NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 050531
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1231 AM CDT Fri Jun 5 2026

.KEY MESSAGES...

- Increasing humidity and thunderstorm chances for late tonight
  through Saturday. A 1 out of 5 (marginal) risk for severe
  storms is forecast Friday. Hail, gusty winds, and lightning
  will be the main hazards.

- Trending less likely for storm chances through the rest of the
  weekend as a cold front pushes through and a Hudson Bay high
  pressure returns to the Upper Great Lakes.

- Next round of rain is expected early next week.

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

&&

.SHORT TERM...
Issued 1139 PM CDT Thu Jun 4 2026

Current Overnight through Friday Night:

A broken line of showers and a few rumbles of thunder have tried
to work into the area this evening but have largely been stymied
by very dry low level air. However, with time, the low levels
should begin to moisten as a shortwave trough aloft pushes east
into our area this morning and an 850mb moist advection axis
leans over into the state this morning. Rain and a few rumbles
of thunder will then linger over the area from 3AM through Noon
as the shortwave passes and the moisture axis slowly translates
eastward.

A lull is expected during the afternoon as subsidence occurs on
the backside of the shortwave, but a second shortwave over MN is
expected to kick off thunderstorm activity over northern WI
Friday afternoon. This storm activity should then track
southeast into our area Friday evening between 6PM and 10PM.
Provided the skies clear in the subsidence lull we'll have
behind the morning rain, moderate instability from 1800 to 2500
J/kg should build over southern WI ahead of the approaching
broken line of storms. Mid level lapse rates may approach 7 C/km
with effective shear of 30 knots, supporting sufficient storm
organization for some gusty winds and hail with the evening
storms.

These storms should then largely weaken after sunset as they
travel southward, growing more scattered with time, although a
few weaker pop-up storms may linger overnight Friday into early
Saturday morning.

CMiller

&&

.LONG TERM...
Issued 1203 AM CDT Thu Jun 4 2026

Saturday through Thursday:

Outflow from Friday's storms is expected to push a cold front
through the region Saturday morning. The front is then expected
to set up south of the area over IL, while high pressure slowly
builds into the region through the rest of Saturday. With the
front south of the state, rain chances are looking less likely
Saturday. High pressure continues to build Sunday, keeping
conditions dry. The familiar easterly wind pattern that plagued
us for most of May will briefly return, leading to cooler
conditions by the lake with highs in the 60s and 70s, while
highs will be in the low to mid 80s far inland. High pressure
will then begin to retreat east on Monday, allowing for
thunderstorm chances (50 to 80%) to return Monday afternoon and
evening.

A strong ridge is then expected to build over the upper midwest
mid to late next week, allowing a hot and humid air mass build
over the region. The NBM projects highs in the 90s by next
Wednesday and Thursday amid dewpoints in the low to mid 70s,
which would cause heat indices between 100 and 105. Model trends will
have to be monitored for potential heat headlines. Along with
the heat, global deterministic models depict a more summer-like
pattern, with nebulous chances for thunderstorms at times from
mid to late next week given the ample instability.

CMiller

&&

.AVIATION...
Issued 1220 AM CDT Thu Jun 4 2026

Dry air will cause VFR conditions to hang out until around
sunrise this morning, with lower ceilings moving in from the west
as widespread rain along a frontal boundary slowly moistens the
lower atmosphere and moves east. Some combination of MVFR west
of KMSN and VFR east of KMSN should exist through 10Z, then
MVFR and IFR ceilings will push east 10-15Z as rain and
thunderstorms push in.

Rain and thunder should persist through the morning hours on
today, pushing east this afternoon. Low ceilings are then
expected to rise and scatter late Friday afternoon. Some
additional thunderstorm activity may occur across central and
east central Wisconsin this evening as a broken line moves in
from the north.

Winds will remain southerly to southwesterly tonight through
Friday and light to moderate. Some gusts to 20 knots may occur
Friday late morning into the afternoon.

CMiller

&&

.MARINE...
Issued 1220 PM CDT Thu Jun 4 2026

High pressure over the southeastern US will continue to drift
east toward the Atlantic into tomorrow as a low over the
Central Plains connects to another low over southwest Ontario
as a cold front between the two tracks east into Friday. The
Canadian low pressure will track east across the northern Great
Lakes through Friday bringing prevailing southwesterly winds to
Lake Michigan along with shower and thunderstorm chances tonight
through Friday ahead of the cold front. Then expect the cold
front to push through the region later Friday into Saturday
bringing additional shower and thunderstorm chances along with a
more northwest to westerly wind shift behind it into Saturday.
Then winds weaken and become more variable as high pressure
builds across the region later Saturday into Sunday. Looking
ahead to the start of next week will bring an additional low
pressure system to develop over the Plains and bring a return of
southerly winds to the Upper Great Lakes.

CMiller

&&

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

$$

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