NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 102335
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
635 PM CDT Sun May 10 2026

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- A Freeze Warning has been issued for tonight for central and
  east-central Wisconsin as well as the Door Peninsula. Widespread
  temperatures from 28 to 34 degrees are forecast.

- Elevated fire weather conditions are expected Monday due to low
  humidities.

- High probability of rain on Tuesday (greater than 90%). A few
  isolated thunderstorms are possible over central and northeast
  Wisconsin as the system passes.

&&

.DISCUSSION...
Issued at 200 PM CDT Sun May 10 2026

The latest RAP analysis and satellite/radar imagery show a broad
and deep upper trough spinning across eastern Canada and the
northern Great Lakes early this afternoon. Cyclonic flow around
this upper low combined with embedded shortwave energy is
producing scattered showers and sprinkles across north-central and
northeast Wisconsin. This activity should wane by late afternoon
or early evening as high pressure currently over southern Manitoba
builds into the western Great Lakes.

As skies clear this evening and winds become light under the
influence of the approaching surface ridge, nearly ideal
radiational cooling conditions will develop. Temps fell lower than
expected last night despite a decent pressure gradient, and
tonight looks even more favorable for cooling. Using last night as
a benchmark, temperatures were lowered below consensus guidance.
As a result, a Freeze Warning has been issued for central and
east-central Wisconsin and the Door Peninsula where the growing
season has begun. While urban areas of the Fox Valley may stay
just above freezing, outlying areas will likely drop to near or
just below 32 degrees. On Monday, the surface high shifts to the
central Great Lakes. Temperatures will moderate into the mid 50s
to near 60 degrees under fair weather clouds.

The next significant weather system arrives late Monday night and
Tuesday in the form of a dynamic clipper. Confidence in
precipitation is high, with rain chances exceeding 90 percent.
Mid-level lapse rates of 6.5 to 7 C/km and modest instability will
support the potential for isolated thunderstorms over central and
northeast Wisconsin Tuesday afternoon. Showers may linger into
Tuesday night, particularly across the far north, before high
pressure returns for Wednesday and Thursday.

A shift in the large-scale pattern is expected late next week as
the eastern trough flattens and a warming ridge over the western
United States shifts eastward. This will result in a pronounced
warming trend starting Thursday, with high temperatures likely
reaching the upper 60s to middle 70s. This warmer airmass will
lead to increasing instability by the end of next weekend, though
uncertainty remains regarding the timing and coverage of the next
round of organized showers and thunderstorms.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 633 PM CDT Sun May 10 2026

VFR through the TAF period. High-based stratocu clouds start the
evening, but these quickly will give way to clear skies tonight
through daybreak on Monday. Scattered fair weather cu (cigs 050-070
AGL) are expected to develop later Monday morning into Monday afternoon.

Northwest winds gusting to around 20 kts (except a northeast
direction over northeast WI due to lake and bay breezes) will
ease quickly this evening with light and variable winds overnight
as high pressure is overhead. Light winds on Monday will shift
southwest over central and north-central WI in the afternoon,
staying less than 10 kts. Meanwhile, a stronger lake Michigan
breeze (around 10 kts) will shift winds to easterly direction,
after 15z at MTW, then after 22z at GRB and ATW.

&&

.FIRE WEATHER...
Issued at 200 PM CDT Sun May 10 2026

Elevated fire weather conditions will continue on Monday. Surface
high pressure will be in close proximity to the region, which
will result in much lighter winds around 5 to 10 mph. Minimum RHs
of 20 to 35% are forecast north and west of the Fox Valley, and
in the middle to upper 30s across the Fox Valley and east-
central WI away from Lake Michigan where a lake breeze is likely
to bring in modified marine air.

While afternoon humidities may fall into the 25-35 percent range
midweek, cool temperatures (Wed) and/or light winds (Thu) should
prevent critical fire weather conditions.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Freeze Warning from midnight tonight to 8 AM CDT Monday for
WIZ022-030-031-035>040-045-048>050.
&&

$$

DISCUSSION.....MPC
AVIATION.......JLA
FIRE WEATHER...MPC