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000
FXUS63 KGRB 171127
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
627 AM CDT Wed Apr 17 2024

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Showers and a few embedded thunderstorms are expected today.
  Widespread severe weather is not expected, but some of the
  stronger showers and storms could produce wind gusts over 40
  mph. Small hail is possible with some of the stronger
  thunderstorms. Locally heavy rainfall is also possible.

- Blustery east to southeast winds are expected today, with gusts
  of 25 to 35 mph.

&&

.DISCUSSION...
Issued at 359 AM CDT Wed Apr 17 2024

Short Term...Today...Tonight...and Thursday

Another round of elevated showers and thunderstorms will track
through the area this morning as a vertically stacked low pressure
system tracks from southern Minnesota through northeast Wisconsin
on its way over northern Lake Michigan by this afternoon. Although
the morning convection will have 1000 J/kg of MUCAPE to work with,
model soundings indicate a steep low level inversion in place
around 925 mb, which should keep the storms elevated with only
around 10 knots of bulk shear. Therefore, while the storms may
bring down a wind gust of around 40 mph to the surface at times,
synoptic surface winds due to the pressure gradient are still
gusting to 30 mph at times.

As the low tracks off to the northeast this afternoon, some modest
SBCAPE of 100 to 300 J/kg is expected across the region as a mid
level shortwave tracks through the western Great Lakes region.
This could bring continued isolated to scattered showers and
thunderstorms to the area through the early evening hours until
drier air and a weak surface ridge build across the western Great
Lakes. High temperatures today are expected to range from the
lower 50s across the north, to the lower 60s south of highway 29.

Dry weather is then expected for the rest of tonight as this
surface ridge tracks through Wisconsin. Although there could be
some partial clearing at times tonight, another low pressure
system tracking to the south will bring increasing clouds from the
west late tonight. Lows tonight are expected to range from the
middle 30s across the north, to the lower 40s across east-central
Wisconsin.

The aforementioned low will bring the chance for showers back to
the region on Thursday as a vigorous mid level shortwave tracks
through the western Great Lakes as a 100 knot upper level jet
streaks across the northern Great Lakes. Highs on Thursday are
only expected to top out in the 55 to 60 degree range.

Long Term...Thursday Night Through Tuesday

Precipitation...A surface boundary extending from Lake Superior to
southern WI will track east across the state Thursday evening.
Models are still not in exact agreement with the strength of this
frontal boundary and its ability to generate rain showers. But,
given the continued signal for this feature and forecast soundings
showing enough saturation in the mid to low levels, anticipate a few
rain showers mainly in far northeast WI Thursday evening. CAA will
follow this frontal boundary as an upper-level low resides over
Ontario. This will leave a jetstreak overhead on Friday, and more
specifically the LFQ. Models indicate precip developing over far
northern WI on Friday, and continuing through early Saturday as the
trailing trough from the low shifts overhead. A mix of rain and snow
will be possible given the cold air aloft and surface temps above
freezing on Friday, but as surface temps fall below freezing Friday
evening, anticipate a switch to all snow. The majority of ensemble
members from the ECMWF, GEFS, and Canadian indicate the potential
for minor snow accumulations along the WI/Upper MI border by
Saturday morning, and the NBM has probs of 15-40% for 0.5 inch or
more of snow in Vilas County.

Besides lingering light snow chances in far northern WI Saturday
morning, dry conditions are anticipated for the remainder of the
weekend as high pressure gradually builds into the region. The next
chance for precip looks to be sometime early next week, but details
are too difficult to nail down at this time.

Winds...Westerly winds will increase on Friday due to strong winds
(35 to 45 kts) in the mid to low levels potentially mixing to the
surface due to steep lapse rates. At the surface, gusts up to 40 mph
will be possible. Winds will decrease into Friday evening as lapse
rates and winds in the low to mid levels decrease.

Temperatures...Following the frontal boundary on Thursday evening,
cooler conditions are anticipated for Friday and Saturday, with
highs slightly below normal ranging from the middle 40s to low 50s.
Temps will then rise to normal or slightly above normal for Sunday
into early next week, with highs mainly in the 50s.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 627 AM CDT Wed Apr 17 2024

An area of showers and thunderstorms will track through the area
this morning along with MVFR/IFR conditions. Additional showers
and thunderstorms are then expected this afternoon as an area of
low pressure tracks through northeast Wisconsin. Dry conditions
are then expected this evening and overnight as the low moves off
to the northeast and a ridge of high pressure builds in from the
west. Conditions are expected to improve to VFR tonight as the
drier air advects into the area.

East to southeast winds of 15-25 kts will slowly decrease this
morning as the low moves overhead. Winds will shift to the west by
this evening and gust up to 30 kts. Locally higher gusts are
possible in/around any heavier showers/storm.

LLWS will end across east-central Wisconsin this morning as the
winds aloft decrease. Marginal LLWS will be possible this evening
across north-central Wisconsin as winds at 2000 ft increase to
around 40 kts, but surface gusts could limit the amount of shear.

&&

.MARINE...
Issued at 359 AM CDT Wed Apr 17 2024

A Gale Warning remains in effect early this morning. Southeasterly
winds could gust to gale force early this morning before
diminishing. Small craft conditions will persist into this evening
before winds and waves diminish below criteria around midnight.

&&

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

&&

$$

DISCUSSION.....Kurimski/Kruk
AVIATION.......Kurimski
MARINE.........Kurimski