140
FXUS63 KMKX 221000
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
500 AM CDT Sat Jun 22 2024

.KEY MESSAGES...

-  Flood Watch continues for flash flooding potential across
   portions of south central and southeast Wisconsin through
   late this evening. Multiple additional rounds of showers and
   storms are expected, with widespread rainfall amounts
   between 1 and 3 inches and locally higher amounts exceeding 3
   inches.

-  There is the potential for strong to severe thunderstorms
   this afternoon/evening (risk 2 out of 5). Damaging winds are
   expected to be the primary hazard, with isolated tornadoes
   and a few areas of large hail possible.

-  Heat index values in the upper 80s to low 90s are expected
   across far southern Wisconsin today, with heat index values
   reaching 90 degrees across much of southern Wisconsin again
   on Tuesday.

- Strong thunderstorms may develop once again along a cold
  front on Tuesday.

&&

.SHORT TERM...
Issued 500 AM CDT Sat Jun 22 2024

Today through tonight:

Scattered showers and thunderstorms are ongoing along the nose
of an 850 mb LLJ, pushing northeastward through the mid-morning
hours. Warm frontogenesis north and west of the I-90/I-94
corridor will allow for scattered to isolated showers and
storms to linger through the day, while areas to the south may
even see brief breaks in cloud cover and temperatures rising
into the upper 80s in far southern Wisconsin. With high
humidity, heat index values in far southern Wisconsin may rise
to near 90 degrees. PWATS of 2 to 2.25 inch will lead to heavy
rainfall rates and wet microburst potential within any
thunderstorms that develop. However, storms will be moving
quickly northeastward. Therefore, training convection will be
needed to realize flash flooding potential. A Flood Watch
remains in effect due to multiple additional rounds of rainfall
over already wet soils. This watch is valid through midnight CDT
tonight to account for any lingering precipitation after cold
frontal passage.

Low pressure strengthens over northern Wisconsin late this
afternoon, developing and pushing a strong cold front
southeastward through southern Wisconsin late this afternoon
into tonight. This cold front will be pushing into a primed
airmass with CAPE of 1000 to 2000 J/kg, 0 to 3 km SRH of 200 to
300 m2/s2, and minimal CIN. PWATs on the order of 2 inches, a
700 mb jet, and at least a few hundred J/kg of DCAPE lends
credence to widespread damaging wind potential along the line.
QLCS tornadoes are also a potential as line normal shear may be
up to 40 kts in places while SRH of 200 to 300 m2/s2 continues.
Storms exit offshore into Lake Michigan into the early overnight
hours, with northwesterly breezes thereafter.

MH

&&

.LONG TERM...
Issued 500 AM CDT Sat Jun 22 2024

Sunday through Friday:

A quiet day on Sunday, with a few isolated showers and
thunderstorms in southeastern Wisconsin during the afternoon
hours (15% chance) as a shortwave passes through. Northwesterly
breezes continue, with highs near 80 degrees. High pressure then
dominates through Monday, allowing temperatures to rise again
into the mid-80s.

Tuesday, low pressure propagating eastward through the Canadian
provinces will shift winds southwesterly and bring in high heat
index values and high humidity once again. A frontal feature
associated with this low is expected to bring showers and
thunderstorms. A few storms may be strong to severe, with
increasing CAPE and PWATs through the day.

Longwave ridging across the Southeast U.S. and Appalachia may
permit the frontal boundary to stall through Wednesday morning
before weakening, bringing additional rainfall to southern
Wisconsin. High pressure and seasonable temperatures are then
expected Wednesday through late week, with an additional
Canadian low producing thunderstorm chances Friday.

MH

&&

.AVIATION...
Issued 500 AM CDT Sat Jun 22 2024

Scattered showers and thunderstorms are producing visibilities
between 3 and 5 SM. Strong thunderstorms are producing
visibilities around 1 SM. Meanwhile, light onshore flow and
humid conditions have lead to patchy dense fog along the Lake
Michigan lakeshore. IFR Ceilings near Lake Michigan and near MSN
reflect lifting fog, with ceilings rising into MVFR/VFR beneath
showers and thunderstorms. Scattered showers and thunderstorms
will give way to more widespread showers with embedded
thunderstorms in southwestern Wisconsin later this morning,
while terminals near Lake Michigan may see a break in
precipitation this morning into early this afternoon. MVFR to
VFR conditions are expected during this time frame. During the
late afternoon to late evening hours, a strong line of
thunderstorms is expected to progress southeastward across
southern Wisconsin, producing damaging winds, isolated
tornadoes, and heavy downpours. Northwesterly winds are expected
after the line exits.

MH

&&

.MARINE...
Issued 500 AM CDT Sat Jun 22 2024

Light winds will transition to southerly and gusty across the
southern two-thirds of the open waters and to easterly and gusty
across the northern one-third this morning into this afternoon as
low pressure develops in southern Minnesota. This low will
progress through northern Lake Michigan this evening into
tonight, bringing widespread thunderstorms along a cold front.
Gusty winds are expected with these thunderstorms, especially in
the southern half of the lake. Winds may approach Small Craft
Advisory criteria tonight after the line of storms moves into
the open waters. Winds across the Lake then shift northwesterly
late tonight into Sunday morning as storms end. Winds will
diminish but remain northwesterly through Sunday night, with
high pressure building in Monday and producing light and
variable winds.

MH

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Flood Watch...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-WIZ057-WIZ058-
     WIZ059-WIZ062-WIZ063-WIZ064-WIZ065-WIZ067-WIZ068-WIZ069
     until midnight Sunday.

LM...None.
&&

$$

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