168
FXUS63 KGRB 210755
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
255 AM CDT Sun Jun 21 2026

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Cloudy but dry today. Larger weather system passes across
  northern Illinois and southern Wisconsin.

- Next chance for widespread rainfall will be the middle of next
  week.

- Near to below normal temperatures and comfortable humidity will
  prevail through next week.

&&

.DISCUSSION...
Issued at 255 AM CDT Sun Jun 21 2026

Today and Monday...

Some patchy fog will be in the area this morning but should burn
off quickly this morning before high clouds from a more southerly
system move in. The rest of the day continues to trend dry for
most of the region. The only exception will be along the Upper
Peninsula border, where isolated showers could develop briefly in
the afternoon. If you are traveling southwards today however,
expect scattered showers in Wisconsin and possibly severe weather
if you`re headed towards Illinois.

Monday will be a fairly quiet day across the region as we get
between systems, so expect a sunny and cool day for the region.

Midweek...
An approaching trough will bring rain back to the region late
Tuesday into Wednesday. Although the potential for rain is
relatively high (70-90%), with a fairly cool airmass, limited
instability, and limited moisture, the potential for severe
weather remains low. Similarly, the overall heavy rain potential
will also be limited, with medium range probabilistic guidance
maintaining around 30-50% chance of exceeding half an inch of
rainfall. After this initial round of rain, additional showers
will be in the region Thursday afternoon (40-60% chance).

Although predictability towards next weekend does remain lower,
early signs do point to a return of warmer temperatures and
increased moisture. High temperatures by next Sunday will get
highs into the middle 80s.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1004 PM CDT Sat Jun 20 2026

With mostly clear skies and light winds during the overnight
period, favorable conditions will exist for ground fog to develop,
particularly in the higher elevations of central and north-
central WI and areas which received measurable rainfall today. No
changes to forecast visibilities in the tempo groups at RHI, AUW,
and CWA to IFR in the 08-12Z time period.

Ground fog will burn off early Sun morning, likely by 13Z. Then
fair weather cumulus will pop in the 15-17Z time frame. Convective
allowing models indicate scattered shower activity will be
possible across north-central WI in the afternoon. Coverage should
not be as widespread as today, but an isolated shower could
impact RHI.

Light winds (under 10 kts) are expected through the TAF period.

&&

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

&&

$$

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

NWS GRB Office Area Forecast Discussion