NWS-Milwaukee/Sullivan Forecast Discussion
FXUS63 KMKX 162350
AFDMKX
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
650 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 Advisory in effect mainly for counties close to Lake
Michigan but extension further west may be needed. 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.
&&
.UPDATE...
Issued 650 PM CDT Thu Apr 16 2026
Dense Fog Advisory has been issued for areas closer to the lake
as dense fog has begun to develop over the lake and roll in
causing the expectation that with model guidance we should dense
fog overspread at least eastern portions of the CWA but
expansion may be needed further west. Low clouds and fog
concerns may extend as far west as Madison tonight and likely
clear by mid morning. This will be the main concern for the
tonight period as conditions otherwise remain quiet and dry.
Kuroski
&&
.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
Michigan, 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 initial 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 650 PM CDT Thu Apr 16 2026
VLIFR/LIFR CIGS and VSBYS are currently developing over Lake
Michigan and will roll in off the lake tonight with MKE already
having dropped to dense fog. With that we have issued a Dense
Fog Advisory through 14z Friday for expected expansion of dense
fog across areas near the lake tonight. In fact model guidance
suggests there may be need to expand further west toward south
central WI but will hold off on that for now. As we break into
daylight Friday morning expect fairly rapid dissipation of the
fog and low CIGS by mid morning.
Then attention turns toward the severe storm potential during
the day and evening Friday. Still plenty of uncertainty on the
timing of storm initiation and who will get hit when but storms
appear likely to impact all of southern WI at some point with
storms into western WI as early as noon. However, more
widespread chances are to be expected by the later afternoon
and early evening with storms tracking across southern WI into
the evening. Storms are generally expected to weaken as they
push east especially with the afternoon lake breeze potentially
being fairly strong and impacting convection further east.
Storms are generally expected to push out of southern WI by the
late evening hours. Some VSBY and CIGS concerns will come with
the storms as well though they would be associated directly with
storms.
Kuroski
&&
.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...Dense Fog Advisory...WIZ052-WIZ059-WIZ060-WIZ065-WIZ066-WIZ071-
WIZ072 until 9 AM Friday.
Flood Watch...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-WIZ057-WIZ058-
WIZ059-WIZ060-WIZ062-WIZ063-WIZ064-WIZ065-WIZ066-WIZ067-
WIZ068-WIZ069-WIZ070-WIZ071-WIZ072...1 PM Friday to 7 AM
Saturday.
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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