NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 202342
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
642 PM CDT Sat Jun 20 2026

.KEY MESSAGES...

- Rain is looking likely from Madison to Milwaukee and south to
  the IL border for Sunday afternoon and evening. Around one
  half inch of rain is expected south of the I-94 corridor.

- Showers likely with chances for thunderstorms Tue night-Wed.

- Below normal temps continue for much of the new week.

&&

.UPDATE...
Issued 643 PM CDT Sat Jun 20 2026

Northwesterly winds will calm shortly after sunset tonight, with
high clouds moving in late tonight. Patchy fog may develop in
low-lying areas. Sunday morning, expecting low pressure to
eject from the central Plains and bring rounds of showers to the
I-94 corridor and southward. Confidence in rainfall is
increasing with multiple 18Z CAMs showing overrunning
precipitation north of the low into southern Wisconsin. However,
expecting that any lightning risk would be minimal (less than
10% chance) and primarily confined to the WI/IL border.
Northeasterly winds will also increase into Sunday as low
pressure makes its closest approach.

MH

&&

.SHORT TERM...
Issued 227 PM CDT Sat Jun 20 2026

Tonight through Tuesday:

There is just a slight chance for a brief shower over east
central WI late this afternoon and early evening due to low
level instability. Otherwise a weak surface ridge will pass tnt
followed by increasing clouds toward sunrise as a shortwave
trough moves into the middle MO Rvr Valley. This shortwave
trough will track into north central IL by 00Z Mon then to nrn
Ohio by 12Z Mon. Its sfc low will track slightly to south of the
upper wave and gradually fill. There is still some disagreement
among the deterministic models and CAMs on the track of the low,
but confidence is increasing on the nrn extent of the rain
shield reaching a line from Madison to Milwaukee for Sun
afternoon and evening. Mid level warm, moist advection,
frontogenesis, and PVA will focus over far srn WI. Rain chances
of 60-90 percent are forecast over far srn WI with only 20-30
percent chances for MQT, Green Lake, FLD, and Sheboygan
Counties. Around one half inch of rain is expected toward the IL
border. Nely winds will follow in the wake of the low on Mon
with any broken stratocumulus ending Mon AM, although sct high
clouds could occur into the afternoon with the passage of a weak
shortwave trough to the south. A north to south sfc ridge will
then slowly move across srn WI Mon nt-Tue. Below normal temps,
but pleasant temps, will continue through this period.

Gehring

&&

.LONG TERM...
Issued 227 PM CDT Sat Jun 20 2026

Tuesday night through Saturday:

A slow moving shortwave trough and weak sfc low will then track
from srn Canada across the Great Lakes for Wed-Thu. Rain chances
of 50-90 percent will begin Tue nt and last into Wed. Thunderstorms
will be possible during this time. Lingering precipitation is
then possible Thu followed by high pressure for Thu nt-Fri.

Yet another shortwave trough and a return to sly flow and warm
advection will approach for Sat with more chances for showers
and storms.

Gehring

&&

.AVIATION...
Issued 643 PM CDT Sat Jun 20 2026

VFR conditions will continue throughout tonight and into Sunday
morning. Ceilings will begin to fall midday Sunday, especially
for JVL/ENW as low pressure makes its closest approach.
Otherwise, expecting light rain showers to affect areas from MSN
to MKE southward late Sunday morning through Sunday afternoon.
Minimal concern for lightning (less than 10% chance), primarily
for JVL/ENW. Rain will taper off into the late afternoon hours,
with ceilings falling to 1000-1500 ft from MSN to MKE southward
as rain ends. SBM is expected to remain VFR throughout the day
Sunday.

Northwest breezes this evening will become calm across the
region after sunset. As winds calm overnight, patchy fog is
possible. Any fog will burn off quickly into Sunday morning. Winds
will then shift to northeasterly Sunday morning and become
gusty Sunday afternoon.

MH

&&

.MARINE...
Issued 227 PM CDT Sat Jun 20 2026

Generally light winds are expected tonight into Sunday morning
as high pressure around 29.9 inches moves across Lake Michigan.
Low pressure around 29.6 inches should then track eastward from
the central Great Plains, reaching central IL early Sunday
evening, then into Ohio by Monday. Light east winds overspread
Lake Michigan Sunday afternoon, becoming breezy northeast winds
over the southern portions of the lake later Sunday into Sunday
night. Lighter 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 due to breezy
nnely winds and high waves from Sheboygan to Winthrop Harbor.

Gehring

&&

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

$$

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