279 
FXUS63 KGRB 031921
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
221 PM CDT Fri Oct 3 2025

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Temperatures warm through the weekend, peaking in the mid to
  upper 80s on Saturday afternoon. Several record highs will be in
  jeopardy on Saturday. 

- Conditions hazardous to small craft are expected Saturday 
  afternoon through early Monday morning.

- Gusty winds paired with near record temperatures will result in
  increased fire weather potential on Saturday and Sunday.

- Rain chances return on Sunday night and continue through Monday
  night. The highest rain chances will occur over east-central WI
  (40-50%).

&&

.DISCUSSION...
Issued at 220 PM CDT Fri Oct 3 2025

Short Term...Tonight and Saturday

The latest analysis and satellite imagery show a weak cold front 
extending from northern Minnesota into the Upper Peninsula this 
morning. Despite the presence of this front and a notable 
precipitable water axis across the state, cloud bases are high, 
generally above 7000 ft. While a few isolated showers have popped 
up over far northeast Wisconsin, coverage has been very small.
Max temperatures have approached or surpassed their records for
the date over northeast WI. The primary forecast concerns will be
the potential for isolated shower or storm activity this 
afternoon, followed by the development of gusty winds that will 
persist through the end of the TAF period as low pressure over the
Rockies moves east into the northern Plains.

Record Temperatures: A combination of moderate mixing and very 
warm air aloft, with 925mb temperatures around +23 to +24 Celsius,
will lead to widespread high temperatures in the middle 80s on 
Saturday. Some locations may even reach the upper 80s. These 
unseasonably warm conditions will put many daily record high 
temperatures in jeopardy.

Thunderstorms: Isolated showers, and perhaps a small cluster of 
thunderstorms, are anticipated to form this afternoon along the 
cold front over the Upper Peninsula. The majority of convective 
allowing models indicate this activity will stay north of the 
Wisconsin border. Consequently, most shower chances have been 
removed from the forecast, with the exception of a lingering 20% 
chance over the Bay and Door County. Otherwise, expect scattered 
mid and high clouds through Saturday afternoon.

Strong Winds: An increasing pressure gradient will result in a
windier day on Saturday. Some gusts could reach as high as 30 
mph during the afternoon.

Dense Fog: The potential for widespread fog is low tonight. An 
increasing pressure gradient overnight is expected to prevent 
significant fog development, limiting it to patchy at most. Short-
term models do not show a significant fog footprint.

Long Term...Saturday Night Through Friday

Strong Winds: Wind gusts are expected to increase further on 
Sunday, potentially reaching 30 to 40 mph with average mixing. The
forecast for Sunday's winds have been slightly increased from the
National Blend of Models.

Elevated Fire Weather: Fire weather conditions will need to be 
monitored this weekend due to the combination of unseasonably warm
temperatures, gusty winds, and humidity levels dropping to around
35-45%. The greatest potential for fire weather concerns will be 
on Sunday due to stronger winds gusting to 35 mph. Although 
current fuel conditions are not favorable for significant fire 
activity, the gusty winds and increasing leaf debris could lead to
isolated powerline fires. The Wisconsin DNR currently rates the 
fire danger as low to moderate across the region. Looking ahead, 
if north-central Wisconsin does not receive rainfall and 
experiences a hard freeze, the fire weather potential could 
increase later next week as fuels cure and dry out.

Rainfall Potential: A cold front is set to move slowly across the
area on Sunday night through Monday night. Despite being under 
the right-rear quadrant of a jet streak and having moderate 
convergence along the boundary, models are not showing significant
precipitation potential. This is due to a lack of deep Gulf 
moisture and little to no instability. The probability of 
receiving a quarter-inch of rain is low, ranging from under 10% in
north-central Wisconsin to 20-40% over east-central Wisconsin by 
Tuesday morning. Rain chances will remain low for the rest of the
work week.

Temperatures: A significant pattern change is expected for the 
middle of the week as a deep trough moves through the Great Lakes 
from Tuesday into Wednesday. A Canadian surface high-pressure 
system will follow this trough, bringing cooler temperatures. 
Temperatures will return to more seasonable levels, with highs in 
the 50s and 60s for the midweek period. Lows in the lower to 
middle 30s are expected over far northern Wisconsin on Tuesday and
Wednesday nights, creating favorable conditions for frost.

Boating Hazards: Small craft advisories are anticipated for the
weekend due to gusty south winds and high waves. Waves on Lake
Michigan are forecast to reach 4 to 6 feet on Saturday and nearly
10 feet on Sunday afternoon. Conditions on the Bay are less
certain, but small craft conditions will be possible there on
Sunday. A Small Craft Advisory will be issued for Lake Michigan
from 5 PM Saturday through 7 PM Sunday. It will likely need to be
extended through Sunday night.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1213 PM CDT Fri Oct 3 2025

VFR conditions are expected to prevail across all terminals 
(KGRB, KATW, KMTW, KAUW, KCWA, KRHI) through the forecast period. 
A weak cold front currently situated over the Upper Peninsula of 
Michigan is expected to be the focus for isolated shower and 
thunderstorm development this afternoon. However, convective 
allowing models indicate this activity will remain north of the 
forecast area, and probabilities are too low to include in the 18Z
TAFs. CIGS will consist of SCT mid and high-level clouds with no 
impact on flight operations.

SFC winds will be out of the southwest and will increase through 
the period as a low-pressure system over the Rockies tracks east 
and the surface pressure gradient tightens. Expect sustained 
speeds of 5-10 kts this afternoon and 6 kts or less tonight. South
winds will gusty up to 20 kts by the end of the taf period. Some 
gusts to 25 kts are possible Saturday afternoon.

Marginal LLWS is possible overnight as southwesterly winds at 
2000 ft increase to around 30 kts.

OUTLOOK...LLWS is possible again Saturday night with gusty south 
winds continuing Sunday, potentially reaching 30 kts.

&&

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

&&

$$

DISCUSSION.....MPC
AVIATION.......MPC