NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 301914
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
214 PM CDT Thu Jul 30 2026

.KEY MESSAGES...

- Increasing chances for showers and weak thunderstorms at
  times from Friday morning through Friday night (80-95%
  chances). Chances gradually taper down through Saturday.

- Breezy onshore winds will lead to high waves and dangerous
  currents at Lake Michigan beaches this weekend, with Moderate
  to High Swim Risk conditions possible Saturday and Sunday.

&&

.SHORT TERM...
Issued 200 PM CDT Thu Jul 30 2026

Tonight through Saturday:

Dry weather continues for the rest of today through tonight, with
high pressure overhead shifting southeast into the Ohio River
Valley. Simultaneously, a positively-tilted 500mb trough swings
southeastward across the upper Midwest. Corresponding surface low
pressure deepens over IA on Friday and continues east through
IL on Saturday. The slow-moving nature of this low coupled with
steady isentropic upglide through its precip shield and ~2" PWAT
values will make it a very efficient rain-maker for portions of
the midwest. The exact track of the system (further north/south in
IA and IL) will heavily influence the amount of rainfall we get
here in southern WI, and a sharp cutoff between a few light
showers (further north) and a drought-busting long-duration
rainfall (further south and west) could easily set up near or
within our CWA. That said, model guidance is beginning to
converge on the system track.

Regardless of the track of the low, we don't expect strong to
severe thunderstorms in southern WI given the lack return flow
and limited MUCAPE (most guidance 500 joules or less). The only
concerns would be the potential for localized heavy rainfall
(level 2 out of 4 risk along and west of the I-90 corridor) and
a chance for lightning.

A gradual southwest to northeast arrival of rain chances unfolds
through the daytime hours on Friday. Activity would then peak
in intensity / coverage later Friday through Friday night, and
slowly diminish through Saturday.

Breezy onshore winds associated with the low will lead to
Moderate or High Swim Risk conditions on Lake Michigan beaches
late Friday night through this weekend, especially from
Milwaukee county southward.

Sheppard

&&

.LONG TERM...
Issued 200 PM CDT Thu Jul 30 2026

Saturday night through Thursday:

Dry weather expected Sunday into Monday as high pressure settles
over the upper Great Lakes. Temperatures begin a gradual uptrend
early next week as a ridge in the upper jet builds east into the
region. The warmth would likely peak on Tuesday as the upper ridge
axis passes, with high temperatures in the mid to upper 80s
possible, with dewpoints in the upper 60s to around 70. An
approaching longwave trough will allow some diffluent flow to
overspread the region Tuesday PM (10-20% shower/storm chances),
intensifying Tuesday night into Wednesday as the right entrance
of an associated jet streak passes by (25-35% shower/storm
chances). The surface pressure response to these features is
certainly not looking organized on model guidance, hence our
confidence in rainfall with it remains low. The longwave pattern
in the jet looks to remain predominantly zonal through next
week, suggesting mostly dry weather and near normal to slightly
above normal temperatures (highs in the low to mid 80s) for
late next week. That said, the proximity of the jet and smaller
perturbations within it merit some continued ~25% precip chances
into Thursday.

Sheppard

&&

.AVIATION...
Issued 200 PM CDT Thu Jul 30 2026

Dry weather and VFR continue today and tonight. Wildfire smoke
aloft may lead to haze in the sky at times today and tonight,
but only trace amounts of it will reach the surface, and surface
visibility should remain 6 SM or greater. Upper-altitude clouds
(over 20,000 ft) will increase in coverage overnight into
early Friday.

Low pressure will track across Iowa Friday and Illinois
Saturday. A southeast breeze is expected as it approaches
Friday, with rain chances gradually increasing from west to east
throughout the day. Cloud ceilings gradually decline, but are
forecast to remain at generally VFR levels through Friday
afternoon and evening (with the exception of far southwestern
WI, where some Fuel Alt MVFR or IFR may arrive early). A few
thunderstorms will be possible with this activity, but no strong
or severe storms are expected.

Sheppard

&&

.MARINE...
Issued 200 PM CDT Thu Jul 30 2026

Light and variable winds will take on a southerly component this
afternoon as high pressure around 30.0 inches starts to drift
toward the Lower Great Lakes. Low pressure around 29.7 inches will
track across Iowa Friday and through Illinois Saturday. The
approaching area of low pressure will bring chances for showers
and a few thunderstorms Friday into Saturday. Severe weather is
not expected in any of this activity. Breezy northeast winds
will develop Saturday and should continue through Sunday
as high pressure of 30.0 inches builds over Lake Superior. A
few gusts upwards of 30 kt will be possible over the southern
half of the lake.

For nearshore zones from Sheboygan to Winthrop Harbor, the gusty
northeast winds and building waves are likely to reach Small
Craft Advisory levels at times Saturday through Sunday night.

Sheppard

&&

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

$$

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