550
FXUS63 KMKX 200502
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1202 AM CDT Sun Sep 20 2026

.KEY MESSAGES...

- Additional storm development is expected this evening,
  particularly along and south of Interstate 94. Additional
  heavy downpours and flooding impacts would be the main
  concerns.

- Prolonged period of high swimming risk conditions continues
  into Tuesday at all Lake Michigan beaches, and may need to be
  extended into Wednesday evening.

&&

.SHORT TERM...
Issued 1112 PM CDT Sat Sep 19 2026

Current Overnight through Sunday Night:

A band of moderate rain is currently angled from Northern Dane
County through Northern Racine County in association with lift
from 925mb frontogensis. Rainfall has been pretty efficient
within this band, with 0.5 inch accumulations recorded within
one hour. This band is generally pushing E-SE and should push
out over Lake Michigan in a progressive manner over the next few
hours.

Meanwhile, convection is currently blossoming south of the
Wisconsin/Illinois border as WAA causes uplift over a sfc
boundary. As the night goes on, high pressure from central
Canada is expected build southward into the Upper Great Lakes,
increasing the sfc pressure gradient and generating
northeasterly flow, which will continue to keep the surface
boundary south of the border. The compression of the environment
between the high and the sfc boundary will also further
intensify the convection over Illinois. It is projected that
some of this convection will deal a glancing blow of rain to the
southern Wisconsin Counties along the Wisconsin and Illinois
border generally from 3am onward. While the heaviest rain will
stay in Illinois, and additional inch to inch and a half of rain
may occur during the early morning hours in these counties. A
Flood Watch will stay out along the WI/IL border until 7am to
account for the possibility of this rain overnight.

Rain should quickly end through the post dawn hours of the
morning on Sunday as the influence of the high pressure
continues to push into the upper Great Lakes region. By the mid
to late afternoon, some breaks in the clouds may occur over
east-central to south central Wisconsin. With the stronger
pressure gradient over the region, wind gusts from 20 mph inland
to 30mph near the lake will be possible.

The strong winds will drive high onshore waves and rip currents
at all Lake Michigan beaches. A Beach Hazard Statement is in
effect from now through Tuesday owing to the long duration
hazards swimming conditions.

CMiller

&&

.LONG TERM...
Issued 1148 PM CDT Sat Sep 19 2026

Monday through Friday:

High pressure will continue to linger over the northern Great
Lakes Monday ahead of an approaching cutoff low over Iowa.
Chances for scattered rain (15 to 30% PoPs) will persist through
the day as some moisture tries to work into the area from the
cutoff low, but ultimately runs into the subsidence of the
high. The cutoff low should lift back into the background zonal
flow aloft Monday night into Tuesday and precip chances should
largely end by Tuesday morning.

Dry conditions then look to be in store for the rest of the
extended period. Some residual troughing aloft will keep us cool
through the mid week period with highs in the low to mid 60s.
70s then return for the upcoming weekend as ridging begins to
build over the upper MS Valley.

CMiller

&&

.AVIATION...
Issued 1148 PM CDT Sat Sep 19 2026

A band of steady rain is currently located from roughly KMSN to
KRAC. This band of steady rain will move east over Lake Michigan
over the next few hours. Thunder is not expected with this
activity. Convection over IL is then expected to deliver a
glancing blow of rain from KEFT over to KENW through the early
morning hours. Some thunder can`t be ruled out with this
activity.

The ample low- level moisture will promote vis and
ceiling reductions into the LIFR to IFR category, with widely
scattered VLIFR conditions. Winds will shift from easterly and
light currently to northeasterly with gusts to 20 knots by
daybreak Sunday.

Rain ends Sunday before noon, with ceilings gradually improving
to MVFR by 18z with VFR then slowly working in from the north
during the afternoon. Some breaks in the clouds may occur over
east central to south central WI during the afternoon.


CMiller

&&

.MARINE...
Issued 1142 PM CDT Sat Sep 19 2026

Low pressure over the central Plains will track to east central
Illinois by Sunday morning, then settle over the southern Ohio
Valley for next week. Meanwhile, high pressure over Manitoba
will strengthen and track across Ontario for Sunday and Monday,
then to Quebec for Tuesday and Wednesday. Modest east winds
tonight will become breezy east to northeast winds Sunday
through Wednesday with the highest winds over the south hal..
Winds may come within a few knots of gales Sunday afternoon and night
over western portions of the lake.

CMiller

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ052-WIZ060-WIZ066-WIZ071-WIZ072
     until 7 PM Tuesday.

     Flood Watch...WIZ062-WIZ063-WIZ064-WIZ065-WIZ066-WIZ067-WIZ068-
     WIZ069-WIZ070-WIZ071-WIZ072 until 7 AM Sunday.

LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 7 PM
     Tuesday.

&&

$$

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