NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 040609
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
109 AM CDT Thu Jun 4 2026

.KEY MESSAGES...

- Warm and dry conditions with low relative humidity today,
  with gusty southwesterly winds. Elevated fire weather
  conditions are possible.

- Increasing humidity and thunderstorm chances for late tonight
  through Saturday. A 1 out of 5 (marginal) risk for severe
  storms is forecast Friday into Friday night, but the timing of
  the severe potential remains in question.

- On and off thunderstorm chances continue Sunday through
  midweek as moisture returns to the region.

&&

.SHORT TERM...
Issued 110 AM CDT Thu Jun 4 2026

Today through Friday night:

Temperatures in the upper 50s early this morning will quickly rise
into the 80s by midday across all of southern Wisconsin as gusty
southwesterly winds keep the lake breeze offshore. Expect highs in
the mid to upper 80s in the afternoon. Cloud cover will increase
throughout the day as storms develop across northern Wisconsin and
Iowa. With breezy southwesterly winds and relative humidity values
falling into the 25-35% range, elevated fire weather conditions
may develop in the afternoon hours. Late this evening, remnant
storms will sag southeastward into southwestern Wisconsin. The
main hazard with these storms will be lightning, with some
potential for gusty winds due to very dry low levels and therefore
evaporational cooling with PWATs around 1.3 inches. However,
minimal CAPE (~300-500 J/kg) will prevent storms from reaching
their full potential for severe. After sunset, any lingering
storms will become elevated. 300-500 J/kg of MUCAPE linger, so a
few bolts of lightning remain possible through the overnight
hours.

Friday morning, southwesterly winds continue, with warm
frontogenesis across central to southern Wisconsin. MUCAPE
increases to 1000-2000 J/kg mid-morning through the afternoon as
lingering showers and thunderstorms exit into Lake Michigan. MUCAPE
values may climb to as high as 2500 J/kg during the
afternoon/evening hours if skies clear. Midday to afternoon
evolution of additional thunderstorms remains uncertain. If skies
clear, broad instability with the warm front in the region would
lead to scattered thunderstorm development across all of southern
Wisconsin (RAP solution). This would bring primarily an isolated
hail/wind threat. However, NAM/NAM-3k/Nest and ARW indicate a
remnant MCV from overnight convection in Iowa sliding across far
southern Wisconsin/far northern Illinois during the midday to
afternoon hours, bringing a threat for wind and isolated tornado
development. Regardless, some severe potential is expected Friday
afternoon. Highs in the low 80s are expected.

Friday evening, prefrontal convection developing in northern
Wisconsin and LLJ-driven convection in Iowa will begin to
southeastward into central Wisconsin. Model discrepancy in timing
becomes more significant at this stage due to the speed of the
front depending on the previous time period's convection. With
MUCAPE around 1000-2000 J/kg lingering and 0-6 km bulk shear just
at 35 kt, some organization may still develop with these storms.
Overnight lows in the low 60s are expected. The cold front looks
to work its way through southern Wisconsin late Friday night into
early Saturday morning, bringing an end to any severe threat.

MH

&&

.LONG TERM...
Issued 110 AM CDT Thu Jun 4 2026

Saturday through Thursday:

The main cold front will move through Saturday morning, bringing
light northwesterly winds to southern Wisconsin. Even with
northwest winds, temperatures are expected to climb into the
mid-80s. With additional moisture aloft and continued
instability, a few thunderstorms (20-30% chances) may still
develop Saturday afternoon in southeastern to far southern
Wisconsin where the frontal feature lingers longer.

High pressure builds back into Ontario and Quebec on Sunday,
keeping the majority of southern Wisconsin dry. Isolated pop-up
storms are possible in southwestern Wisconsin as moisture
return from the Gulf nudges up into the Mississippi Valley.
Broad low pressure will develop in the High Plains Sunday into
Monday, continuing to bring moisture northward into the
Mississippi Valley. Modeling is consistent regarding the low
pressure ejecting northeastward into Monday, bringing higher
chances for precipitation into southern Wisconsin (40-60%). This
will also whittle away the edges of the high pressure sitting
over eastern Canada, allowing for additional shortwaves to bring
continued potential for thunderstorms on and off through
midweek. With continued southerly flow, temperatures will also
continue to rise, potentially reaching 90 degrees Wednesday and
Thursday.

MH

&&

.AVIATION...
Issued 110 AM CDT Thu Jun 4 2026

VFR conditions expected throughout today, with light winds this
morning becoming southwesterly and gusty around 20 kt through
the afternoon and evening. Late this evening into tonight,
expect ceilings to lower to MVFR and thunderstorms to progress
west to east. A few thunderstorms may produce gusty and erratic
winds, but will weaken as they move eastward.

MH

&&

.MARINE...
Issued 110 AM CDT Thu Jun 4 2026

Influence from the high pressure finally releases it hold over the
region as it settles over the Mid-Atlantic through today. Light and
variable winds early this morning will give way to gusty southerly
winds over the lake as low pressure develops and deepens across
Manitoba into Ontario through the day. Will see a brief window late
this afternoon and evening for small craft winds and waves to
develop for east-central WI nearshore waters,but will diminish by
tonight as winds turn more offshore. Continue to see this low track
east across the northern Great Lakes through Friday bringing
prevailing southwesterly winds 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.

Wagner

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643...2 PM Thursday to 10 PM
     Thursday.

&&

$$

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