756 
FXUS63 KGRB 011134
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
634 AM CDT Wed Oct 1 2025

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Warming trend through the weekend, with daily high temperatures
  peaking Friday and Saturday in the mid 80s which will be near 
  record highs. 

- Hazardous conditions for small craft on Lake Michigan late 
  tonight through Thursday afternoon. Another round of strong 
  winds and higher waves this weekend. Could also be very breezy 
  even on land for Sunday.
 
- Most locations stay dry until Sunday night with arrival of
  stronger cold front. Chance for scattered showers lasts through
  Monday night, but average rainfall amounts will be less than 
  0.25 inch.

&&

.DISCUSSION...
Issued at 253 AM CDT Wed Oct 1 2025

Large high pressure centered on Hudson and James Bay settles to 
the northeast United States while weak front pushes over northern
Plains. This front will weaken and wash out as it crosses northern
Great Lakes late Thursday into Friday. Stronger cold front that 
brings chances for scattered showers to the state does not arrive
until Sunday night and Monday. Though the weather pattern becomes
a bit more active this weekend into early next week, no high impact
weather is expected. However, for marine interests, there will be 
occasional conditions hazardous for small craft. 

Temperatures: Warming trend lasts through this weekend. Today will
be the coolest day (70s) and really it is not all that cool, with
readings still over 10F above normal. Warmth peaks Friday and 
Saturday. Spread in NBM 25th to 75th percentile remains very low, 
increasing confidence that highs will reach well into the 80s 
Friday and Saturday. These values will be near records. Nighttime 
lows in the low to mid 60s will be more typical of what highs 
should be to start October. Now looking like Sunday will have
highs reaching 80 as well. Sharp cold front sweeps through 
Sunday night into Monday, cooling daytime highs back into the 60s 
to start next week. 

Winds and marine hazards: First up, southeast winds increase 
tonight, especially on Lake Michigan, leading to hazardous 
conditions for small crafts as waves build to 4 to 6 feet. 
Highest waves will be south of Sturgeon Bay. Small Craft 
Advisories will be issued this morning but no Beach Hazards 
Statements as the Beach Hazards season ended on 9/30. Next period 
of stronger winds occurs this weekend as pressure gradient 
tightens ahead of stronger cold front. Another period of even 
higher waves expected Saturday afternoon through Monday morning. 
Unlike tonight and Thursday, stronger winds will also occur on 
land this weekend. Breezy conditions expected on Saturday as 
southerly winds gust 20-30 mph. Stronger southwest winds on Sunday
with gusts 25-30 mph. NBM data suggest these values may increase 
further as probabilities of seeing 35+ mph gusts are 40-60% over 
much of the area. Given the 40-50kt low-level jet shown in some 
guidance ahead of the front along with well mixed profile, could
see a very breezy day on Sunday. 

Shower and thunderstorm chances: A few models show weak front may
have enough mid-level moisture and weak elevated instability to 
produce a few showers late Thursday night into Friday morning 
north/far northeast. Overall though, we wait until Sunday night 
and Monday for rain chances. Chances for thunder look low. 
Rainfall amounts and coverage of showers will be lower as the 
front is running into dry airmass. NBM probabilities of seeing 
rainfall over 0.25 inch are a meager 20-30%, which lines up with 
WPC guidance.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 633 AM CDT Wed Oct 1 2025

VFR flight conditions are expected across most of the forecast
area through the TAF period, with BKN high clouds prevailing. 
IFR stratus and fog has recently developed. Though patchy in
coverage, it could impact central and north-central WI terminals 
(especially AUW and RHI) through 14z. ESE winds of 5 to 10 kts 
will occur through the period, with gusts to 15 kts this afternoon
into this evening.

&&

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

&&

$$

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