190
FXUS63 KMKX 190316
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1016 PM CDT Tue Jun 18 2024

.KEY MESSAGES...

- Decaying thunderstorms with gusty winds will move into south
  central WI after midnight but more storms to follow later in
  the morning. Otherwise chances for storms (30 to 60 percent)
  will continue for Wed and the remainder of the week.

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


&&

.UPDATE...
Issued 1016 PM CDT Tue Jun 18 2024

See no reason to veer away from the forecast of a decaying line
of storms moving into south central WI after midnight. The low
pressure area over ne MN will lift newd into Canada during the
overnight with a weakening wind field and cold front. The MCS
over IA is exhibiting front to rear flow and within weak deep
layer shear so expect it to continue to weaken as it approaches
WI. The gust front should still be able to initiate sct
convection over south central WI for the early morning hours.

Scattered convection could then continue from sw-ne on the tail
end of the LLJ and just ahead of or along the slow moving cold
front over south central WI for later in the morning. This will
occur within a PW plume of 1.7-1.9 inches with some training of
storms possible but believe any flash flood threat will remain
low. The cold front will then slowly move sewd across srn WI
through the day within the same high PW airmass. Scattered
convection will likely reignite with heavy rainfall as the main
hazard. A MCV or vorticity maximums will then approach srn WI
from IA for Wed nt with possibly more heavy rain that could
become better organized if a sufficient swly LLJ forms.

Gehring

&&

.SHORT TERM...
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

&&

.LONG TERM...
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

&&

.AVIATION...
Issued 1016 PM CDT Tue Jun 18 2024

MVFR Cigs will develop Wed AM over much of south central WI but
especially where training of showers and storms occur. The MVFR
Cigs should then rise to 3.5-5.0 kft for the afternoon and
evening with scattered storms continuing over all of srn WI.

Gehring

&&

.MARINE...
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

&&

.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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