NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 060604
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
104 AM CDT Sat Jun 6 2026

.KEY MESSAGES...

- Scattered thunderstorms are possible through the night, mainly
  west/south of I-90/94.

- A very humid airmass will return Monday and Monday night ahead
  of approaching low pressure with widespread showers and
  scattered thunderstorms forecast.

- Hot and humid conditions expected mid to end of next week with
  some potential for Heat Advisory conditions late next week.

&&

.SHORT TERM...
Issued 104 AM CDT Sat Jun 6 2026

Overnight through Saturday Night:

The east-west broken line of storms will continue to slide
southward and exit southern WI between 1 and 2 AM. There is one
area of additional storms that are developing between La Crosse
and Wisconsin Dells. This is associated with the back edge of a
weak shortwave trough sliding through southern WI. The
vorticity advection with that feature will help whatever ongoing
storms progress into northern IL around daybreak. The main
thing we need to watch overnight is for training storms. With
precipitable water around 1.5 inches, the storms are efficient
rain producers.

High pressure will return to the Upper Great Lakes on Saturday
(today). We can expect mostly sunny skies and warmer
temperatures than yesterday, with highs in the mid 80s. We will
still be within the warm and humid air mass with dewpoints in
the 60s. The lakeshore will see some relief from from the heat
in the afternoon with a lake breeze, but the lake breeze is not
going to make it very far inland until the evening. Temps will
drop into the 50s for east central and southeast WI Sat nt as
drier air briefly moves in.

Sunday through Monday:

A closed upper low that will be over Texas today will make its
way into the Plains on Sunday. The position of this upper low as
it approaches the Upper Midwest will draw moisture up from the
Gulf and we can expect widespread showers with thunderstorms
over southern WI on Monday. They should spread in Sunday night
and exit Monday night, although the movement of this weak upper
low has uncertainty. This should bring another soaking rain.
There could be a few strong storms with this system on Monday,
given the negatively tilted upper trough, but the overall system
lacks the strong synoptic forcing for a bigger severe event.

Cronce

&&

.LONG TERM...
Issued 104 AM CDT Sat Jun 6 2026

Tuesday through Saturday:

Broad low pressure in the Great Plains will continue to pivot 500
mb shortwaves northeastward through the Great Lakes region Tuesday
and Wednesday, leading to on and off thunderstorm potential
(20-30% chances). Meanwhile, stiff southwesterly winds will
develop on Wednesday, bringing a warm, humid airmass into southern
Wisconsin. Expecting highs in the low 90s, with high temperatures
reaching all the way to Lake Michigan as southwest winds keep the
lake breeze offshore.

Thursday, low pressure ejects into the Canadian Prairies and
brings an occluded warm front through southern Wisconsin. This is
a potential trigger for additional storm development in the
afternoon (~35%), which may prevent temperatures from rising as
dramatically as Wednesday. However, highs in the upper 80s to
near 90 degrees are expected as southwest winds continue to
bring in plenty of warm, moist air from the Gulf. Thunderstorm
potential continues through Thursday night (20-35%) as winds
shift northwesterly and bring in upper 60s for the overnight
hours.

Winds shift back to southwesterly Friday as low pressure lifts
into northern Ontario and additional low pressure develops in the
central High Plains. Heat and humidity will increase again, with
heat index values potentially rising into Heat Advisory levels.
Pop-up thunderstorms are possible, but confidence is low at this
time (15-20%). Friday night, expect low pressure to eject into the
Plains. Model discrepancy develops as to the path this low takes,
but either solution (northern would result in more cloud cover and
less warming, southern would result in easterly winds off Lake
Michigan) would lead to a respite in high temperatures with the
most likely solution in the mid-80s.

MH

&&

.AVIATION...
Issued 104 AM CDT Sat Jun 6 2026

Storms will gradually shift southward into northern IL
overnight. This includes the additional development between La
Crosse and Wisconsin Dells that may affect MSN and JVL. Gusty
winds and small hail are the threats with these isolated storms.
Ceilings within the storms may briefly drop to MVFR, but
otherwise VFR conditions are expected through Saturday.

Light northerly winds will develop Saturday, with a lake breeze
in the afternoon that will shift inland during the evening.
Marine fog is possible later Saturday into Saturday night for
lakeshore areas.

Cronce

&&

.MARINE...
Issued 104 AM CDT Sat Jun 6 2026

Broad low pressure will move from Lake Superior into eastern
Ontario tonight, bringing a cold front through Lake Michigan
late tonight. Southerly winds this evening will allow for
continued warm air over cold waters and dense marine fog over
the northern half of the lake through Saturday morning. This may
need to be extended. The cold front from the low pressure will
produce storms across the southern open waters into early
Saturday morning. Winds will shift northwesterly behind the
cold front, but will remain light. Fog will gradually lift
through the afternoon hours Saturday, but may return Saturday
night. High pressure builds across the region Sunday, bringing
lighter and variable winds through the day. Low pressure
develops in the Great Plains Monday, bringing south-
southeasterly winds through at least midweek. Additional chances
for thunderstorms develop Monday and Tuesday.

Cronce

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Dense Fog Advisory...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
     LMZ567-LMZ868 until 1 PM Saturday.

&&

$$

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