Sullivan, Wisconsin Weather Forecast Discussion

706
FXUS63 KMKX 211454
AFDMKX
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
954 AM CDT Sun Sep 21 2025
.KEY MESSAGES...
- Additional shower and thunderstorm chances (20 to 30 percent)
  are forecast today into Monday.
- Mild temperatures are expected today, with near normal
  temperatures into the start of the work week.
&&
.UPDATE...
Issued 955 AM CDT Sun Sep 21 2025
Forecast is largely on track this morning. Early fog is
improving in the Wisconsin Valley, as well as over impacted
portions of southeast and east-central Wisconsin. Expect
visibilities to continue to improve through late morning under
mostly cloudy skies. Visible satellite shows pockets of broken
sunshine over southwest Wisconsin & near the state line, with
said breaks projected to shift into the remainder of the region
by early afternoon. Resultant surface heating, in addition to
increasing southwest flow aloft, will encourage scattered shower
& thundershower development following the lunch hour. Lesser
sunshine may result in lesser storm coverage and intensity
relative to yesterday afternoon, though brief heavy downpours
and cloud to ground lightning will remain possible in any
activity. Will monitor trends through the afternoon hours.
Quigley
&&
.SHORT TERM...
Issued 407 AM CDT Sun Sep 21 2025
Today through Monday:
A broad troughing pattern across the region will persist today
through Monday. A decent amount of moisture will linger through
this period, allowing a chance for showers and a few storms at
times. Overall forcing is on the weaker side, so kept precip
chances under 50%, as showers/storms are not anticipated to be
widespread. The better chance for thunderstorms will come during
the afternoon today and tomorrow when daytime heating
contributes to higher instability. Despite the anticipated
clouds and scattered showers, highs will still be mainly in the
mid 70s today and tomorrow, a couple degrees above normal for
this time of the year.
DDV
&&
.LONG TERM...
Issued 407 AM CDT Sun Sep 21 2025
Monday Night through Saturday:
Some weak warm air advection and moisture advection may linger
Monday night, before an inverted trough axis shifts through the
area Tuesday and to the southeast Tuesday night. The area remains
in cyclonic flow aloft, with various vorticity maxima rotating
through the area at times.
Forecast soundings are showing enough low level moisture and tall
skinny mean layer CAPE Monday night into Tuesday night to
continue to bring mainly 20 to 30 percent chances for showers and
thunderstorms. No all day washouts are expected, as any activity
should be scattered at best. Temperatures look to remain mild
Tuesday, with highs into the middle 70s. Lows should be in the
upper 50s to lower 60s Monday night, and a little cooler Tuesday
night.
It appears that there may be a closed 500 mb low that develops
somewhere over or to the southeast of the region by Wednesday into
latter portions of the week. There is a fair amount of uncertainty
in where this may occur, and its effect on the forecast during
this time. The latest 500 mb Cluster Analysis products are
generally favoring the closed low developing to the south of the
region later in the week.
For now, will lean toward the NBM and keep small chances (around
or under 20 percent) for showers going for now. There could be a
few thunderstorms, if enough instability develops. It may also end
up dry if the southern solution of the 500 mb low development
occurs. Temperatures may trend more toward seasonal normal
values, especially if the upper low develops over the region.
Wood
&&
.AVIATION...
Issued 955 AM CDT Sun Sep 21 2025
Early morning FG has resulted in a variety of different flight
categories at southern Wisconsin terminals this morning. Have
amended near-term forecasts at most sites to better align with
trends, and will continue to monitor observations through the
remainder of this morning. Expect VFR flight categories to
gradually return at all fields by early afternoon. Similar to
yesterday, scattered -SHRA and -TSRA are anticipated this
afternoon, though confidence in precise storm development
locations is low. Have thus maintained PROB30 groups in the 15Z
update, and will consider TEMPO/prevailing groups as radar
trends warrant later today.
Quigley
&&
.MARINE...
Issued 407 AM CDT Sun Sep 21 2025
Light south winds are expected to develop today, with light
south to southwest winds tonight into Monday. High pressure
around 30.2 inches to the northeast of the region will then
bring north to northeast winds on Tuesday. Low pressure around
29.8 inches should move from the Central Plains and skirt south
of Lake Michigan Wednesday, bringing increasing winds and a more
easterly wind shift by Thursday.
DDV
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&
$$
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NWS MKX Office Area Forecast Discussion