isolated storms will continue to sink
southward this afternoon. The probabilities of thunder was so
low, only went with a tempo group for showers at the TAF sites.
Also, any lingering MVFR CIGS will rise into the VFR category
during the afternoon. Skies will become clear to partly cloudy,
with only high clouds streaming across central and east-central
WI after sunset. Fair weather cumulus is expected to develop
again late Friday morning from 1,500 to 2,500 feet.

&&

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

&&

$$

DISCUSSION.....Goodin
AVIATION.......Eckberg

NWS GRB Office Area Forecast Discussion