215
FXUS63 KMKX 150929
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
429 AM CDT Mon Jul 15 2024

.KEY MESSAGES...

- Showers and thunderstorms will develop along & ahead of an
approaching cold front late this afternoon and this evening. Storms
could be strong to severe, with damaging winds and large hail being
the primary concerns. An isolated tornado can`t be completely ruled
out.

- Areas of patchy fog are expected through sunrise, particularly
along and west of I-39.

- Elevated heat indices in the mid to upper 90s are expected once
again this afternoon.

- Drier, quieter weather conditions return behind a departing
  cold front by mid week.

&&

.SHORT TERM...
Issued 428 AM CDT Mon Jul 15 2024

Today through Tuesday:

Synopsis/Mesoanalysis: Much quieter conditions prevail across
southern Wisconsin early this morning. Satellite imagery depicts the
back side of the cirrus canopy connected to last night`s storms
pushing east toward the Lake Michigan shoreline, with mostly clear
skies taking hold across south-central and southwestern Wisconsin.
Efficient radiational cooling has been able to occur beneath the
clearing skies, allowing for pockets of fog development to occur as
temps fall back to the still elevated dew points in place across the
state. Anticipate that some areas of fog will develop in low-lying
spots across the region through daybreak, with the best chances
residing along and west of Interstate 39. Fog will quickly burn off
after sunrise as temperatures quickly begin to climb regionally.
Attention will then turn to northern Iowa & southern Minnesota this
afternoon, where thunderstorms are expected to erupt along/ahead of
an approaching cold front. The precise location of storm initiation
within this region remains uncertain, though the general expectation
is that storms that do ultimately form will move into southern
Wisconsin during the late afternoon and evening hours today. A moist
& unstable atmosphere, combined with increasing wind shear aloft,
will support severe weather potential in these storms. Along with
the responsible cold front, thunderstorm activity will push east of
the area after midnight. Much quieter conditions will prevail
Tuesday and Tuesday night behind the departed front.

Rest Of Overnight: Expect pockets of fog to persist through
daybreak, focused in greatest concentration along and west of
Interstate 39. Widespread dense fog is not expected, though
localized pockets of half to one mile visibilities can`t be ruled
out. Be sure to slow down, use low beam headlights, and allow for
extra following distance if encountering areas of fog on the roads
this morning. Fog will quickly burn off as temperatures climb
following sunrise.

This Afternoon: Hot and humid conditions continue for one more
afternoon. Heat indices in the mid to upper 90s are expected
areawide. Stay hydrated, wear light-colored & loose-fitting
clothing, and take frequent breaks in the shade if spending
prolonged periods of time outdoors this afternoon.

This Evening: Ongoing along/ahead of an approaching cold front,
expect at least scattered thunderstorm potential across the region
from late afternoon through the first half of the evening. Precise
evolution, as well as coverage of storms remains uncertain, with 00
and 06Z CAMs suggesting multiple possible scenarios/convective
evolutions. The general expectation is for scattered to numerous
storms to develop by late afternoon somewhere in the northeastern
IA/southeastern MN vicinity. Precise placement of initiation
corridors will be highly dependent on the approach of several
convectively-enhanced shortwaves from the Plains, as well as the
interaction of said shortwaves with a residual outflow boundary from
last night`s storms in Iowa. The aforementioned surface boundary
will act as an essential warm front moving into this afternoon,
forming the northern bound on an extremely unstable (3000-4000+
J/kg) air mass to its south. While each 00/06Z CAM solution has a
different depiction of the northeastward progress of this boundary,
the majority are in agreement that storms developing over
northeastern IA/southeastern MN will organize into 1+ bowing
segments tracking along the boundary. How far northeast the outflow
can return will thus have large implications on the extent of
southern Wisconsin ultimately impacted by activity. Placement
uncertainties aside, a warm/muggy & unstable air mass, combined with
increasing shear aloft, will support damaging wind and large hail
potential in activity forming/tracking along the remnant outflow
boundary. While secondary to the wind/hail potential, an isolated
tornado can`t be ruled out. Additional showers and storms are also
possible further north/in central WI along the primary cold front,
and would also pose large hail and damaging wind potential.
Observational trends will be monitored closely through the morning
hours, with forecast adjustments being made as conditions warrant.

Tuesday: Significantly quieter conditions will prevail as cooler &
drier air filters into the region behind the departed cold front. A
few pop-up rain showers can`t be ruled out during the afternoon
hours. Negligible impacts are expected in any activity that
materializes.

Quigley

&&

.LONG TERM...
Issued 428 AM CDT Mon Jul 15 2024

Tuesday night through Sunday:

A robust upper level shortwave trough will swing across northern
WI early Wed morning. Highs Wed will only be in the mid to upper
70s, which is below normal for mid July. Dewpoints will gradually
decrease from the lower 60s to the mid 50s through the day. Steep
mid level lapse rates overhead during the day Wed will allow for
a few showers and thunderstorms, but these are expected to be over
the northeast half of WI. The showers (probably not thunder) may
clip northeast sections of our forecast area (Fond du Lac,
Sheboygan and West Bend) during the afternoon hours.

Surface high pressure will dominate southern WI Thursday through
Saturday. Expect quiet weather and high temperatures in the upper
70s to around 80 with comfortable dewpoints in the 50s. As we get
into next weekend, there will be more unsettled weather in the
central Plains and high pressure over the Great Lakes. Portions of
southern WI may end up getting clipped by remnants of those Plains
showers and storms at times.

Cronce


&&

.AVIATION...
Issued 428 AM CDT Mon Jul 15 2024

Mostly VFR conditions are in place early this morning in the wake of
last evening`s showers and storms. One exception is at KMSN, where a
BKN deck based between FL025 and FL030 has persisted. Have accounted
for the aforementioned near-term trends in the 06Z and coming 09Z
updates. Expect pockets of fog to develop through daybreak, with
greatest coverage over south-central Wisconsin and the Wisconsin
River Valley. Have inserted a brief period of VIS reductions in the
MSN and JVL TAF given this anticipated development. VIS reductions
will quickly improve following sunrise. Periods of SHRA and TSRA are
still expected ahead of an encroaching cold front this afternoon &
evening. Uncertainties remain regarding precise placement and timing
of this activity. Have thus carried PROB30 mentions at all terminals
in the 06 and 09Z updates, with TEMPO and/or prevailing mentions
being inserted in later updates.

Quigley

&&

.MARINE...
Issued 428 AM CDT Mon Jul 15 2024

Ongoing rain showers will push east of the southern half of the open
waters through daybreak, giving way to a break in shower and
thunderstorm activity through late morning and early afternoon.
Pockets are expected to develop through sunrise, particularly across
the northern half of the open waters. Don`t currently anticipate
widespread visibility reductions below one mile, so have thus held
off on any marine dense fog advisories in the overnight forecast
update. Will nevertheless monitor trends through sunrise and make
adjustments if necessary. Additional shower and thunderstorm chances
enter the forecast late this afternoon and evening as a cold front
crosses the lake. A few storms could be strong to severe with large
hail and gusty winds, particularly over the southern third of the
open waters. Winds will turn out of the northwest behind the front
on Tuesday, with gusts between 15-20 knots possible through
sunset.

Quigley

&&

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

$$

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