Flower Lake, Wisconsin Weather Forecast Discussion

754
FXUS63 KGRB 202011
AFDGRB
Area Forecast Discussion
National Weather Service Green Bay WI
311 PM CDT Sat Sep 20 2025
Forecast discussion for routine afternoon forecast issuance
.KEY MESSAGES...
- Multiple rounds of showers and thunderstorms are expected this
  afternoon through Monday. Isolated strong storms with gusty
  winds, small hail, and heavy rain with localized flooding  will
  be possible at times.
- An isolated severe storm with hail to one inch in diameter
  can`t be ruled for the rest of this afternoon into early this
  evening, especially across central and east-central WI.
- Above normal temperatures are expected for much of next week.
&&
.DISCUSSION...
Issued at 310 PM CDT Sat Sep 20 2025
SHORT TERM (This Afternoon through Sunday)
First upper level disturbance moved away from the area late this
morning, bringing a lull in the shower and storm activity early
this afternoon. The second piece of energy was moving towards the
area as of mid-afternoon. In response, scattered showers and
thunderstorms developed across central and east-central WI. The
local mesoanalysis page indicated surface based CAPE values of
1,000-1,800 J/KG across central and east-central WI. 0-6km shear
values were around 25 knots. The upper level feature is expected
to move across the area for the rest of the afternoon into this
evening, bringing scattered showers and storms to the area. The
risk of severe weather is low, however an isolated severe storm
with 1" inch hail can`t be ruled out. As the feature moves away
from the area later tonight, the shower and storm activity will
wane. With the upper trough overhead, can`t go completely dry
later tonight as a few isolated showers could pop up at times.
Also, areas of fog are possible later tonight. The HREF indicated
a 30-60% probability of visibilities dropping below one mile,
especially north and west of the Fox Valley. Any lingering fog
will burn off by mid-morning on Sunday, then the chances of
showers and storms will increase during the late morning and
afternoon. Lows tonight will drop into the middle 50s to lower 60s
with highs Sunday in the upper 60s to middle 70s.
LONG TERM (Sunday Night through next Saturday)
The 500mb trough will linger through Monday, bringing continued
chances of showers and thunderstorms. 500mb heights will begin
to rise Monday night and Tuesday as ridging develops across the
northern plains into the western Great Lakes. By the middle of
next week, ensemble height anomalies indicate a ridge will develop
over central Canada while a low-pressure system forms over the
Ozarks. This pattern will help funnel drier, more stable air into
the region, shunting most of the precipitation chances south of
the area through Thursday. The GFS model indicated a decent
rainfall event Wednesday into Thursday, but was the outlier
at the moment. Temperatures for much of next week will end up
above normal.
&&
.AVIATION...for 18Z TAF Issuance
Issued at 1224 PM CDT Sat Sep 20 2025
Latest model and radar trends support only isolated showers and
storms (20%) through 20-21z, then become scattered to numerous
(40-60%) during the remainder of the afternoon into the evening
before diminishing during the late evening and overnight hours
(15-30%). Scattered showers and storms (30-50%) are again
expected on Sunday. For later tonight into Sunday morning, IFR or
low CIGS are likely (60-74%) at KRHI/KAUW/KCWA. Still a lot of
uncertainty of CIGS at KGRB/KATW/KAUW due to model guidance
suggesting VFR/MVFR category. Decided to put a tempo group for
IFR or lower CIGS at these 3 sites. Also, areas of fog are
expected overnight. HREF probabilities are 30-60% for visibilities
of 1 mile or less north and west of the Fox Valley. Have not gone
that low in the 18z TAFS, but will pass on concerns to the next
shift that may need to lower visibilities in the KRHI/KAUW/KCWA
TAFS.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
Beach Hazards Statement until 4 PM CDT this afternoon for WIZ040-
050.
&&
$$
DISCUSSION.....Eckberg
AVIATION.......Eckberg

NWS GRB Office Area Forecast Discussion