436
FXUS63 KGRB 150315
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1015 PM CDT Sat Jun 14 2025

.KEY MESSAGES...

- Periods of showers expected through the weekend, especially
  west and north of the Fox Valley/lakeshore areas.

- A warm, humid and stormy period expected for the early to mid
  part of the next work week, and again toward Friday/Saturday.
  Strong to severe storms and heavy rainfall will be possible at
  times.

&&

.DISCUSSION...
Issued at 339 PM CDT Sat Jun 14 2025

A band of light to moderate showers extended from RRL/AUW/CWA
east-northeast to northern Door County. These showers were
supported by H8 WAA and moisture convergence along a fairly tight
baroclinic zone. The showers have been very slowly weakening as
they have drifted south this afternoon. Low stratus has held
temperatures in the lower to middle 50s north, but clearing has
allowed readings to rise into the lower to middle 70s in parts of
central Wi and the Fox Valley.

Precipitation Chances through the rest of the Weekend:
Precipitation chances are difficult to pinpoint due to generally
weak forcing. CAMs suggest that the current showers will become
more scattered overnight, possibly increase again over our western
counties late tonight into early Sunday, then decrease in coverage
during the day. Kept chance pops going in our western counties
through the afternoon on Sunday, and carried a slight chance of
thunderstorms late, as elevated instability will be arriving then.
East to southeast winds, combined with scattered showers and
mostly cloudy skies, will keep temperatures from getting out of
the 60s in northern WI, but low to middle 70s will be possible
C/EC WI.

Stormy Period expected through much of the next Week:
The Canadian high will shift east early in the week, which will
allow a warm front to lift north through the region Sunday night
into Monday. This will cause southerly winds to develop and bring
warmer, more moist and unstable air into the region. Scattered
storms could develop in association with the warm frontal passage.
A cold front will move through MN on Monday, reach northwest WI
Monday night, then shift into GRB CWA on Tuesday, with additional
rounds of storms possible during this period. The front will edge
eastward Tuesday night into Wednesday, with a surface wave lifting
northeast along the boundary on Wednesday. It is possible that the
front will be east of the forecast area by Wednesday, which would
push the best potential for severe storms to our southeast.
Although timing is uncertain, this period has potential for a
couple rounds of severe weather, given sufficient instability and
deep layer shear. Timing of individual short-waves may be the
determining factor in whether we see a more significant/widespread
event.

Models are showing an even more unstable pattern setting up Friday
into Saturday, but with potential for significant capping as a
very warm air mass arrives. This will bear watching, as models are
showing CAPE as high as 4000-6000 j/kg, along with fairly strong
deep layer shear.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1015 PM CDT Sat Jun 14 2025

Observational trends and short term forecast guidance continues
to indicate persistent stratus overnight ranging from LIFR to
MVFR from central to northern Wisconsin, with higher likelihoods
for VFR conditions along Lake Michigan and through the Fox
Valley. Some MVFR/IFR fog may also persist overnight over
northern Wisconsin.

Confidence remains lower on coverage and placement of showers
overnight into Sunday. Maintained some SHRA at central Wisconsin
sites late tonight into Sunday, based on loose consensus of
high res model, but some adjustments may be needed. Otherwise,
there is not a strong precip signal evident through the rest of
the TAF period.

Winds will generally remain easterly, but will shift a bit more
southerly in spots on Sunday.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
WI...None.
MARINE...None.

&&

$$

DISCUSSION...Kieckbusch
AVIATION...JM