Sun Prairie, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

617
FXUS63 KMKX 070855
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
355 AM CDT Mon Jul 7 2025

.KEY MESSAGES...

- Patchy fog possible through daybreak.

- Small Craft Advisory & high swimming risk conditions continue
  through mid-morning over far southeastern Wisconsin.

- Drier and more comfortable conditions expected through this afternoon.

- Shower and thunderstorm chances (~30-55%) return Tuesday,
  though an all-day washout is not expected.

- Additional shower and thunderstorms forecast Friday through Saturday
  ahead of the next disturbance.

&&

.SHORT TERM...
Issued 355 AM CDT Mon Jul 7 2025

Today through Tuesday Night:

Synopsis/Mesoanalysis: 3 AM surface observations show an area of
high pressure centered over the southern Hudson Bay. An affiliated
surface ridge extends from said surface high into southern
Wisconsin, which has allowed winds to go light and variable across
most of the area. The light winds, combined with clear skies
away from the state line, have allowed for noticeably cooler
overnight temperatures mostly in the upper 50s and low 60s. Low
clouds are apparent in satellite from Darlington east to Racine,
where temperatures have remained a touch milder. Areas of
patchy fog remain possible through daybreak within these low
clouds, in addition to any locations that decouple under mostly
clear skies. Areas along the Kettle Moraine and west of Madison
will be most favored for patchy fog. Drier and more comfortable
conditions are anticipated today as high pressure slides into
the western Great Lakes. Currently apparent in water vapor
imagery over southern Saskatchewan, an upper trough will
progress across the Lake Superior & Michigan vicinity late
tonight through Tuesday evening. Accompanied by a weak surface
front, the feature will bring the next chances for showers and
thunderstorms to southern Wisconsin from Tuesday morning through
Tuesday night. Neither severe weather nor an all-day washout is
expected. Higher than usual uncertainty remains regarding the
precise locations, timing, and coverage of storms on Tuesday,
with trends being monitored in the coming forecasts. Storms will
gradually work east of the region Tuesday night into early
Wednesday morning.

Today: Affiliated with approaching high pressure, noticeably drier
air will lead to more comfortable conditions for most. Abundant
sunshine will lead to still warm high temperatures, with highs
ranging from the upper 70s to low 80s away from Lake Michigan.
Expect largely rain-free conditions, though there is a very small
chance (~10% or less) of an afternoon shower or thundershower in the
Wisconsin Valley. Withheld any mentions in the overnight update
given these low probabilities, but will nevertheless be monitoring
trends through today. Winds will remain breezy through mid-morning
over southeast Wisconsin, resulting in a lingering high swimming
risk at Milwaukee, Racine, and Kenosha County beaches. Have thus
extended the Beach Hazards Statement through 10 AM in these
locations. Continue to exercise extreme caution if heading lakeside
early this morning in southeast Wisconsin.

Tonight Through Tuesday Night: An encroaching upper trough & weak
surface front will bring the next chances of showers and storms to
the area. Precip could begin as early as predawn Tuesday in areas
north and west of Madison, with 30-55% PoPs overspreading all of
southern Wisconsin after sunrise. Noted above, forecast confidence
remains low regarding the precise timing, location, and coverage of
storms during this time frame, with each available CAM
depicting different solutions. The wide amount of spread in the
guidance appears linked to the positioning of the weak surface
boundary, which is likely to be heavily influenced by the
evolution of showers & storms developing in the Northern Plains
this afternoon and evening. The further east storms make it into
the Mississippi Valley tonight, the further east the surface
boundary will be positioned by daybreak Tuesday. Further
influences from any lingering MCV`s will also play a role in the
evolution of storm development. Thus expect areas of showers
and storms to be around the area late tonight through Tuesday
evening, though their coverage & locations will be heavily
dependent on the overlap of the aforementioned forcing
mechanisms. A few storms could produce brief heavy downpours and
gusty winds, though more organized severe weather is not
anticipated at this time. Will continue to monitor trends
through today.

