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327
FXUS63 KMKX 182025
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
325 PM CDT Tue Jun 18 2024

.KEY MESSAGES...

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- Small chances (15 to 20 percent) for showers and storms in
  southern and southeastern parts of the area until early this
  evening.

- Better chances (30 to 60 percent) for showers and storms
  overnight into Wednesday night.

- Heat index values will be between 95 and 100 degrees until
  early this evening away from Lake Michigan.

- Dangerous swim conditions are likely into tonight at Lake
  Michigan beaches in Sheboygan and Ozaukee Counties.
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&&

.SHORT TERM...
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Issued 324 PM CDT Tue Jun 18 2024

Tonight through Wednesday night:

The low clouds have scattered out across the area, allowing for
the very warm and humid conditions to take hold. Heat index
values in the middle to upper 90s are generally expected inland
from Lake Michigan until early this evening. A southeast lake
breeze has developed near the lake, and those areas will cool
down as a result.

Peak temperatures will be close to convective temperatures,
especially toward the Illinois border area. Isolated to widely
scattered pop up showers and storms are still possible to
occur in these areas. There is enough mean layer CAPE to
possibly bring gusty winds with any storms. Deep layer bulk
shear is quite weak, around 15 knots or less. So, would expect
any showers and storms to be fairly short-lived.

Beach Hazards Statement remains in effect until later tonight
for the Sheboygan and Ozaukee County beaches. Gusty south winds
will bring waves up to 4 feet for these beach areas, which will
result in dangerous conditions for being in the water. A
moderate swim risk remains for beaches to the south of there as
well.

There are better chances for showers and storms (30 to 60
percent) overnight into Wednesday night, as a cold front sags
southeast into the area and washes out. There are some
indications from the CAMs that the cold front could shift south
of the area as well by Wednesday evening.

Generally weakening showers and storms from the west overnight
may shift into the western parts of the area. This may linger
into Wednesday morning. CAMs generally support the weakening
trend with this overnight and early morning activity.

Clouds associated with this activity may linger through the
rest of Wednesday, so there is uncertainty with how much
instability will be available for possible storms later
Wednesday into Wednesday evening. Deep layer bulk shear is
expected to increase to 25 to 35 knots Wednesday afternoon and
evening, so if storms can develop, there is some risk for strong
winds from downbursts to occur. This will be conditional on
clouds scattering out and enough instability developing.

Heat index values may still reach the middle to upper 90s in
far southeast Wisconsin, where the most sunshine could occur.
Again, this will depend on if the clouds can scatter out by the
afternoon.

Wood
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&&

.LONG TERM...
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Issued 324 PM CDT Tue Jun 18 2024

Thursday through Tuesday:

The upper flow will transition to nearly zonal between
Wednesday night and Thursday as high pressure settles over the
southeast US. Weak ripples in the flow will roll across southern
WI and northern IL at times through Saturday. The effective
front will waffle north and south a little, but overall we will
remain in a warm and unstable pattern with at least small
chances for showers and thunderstorms through the period. It
looks like a stronger wave will cross the region Saturday and
drag a weak cold front through southern WI Saturday afternoon or
evening. This is a more certain time for storms, but the time
of day will determine their severity so this is something to
keep an eye on.

There will be a brief period of northwest flow and a relief from
the warm temps and storms Sunday into Monday night, but it looks
like we will be warm again by Tuesday.

Cronce
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&&

.AVIATION...
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Issued 324 PM CDT Tue Jun 18 2024

Low clouds have scattered out and any ceilings have risen above
3500 feet AGL. South winds will continue to be gusty this
afternoon, before weakening somewhat tonight. A southeast lake
breeze has developed and has shifted the gusty winds southeast
at Milwaukee. These winds may vary from south southeast to south
southwest at this location, if the lake breeze boundary gets
pushed back to the east.

There should be low level wind shear conditions tonight, with
southwest winds around 2000 feet AGL of 40 to 45 knots.

A few showers and storms may pop up until early this evening.
Weakening showers and storms should move into areas west of
Madison overnight, and may spread over the area into Wednesday
morning.

Low clouds with ceilings of 1500 to 2500 feet AGL may spread
over the area during this time, and may linger into the rest of
Wednesday and into Wednesday night. There may be more showers
and storms that form along a weakening and stalling cold front
Wednesday afternoon and evening, but it is still uncertain how
much of this activity will occur at this time.

Wood
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&&

.MARINE...
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Issued 324 PM CDT Tue Jun 18 2024

Low pressure around 29.5 inches will move from west central
Minnesota to near James Bay tonight. Gusty south winds are
expected to linger tonight into early Wednesday.

A Small Craft Advisory remains in effect through this evening
for the nearshore waters, with the gusty winds and building
waves. Gusts over the open waters will reach 30 knots at times
into tonight, mainly over the northern portions of the lake.

Some fog may develop at times over the lake into Wednesday,
with the very warm and humid airmass in place.

Winds will gradually ease Wednesday and shift to the north by
Wednesday evening, as a cold front sags into the region. North
to northeast winds should then linger into Thursday night, as
high pressure around 30.4 inches moves into Lake Superior.

Wood
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&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ052-WIZ060 until 4 AM Wednesday.

LM...Small Craft Advisory...LMZ643 until 1 AM Wednesday.

     Small Craft Advisory...LMZ644-LMZ645-LMZ646 until 10 PM
     Tuesday.

&&

$$

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