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000
FXUS63 KGRB 121140
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
640 AM CDT Fri Apr 12 2024

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Northwest winds will gust to 35 mph over east central Wisconsin
  today.

- There is a chance of thunderstorms Saturday night across the
  north, and over all of the region Tuesday and Tuesday night. A
  few strong storms are possible Tuesday afternoon and evening.

&&

.DISCUSSION...
Issued at 420 AM CDT Fri Apr 12 2024

Short Term...Today...Tonight...and Saturday

Northwest winds will increase and become gusty today
as a surface low over Lake Huron intensifies and moves slowly east.
Some scattered showers are possible in northcentral Wisconsin this
morning, but otherwise it should be dry today, with highs around
five degrees above usual. Stratocumulus clouds will likely form
this morning, but then dissipate by evening.

Clearing skies and diminishing winds will allow for temperatures
to fall to normal values for this time of the year. Saturday will
be sunny and very mild as an upper ridge approaches and surface
winds become south. Highs will be around 15 degrees above normal,
except near Lake Michigan.

Long Term...Saturday Night Through Thursday

Focus in the extended period centers around thunderstorm potential
Saturday night before turning to the potential of some stronger
and more widespread thunderstorms early to middle of next week.

Active Weather...

Saturday night... A warm front will lift northwards through the
evening hours Saturday, bringing increasing warmth and moisture to
the mid- levels. Instability by the early overnight hours will be
around a couple hundred J/kg with around 20-30 knots of bulk
shear. Between the warm front, modest instability, and some weak
convergence in the wind fields at 850mb, isolated to scattered
precipitation will be possible in the evening to overnight hours.
Any convection that does form will likely be elevated, supported
by modest mid-level lapse rates, producing some thunder and
possibly small hail. The best chance for any active weather will
be along the strongest warm air advection in northern Wisconsin
and across the Upper Peninsula of Michigan. Thunder potential will
likely wane quickly overnight, with rain moving out by early
Sunday morning as colder, drier air returns through the mid
levels.

Next week...An upper low will cross the Rockies over the weekend,
rapidly strengthening as it crosses into the Central Plains. The
resultant wind field will bring warm and moist air northwards from
the Gulf through the Central Plains and into the Great Lakes.
While this will make for a mild Monday for us, active weather will
follow shortly after for Monday night through Tuesday. Current
ensemble guidance would certainly bring enough moisture and
instability for convection, and at least a few strong storms would
certainly be possible. Severe weather is less clear, as the
overnight arrival may hamper instability in our area and keep the
strongest convection southwards towards Illinois. Storm strength
aside, ample moisture will be available for moderate to heavy
rainfall, with PWATS pushing well above normal to around 1.25+
inches over portions of the region Tuesday. WPC has placed most of
Wisconsin in the marginal risk of excessive rainfall, which seems
reasonable. With this system still being 6 days out, the details
may yet be subject to change, but this system will bear watching
especially if you have Tuesday travel or outdoor plans.

Active weather then has some potential to stick around through the
end of next week, as a second low pressure system follows on the
heels of the first.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 640 AM CDT Fri Apr 12 2024

An intense low pressure system over Lake Huron will
produce northwest winds gusting to 30 knots today. Stratocumulus
clouds with bases between 2000 and 3000 feet should form this
morning. The bases will rise during the day and the clouds should
dissipate in the late afternoon and evening. The lowest ceilings
will be northwest of a Wisconsin Rapids to Iron Mountain line.

Skies will clear tonight, and remain mostly clear through midday
Saturday. Middle clouds are expected during the afternoon near
the Michigan border in the vicinity of a warm front.

&&

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

&&

$$

DISCUSSION.....RDM/Uhlmann
AVIATION.......RDM