Sun Prairie, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

143
FXUS63 KMKX 160333
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1033 PM CDT Thu May 15 2025

.KEY MESSAGES...

- Additional scattered (30 to 60 percent chances) showers and
  thunderstorms are possible Friday afternoon and early evening.
  A couple of these storms may reach severe levels.

- Gusty south to southwest winds are expected Friday in the late
  morning and afternoon hours. Gusts of 35 to 45 MPH are
  expected.

&&

.UPDATE...
Issued 1033 PM CDT Thu May 15 2025

With a frontal boundary to our east and mostly clear skies,
southern Wisconsin can expect dry and quiet conditions through
Friday morning.

Breezy south to southwest winds and additional chance for
showers and storms are expected Friday. The environment
continues to look well mixed with high LCLs for tomorrow which
will lead to any storms being elevated. The forecast is still on
track with showers and storms expected to develop around 1 to 4
PM and move through southern Wisconsin at their peak intensity
from roughly 3 to 8 PM. This set up will be much weaker than
earlier in the afternoon/evening. The main hazards are expected
to be frequent lightning, small hail and brief gusty winds.

Patterson

&&

.SHORT TERM...
Issued 325 PM CDT Thu May 15 2025

Rest of today through Tonight:

Convection has initiated in southwestern / western Wisconsin,
and from this point forward, storms are expected to grow more
intense and increase in coverage, tracking northeastward. A
Tornado Watch is in effect until 10 PM this evening for the
entire region. Please be on alert for severe thunderstorm and
tornado warnings!

Breezy southeast winds expected ahead of the approaching
frontal boundary, veering southwest behind the boundary after
thunderstorms pass. Boundary is currently along a La Crosse to
Monroe WI Line.

Friday:
A level 1 out of 5 risk for severe thunderstorms is also present
Friday afternoon, with the highest potential in southeastern /
east-central WI. HREF mean SBCAPE exceeds 1000 joules Friday
afternoon, with most CAMs developing scattered convection
beginning in the early to mid afternoon, roughly 1 to 4 PM. Peak
coverage / intensity 3 to 7 PM, then winding down thereafter.
Forecast soundings feature a very / well mixed column, with very
high LCL heights (reducing the tornado threat to near zero).
Lapse rates, however, would be supportive of a marginal severe
hail and wind gust threat from any storms that are able to
survive dry air entrainment and persist / strengthen. Wind gusts
will likely be the primary concern (combo of strong low-level
lapse rates and plenty of momentum aloft).

Even without the thunderstorms, soundings indicate that strong
wind gusts could mix down to the surface. 35 to 45 MPH wind
gusts are in the forecast, and a Wind Advisory cannot be ruled
out for the late morning and afternoon hours of Friday. A Gale
Watch is in effect for all adjacent nearshore zones of Lake
Michigan.

Sheppard

&&

.LONG TERM...
Issued 325 PM CDT Thu May 15 2025

Saturday through Thursday:

Low pressure continues northeastward from the upper Great Lakes on
Saturday, allowing breezy west winds to continue ushering in a
cooler airmass, with daytime highs in the mid 60s expected all areas
and only a slight chance (10-30%) for lingering light rain
showers, mainly in central and east-central Wisconsin. Strong
high pressure builds into northern Manitoba and Ontario Canada
on Sunday, allowing for slow north winds, dry weather, and a
weak backdoor cold front / lake breeze (modest northeast winds)
for eastern WI through the afternoon hours of Sunday. Hence,
high temps moderate to the mid to upper 60s inland, while
eastern WI remains cooler, with low 50s along the lakeshore.

Low pressure tracking eastward from the central Plains and passing
just south of our region is likely to deliver a wetting rainfall to
the region next Tuesday or Wednesday. Generally expecting
daytime highs to hold in the 60s for inland areas through the
period. East winds induced by the low to our south should keep
eastern WI cool.

Sheppard

&&

.AVIATION...
Issued 1033 PM CDT Thu May 15 2025

Dry weather and clear skies are expected tonight into early
Friday morning. Mid to high level cloud are expected to develop
and move back in from the southwest mid to late Friday morning.

By Friday afternoon there will be additional chances for shower
and thunderstorms across southern and central Wisconsin. Lower
MVFR to IFR ceilings are expected to develop with the showers
and thunderstorms. Showers ans storms are expected to develop
between 1 to 4 PM. They are expected to move northeast through
the evening and exit the region between 7 to 9 PM. There is a
small chance for some stronger storms to develop. The main
concerns with any stronger storms will be frequent lighting,
brief gusty winds and small hail. Beyond 9 PM, isolated to
scattered showers are expected to linger into Saturday morning
across south central and central Wisconsin. Ceilings around 1 to
4 kft are expected to remain through the overnight hours Friday
night.

The currently breezy south to southwest winds are expected to
diminish over the next few hours. By late Friday morning breezy
winds will develop again with south to southwest wind gusts of
25 to 30 MPH expected. After dark Friday evening into Friday
night the winds will shift to westerly and remain breezy.

Patterson

&&

.MARINE...
Issued 325 PM CDT Thu May 15 2025

The northern three quarters of the lake remain under a Dense Fog
Advisory until 7 PM CDT this evening. The majority of this fog
along southern and eastern portions of the lake has already eroded
based on satellite observations. Western nearshore and open
water zones could continue to observe fog until the front clears
it out this evening.

South to southeast winds this afternoon and evening are expected
to remain well below gale force, due to warmer air over the cold
lake. Thunderstorms are expected along a cold front this
evening. Strong to severe storms with large hail will be
possible. Winds will turn southwest behind the front.

Low pressure will then move through northern Minnesota and
northwest Wisconsin Friday, while weakening a bit to around 29.2
inches. Winds will remain southerly over the open waters. Could
see gusts approach gale force over the western shoreline areas
ahead of the main cold front Friday afternoon. An additional round
of thunderstorms will be possible with this secondary front, with
a few strong to severe storms possible again, especially across
the south half of the lake.

Breezy westerly winds are likely Saturday behind the cold front,
as low pressure passes by to the north. Winds decelerate and turn
north Saturday night into Sunday, as high pressure builds in north
of the region.

Sheppard

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 11 PM
     Thursday.

     Gale Watch...LMZ643-LMZ644-LMZ645-LMZ646...noon Friday to 10
     PM Friday.

&&

$$

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