653
FXUS63 KMKX 111503
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1003 AM CDT Tue Jun 11 2024

.KEY MESSAGES...

- Showers and thunderstorms are possible at times Wednesday
  night into Thursday evening, with uncertainty with timing and
  placement of convection lingering.

- Warmer and more humid conditions for Wednesday into Thursday.

- A significant warm up still looks likely for Sunday into early
  next week.

&&

.UPDATE...
Issued 1003 AM CDT Tue Jun 11 2024

Some mid to high level clouds are slowly moving in from the
northwest late this morning ahead of a incoming sfc trough.
Ahead of the sfc trough is a line of rain showers advancing
southeast. Soundings show a very dry low level with dewpoints in
the 40s to help support that. As this line of showers continues
to move southeast it will battle increasing drier air. This
should cause the line to break or scatter out a bit more
overtime. Any rain that does persist will struggle to make it to
the ground the further east it gets.

Additional widely scattered showers and a few thunderstorms will
be possible later this afternoon into tonight. These widely
scattered showers will be better routed along the sfc trough.
Again moisture will be lacking, but any storms that do develop
will quickly fall apart as we loose daytime heating.

Patterson

&&

.SHORT TERM...
Issued 425 AM CDT Tue Jun 11 2024

Today through Wednesday:

Middle to high clouds will gradually increase today, as a 500
mb shortwave trough approaches the region from the west
northwest. This feature should move across the region tonight,
along with a surface trough. Forecast soundings are showing just
enough warm air and moisture advection in the 850 mb layer to
bring in some weak to modest elevated instability later this
afternoon and tonight.

These features should result in widely scattered showers and
perhaps a few thunderstorms from later this afternoon into the
overnight hours tonight. CAMs are showing this general trend
with the showers as well, with any more organized thunderstorms
with the surface trough to the west of the area later this
afternoon into early this evening. These storms should
dissipate this evening with the loss of daytime heating.

Another pleasant day is expected today, with highs in the lower
to middle 70s. A southeast lake breeze may cool things down near
Lake Michigan this afternoon.

Steady warm air advection tonight into Wednesday will bring
warmer and more humid air into the region, with southwest winds.
It looks to remain dry for most of Wednesday, as any convection
should remain to the west. Highs should reach into the middle
80s for most of the area, with a lake breeze possible near the
shoreline in the afternoon.

Wood

&&

.LONG TERM...
Issued 425 AM CDT Tue Jun 11 2024

Wednesday night through Monday:

CAMs are showing convection developing somewhere near the warm
front in southern Minnesota Wednesday afternoon, then shifting
southeast into northern Iowa and perhaps clipping far southwest
Wisconsin Wednesday night. Additional convection may develop
further northeast across northwest Wisconsin Wednesday evening
and perhaps shift southeast toward the area overnight. A lot
will depend on the low level jet feeds into these areas, and
where it focuses upward vertical motion. It should weaken
somewhat overnight as it shifts more to the southeast over the
area.

All in all, probably will see weakening convection move southeast
toward and into the area later Wednesday evening and overnight,
perhaps lingering into Thursday morning. There is enough
elevated CAPE for perhaps gusty winds and small hail, but think
most of this activity should be weakening and bring some locally
heavy rainfall at worst. Have likely PoPs for the rain and some
thunderstorms over northern and western parts of the area later
Wednesday night.

Warm and more humid conditions will linger Thursday, with highs
in the middle 80s and dew points in the 60s. Any chances for
convective development on Thursday will depend on how far south
the effective cold front develops. The models and ensembles seem
to be trending south with the frontal position into northern
Illinois, where most of them develop more convection Thursday
afternoon and evening. The decaying showers and storms from
overnight Wednesday night into Thursday morning may also help
push the effective front southward.

Kept chances for showers and storms going for Thursday
afternoon and evening, mainly in southern and southeastern
portions of the area closest to the front. Strong to perhaps
some severe storms could occur in the moist and unstable airmass
ahead of the front, but this could be in northern Illinois. Also
lacking good upper level support over the region, so the front
may be the only good trigger mechanism for storms. Will
continue to watch this potential and where the front may set up.

High pressure then moves southeast into the region for Friday
and to the east Saturday, bringing dry conditions and more
seasonable temperatures with less humidity.

Ensembles remain fairly confident with a warm up for Sunday into
early next week over the region. Cluster Mean forecasts
generally show a 500 mb ridge axis building over the eastern
Great Lakes region, with southwest flow over the northern and
central Plains into the western Great Lakes region.

This setup should allow for south to southwest winds to bring
very warm and humid conditions back into the region. NBM is
showing 25th to 75th percentile spreads of middle 80s to lower
to middle 90s for highs for most of the area. Went with upper
80s to lower 90s for highs Sunday into Monday, and heat index
values may climb into the middle 90s each day.

In addition, rounds of showers and thunderstorms may occur,
though there is a good amount of uncertainty in the timing and
placement of frontal features and subsequent convection.
Ensemble members continue to show more wetness than not, so
another thing to watch for the extended period.

Wood

&&

.AVIATION...
Issued 1003 AM CDT Tue Jun 11 2024

Largely VFR ceilings are expected to persist through the period.
A line of showers advancing southeast late this morning will
move through southern Wisconsin this afternoon. Ceilings are
expected to be around 5-8 kft as this line of showers moves
through. Dry air in the low levels will slowly cause this line
to become scattered as it moves east. Additional widely
scattered showers and a few thunderstorms will be possible later
this afternoon which will bring the same chance for some MVFR
ceilings or visibilities with any storms.

By tonight, dry weather will return and continue into Wednesday
afternoon. Clouds will clear out again early Wednesday morning
leading to clear skies for much of the day. Light south to
southwest winds will persist through the period.

Patterson

&&

.MARINE...
Issued 425 AM CDT Tue Jun 11 2024

Winds will become south to southeast today, as high pressure
around 30.0 inches moves to the southeast of the region. South
to southwest winds will then linger tonight into Wednesday.

Increasing southwest winds are expected for Thursday, ahead of
an approaching cold front. These winds may reach Small Craft
Advisory levels for the nearshore waters.

There are chances of thunderstorms at times Wednesday night into
Thursday evening, though there is uncertainty with the timing
and location of storms. Later forecasts should get a better
handle on where storms may occur during this time.

Winds will shift to the northwest and north behind the front
Thursday night into Friday, with high pressure around 30.2
inches moving into the region.

Wood

&&

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

$$

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