055
FXUS63 KGRB 111144
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
644 AM CDT Mon May 11 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Temperatures will be in the middle 20s to low 30s this morning.
  A Freeze Warning remains in effect until 8:00 AM for locations
  where the growing season has started.

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

- High probability of rain on Tuesday (greater than 80%). A few
  isolated thunderstorms are possible over central and northeast
  Wisconsin as the system passes.

&&

.DISCUSSION...
Issued at 110 AM CDT Mon May 11 2026

Clear skies and light to calm winds were allowing for radiational
cooling tonight, with some locations in north-central WI already
in the middle 20s as of 06Z. Expect temps to keep falling until
sunrise, with lows in the mid 20s to low 30s for most locations.
A Freeze Warning remains in effect until 8:00 AM for locations
where the growing season has started.

Surface high pressure drifts across WI this morning, then moves to
the east this afternoon. Winds will shift around to the south as
the high moves east, aside from near the bay and Lake Michigan
where an east-southeast lake breeze will move inland. Despite the
sunshine and southerly wind shift, temperatures will still be
below normal today, reaching the mid 50s to low 60s (cooler near
the lake).

A clipper system comes across northern WI Tuesday morning into the
early afternoon, bringing in rain and a few thunderstorms. Models
and forecast soundings show the greatest forcing and moisture
during the morning, and expect most of the rain to fall before
18Z. There will likely be a break in the precipitation, followed
by some afternoon redevelopment as a trailing shortwave moves
across northern WI. There is some instability (~300 to 600 J/kg)
during both time periods, making embedded thunder possible.
However, severe thunderstorm potential is low. As for rain
amounts, LREF probabilities remain around 70-90% for at least
0.10", then fall off to 5-20% for at least 0.50". This indicates
most places will likely get some rain, but amounts will generally
be light with no flooding concerns. Some light showers could
linger into Tuesday night, and perhaps Wednesday morning, mainly
across northern WI. Then, high pressure builds in for the rest of
Wednesday and Thursday.

Upper ridge shifts into Wisconsin on Friday, leading to southwest
flow and a trend towards above normal temperatures Friday into
the weekend. Along with this transition, more unstable conditions
develop, with on and off rain and thunderstorms likely. However,
narrowing down the timing and strength of any round of precip is
uncertain this far out.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 644 AM CDT Mon May 11 2026

VFR conditions are expected today into tonight. Pesky stratus desk
across northern WI will linger this morning, then isolated to
scattered fair weather cu (050-070 AGL) will develop late this
morning into the afternoon. Mid and high clouds will begin to
increase this evening ahead of a low pressure system that brings
showers and a few storms across the area on Tuesday. Look for
ceilings to fall to MVFR from west to east after 12z Tuesday.

Winds will be light and variable this morning as high pressure
drifts overhead. Winds then shift west/southwest over central and
north-central WI this afternoon, staying less than 10 kts.
Meanwhile, a lake Michigan/ bay breeze (around 10 kts) will shift
winds to the east/southeast direction, after 17z at MTW, then
after 22z/23z at GRB and ATW. Some signal this lake breeze
boundary will make it into central WI this evening, before
diminishing. However, the southeast gradient wind will slowly be
increasing overnight into Tuesday morning, which switch winds to
the south/southeast in central regardless if the lake breeze makes
it. Some LLWS is possible towards dawn on Tuesday as winds at
2000 ft increase to 30-40 kts.

&&

.FIRE WEATHER...
Issued at 110 AM CDT Mon May 11 2026

Elevated fire weather conditions will continue today. 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 30% are forecast north and west of the Fox Valley, and in
the 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 until 8 AM CDT this morning for WIZ022-030-031-
035>040-045-048>050.
&&

$$

DISCUSSION.....KLJ
AVIATION.......Bersch
FIRE WEATHER...KLJ

NWS GRB Office Area Forecast Discussion