NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 270540
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1240 AM CDT Sat Jun 27 2026

.KEY MESSAGES...

- Patchy fog possible tonight, mainly along the Lake Michigan
  shoreline and in the Wisconsin River Valley.

- Chance for showers and storms for Sunday night toward east
  central WI.

- Prolonged period of hot and humid conditions expected for all
  of next week. Potential for heat indices around to above
  100F.

- Additional shower/storm chances accompanying the heatwave
  Tuesday through the end of the week.

&&

.SHORT TERM...
Issued 1240 AM CDT Fri Jun 26 2026

Overnight through Sunday night:

Low clouds and fog briefly affected shoreline areas from
Milwaukee to Kenosha but has since dissipated. Patchy fog is
still possible in river valleys. We can expect a mostly clear
skies with few mid and high level clouds overnight, and a light
easterly breeze.

With high pressure centered over the Upper Great Lakes, easterly
winds will continue across southern WI and keep the (barely) below-
normal temperatures going for one more day. Highs will range
from the lower 70s near Lake Michigan to around 80 west of
Madison under mostly sunny skies.

Our shower/storm chances diminished for Saturday night into
Sunday. We still have storm chances for east central WI on Sunday
night, as there could be a storm complex that rolls across the
north half of the state. This would also coincide with the low
level warm front.

Cronce

&&

.LONG TERM...
Issued 1240 AM CDT Fri Jun 26 2026

Monday through Thursday:

The 925mb temps will surge to 26C on breezy south-southwest
winds. This would yield highs around 91-92 with dry adiabatic
mixing. Dewpoints should mix out a bit during the afternoon (NBM
and bias-corrected model guidance has a high bias), but still
top out in the lower 70s. This is VERY hot and humid and the
heat advisory criteria of 100 is expected to be met. We would
need heat indices of 105 or higher to meet the extreme heat
warning criteria. The southerly wind component could allow a
lake breeze to develop but not move very far inland.

While the 925mb temps will be similar on Tuesday and our
forecast is for Heat indices of 100-104, there is a small chance
that clouds from remnant storm complexes could end up over
southern WI.

Wednesday and Thursday will continue to have the warm bubble
with 925mb temps around 26 over southern WI. Therefore, heat
index values will likely continue to be just over 100 but we
will continue to watch for clouds to hinder that at times. With
low temps over 70 each night during this long stretch of heat
and humidity, this prolonged heat wave may warrant an extreme
heat warning which can be issued if we are expecting to meet
heat advisory criteria for four days in a row.

The ridge over the center of the country looks like it will
break down a little on Friday and give us increasing chances
(30-45%) for showers and thunderstorms Friday through Saturday.
This is during the July 3rd-4th fireworks shows. At this time,
there is very low confidence on these storm chances and we will
continue to watch closely.

Cronce

&&

.AVIATION...
Issued 1240 AM CDT Fri Jun 26 2026

Mid level clouds will gradually diminish along the IL border
overnight. Patchy fog is possible in the river valleys. Expect mostly
sunny skies with a few mid and high clouds during the day and
steady easterly winds.

Cronce

&&

.MARINE...
Issued 1240 AM CDT Fri Jun 26 2026

High pressure continues to track across the Upper Great Lakes
and influence the weather pattern through Saturday, with light
north to northeast winds. Patchy fog may occur at times.

Low pressure will deepen over the Central Plains for Sunday,
bringing breezy southeasterly winds to the lake. Winds then turn
southerly and strengthen more into Monday, as the low pressure
lifts into the Canadian Prairies. Gusty southerly winds may
linger into most of next week. Gales are not expected at this
time.

Waves may reach Small Craft Advisory Criteria Sunday night
through Monday night, especially north of the North Point Light.
Gusty southwest winds up to 25 kt are expected at times Monday
through Tuesday.

Cronce

&&

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

$$

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