125
FXUS63 KMKX 180646
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
146 AM CDT Mon Aug 18 2025

.KEY MESSAGES...

- Beach Hazards Statement in effect for waves of 3-6 feet
  through the early afternoon.

- Multiple rounds of showers and thunderstorms possible through
  early Tuesday morning. Lightning and heavy rainfall are the
  main concerns this morning into tonight. Localized damaging
  winds are an additional concern this afternoon and evening.

- River rises will greatly depend on where the heaviest rain
  occurs this morning through Tuesday morning, with rises to
  minor flood stage if rain falls in our most saturated regions.

- Drying out and becoming less humid by Wednesday.

&&

.SHORT TERM...
Issued 145 AM CDT Sun Aug 17 2025

Today and Tonight:

Lingering activity early this morning continues to drift east
from the remnant from a complex that pushed across the Central
Plains yesterday. Given the instability gradient remains largely
pinned to southwest WI with limited instability north of that we
expect some lightning but likely remaining limited especially
further north. Early this morning some low to mid level
isentropic upglide and mild WAA may continue to keep some
showers going across parts of west central WI for the next few
hours.

Later this morning attention will turn toward the MCS pushing
across southeast ND/northeast NE. Models continue to be all over
the place with exactly how this will pan out with various
solutions bringing different results to southern WI. Some models
track this all the way through southern WI during the late morning
and early afternoon while others have the MCS essentially dying
off leaving southern WI on the drier side through the morning
and early afternoon (outside of some shower activity in central
WI). How this plays out will likely effect the afternoon
instability recovery. While severe storms are not expected even
if this does push through during the late morning and early
afternoon there will still be a risk for heavy rain with this
however with PWATs over 2 inches. Fortunately any storms/heavy
rain will likely be fairly progressive and push out quickly.

Into the late afternoon and evening the expectation will largely
be driven by the morning/early afternoon convection. With some
level of recovery expected and increasing southerly flow with
the surface low/front in northern WI there is expected to be
some level of storm activity with uncertainty primarily coming
from exactly how any remnant boundary/MCV from earlier sets up
in addition to the surface cold front. Most of the instability
today looks likely to be focused across southern and southwest
WI with limited instability as you go north. Cannot rule out a
severe storm or two with decent deep layer shear and plenty of
instability but this will likely be restricted to southwest and
southern WI. This potential is primarily driven by the possible
initiation of storms developing into another MCS from the
remnant boundary/MCV from earlier in the day.

There will be continued shower/storm chances into the overnight
hours in association with the front but will not really carry
much, if any, severe risk. The primary concern for the late
afternoon through the overnight period will continue to be the
heavy rain risk with PWATs still around 2+ inches. These storms
again look likely to be progressive but the flooding risk will
come if certain localized areas or already vulnerable areas are
hit with multiple rounds of heavy rainfall.

In addition to these concerns, a Beach Hazards Statement remains
in effect now until 3pm today for onshore waves from 3 to 6
feet from breezy onshore winds. Expect dangerous swimming
conditions especially for areas near piers and/or breakwalls
which will be most vulnerable to these dangerous currents.

Kuroski

&&

.LONG TERM...
Issued 145 AM CDT Sun Aug 17 2025

Tuesday through Sunday:

A welcome pattern change on the way as the upper level pattern
becomes a bit more amplified and northwest flow allows surface
high pressure to build in from the north and northeast.

The airmass change looks to take a bit of time Tuesday into
Tuesday night as cyclonic flow gradually takes over. Residual low
level moisture and diurnal instability suggest widely scattered
showers and perhaps a few storms developing and moving south
Tuesday afternoon. Have introduced low PoPs for this potential,
which should end shortly after sunset.

Airmass change begins in earnest Tuesday night, with a good drop
in temperatures with lows around 60 (give or take) each night
Tuesday night through Friday night. Highs will drop back into the
70s Wednesday and Thursday, warming briefly back into the 80s
Friday before a reinforcing shot of cooler air arrives for the
weekend. Will need to monitor for rain chances with a frontal
passage late Friday/Friday night, but aside from this boundary,
little if any rain is expected during the extended forecast.

Gagan

&&

.AVIATION...
Issued 145 AM CDT Sun Aug 17 2025

The primary forecast challenge continues to be timing multiple
rounds of showers and storms. Will continue to use PROB30 groups
to highlight general timeframes where convection is possible,
with amendments to hone in on development and timing. Overall,
ceiling/visibility will be VFR, with occasional bouts of MVFR
stratus overnight. Any storms will be capable of producing
shorter periods of IFR visibility. Scattered storms are expected
through Monday morning, with redevelopment from west to east
during the afternoon and evening, ending overnight Monday night.

Will need to keep an eye on how fast we clear out Monday night
as this may lead to patchy fog. Right now that risk appears to
be west and north of Madison, but bears watching.

Gagan

&&

.MARINE...
Issued 145 AM CDT Sun Aug 17 2025

The onshore winds will create high waves and a Small Craft
Advisory is in effect.

Low pressure will continue to exit toward the Atlantic tonight
with high pressure around 30.4 inches developing across Ontario. A
developing low pressure over South Dakota will move into southern
Minnesota overnight. A front associated with this low pressure
will gradually move southeast across the region, clearing the
south end of Lake Michigan by midday Tuesday. This front will
bring multiple rounds of showers and storms from tonight through
Monday night.

Winds will shift northeast to southeast this morning. A small
craft advisory remains in effect until 1 PM today for these
onshore winds and resulting waves. After the front exits the area,
winds will shift to the north from Tuesday through Friday.

Gagan


&&

.HYDROLOGY...
Issued 145 AM CDT Sun Aug 17 2025

A few more rounds of showers/storms will maintain a locally heavy
rainfall threat through Monday night. Area rivers (particularly
in the Milwaukee metro area and surrounding counties) will be
monitored for potential rises.

Gagan

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ052-WIZ060-WIZ066-WIZ071-WIZ072
     until 3 PM Monday.

LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 1 PM
     Monday.

&&

$$

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