NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 291831
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
131 PM CDT Wed Jul 29 2026

.KEY MESSAGES...

- Warm and humid conditions return Thursday.

- Chances for showers and weak thunderstorms at times from
  Friday morning through Friday night (65-85% chances). Chances
  gradually taper down through Saturday.

&&

.SHORT TERM...
Issued 130 PM CDT Wed Jul 29 2026

Tonight through Thursday night:

Dry and quiet weather continues through the period, with high
pressure established across the Great Lakes region. HRRR model
output and GOES Geocolor images do hint that some wildfire smoke
is present aloft, leading to a thin haze in the clear skies,
particularly for areas west of Madison / Janesville. The
synoptic subsidence associated with the high pressure could
(potentially) cause some of this smoke to reach the boundary
layer and mix down to the surface later today into tonight,
though it would likely be quite sparse / dilute by the time that
occurs. Our best guess is that surface visibility will remain 6
SM or greater, with only trace amounts of it. A similar story
for Thursday, with area-wide potential for trace amounts of
smoke.

The centroid of the high pressure shifts southeast of the region
Thursday, with light southwest surface winds allowing for a
brief return of heat and humidity. Forecast high temps in the
mid to upper 80s, with dewpoints in the mid 60s.

Sheppard

&&

.LONG TERM...
Issued 120 PM CDT Wed Jul 29 2026

Friday through Wednesday:

A positively-tilted 500mb trough tracks southeastward across the
midwest late this week, with a corresponding surface low developing
near Nebraska / the Dakotas late Thursday and crossing Illinois
Friday night into Saturday morning. The track of this system (south
of our region) should strongly limit the buildup of instability,
with most guidance suggesting ~500 joules or less MUCAPE. As such,
we're expecting showers and weak thunderstorms to gradually
overspread southern WI from west to east on Friday (65-85%
chances). Shower and weak storm chances continue into Friday
night and taper down into Saturday. Though overall precip
chances are relatively high with this event, a known bias in
long-range model guidance is to over emphasize the synoptic
features (ex. the precip shield on the north edge of the low)
with the forecast QPF then shifting south towards the
instability axis / deep convection when high-res model guidance
enters the picture. As such, it's too early to "guarantee"
rainfall across all of southern WI at this time, but the odds
are high for at least some of the region to receive some much-
needed rainfall. Our highest confidence in precip is over far
southwestern WI.

Predominantly dry weather expected Sunday into Monday as high
pressure settles into the region. A slow warming trend unfolds early
next week as the high continues southeastward. The upper ridge axis
passes overhead Tuesday, suggesting that the warmth (perhaps mid to
upper 80s high temps) may peak then. Predominantly zonal flow
looking likely in the jet through next week, though a few ripples
merit some slight chances for showers and thunderstorms in the
extended forecast.

Sheppard

&&

.AVIATION...
Issued 120 PM CDT Wed Jul 29 2026

Dry weather and VFR expected to continue through Thursday. Trace
amounts of wildfire smoke may pass through the region at times,
though the majority of it appears to remain aloft, and surface
visibilities should generally remain 6 SM or greater. Fog may
form in the Wisconsin River Valley late tonight into early
Thursday morning, mainly impacting KLNR.

Light and variable winds today and tonight (practically calm at
times). A light southwest breeze around 5 to 10 knots on
Thursday. A due south or southeast lake breeze expected at
terminals along the shoreline of Lake Michigan Thursday
afternoon.

Sheppard

&&

.MARINE...
Issued 120 PM CDT Wed Jul 29 2026

The ongoing light northerly winds will transition to light and
variable in a north to south manner as high pressure around 30.0
inches builds into the Great Lakes region today. The centroid
of this high should slowly shift southeast of Lake Michigan on
Thursday, allowing for light southerly winds Thursday and
Thursday night.

Low pressure develops near Nebraska / the Dakotas late Thursday,
deepening to around 29.6 inches before crossing Illinois Saturday
morning. Light south winds turn southeast and accelerate over the
southern half of the lake Friday, backing northeast with 15-20
KT gusts Saturday morning, then north-northeast with gusts up to
25 KT Saturday afternoon and evening. An additional period of
breezy north winds may unfold Sunday afternoon and evening as
high pressure builds over Lake Superior (20-30 KT possible).
Slower winds and gusts expected over the north half of Lake
Michigan through the aforementioned timeframes.

Sheppard

&&

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

$$

Visit us at weather.gov/milwaukee

Follow us on Facebook, X, and YouTube at:
www.facebook.com/NWSMilwaukee
www.x.com/NWSMilwaukee
www.youtube.com/NWSMilwaukee