NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 111730
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1230 PM CDT Mon May 11 2026

Updated aviation portion for 18Z 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 18Z TAF Issuance
Issued at 1138 AM CDT Mon May 11 2026

Fair weather cu with bases at around 5 to 6k ft AGL have developed
over the majority of the forecast area this afternoon. Otherwise,
mid clouds begin to increase and thicken ahead of approaching low
pressure overnight, eventually lowering to MVFR mainly at RHI by
early Tuesday morning. Scattered showers will accompany the
lowering cigs beginning early Tuesday morning, exiting the area by
the end of the TAF period.

Winds have already begun to shift to the east along the Lake
Michigan shoreline this afternoon, with the lake breeze expected
to make it to ATW within the next hour or two. Gusts to 15 knots
will be possible during this time. Gradient winds then increase
late tonight into Tuesday morning, increasing and backing surface
winds to the south. Gusts of 25 to 30 knots will be possible
Tuesday afternoon at all terminals. LLWS will likely become a
concern Tuesday morning as winds increase to 50 knots at 2k ft
AGL.

&&

.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...
None.

&&

$$

DISCUSSION.....KLJ
AVIATION.......Goodin
FIRE WEATHER...KLJ