Sullivan, Wisconsin Weather Forecast Discussion

814
FXUS63 KMKX 140241
AFDMKX
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
941 PM CDT Sat Sep 13 2025
.KEY MESSAGES...
- Above normal temps and humidity this weekend into next week.
  Daily thunderstorm chances return for the 2nd half of the new
  week.
- Areas of fog are forecast over much of the region tonight into
  Sunday morning, with the worst of it towards eastern and
  central WI.
&&
.UPDATE...
Issued 940 PM CDT Sat Sep 13 2025
Light easterly winds off of Lake Michigan are allowing humid air
to pool up over eastern and east-central Wisconsin at the
moment. An arc of low stratus clouds pushing west of the I-41
corridor has moved clear of far eastern Wisconsin, allowing
radiational cooling underneath clear skies. The GOES Satellite`s
Night Fog RGB product is picking up on an intensifying signal
over east-central Wisconsin, rapidly spreading south and west
as the airmass reaches crossover temperatures (Kenosha, West
Bend, Waukesha, and Timmerman in Milwaukee are already at 100%
RH). The epicenter of said signal (Sheboygan Airport) has
intermittently dropped to 1/4 SM visibility. Towards
southwestern Wisconsin, an arc of high altitude cloud cover is
slowing the temperature falls, resulting in lower humidity and
less fog potential, though these clouds are beginning to erode.
East-central Wisconsin will likely require a Dense Fog Advisory
at some point in the not too distant future, with a chance for
the rest of eastern Wisconsin and portions of central Wisconsin
to follow suit.
Sheppard
&&
.SHORT TERM...
Issued 204 PM CDT Sat Sep 13 2025
Tonight through Monday night:
The low stratus has been slow to mix out over east central WI
but it is still making progress. More low stratus and fog may
develop late tnt, but would likely be most concentrated from
south central into southwest WI as slightly drier air on ely
winds will move into ern WI. This drier air is in response to
large surface high pressure moving from Ontario to srn Quebec
through Monday night, while the narrow upper ridge axis to the
west will shift over WI and Lake MI for tomorrow into Monday.
Warm and humid conditions are expected but no precipitation into
early next week.
Gehring
&&
.LONG TERM...
Issued 204 PM CDT Sat Sep 13 2025
Tuesday through Saturday:
The narrow upper ridge axis will weaken and roll over into the
Lower Great Lakes from Lake Huron and Lower MI for this period.
A mean upper trough comprised of many vorticity maximums will
initially be over the nrn and central Great Plains but will
consolidate into a trough passage over srn WI late in the week.
Thus Wed nt to the end of the week will see a return of
thunderstorm chances each day and very humid conditions.
Gehring
&&
.AVIATION...
Issued 940 PM CDT Sat Sep 13 2025
Areas of dense fog expected across portions of eastern and
central Wisconsin overnight into Sunday morning, with east-
central Wisconsin (KSBM airport) already reporting intermittent
visibility drops to 1/4 SM. The fog is expected to grow further
south and west from there, though an arc of high altitude clouds
is likely to prevent much fog from forming towards southwestern
Wisconsin.
Fog begins to erode rapidly after sunrise Sunday, with mostly
sunny skies and VFR conditions expected through Sunday
afternoon. Light east winds, with a light east to northeast
lake breeze for terminals near Lake Michigan.
Sheppard
&&
.MARINE...
Issued 204 PM CDT Sat Sep 13 2025
Low pressure around 29.7 inches over the northern Great Plains
will remain in place through early next week, while large high
pressure of 30.3 inches moves from Ontario to southern Quebec,
Canada. This will yield mean light to modest easterly winds
into early next week. Areas of fog, possibly dense, may develop
late tonight into Sunday morning over the northern one third of
the lake.
Gehring
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Dense Fog Advisory...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
     LMZ567-LMZ643-LMZ669-LMZ868-LMZ870 until 10 AM Sunday.
&&
$$
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NWS MKX Office Area Forecast Discussion