Quigley

&&

.LONG TERM...
Issued 355 AM CDT Mon Jul 7 2025

Wednesday through Sunday:

Upper-level trough is expected to slide east by Wednesday, but some
models hint at the cold front and some of its shower activity
lingering in southern portion of the CWA Wednesday morning.
Otherwise Wednesday/Thursday is progged to be less active as an
upper-level ridge works its way across the Northern Plains/Canadian
Plains. Meanwhile southern WI looks to be sandwiched between a
surface high to the the north and a stalled frontal boundary to the
south through Thursday, which will bring prevailing easterly winds
and slightly milder, near normal temps. Given the pattern with
lingering moisture and nearby forcing, cannot rule out a few stray
showers/storms at times through midweek.

Temps look to warm up by the end of the week as the upper-level
ridge slides east and southerly flow advects in warmer temps ahead
of an upper-level trough. Continue to see models vary on the time of
this trough trekking across the Upper Midwest with the 00z long
range runs leaning more into the start of the weekend compared to
previous runs. However, this would be another window for increased
shower and thunderstorm chances given the influx of moisture
accompanying the warmer temps.

Wagner

&&

.AVIATION...
Issued 355 AM CDT Mon Jul 7 2025

Areas of scattered low clouds have formed early this morning,
particularly across the Wisconsin River Valley and southeastern
Wisconsin. Said clouds have resulted in reported CIGs between FL008
and FL015 at affected stations, resulting in pockets of MVFR to IFR
flight categories. Clear skies and VFR prevail at other locations
unaffected by low clouds. Have accounted for observational
trends through sunrise at the southern Wisconsin terminals, with
JVL, UES, and ENW the most likely terminals to see continued
impacts. With high pressure gradually working in from the west,
do continue to monitor for some patchy fog potential along the
Kettle Moraine and in the Wisconsin Valley through sunrise. Thus
can`t rule out brief periods of VIS reductions at UES through
daybreak, though forecast confidence is too low to justify any
mentions in the 06/09Z updates. Anticipate that any patchy fog
developing in the Wisconsin Valley will remain far enough west
to cause any VIS impacts at MSN or JVL. Any lingering low CIG
and VIS readings will quickly improve after sunrise, resulting
in a return of VFR flight categories at all southern Wisconsin
fields.

Quigley

&&

.MARINE...
Issued 355 AM CDT Mon Jul 7 2025

With 1018 mb high pressure positioned over near the Hudson Bay and
1009 mb low pressure centered over Ontario, breezy north-northeast
winds continue across the open waters this morning. Winds will
gradually taper this afternoon as a second area of 1016 mb high
pressure moves into the western Great Lakes from the Great Plains.
Said area of high pressure will cross Lake Michigan tonight,
allowing winds to turn light and variable across the open waters.
Winds will shift out of the south-southeast during the day on
Tuesday as a broad area of 1014 mb low pressure moves into the Upper
Mississippi River Valley. The low will pull a weak surface front
across Lake Michigan Tuesday night, resulting in a northerly wind
shift. Areas of showers and thunderstorms will accompany the
approaching boundary, with severe weather not expected at this time.
North to northeast winds will remain entrenched through Thursday.
Winds will turn out of the southeast on Friday as a second area of
1010 mb low pressure moves into the Great Plains. The low`s approach
will bring additional chances for showers and thunderstorms to the
open waters Friday into Saturday.

Breezy northeast winds continue in nearshore zones through this
morning as low pressure lingers over southern Ontario. Have extended
the Small Craft Advisory through 10 AM CDT from North Point south to
Winthrop Harbor, where elevated wave heights will linger slightly
longer than initially forecast. Expect that the Small Craft Advisory
will be able to expire as scheduled at 7 AM between Port Washington
and North Point. Winds and waves will gradually taper this afternoon
through tonight as high pressure moves in from the Upper Mississippi
River Valley. Scattered showers and thunderstorms are forecast
Tuesday afternoon and evening as a weak surface front crosses Lake
Michigan. Severe weather is not expected at this time.

Quigley

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ066-WIZ071-WIZ072 until 10 AM
     Monday.

LM...Small Craft Advisory...LMZ644 until 7 AM Monday.

     Small Craft Advisory...LMZ645-LMZ646 until 10 AM Monday.

&&

$$

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