269
FXUS63 KGRB 022329
AFDGRB

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

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- Rain chances will increase late tonight into Sunday morning. The
  highest probabilities for precipitation are currently focused
  across north-central Wisconsin (30-40% 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 (40-50% 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 1253 PM CDT Sat May 2 2026

A clipper system will approach the area from the west tonight,
bringing a chance for light rain showers late this evening through
Sunday. The main driver for the precipitation appears to be 2
separate PV anomalies that track through southwest Wisconsin and
the Michigan UP, with northeast Wisconsin in between these two
features. In addition, model soundings show not much in the way
of moisture across our area. Therefore, will taper down POPs into
the 30-40% range as the best moisture and lift will not actually
be in our area, rather it will be to our north and southwest.
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 upper-level 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. 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" 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; however, confidence in coverage is
low. Frost and freeze potential will peak again during the early
morning hours of Wednesday through Friday.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 519 PM CDT Sat May 2 2026

Shortwave energy over northern Minnesota will push a weak cold
front across the region tonight. Look for mid-clouds to increase
quickly this evening (already over northwest WI). Then shower
chances look mainly confined to 06z-14z Sunday. Probabilities are
highest at KRHI (50-70%) and 30-40% elsewhere. Upgraded KRHI to a
tempo group, but kept the prob30s at the other terminals. Flight
conditions should remain VFR in the showers since cloud bases will
be quite high.

After the showers depart, clearing skies and breezy conditions can
be expected from late morning Sun through the end of the taf
period. Southwest winds overnight will veer to the northwest and
gust to 20 kts on Sunday afternoon.

Lastly, probabilities for low level wind shear have increased in
the 06z-14z time frame and have adjusted the tafs accordingly.

&&

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

&&

$$

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

NWS GRB Office Area Forecast Discussion