NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 221112
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
612 AM CDT Mon Jun 22 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Next chance for widespread showers and thunder Tuesday night
  through Wednesday. Risk of severe weather is low.

- Near to below normal temperatures most of the week, then more
  summer-like conditions arrive over the weekend.

&&

.DISCUSSION...
Issued at 306 AM CDT Mon Jun 22 2026

Patchy fog has returned to portions of the northwoods early this
morning as high clouds moved out and winds remained light. This
fog is not expected to become dense during the morning hours and
will depart fairly quickly around sunrise. Quiet weather and sunny
skies are then in store for the remainder of the day that will
last into Tuesday afternoon.

The next round of active weather arrives Tuesday evening. A mid-
level trough over the Upper Plains will allow for a period of
warm/moist air advection to the region. Showers and some thunder
then develop through the overnight hours as a LLJ develops
overnight with the exit region point into central to east-central
Wisconsin by the early morning hours. Instability ahead of this
will be relatively meager, hampered largely by the overnight
timing. Thus severe weather potential remains low. PWATs during
the overnight period have come up to around 1.25-1.50", which in
turn has brought up the overall rainfall totals. Probabilistic
guidance now brings a 50-70% chance of exceeding half an inch of
rainfall to the region, with much of that falling early Wednesday.
Probability of exceeding an inch remains low however, around
15-20%. Therefore would expect this to represent a reasonable
locally high amount for the current forecast. The main push of
precipitation will likely move through by the morning hours, but
some additional showers and non- severe storms may follow during
the day Wednesday. Any following afternoon storms will lack the
moisture from the overnight period, so rainfall amounts will be
much lighter.

Thursday continues to have some active weather in the forecast as
well, relying largely on diurnally driven instability to produce
rainfall. Without significant moisture return and MUCAPE ~400-500
J/kg or less, would expect low potential for any severe weather on
Thursday as well.

Finally, a pattern shift is expected over the weekend as upper
flow becomes more amplified and a broad trough digs into western
CONUS. This will bring fairly strong southwesterly flow and allow
for much warmer and more moist air to move into the region. Long
range models bring high temperatures into the middle to upper 80s
by early next week. Active weather could certainly accompany this
more unstable airmass and some showers and storms are in the
forecast, which does provide some early hints this may be our next
chance for some stronger storms, but its early yet to truly assess
severe weather details.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 612 AM CDT Mon Jun 22 2026

Brief area of low clouds will cross the region this morning,
exiting the region early in the TAF period. A period of good
flying weather follows with mostly clear skies and light winds.

&&

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

&&

$$

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