508
FXUS63 KMKX 240335
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1035 PM CDT Thu May 23 2024

.KEY MESSAGES...

- Two rounds of showers and thunderstorms will likely occur from
  Friday morning into Friday evening. There is a slight risk for
  severe storms (2 out of 5) Friday, mainly for hail and gusty
  winds, although a brief, isolated tornado can`t be ruled out.

&&

.UPDATE...
Issued 1021 PM CDT Thu May 23 2024

Conditions will remain quiet through most of the overnight.

Most 00z model runs favor a dying line of thunderstorms moving
toward the lakeshore in the morning to early afternoon on Friday,
with redevelopment in the afternoon and evening causing most of
the severe weather threat for tomorrow.

Of note, the HRRR does depict an unstable sfc environment
lifting north ahead of the morning line of storms. While this
appears to be an outlier solution compared the the Nam 3km and
WRFs at the moment, if this solution were to pan out, there
could a brief window for severe weather with the morning round
inland from Lake Michigan before the line weakens as it moves
toward the lake. We`ll continue to monitor this potential
outcome overnight, especially as models get a better handle on
the MCS forming over the Central Great Plains.

CMiller

&&

.SHORT TERM...
Issued 234 PM CDT Thu May 23 2024

Tonight through Saturday:

Broken high based cumulus and isold showers have formed north
and west of Madison as a weak shortwave trough moves across
central WI. Isold to sct showers and isold storms will remain
possible north and west of Madison toward east central WI the
remainder of the afternoon. Upper ridging and quiet wx is then
expected tnt.

For Fri, a negative tilt upper wave and associated sfc low will
move from the ern Dakotas into Canada while deepening then
occluding. A surge of low to mid level warm, moist advection and
elevated CAPE will bring a 1st round of showers and storms from
west to east across srn WI Fri AM into the early afternoon,
with some weakening expected in the east, especially toward east
central WI. A few hours or more of decreasing pcpn coverage and
the nwd advance of the warm front is then expected over srn WI
before the cold front arrives from late afternoon into the
evening. There is uncertainty on the airmass recovery and the
amount of MLCAPE and MLCIN within the narrow warm sector, but
believe MLCAPE of 1000 J/KG is very probable while some MLCIN
will remain. However some PVA should aid the frontal forcing
and the HREF suggests another round of storms.

Deep layer shear will range from 30-45 kts while 0-2km SRH will
likely be rather high around 200-300 m2/s2 as veering profiles
remain in the narrow warm sector. As the fronts advance the lake
breeze should eventually retreat toward the lake but early
afternoon convection could reinforce it as well. All SVR threats
will be possible with supercellular development and/or QLCS
development. If the airmass recovery suffers, any meaningful
MLCIN would keep the tornado threat rather small.

Nwly winds and cold advection will then drop temps into the
middle 40s to lower 50s by sunrise Sat. High pressure will then
shift across the state on Sat with temps rebounding into the
lower 70s for the afternoon.

Gehring

&&

.LONG TERM...
Issued 234 PM CDT Thu May 23 2024

Saturday night through Thursday:

High pressure is expected to shift east of the region Saturday
night, as low pressure moves across Kansas. The low track is
generally northeast into far northern Illinois or southern
Wisconsin Sunday, before moving into northern Lake Michigan
Sunday night. Ensemble low track trends have been shifting a
little northward, so a track across far southern Wisconsin is
possible Sunday afternoon and early evening.

Warm air advection ahead of the low will bring deep moisture into
the area, and should bring clouds and showers/thunderstorms into
the area Sunday morning into the afternoon. There may be a couple
of shortwave troughs that rotate through the area as well, as the
main 500 mb remains northwest of the area.

The main question will be if and how much instability may develop
if the warm sector airmass can push into southern Wisconsin,
given the northward trend on the ensembles with the low track.
There is enough deep layer bulk shear to bring some severe storm
potential, so instability will be key. The further north the low
can track into southern Wisconsin, the better the severe weather
potential may be. Kept the higher PoPs for Sunday into Sunday
evening for now. Warm temperatures are expected to continue.

Another 500 mb shortwave trough may shift southeast through the
region Monday or Monday night/Tuesday, with the area getting into
more northwesterly flow. Some semblance of a cold front may shift
southeast through the region on Tuesday as well. Thus, kept PoPs
for showers and a few storms going for most of this period. High
pressure should bring back quiet weather for mid-week.
Temperatures via ensembles and NBM still look rather mild into
next week.

Wood

&&

.AVIATION...
Issued 1034 PM CDT Thu May 23 2024

Mainly VFR overnight with southeasterly winds. Clouds will
increase overnight and lower in height to low VFR as an MCS
moves in from the central plains. Rain and thunderstorms will be
possible between 12z and 18z as the line moves from west to
east tomorrow morning. Another round is expected to develop
tomorrow afternoon and move through from west to east between 18
to 21z through 03z. Hail and gusty winds will be possible with
these storms.

CMiller

&&

.MARINE...
Issued 234 PM CDT Thu May 23 2024

High pressure around 29.9 inches will drift across the Great Lakes
this afternoon into tonight. Light to modest southerly winds will
prevail over the entire lake becoming easterly late tonight.
Modest east-southeast on Friday are expected as a warm front
approaches followed by a cold front Friday night. A couple rounds
of thunderstorms are expected with the fronts. Modest westerly
winds will occur after the cold frontal passage and continue into
Saturday. High pressure around 29.9 inches will then move across
Lake Michigan for Saturday afternoon and evening.

Gehring

&&

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

$$

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