NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 161938
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
238 PM CDT Thu Apr 16 2026

.KEY MESSAGES...

- Mostly dry tonight into tomorrow, save for a few potential
  showers along the lake breeze this afternoon.

- Dense fog is possible tonight. Mainly for counties close to
  Lake Michigan. Marine Dense Fog continues into Friday morning.

- A Flood Watch is out for all of southern Wisconsin from 1pm
  Friday to 7am Saturday for more heavy rain Friday afternoon
  and evening.

- Another round of heavy rainfall, flooding, and severe
  thunderstorms is expected Friday afternoon into Friday night.
  An Enhanced Risk (3 out of 5) for severe weather exists over
  the western half of the CWA.

&&

.SHORT TERM...
Issued 208 PM CDT Thu Apr 16 2026

Tonight through Friday night:

Subsidence will linger over the region tonight as a weak surface
ridge moves southeast over southern Wisconsin. As winds ease,
fog is expected to occur for the counties adjacent to Lake
Michgan, given the ample surface moisture that is present over
the region. This fog may become dense and a dense fog advisory
may be needed.

Tomorrow, a warm front is expected to lift north across the
region as a rapidly moving surface low lifts northeast from
Omaha near daybreak to Duluth by the late afternoon and drags a
cold front through the area. Given the fast motion of the low,
warm advection will occur quickly, and northerly moisture return
is expected to push the warm front into Northern Wisconsin.
Following the warm frontal passage, daytime heating is expected
to allow for moderate to high instability to build over the
state, with CAMs showing model soundings supportive of 3500 J/kg
of SBCAPE along the MS River Valley by 1PM in the afternoon. As
the surface low passes the area as it races northeast, lift
from the surface low will drive forcing for ascent and storm
development is expected to rapidly occur near the MS River
Valley, with storms then traveling east into southern Wisconsin.
Models suggest convective initiation may occur between 2-4 PM,
with activity then moving through southern WI through the rest
of the afternoon into the evening.

CAM soundings and model guidance suggests that the inital mode
should be supercells in southwest to south central WI, before
storms conglomerate into lines as they travel east over southern
Wisconsin and transition to a QLCS mode. Given lapse rates of 8
C/km, turning in the low level hodograph, and 3CAPE eclipsing
200 J/kg, initial supercells will be capable of all severe
weather hazards. As storms go linear with eastward extent
through southern, instability may lessen, but will still be
enough to support gusty winds, and a brief spin-up QLCS tornado
to the lakeshore.

On top of the thunderstorm threat, flooding is again a concern
given the anticipated rainfall with the storms and saturated
antecedent conditions. A widespread 1 to 2 inches of rain is
expected, with locally higher amounts possible. A Flood Watch is
anticipated from 1pm Friday to 7am Saturday.

CMiller

&&

.LONG TERM...
Issued 207 PM CDT Thu Apr 16 2026

Saturday through Thursday:

Cold advection takes hold Saturday following the passage of the
cold front. Rain is expected to end fairly quickly following the
front and skies should clear out during the late morning. Given
the CAA and breezy northwesterlies, high temperatures will only
reach from the mid to upper 40s to low 50s across the area. High
pressure will begin to slowly build in on Sunday, but breezy
northwesterly winds will continue out ahead of the high. Similar
high temperatures to Saturday are expected on Sunday.

Monday, the high pressure center moves overhead and shifts east.
Light southerly winds return and slightly warmer temperatures in
the 50s are expect. Ridging then builds over the plains, and
warmth builds Tuesday with highs in the 70s. We'll then remain
on the edge of the ridge into the middle of next week with warm
temperatures lingering. Very nebulous probs for storms (15 to
25%) return on Thursday.

CMiller

&&

.AVIATION...
Issued 152 PM CDT Thu Apr 16 2026

Subsidence is battling lingering surface moisture over southern
Wisconsin. Current ceiling conditions range from OVC and BKN
LIFR to IFR along the lakeshore, to SCT to CLR conditions over
southwest and central WI. Fog has also taken hold at KMKE.
These general conditions will continue into tonight, with fog
and low cigs becoming more likely with time. Some of the fog
will become dense overnight, especially for terminals along the
lakeshore, as winds ease beneath a weak surface ridge. Fog is
then expected to linger a few hours past daybreak as a warm
front lifts north into the area and surface moisture increases.

Tomorrow afternoon into the evening, another round of severe
storms is expected. All severe hazards will be possible, as well
as flash flooding given the already saturated ground.

CMiller

&&

.MARINE...
Issued 121 PM CDT Thu Apr 16 2026

A weakening boundary is slowly moving toward the southern end of
Lake Michigan. This boundary is expected to clear the southern
end of Lake Michigan this evening, with winds becoming light and
variable tonight for a time as a weak surface ridge moves over
the lake. Dense fog will continue over the lake through this
time. Winds then come around to southerly tomorrow morning as a
surface low of 29.5 inches approaches from the central plains.
This surface low will quickly move from Omaha to Duluth from the
morning into the afternoon. Winds will become gusty and
southeasterly Friday night, and strong to severe storms will
move east over the lake as a cold front sweeps through the area.
Winds then become northwesterly behind the cold front Saturday
morning. Breezy northwesterly winds then continue Saturday
through Sunday as the low then races northeast toward Hudson
Bay.

Winds ease Monday morning as high pressure move southeast over
the upper Great Lakes.

CMiller

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Flood Watch...WIZ059-WIZ060-WIZ064-WIZ065-WIZ066-WIZ069-WIZ070-
     WIZ071-WIZ072 until 1 PM Thursday.

LM...Dense Fog Advisory...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-
     LMZ565-LMZ567-LMZ643-LMZ644-LMZ645-LMZ646-LMZ669-LMZ671-
     LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-
     LMZ876-LMZ878 until 7 AM Friday.

&&

$$

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