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623
FXUS63 KMKX 252000
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
300 PM CDT Tue Jun 25 2024

.KEY MESSAGES...

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-  Heat index values in the middle to upper 90s are expected
   until early evening across portions of the area.

-  Strong to severe storms should remain to the south of the
   area later into tonight, with strong thunderstorms possibly
   returning later on Friday into Friday night.

-  River flooding and high water levels will continue this week
   and into this weekend.
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&&

.SHORT TERM...
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Issued 300 PM CDT Tue Jun 25 2024

Tonight through Wednesday night:

The main cold front is still working its way southeast through
the area. Very warm and humid conditions will continue ahead of
it, with dew points in the 70s and heat index values into the
middle to upper 90s in some areas.

CAMs continue to suggest that the front should be southeast of
the area by early this evening. They develop new strong to
severe convection along the front in northern or central
Illinois by later this afternoon, within a very unstable airmass
with 35 to 40 knots or more of 0 to 6 km bulk shear. CAMs have
been consistent with the strong to severe convection remaining
south of the area, though the latest HRRR has convection
developing just south of the Illinois border by 00Z Wednesday.

Forecast soundings still show a cap with the warm temperatures
in the low levels, so that may hinder development with the lack
of any other forcing mechanisms. Thus, will maintain low PoPs
near the Illinois border into tonight. Will watch the far
southern portions of the area for any signs of convection.

Dew points may remain high enough overnight into Wednesday
morning with the light winds to have some fog, possibly dense,
move onshore from Lake Michigan. Will continue to watch for this
potential and adjust the forecast near the lake if needed.

High clouds from convection to the south may linger tonight,
before scattering out on Wednesday. A passing shortwave trough
may bring more clouds, along with a few showers, with lingering
low level instability. For now, kept forecast dry but may need
to add in some PoPs in later forecasts. It looks to be a less
humid day but still mild. Winds may shift onshore near the lake
in the afternoon, bringing cooler temperatures there.

High pressure should move into the region Wednesday night,
bringing quiet weather and cooler temperatures.

Wood
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&&

.LONG TERM...
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Issued 300 PM CDT Tue Jun 25 2024

Thursday through Tuesday:

High pressure should continue to bring pleasant summer weather
to the area for Thursday into Thursday night.

Warm air advection will develop later Thursday night into
Friday, as a southwesterly low level jet develops and transports
more moisture into the region. A cold front should pass eastward
through the region sometime Friday night or Saturday morning.
The main 500 mb shortwave trough misses the area to the north,
but there will be low level frontogenesis with the front to help
bring chances for showers and thunderstorms.

Any strong to severe potential will be tied to the timing of
the front and if the low level jet can sustain elevated
convection. This will be the next period to watch for potential
strong to severe storms, though forecast soundings are showing
mainly elevated CAPE with modest bulk shear of 20 to 25 knots.
This could lead to multicell development with some heavy rain
potential as well, with precipitable water values approaching or
reaching 2.00 inches.

Strong cold air advection with high pressure should bring cooler
and less humid air into the region later Saturday, with quiet
weather into Sunday. This trend is generally supported by
ensembles. Ensembles then show more potential for showers and
thunderstorms early next week, as more warm air advection and
moisture moves into the region. Thus, the active weather pattern
continues.

Wood
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&&

.AVIATION...
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Issued 300 PM CDT Tue Jun 25 2024

May see some sprinkles move through the area into early this
evening, with middle level clouds.

Gusty west winds will weaken somewhat and become northwest into
early this evening, as a cold front moves through and to the
southeast of the area. Ceilings should gradually scatter out or
rise above 3000 feet AGL during this time. Any thunderstorm
development with the cold front should remain south and
southeast of the area into tonight.

Light northwest winds tonight will become north to northwest on
Wednesday. May see patchy fog, some dense, move onshore from the
lake overnight into Wednesday morning, but confidence is too low
to mention in TAFs.

May see northeast winds for terminals near Lake Michigan by
Wednesday afternoon. High clouds from thunderstorms to the south
may cover the area tonight into early Wednesday morning, before
scattering out in the afternoon. May see some light rain
showers move through Wednesday afternoon.

Wood
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&&

.MARINE...
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Issued 300 PM CDT Tue Jun 25 2024

Gusty southwest winds will become lighter and veer to the west
and northwest this evening, as a cold front moves across the
lake. There are chances for showers and thunderstorms into
tonight across far southern portions of the lake, as the cold
front pushes through.

Winds will shift to the north later tonight into Wednesday,
becoming gusty at times. Lighter winds return later Wednesday
night into Thursday night, as high pressure around 30.0 inches
shifts across the region. Increasing south winds are then
forecast for Friday, becoming southwest to west on Saturday, as
a cold front moves through the region. Chances for showers and
thunderstorms increase during this period.

Wood
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&&

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

$$

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