NWS-Milwaukee/Sullivan Forecast Discussion
FXUS63 KMKX 261124 AAA
AFDMKX
Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
624 AM CDT Wed Aug 26 2026
.KEY MESSAGES...
- An isolated shower or storm is possible in the east this
afternoon.
- Rain-free & pleasant conditions late week.
- Trending active this weekend into early next week, with
multiple periods of showers and storms forecast.
&&
.UPDATE...
Issued 623 AM CDT Wed Aug 26 2026
An instability axis and coincident area of effective bulk shear
continue to track across southeast WI early this morning. The
values were up to 1500 j/kg of MLCAPE and 40kt shear around 2AM,
but they have dropped to 750 MLCAPE and 35kt shear. Within that
axis, one stronger storm developed in southwest WI and was able
to maintain its strength all the way into Iowa County. It
started weakening as it tracked into Green County and has now
finally diminished. There was a signal for marginally large hail
(0.75 to 1 inch diameter), and there were a couple reports of
40 to 50 mph winds from home weather stations. when it was in
Richland County. The most recent report was a gust up to 34 mph
when it went over the Monroe Airport.
All of the storms over land have completely diminished and there
is some patchy fog and stratus developing across most of
southern WI, especially in south central WI where it rained.
These low clouds will be temporary, as mid level dry air is
working its way into the region.
Diurnal cumulus clouds are likely this afternoon, and highs are
forecast to get into the lower 80s. Since the relatively warm
and humid air mass is going to stay in place over southeast WI
into the early afternoon, there are some model indications that
a few showers could develop in far southeast WI and also near
the lakeshore as the surface "cold" front slides through the
area. While there is not a lot of moisture or forcing to work
with for these to develop, we are maintaining some low chance
pops to account for this. Expect fairly gusty westerly winds
this afternoon and lighter northwesterly winds this evening once
the front finally gets through the area.
Cronce
&&
.SHORT TERM...
Issued 1203 AM CDT Wed Aug 26 2026
Tonight through Wednesday:
Much of the initial round of showers has weakened late this
evening and stayed mainly north of the forecast area. The focus
is now on the second round of showers and storms approaching
from the northwest, as warm advection persists tonight ahead of
an approaching shortwave and weak front. This line of showers
and storms is expected to largely hold together as it moves
through the forecast area. This activity will likely arrive in
the northwest between 2 and 3 am, exiting the southeast between
7 and 9 am. Still not expecting severe weather based on current
shear, available instability, and ongoing upstream conditions.
Not out of the question for some small hail and brief gusty
winds, though.
The front and shortwave is expected to move through late
morning into early afternoon tomorrow. The better forcing,
moisture, and instability will be largely east of the forecast
area by mid- afternoon along with the resultant higher precip
chances. Could see an isolated shower or storm in the
east/southeast early afternoon as the front exits. With no big
push of cooler temps behind the front, highs into the low 80s
are likely tomorrow along with breezy west to northwest winds by
afternoon.
DDV
&&
.LONG TERM...
Issued 1203 AM CDT Wed Aug 26 2026
Thursday through Tuesday:
High pressure will bring quiet weather to southern Wisconsin
Thursday and Friday, with mostly clear to partly cloudy skies,
light winds, and near normal temperatures expected.
Clouds may increase on Saturday ahead of an approaching
shortwave, though precip chances are currently expected to hold
off until at least the evening hours.
A series of shortwaves will bring more active weather to the
forecast area Saturday night through at least early next week.
Increased moisture and instability during this period will also
contribute to higher chances for showers and storms.
Temperatures will be near to a bit above normal during this
period, with more humid conditions returning with dewpoints in
the 60s to around 70.
DDV
&&
.AVIATION...
Issued 623 AM CDT Wed Aug 26 2026
All of the storms over land have completely diminished and there
is some patchy fog and stratus developing across most of
southern WI, especially in south central WI where it rained.
These low clouds will be temporary, as mid level dry air is
working its way into the region.
Diurnal cumulus clouds with bases around 5000 ft are likely
this afternoon. A few showers could develop in far southeast WI
and also near the lakeshore, but there is not a lot of moisture
to support these, so I kept them out of the TAFs for now. Expect
fairly gusty westerly winds this afternoon and lighter
northwesterly winds this evening once the front finally gets
through the area.
Cronce
&&
.MARINE...
Issued 623 AM CDT Wed Aug 26 2026
Breezy south winds will continue through the morning as the
pressure gradient sharpens ahead of a slow-moving cold front and
low pressure of 29.7 inches just north of Lake Superior. Winds
will become more southwesterly later this morning, then westerly
with the frontal passage in the afternoon. Look for lighter
northwesterly winds behind the front tonight.
The northwest winds will grow breezier for a bit on Thursday
ahead of another cold front dropping south over the lake, but
winds will then become lighter and northeasterly Thursday night
into Friday as high pressure of 30.2 inches moves into the upper
Great Lakes region.
Cronce
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&
$$
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