039
FXUS63 KGRB 071736
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1236 PM CDT Mon Jul 7 2025

Updated aviation portion for 18Z TAF issuance

.KEY MESSAGES...

- Seasonal summer weather is expected this week. Shower and
  thunderstorm chances expected tonight into Tuesday, and again
  Friday into Friday night.

&&

.DISCUSSION...
Issued at 219 AM CDT Mon Jul 7 2025

Today...

Mid-level clouds have developed over central and north-central WI
early this morning limiting the potential for fog to develop.
Will continue to monitor obs for any patchy ground fog that
develops early this morning, but widespread dense fog has become
unlikely.

A dry continental airmass in place over the region will deliver
pleasant summer conditions today. Highs this afternoon will reach
the upper 70s to low 80s at most locations with comfortable humidity
levels (dew points in the low 50s to around 60 degrees).

Precipitation Chances...

Next chance for precipitation arrives late tonight as an upper-
level short-wave tracks along the US/Canada border toward Lake
Superior. Severe weather parameters are not that impressive during
the period, CAPE 500-1000J/kg, 0-6km shear 25-30kts, and PWATS
1.3- 1.4 inches. Likely result will be scattered to widespread
showers through Tuesday morning with a few isolated thunderstorms
developing during the late morning and afternoon. Total rainfall
amounts are also not expected to be overly impactful as current
NBM probs for greater than 0.5" are only 30-40%. Probs fall to
10-15% for the chance of greater than 1".

Another round of rain is expected Friday and Friday night as a more
amplified trough digs over the upper Midwest. Similar to Tuesday
severe weather parameters are not all that impressive. PWATs are
higher (1.6-2") which could point to the potential for periods of
heavier rainfall within any stronger thunderstorms. However, global
ensembles show very weak vertical wind fields suggesting storms will
have a difficult time becoming organized and long lived.

Temperatures for the remainder of the week should remain seasonal
with limited humidity most days.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1226 PM CDT Mon Jul 7 2025

SCT-BKN stratocumulus clouds (VFR) were observed across much of
the forecast area at issuance time, along with light and variable
winds. No precipitation was reported regionwide, though a line of
showers and storms was moving into NW MN.

VFR conditions will persist through this evening. A round of
showers and storms will arrive at the western TAF sites by
09z-10z/Tue, and the eastern TAF sites by 12z-13z/Tue. Have added
TEMPO groups for thunderstorms at each site, with the most
favorable 4-hour time period for occurrence. MVFR conditions may
accompany storms, and some low clouds (MVFR/local IFR) will
probably impact RHI/AUW/CWA after the main band of showers moves
through. Light and variable winds will become SE-S tonight into
Tuesday morning.

&&

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

&&

$$
DISCUSSION.....GK
AVIATION.......Kieckbusch