NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 211525
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1025 AM CDT Sun Jun 21 2026

.KEY MESSAGES...

- Rain is delayed today but still looking likely from Madison to
  Milwaukee and south to the IL border for mid afternoon and
  evening. Around one half inch of rain is expected toward the
  IL border.

- At least Moderate Swim Risk is expected for the Lake Michigan
  beaches Monday with the possibility for High Swim Risk to
  develop. Keep out of the water and away from dangerous areas
  like piers and breakwalls!

- On and off thunderstorm chances Tuesday through Thursday, and
  potentially again next weekend.

- Below normal temps continue.


&&

.UPDATE...
Issued 1025 AM CDT Sun Jun 21 2026

Delayed onset of rain today but still expecting 60-90 percent
chances along and south of a line from Madison to Milwaukee for
mid to late afternoon and into the evening. The shield of rain
is finally moving newd across ern IA and nrn IL. The shortwave
trough over far srn IA and nrn MO will move due east, but
another shortwave trough over nw IA will move across far srn WI
this evening. This feature and associated PVA, along with mid
level warm advection and frontogenesis reaching the WI and IL
border, may be enough for measurable light rain as far north as
Madison and Milwaukee. Moderate rainfall rates are still expected
at times near the IL border with rainfall totals around one
half inch there.

Gehring

&&

.SHORT TERM...
Issued 1253 AM CDT Sun Jun 21 2026

Today through Monday night:

Patchy fog early this morning will burn off quickly as the sun
rises, even with high cloud cover increasing. By mid-morning,
expecting northeasterly onshore winds to increase and steady
rainfall to spread west to east generally along and south of the
I-94 corridor. More isolated to scattered rainfall is expected
to the north of the corridor, with the NAM family still indicating
the farthest north trajectory all the way through
Marquette/Green Lake/Fond du Lac/Sheboygan during the late
afternoon to evening hours. However, with a known moisture bias,
tend to lean toward the isolated shower solutions for those areas.
In addition, global models are still showing dry conditions across
southern Wisconsin, which leads to the continued hedging against
higher PoPs along and north of the I-94 corridor. Very minimal
(~100-200 J/kg) MUCAPE exists in the 0 to -20 C portion of the
column right along the WI/IL border during the late afternoon to
evening hours, so cannot rule out an isolated bolt of lightning,
but the probability is very low (~10%).

As low pressure makes its closest approach this afternoon into
tonight, expecting gusty northeast winds to develop and persist
along Lake Michigan counties and far southern Wisconsin. Gusts 20
to 25 mph expected. With rain and onshore winds, expecting
temperatures to struggle to exit the 60s, with some areas farther
north where sunlight lingers longer seeing highs in the low 70s.

Low pressure exits to the east overnight tonight, with gusty winds
continuing and turning more northerly. Moderate to high swim risk
is expected to develop along Lake Michigan beaches during the
overnight hours, continuing into Monday, with high swim risk
generally expected Milwaukee County southward. Stay out of the
water during this period, and stay away from dangerous areas like
piers and breakwalls! Highs in the 60s are expected near Lake
Michigan, gradually increasing westward to the upper 70s in
southwest WI. Winds will gradually diminish Monday night, allowing
waves to diminish below hazardous levels. Lows Monday night in
the low 50s.

MH

&&

.LONG TERM...
Issued 1253 AM CDT Sun Jun 21 2026

Tuesday through Sunday:

High pressure persists over the Great Lakes region through
Tuesday, with low pressure deepening over the northern Plains.
Expect southwesterly winds to bring in highs in the upper 70s.
Low pressure looks to pivot northeastward into Tuesday night,
bringing the next widespread chances for rainfall to southern
Wisconsin (60-80%). Lightning will also be expected with this
rainfall, but low potential for severe at this time (time of day
and lack of LLJ dynamics lead to a very conditional threat,
especially with the parent low so far northwest).

Lingering precipitation across the Midwest along a frontal
boundary from the northern Plains low then looks to phase with a
shortwave from the southern Plains, allowing for cyclogenesis
across the Great Lakes and therefore bringing an additional wave
of precipitation on Wednesday (60-80%). The timing of this wave
looks to be more favorable, with southern Wisconsin remaining in
the warm sector. Lightning is expected, and potential for severe
may develop during the afternoon hours on Wednesday. Low pressure
exits into Wednesday night, with a cold front bringing in one last
round of showers and storms. Modeling diverges on whether low
pressure continues to bring a final shortwave of precipitation
across the region on Thursday, so left in 20-40% PoPs due to
uncertainty.

High pressure makes a brief return on Friday, but an active
pattern with frequent shortwaves propagating through the southern
Plains into the Upper Midwest will continue through the weekend.

MH

&&

.AVIATION...
Issued 1025 AM CDT Sun Jun 21 2026

Widespread rainfall will move from IL into srn WI through the
afternoon and continue into the evening mainly along and south
of a line from Madison to Milwaukee. Areas of MVFR Cigs and
Vsbys can be expected with the rain over far srn WI but
extending into the MKE metro area during the evening. The low
Cigs and lingering rain showers will continue into early Tue AM
from MKE south to ENW. Partly cloudy skies and VFR conditions
will then return for the daylight hours of Tue.

Gehring

&&

.MARINE...
Issued 1025 AM CDT Sun Jun 21 2026

Low pressure around 29.5 inches will track eastward from the
central Great Plains into central Illinois early this evening,
then into Ohio by Monday. This will bring light easterly winds
through the daytime hours today, becoming breezy northeast to
north winds over the southern portion of the lake tonight and
Monday. Lighter northerly winds return late Monday evening into
Tuesday as high pressure around 30.1 inches builds into the
region. A Small Craft Advisory may be needed on Monday from
Sheboygan to Winthrop Harbor IL, but there is still some
uncertainty with the magnitude of nly winds and resultant wave
heights.


&&

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

$$

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