601
FXUS63 KGRB 021700
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1200 PM CDT Sat May 2 2026

Updated aviation portion for 18Z TAF issuance

.KEY MESSAGES...

- Rain chances will increase late tonight into Sunday morning. The
  highest probabilities for precipitation are currently focused
  over north-central Wisconsin (60-80% chance).

- A stronger cold front will move through the region on Monday.
  This system will bring a high chance for rain, along with a few
  thunderstorms, Monday afternoon (50-70% chance).

- Other than Sunday and Monday, below normal temperatures will
  will return mid to late next week, with several opportunities
  for frost and freeze conditions.

&&

.DISCUSSION...
Issued at 1234 AM CDT Sat May 2 2026

The high pressure system will slide southeast of the area today,
allowing southerly return flow to develop. This will lead to a
modest warming trend with highs reaching the mid to upper 50s.
Troughing aloft will likely support the development of fair-
weather cumulus clouds by late morning, similar to the coverage of
Minnesota yesterday.

Attention then turns to a clipper system progged to approach
tonight. Low-level convergence and a surge of moisture will
increase precipitation chances, particularly for areas north of
Highway 29. Rain chances have steadily increased over the past 24
hours, and have increased again tonight (now up to 60-80%). As
such, have opted to boost NBM PoPs for the late tonight into
Sunday timeframe. Most of this activity should exit the region by
midday Sunday, leading to decreasing clouds and high temperatures
returning to the 60s for inland locations on Sunday afternoon.

For the early to middle part of next week, the pattern will be
dominated by an anomalous closed upper low spinning over northern
Ontario and the Hudson Bay. A more robust cold front associated
with this feature is forecast to sweep across Wisconsin on Monday.
Probability of precipitation has increased to 70-80 percent with
this front. While overall moisture remains somewhat limited, weak
instability up to 100 J/kg during the afternoon hours may be
sufficient to support a few isolated thunderstorms. Precip amounts
will generally be light as there is a less than 20% chance of
1/4" of rain. But with thunderstorms, high end amounts (95
percentile) up to 1/2 inch are possible.

Behind this front, another surge of cold air will drop
temperatures back below seasonal normals from Tuesday through
Friday. Under the cold pool of the upper trough, scattered
diurnally enhanced showers are possible during the afternoons from
Wednesday through Friday though confidence in coverage is low.
Frost and freeze potential will peak again during the early
morning hours of Wednesday through Friday.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1200 PM CDT Sat May 2 2026

VFR conditions are expected this afternoon with SCT-BKN fair
weather CU with bases at 6-7k ft. Mid clouds then increase in
coverage this evening and tonight ahead of an approaching low
pressure and accompanying shower chances. The chance for showers
looks a bit lower this run; therefore, will handle the showers
with PROB30 groups this run. No deterioration of flight category
is expected for CIGs or VSBYs.

Surface winds will mainly be from the west today, backing
southwest tonight ahead of the cold front, then veering to the
west Sunday as the cold front moves through the region. Wind
speeds will generally be 5 to 10 knots, gusting to 15-20 knots
late tonight into Sunday.

&&

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

&&

$$

DISCUSSION.....MPC/Goodin
AVIATION.......Kurimski

NWS GRB Office Area Forecast Discussion