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184
FXUS63 KMKX 191954
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
254 PM CDT Thu Sep 19 2024

.KEY MESSAGES...

- Showers and thunderstorms moving into south central WI this
  evening then weakening as it moves into SE WI late at night.

- More chances for showers and storms Sat nt into early next
  week.

- Cooler temperatures much closer to normal for next week.


&&

.SHORT TERM...
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Issued 253 PM CDT Thu Sep 19 2024

Tonight through Saturday:

Deep convection has formed a little early along the IA/MN border
and is oriented w-e and moving newd with the mean flow. This may
have been triggered by low to mid level warm advection, but
additional n-s convective development is expected over that
region late this afternoon, as a cold front approaches the
area. MLCAPE around 2500 J/KG is in place ahead of the front
with the front being aided aloft by the left exit region of a 90
kt jet streak and PVA from a upper wave passage. A sly LLJ and
warm, moist advection will increase just ahead of the front to
30-40 kts during this time.

The HREF produces a line of deep convection that will begin to
weaken after 03Z as it is moving across south central WI. This
seems reasonable as MUCAPE quickly drops after sunset with
perhaps 1000 J/KG over south central WI but much less to the
east. The better upper dynamics also track to the north during
this time. Nevertheless expect most locations to see measurable
rain tnt but probably fairly light for se WI. The actual cold
front will then pass for the morning daylight hours on Fri but
only with slight chances for development over ern WI. A drying
wly wind and clearing skies will still lead to another day with
high temps in the lower to middle 80s. Weak high pressure will
then follow for Fri nt into Sat with low temps falling back
into the 50s but highs once again in the 80s.

Gehring
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&&

.LONG TERM...
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Issued 253 PM CDT Thu Sep 19 2024

Saturday night through Thursday:

High pressure will move east of the area with swly flow aloft
becoming established into early next week. A series of shortwave
troughs including a passing wave of low pressure for Sat nt-Sun
will bring rounds of showers and storms to the region. However
the amounts are in question and a precipitation gradient from
north to south is expected. 1 inch amounts will be possible over
far srn WI during this time. A shortwave trough may dig swd from
Canada for mid week keeping slight chances for showers in the
forecast. Cooler temps, much closer to normal, are expected for
this period.

Gehring
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&&

.AVIATION...
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Issued 253 PM CDT Thu Sep 19 2024

VFR conditions this afternoon into the early evening. Areas of
MVFR Cigs may then develop over south central WI late tnt
following the showers and storms. Also cannot rule out patchy
fog toward morning west of Madison and especially in the WI
River Valley. Any pockets of MVFR Cigs and light fog will burn
off within a few hours of sunrise on Fri with VFR conditions by
late morning through the afternoon.

Gehring
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&&

.MARINE...
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Issued 253 PM CDT Thu Sep 19 2024

High pressure around 30.0 inches over the lower Great Lakes will
gradually weaken, while low pressure around 29.4 inches tracks
northeast across Manitoba, Canada. This will produce light to
modest south to southeast winds into Friday. A weak cool front
will push southeastward across the open waters Friday evening,
bringing scattered showers and isolated thunderstorms from late
tonight into Friday evening.

Weak high pressure will then settle over the lake for Saturday
morning, followed by the passage of a weak wave of low pressure
around 29.7 inches for late Saturday night and Sunday. Light to
modest southeasterly winds can be expected ahead of this low.

Gehring
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&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$

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