NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 171955
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
255 PM CDT Wed Jun 17 2026

.KEY MESSAGES...

- Widespread showers and scattered thunderstorms expected today
  into tonight. Still monitoring an isolated risk for a few
  severe storms (hail/wind) late afternoon into the evening,
  though the greatest chances will be to the south of the area.

- A Small Craft Advisory and High Swim Risk are both in effect
  for nearshore regions and beaches through late tonight. Gusty
  southeast winds will lead to high waves and dangerous
  currents.

- The next substantial chance for thunderstorms arrives Sunday
  (45-65% chances), although on and off periods of isolated to
  scattered storms are possible through much of the week.

&&

.SHORT TERM...
Issued 255 PM CDT Wed Jun 17 2026

Tonight through Thursday:

Light rain continues across the WI/IL border into this evening,
with the line of expected thunderstorms along a cold front
progressing eastward from southern Minnesota. Expecting storms
to arrive in southwestern Wisconsin around 5 PM CDT, progressing
to southeastern Wisconsin by 7 PM CDT. With plenty of cloud
cover and very little instability building into the region
(MUCAPE 500-750 J/kg riding just ahead of the cold frontal
boundary), expecting the primary hazard with this activity to be
lightning. An isolated storm may become severe in primarily
southwestern Wisconsin, with wind and hail as the main threats.
Storms will exit into Lake Michigan by sunset, with only a few
showers in central and southeastern Wisconsin lingering after
dark.

Winds are also expected to build waves up along Lake Michigan
beaches, with a High Swim Risk expected throughout this
afternoon and tonight. Stay out of the water and away from
dangerous areas like piers and breakwalls!

Winds become northwesterly overnight as low pressure exits to
the east, with gusty conditions possible in southeastern
Wisconsin Thursday morning before becoming steady midday.
Thursday afternoon, isolated thunderstorms along a weak 500 mb
shortwave are possible. No severe weather is expected with these
storms, but lightning is anticipated.

MH

&&

.LONG TERM...
Issued 255 PM CDT Wed Jun 17 2026

Thursday night through Wednesday:

Drier conditions are expected Thursday night as a surface high
pressure system begins to move in from the Plains following a
surface low. There is a slight chance for isolated precipitation
Thursday night (10-20%). As the high pressure enters from the
west Friday morning behind a cold front, primarily stable and
drier conditions are expected. However, the development of a NW-
SE jet streak over the region could bring a chance for
precipitation (20-40%) due to the upward motion following the
pattern. Temperatures for both Thursday and Friday suggest highs
in the low to mid-70s.

Into Saturday, an upper-level trough propagates eastward, with
the geopotential height gradients tightening around the upper-
level jet streak. A shortwave ridge in this region decreases the
chance for precipitation Saturday (<10%) with temperatures
rising into the upper 70s. With the tropical jet and polar jet
enhancing the jet streak, conditions favor the intensification
of a low pressure system in the Plains Saturday night, which
could create showers and thunderstorms in our region (50-70%).
As low pressure moves through Sunday, temperatures are expected
to drop into the low 70s.

Conditions are expected to become dry and warmer Monday, as a
surface high pressure system and upper-level ridge favor these
conditions. Tuesday and Wednesday still pose uncertainty with the
position of an eastward-propogating trough and a surface low in
the Plains moving toward the Mississippi River Valley. There is a
potential for showers on both Tuesday and Wednesday (10-30%), but
likelihood depends on the location of these systems.

Zawlocki

&&

.AVIATION...
Issued 255 PM CDT Wed Jun 17 2026

Southeasterly winds remain gusty at 25 to 30 kt outside of a
band of rain slowly moving across the I-94 corridor. Inside of
rain showers, gusty winds up to 20 kt are expected. Expecting
ceilings to continue to fall to become IFR by this evening and
through the overnight. Lightning chances have diminished
greatly for the afternoon, with the better chances for
thunderstorms now looking to arrive between 21Z and 00Z. A few
of these storms earlier in the evening may become capable of
producing damaging wind and hail. These storms will exit into
Lake Michigan by sunset, with showers lingering into the
overnight hours in southeast and central Wisconsin. Winds will
shift to become northwesterly overnight as well. Northwest winds
will continue into Thursday, with steady winds between 12 and 15
kt expected through much of the day. Thursday afternoon,
isolated (~15% coverage) thunderstorms are possible.

MH

&&

.MARINE...
Issued 255 PM CDT Wed Jun 17 2026

Southeasterly winds gusting consistently around 30 kt will build
waves in the southern half of Lake Michigan into this evening
as low pressure around 29.2 inches approaches. Winds will become
northeasterly in the northern half and westerly in the southern
half as low pressure crosses central portions of the open waters
late tonight. Winds in the southern half will continue to gust
near 30 kt. For both periods, a few gales are expected. Isolated
thunderstorms are also expected across the southern half this
evening.

As low pressure exits into Michigan early Thursday morning,
expect all winds to shift to become northwesterly and diminish
gradually into Thursday. Winds remain light and northwesterly
through the remainder of Thursday and through Friday as high
pressure around 30.0 inches progresses southeastward into the
Lower Mississippi Valley. Winds may briefly turn southwesterly
Friday night as weak low pressure moves through the region, but
high pressure will rapidly regain dominance by Saturday,
keeping winds light and variable. Stronger low pressure will
approach from the central Plains on Sunday, bringing more
widespread rain and thunderstorms and turning winds to
northeasterly. Northeast winds will continue into early next
week.

MH

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ052-WIZ060-WIZ066-WIZ071-WIZ072
     until 4 AM Thursday.

LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 4 AM
     Thursday.

&&

$$

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