NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 021130
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
630 AM CDT Sat May 2 2026

Updated aviation portion for 12Z 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.

- Minor flooding lingers on the Wolf River and Winnebago system.
  Water levels will continue to slowly recede given lack of
  significant rainfall.

&&

.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 12Z TAF Issuance
Issued at 612 AM CDT Sat May 2 2026

Mostly clear skies and VFR conditions prevailed across the
forecast area early this morning as high pressure continued to
build. SCT fair weather cu with bases at around 6 to 7k ft may
develop later this morning with the heat of the day, lasting
through the afternoon. Mid clouds then increase in coverage this
evening and tonight ahead of approaching low pressure and
accompanying shower chances. Opted to go with prevailing -SHRA for
the western sites beginning at 06 Sunday, and at 08Z for the
eastern terminals. No deterioration of flight category is
expected. Otherwise, winds will be mainly out of the west at 5 to
10 knots, gusting to 15 knots.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Freeze Warning until 8 AM CDT this morning for WIZ022-030-031-
035>040-045-048>050.
&&

$$

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