587
FXUS63 KGRB 241234
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
734 AM CDT Wed Jun 24 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Chances for showers and storms at times through Thursday
  afternoon. A few of the storms this afternoon and evening may
  become strong or severe, producing gusty winds and hail.

- Near to below normal temperatures rest of this week, trending
  above normal and humid by early next week. Periodic chances for
  thunderstorms are also possible early next week, with the
  potential for severe weather.

&&

.DISCUSSION...
Issued at 108 AM CDT Wed Jun 24 2026

Precipitation/Thunder Chances...Radar early this morning shows
cluster of showers and thunder from southern MN into southern WI
closely tied to sfc-925mb front. Majority of lightning is downstream
of highest MUCAPE along nose of LLJ. Farther into our area, earlier
area of showers that moved into central WI faded fast, with just
some light showers and sprinkles left shifting toward the Fox
Valley and far northeast WI. Still think southern Fox Valley to
lakeshore will see expansion of showers and perhaps some thunder
late tonight through mid morning as main frontal zone is impinged
on by increasing LLJ. Beyond this, a bit murky how much additional
showers and storms form through the rest of the morning as warm
front tries to lift in from the south. Could be the wave causing
more organized area of showers and storms over central MN (well
beyond the peak of the diurnal cycle) that will serve as the
mechanism to keep a few showers and storms going for the morning
as some models show.

Better agreement that once clouds scatter out and some insolation
is realized, another batch of showers and some storms will
develop this afternoon (per HREF paintballs of 40+ dbz echoes and
higher probs of 1hr qpf >= 0.01") with the approach of main mid-
level low and sfc low. Stronger storms will be capable of hail,
gusty winds with wbzero heights 7-8kft and sufficient effective
shear. One other thing that could have to be watched is our area
being in favorable spot for non-supercell spin ups or funnel
clouds with the low overhead increasing sfc vorticity and with
steeper low-level lapse rates nearby this afternoon. Shower
chances will then slowly wane this evening as the parent trough
slides across the upper Great Lakes. Some fog could occur late
tonight, with best chances of sharply reduced visibility over
northern WI and maybe closer to Lake Michigan. Agreement on this
is not great though.

Next round of showers and some thunder will come during peak heating
on Thursday. There is a hint of a stronger wave on the west side
of the departing trough which would enhance at least the coverage
of the SHRA/TSRA. Severe weather not expected through as probabilities
of sufficient cape/shear for organized storms is pretty low (

NWS GRB Office Area Forecast Discussion