NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 190659
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
159 AM CDT Fri Jun 19 2026

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Scattered showers and thunderstorms will bring a 50-70% chance
  of rain this evening and tonight. Any storms will be capable of
  producing hail.

- A few storms may also develop on Saturday afternoon across far
  northeast Wisconsin near the Upper Peninsula of Michigan.

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

&&

.DISCUSSION...
Issued at 158 AM CDT Fri Jun 19 2026

Active Weather Today and Tonight... Mostly sunny skies will start
off the day before cloud cover moves in ahead of a strong
shortwave during the afternoon. Expect storms and showers to
develop upstream over Minnesota and northwestern Wisconsin before
crossing into portions of western and central Wisconsin by the
late afternoon. Surface based instability shows a corridor of
higher values upstream of our area but will still have around
400-700 J/kg available when storms arrive. Main concern for any
storms will be hail, as the colder airmass keeps freezing levels
relatively low around 7000 feet while mid-level lapse rates for
the late afternoon to evening get to around 6.5-8 C/km which
would support elevated updrafts through the hail zone. Again, the
better potential for hail will be to our west where instability
and bulk shear may better organize storms, but would watch for
hail in our area as well as storms roll into the region. Showers
and storms will continue to track eastwards with the shortwave
overnight, but hail potential is expected to decrease through the
overnight period. SPC has a Marginal risk area from eastern
Minnesota to western and portions of central Wisconsin, which
makes sense given the decent hail parameters at play.

Rest of the forecast...
Upper troughing over Canada will persist through the remainder of
the forecast, with several low amplitude shortwaves expected to
cross the region through the weekend and into next week. The next of
these will be on Saturday afternoon, bringing a chance for rain to
northeastern Wisconsin, mainly along the Upper Peninsula border.
The main factor in any showers will likely be diurnal instability,
but the shortwave will help bring a small thunder chance in
supporting the updrafts for any showers. The northwesterly flow
will also play a factor in whether or not we see rain on the
northern edge of a strong system on Sunday. This track has changed
as we get closer, with the previously dry forecast for the entire
area now bringing a chance for rain into central and east-
central Wisconsin.

Unsettled weather then continues into the middle of next week,
when another round of more widespread active weather will be
possible.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 928 PM CDT Thu Jun 18 2026

VFR conditions are expected to prevail throughout the TAF period.
Agitated cu field with bases at around 5 to 6k should develop late
Friday morning with daytime heating, followed by SCT showers and
storms arriving from the west during the afternoon. Gusty outflow
winds, small hail, and periods of heavy rain will be possible with
any stronger storms. The best chances for thunder (20 to 30%) will
be over central Wisconsin, especially near AUW and CWA. Brief
vsby reductions to MVFR or IFR will be possible if a heavier
shower or storm moves over a terminal.

Prevailing northwest winds will continue to subside overnight,
before increasing slightly and gusting to 15 knots at times
Friday afternoon. Locally higher gusts will be possible with any
shower/storm activity.

&&

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

&&

$$

DISCUSSION.....Uhlmann
AVIATION.......Goodin