064
FXUS63 KMKX 150152
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
852 PM CDT Tue May 14 2024

.KEY MESSAGES...

- Decreasing clouds overnight. Dry conditions Wednesday.

- Next round of showers and storms expected to impact southern
  Wisconsin on Thursday, with additional rounds into this
  weekend.

&&

.UPDATE...
Issued 850 PM CDT Tue May 14 2024

A gradual decrease in cloud cover is expected to continue from
northwest to southeast overnight tonight as low pressure drifts
eastward across Kentucky. The southeastern half of the CWA may
hold on to some of its mid and upper altitude clouds into the
early morning hours of Wednesday, hence the coolest overnight
low temps in our forecast (low 40s) are found in the north CWA
where it is already clear. Still expecting dry wx on Wednesday,
with a continued northeast breeze keeping Lake Michigan counties
much cooler than their inland counterparts.

Sheppard

&&

.SHORT TERM...
Issued 255 PM CDT Tue May 14 2024

Tonight through Wednesday night:

Weak 925-850mb frontogenesis and plenty of moisture in the
850-700mb level, along with deformation in the upper levels, are
responsible for the lingering clouds and light showers/drizzle.
Weak low pressure slowly moving across southern WI this
afternoon will make its way to the Ohio River Valley while
weakening tonight through Wednesday. With the slower movement of
this system, the clouds are much slower to clear across
southern WI this afternoon. In fact, mid level clouds may
linger across southeast WI until mid Wednesday morning due to
the lack of any advection of dry air.

Once the clouds do clear from northwest to southeast late
tonight to mid Wednesday morning, temps will increase into the
lower 70s for inland areas. The onshore winds will keep
lakeshore areas cooler, but warmer than today, with highs in the
60s.

Cronce

&&

.LONG TERM...
Issued 255 PM CDT Tue May 14 2024

Thursday through Tuesday:

A surface low pressure center will propagate into northwestern
Wisconsin Thursday morning supported by a weakening 500hPa
shortwave trough before moving off into Lake Superior by Thursday
night. Forcing via the associated occluded front is expected to
move eastward across the state throughout the day which combined
with the upper trough and low level moisture advection will bring
precipitation chances to southern Wisconsin (60%-70%). MUCAPE of
500-1000 J/kg and ~30kt 0-6km bulk shear suggests thunderstorm
development along the boundary is possible with a generally
discrete storm mode currently expected given 0-6km shear is
roughly perpendicular to the front. Model soundings also depict a
saturated column with PWATs of ~1.25 inches and mid-level lapse
rates of ~6.5 C/km which suggest that showers and storms that
develop will likely be efficient rain producers.

Decreasing clouds and drier conditions are expected on Friday,
but with another weak shortwave trough and PVA running across the
state combined with a well-mixed boundary layer, there may be
showers and perhaps a few rumbles of thunder across southern
Wisconsin in the afternoon (20%-30%).

A lot of uncertainty surrounds the forecast this weekend. Models
are starting to come into better agreement surrounding a 500hPa
shortwave trough and surface low traversing the northern Great
Plains Friday night into Saturday before entering the Great Lakes
region on Saturday night. Amplitude and timing of this trough are
still things to monitor with coming model runs, but it is
noteworthy that the long range deterministic guidance now depicts
this 500hPa trough as compared to a few runs ago where there was
discrepancy between if zonal or meridional flow was dominant
aloft. Have stuck with NBM guidance for the weekend due to this
uncertainty. However, upper level ridging and surface high
pressure appear to build across Wisconsin on Monday before
precipitation chances return again on Tuesday.

Falkinham

&&

.AVIATION...
Issued 850 PM CDT Tue May 14 2024

Though scattered to broken clouds currently linger in far
southeastern WI, cigs are already at VFR altitude, and should
remain so as cloud coverage continues to decrease overnight. Dry
weather and VFR continue through Wednesday evening, with mostly
clear skies. A northeast breeze is expected to continue in
Lakeshore counties, with slower due east winds for inland areas
on Wednesday.

Sheppard

&&

.MARINE...
Issued 255 PM CDT Tue May 14 2024

Low pressure over southern IL will continue to weaken overnight
as it tracks along the Ohio River Valley. Northerly winds up to
30 kt over Lake Michigan will diminish overnight, but remain
northerly into Wednesday evening. Southerly winds will develop
Thursday as a weak low pressure trough tracks into western WI
Thursday afternoon. Scattered showers and thunderstorms are
expected along the trough. Winds will become variable behind the
trough passage Friday as weak high pressure builds over the
Upper Great Lakes. The pattern remains unsettled for the weekend
with chances for showers and thunderstorms, but no periods of
elevated winds are anticipated.

Cronce

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 4 AM
     Wednesday.

&&

$$

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