NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 261823
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
123 PM CDT Tue May 26 2026

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Hot this afternoon with record to near-record temperatures in
  the upper 80s to lower 90s.

- 50 to 70% chance for showers and thunderstorms this afternoon
  and this evening, with some strong to marginally severe storms
  possible with large hail and strong winds.

- Isolated thunderstorms are possible Wednesday afternoon across
  central Wisconsin. An isolated storm could become severe with
  large hail and damaging winds.

- Above normal temperatures for the next week, with highs mainly
  in the upper 70s and 80s.

&&

.DISCUSSION...
Issued at 120 PM CDT Tue May 26 2026

Backdoor cold front/composite lake breeze off Superior is slowly
dropping across Upper Michigan into northern WI. Ahead of the front
it is hot and dry with early afternoon temperatures already into
the mid to upper 80s. Highs will reach the lower 90s, so could
see records in some locations. Record high for GRB today is 92
set in 2018.

Despite the heat, dewpoints are lagging the models which is
leading to MLCAPEs only up to 200J/kg thus far while SBCAPE is
over 1000J/kg. 18z sounding at GRB is quite dry through 700-600mb.
Overall think the drier air is why some models have backed off of
coverage and intensity of storms this afternoon and evening. CI
most likely will be closer to the front where there is currently a
batch of developing cu from Oneida into Marinette counties.
Expect isolated to scattered showers and storms to eventually form
in this area, then spread/expand as front moves southward into
this evening. Dry air and DCAPE over 1000 do lead to downburst
winds as the primary hazard. For storms that get taller, CAPE in
the hail growth zone also results in hail as hazard. Overall the
forecast is pretty similar, but the coverage of storms does look a
bit less.

Once the front slides through north to south this evening, winds
turn northeast and cooler/moisture airmass arrives. Could be fog
late tonight, especially where showers and storms are most
prevalent into this evening. Post frontal airmass with gradient
northeast winds on Wednesday will not be as toasty. Trimmed highs
from NBM and went more with consensus of models/ensembles. Result
will be upper 60s near Lake Michigan, upper 70s/near 80 Fox Valley
and northern WI, and mid 80s over central WI. Greatest potential
for storms, mainly non-severe, on Wednesday will be across central
WI.

High pressure then builds in the rest of the week into the coming
weekend. Dry weather is expected. Other than Thursday when temperatures
will be around normal, readings will push above normal into early
next week, with highs in the mid 70s to mid 80s. The warmest day
will be Friday. Despite the Canadian high settling overhead, temps
at night even in northern WI will remain above 40, so no frost issues.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1224 PM CDT Tue May 26 2026

A cold front will sag south across the area this afternoon, with
scattered showers and thunderstorms developing by late afternoon,
and continuing across central and east-central Wisconsin through
the evening. Kept TEMPO groups for mostly likely 4-hour period
for thunderstorms for the TAF sites. Dry weather is then expected
overnight, though where storms occur some IFR/MVFR fog is possible.

South to southwest winds will gust to around 15 kts at times
this afternoon, but will turn northeast in the wake of the frontal
passage this afternoon/evening. Light winds below 10 kts are then
expected overnight. NE winds around 10 kts are expected Wednesday.

&&

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

&&

$$

DISCUSSION.....JLA
AVIATION.......JLA