410
FXUS63 KMKX 252112
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
412 PM CDT Sat May 25 2024

.KEY MESSAGES...

- Widespread showers and storms on Sunday, with at least a small
  potential for severe thunderstorms with hail and/or wind
  gusts.

- Southeast winds and building waves are likely to create
  Moderate Swim Risk conditions on Sunday for Lake Michigan
  beaches. A High Swim Risk cannot be ruled out, and a Small
  Craft Advisory may be needed as well.

- Chance for showers/storms Monday and Tuesday, particularly in
  the afternoon hours (roughly 40% chance), but quieter weather
  midweek.

&&

.SHORT TERM...
Issued 410 PM CDT Sat May 25 2024

Tonight through Sunday night:

Quiet weather this evening into tonight, with high clouds
gradually approaching. Showers and storms approach from the
southwest Sunday morning, likely arriving at Janesville and
Madison after 7 AM CDT and overtaking the entire CWA by noon or
1 PM. 700mb charts indicate this first wave of showers and weak
thunderstorms will be driven by strong WAA and frontogenesis
(decent coverage expected) but should be elevated convection and
should not be severe. With a dry slot wrapping into the low
pressure Sunday afternoon, and the surface warm front advancing
deep into the CWA, a small window for a few severe storms is
present, generally between 2 PM and 7 PM Sunday. Hail and wind
gusts would be the primary concerns if applicable, and this
threat is conditionally dependent on airmass recovery from the
morning round of convection.

Steady southeast winds are expected over a decent fetch of Lake
Michigan on Sunday, with WAVEWATCH III producing waves up to 4
feet offshore of Lake Michigan beaches. This would meet the
criterion for a Moderate Swim Risk on Sunday, specifically in
the afternoon and evening hours. A High Swim Risk cannot be
ruled out at this time.

Sheppard

&&

.LONG TERM...
Issued 410 PM CDT Sat May 25 2024

Monday through Saturday:

Monday and Tuesdays upper air pattern features a negatively
tilted trough axis from Manitoba into Wisconsin, with multiple
shortwave perturbations rotating through. Though it is less
organized than Sunday`s thunderstorm setup, showers and
thunderstorms will be possible Monday and Tuesday (roughly 40%
chance each day), particularly in the afternoon hours. Daytime
highs in the upper 60s to around 70 expected each day, with a
synoptic northwest breeze strong enough to prevent any lake
breeze from forming (hence, lakeshore and inland temps should be
equal). A ridge in the jet gradually builds in Wednesday into
Thursday, with quiet weather expected, daytime highs rising a
few degrees, and a lake breeze possible. Next (potentially)
active pattern would be Friday into the weekend, though
predictability is very low.

Sheppard

&&

.AVIATION...
Issued 410 PM CDT Sat May 25 2024

VFR conditions and quiet weather continue into tonight, with
high clouds gradually approaching and winds turning
southeasterly. Southeast winds become breezy after sunrise
Sunday, with showers and thunderstorms overtaking the region
from southwest to northeast. If we had any severe thunderstorms
(low chance, but still possible) they would likely be in the 2
to 7 PM CDT timeframe. As periods of showers and storms continue
on Sunday, expect cloud ceilings to lower to MVFR and
eventually Fuel-Alt MVFR levels. IFR ceilings are possible late
Sunday into Sunday night, with winds veering northwesterly
behind the departing low pressure.

Sheppard

&&

.MARINE...
Issued 410 PM CDT Sat May 25 2024

High pressure around 29.9 inches will remain over Lake Michigan
this evening, then exit northeastward into Sunday. Light
southerly winds continue this evening, then back southeasterly
late tonight as low pressure around 29.4 inches approaches from
the Central Plains. This low will move across either central or
northern Lake Michigan Sunday night. Expect southeasterly winds to
increase as this low approaches, followed by west to northwest
winds on Monday as the low departs northeastward.

Marine Hazards: Numerous showers and thunderstorms will move
across the lake Sunday and Sunday night. Southeast winds and
building waves on Sunday might reach Small Craft Advisory
levels. On the back side of the departing low pressure,
northwest wind gusts could reach Small Craft levels again on
Monday, but waves will be small given the offshore flow.

Sheppard

&&

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

$$

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