NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 250002
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
702 PM CDT Wed Jun 24 2026

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- Chances for showers and storms at times through Thursday
  afternoon. Some of the storms this afternoon and evening may
  become severe, producing large hail and damaging winds.

- 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 146 PM CDT Wed Jun 24 2026

Precipitation/Thunder Chances...Scattered low clouds prevailed
across the region early this afternoon ahead of an impending surface
low and it's weak cold front. Decent destabilization has already
occurred over western WI early this afternoon with SBCAPE of 1500-
2000 J/kg, paired with 30-40 of effective bulk shear across central
WI. As a result, isolated storms have developed in portions of
northern WI and west-central WI, some of which have already had
reports of severe hail. Generally, scattered to numerous showers and
storms are anticipated this afternoon and evening, ending soon after
sunset with the loss of diurnal heating. SBCAPE of 1500-2000 J/kg
and deep-layer shear of 30-40 kts is anticipated during this time,
leading to updraft organization producing a mix of multicells,
supercells, and perhaps some splitting cells, aiding in a risk of
large hail up to 1.50 inches and damaging winds up to 60 mph. There
is also a very low risk for spin ups or funnel clouds due to the
proximity to the surface low and steeper low-level lapse rates,
mainly in central and north-central WI.

As the surface low and a mid-level trough move over MI on Thursday,
additional isolated showers and storms are anticipated Thursday
afternoon into the early evening, aided by up to 500 J/kg of CAPE.
However, no severe weather is expected.

Models continue to indicate a stark pattern change occurring this
weekend with an upper-level ridge building over the area before
breaking down sometime during the middle of next week. This would
bring more summer-like conditions to the area with increasing Gulf
moisture and potential ridge riders resulting in thunderstorms at
times, including possible severe storms at times. Will continue to
watch how this pattern change evolves over the coming days for any
impactful weather. At this point, the main takeaway is to plan on a
much more active weather pattern developing, with storm potential
not tied exclusively to peak heating of the day.

Fog Potential...Following the showers and storms this afternoon and
evening, 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.

Temperatures...Below normal temperatures in the low to mid 70s and
comfortable humidity levels will continue through Friday.
Temperatures then gradually warm to normal on Saturday and above
normal on Sunday through early next week into the upper 80s to mid
90s due to the ridging pattern change. In addition to the much
warmer temperatures, dew points will also rise into the low to
possible mid 70s by Monday. If this pattern pans out, we could be
looking at a couple day stretch of heat-related impacts occurring.
This is already being highlighted with the NWS HeatRisk on Monday
with the Major (level 3 of 4) category and Major with some Extreme
(level 4 of 4) category on Tuesday.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 627 PM CDT Wed Jun 24 2026

Scattered showers and thunderstorms will gradually diminish
this evening, with any lingering showers ending late this evening
or overnight. The main concern will be low stratus and areas of
fog developing late this evening and overnight. Any low clouds
and fog should lift Thursday morning. Another chance of showers
and storms arrive Thursday afternoon.

&&

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

&&

$$

DISCUSSION.....Kruk
AVIATION.......Eckberg