Sun Prairie, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

713
FXUS63 KMKX 112028
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
328 PM CDT Mon Aug 11 2025

.KEY MESSAGES...

- Flood Warnings remain in effect along portions of several
  metro Milwaukee rivers and adjacent tributaries. Stay away
  from flood waters and continue to heed any remaining road
  closures in these areas.

- Scattered showers and storms possible (~30-60% chances)
  overnight into early Tuesday morning. Conditions will be
  favorable for heavy downpours in storms, though activity will
  be moving fast enough to prevent any additional significant
  flooding concerns.

- Chances (~30-50%) for additional scattered storms Tuesday afternoon,
  particularly over the northwest half of the area. A few
  storms could produce small hail and gusty winds.

- Slightly more comfortable conditions behind a cold front on
  Wednesday, with humidity quickly returning by the end of the
  week.

&&

.SHORT TERM...
Issued 330 PM CDT Mon Aug 11 2025

Tonight through Tuesday night:

Synopsis/Mesoanalysis: A pair of MCV`s are apparent over the Central
Plains this afternoon, with a scattering of convection beginning to
blossom from south-central Nebraska into northwest Missouri. Storms
will gradually migrate northeast tonight as their affiliated forcing
translates into the Upper Mississippi Valley, ultimately approaching
southern Wisconsin late this evening through the early morning hours
Tuesday. Heavy downpours will accompany activity, though progressive
storm motions should keep additional significant flooding impacts
low across the region. Currently situated across the Dakotas, a
surface cold front will progress into Minnesota tonight, ultimately
crossing southern Wisconsin Tuesday afternoon and evening.
Additional scattered storm development will be possible along the
boundary, particularly over the northwest half of the area where the
front will arrive first. A few storms could produce small hail and
gusty winds, though widespread severe weather potential is low in
any Tuesday afternoon/evening storms. Areas of fog are possible late
tonight, particularly along and west of Interstate 39.

Tonight through Tuesday Morning: Scattered storm development
beginning over the Central Plains will approach and ultimately move
into parts of southern Wisconsin. Well-sampled by the 12Z sounding
from ILX, an air mass characterized by 1.7"+ precipitable water
values will be advancing into the area with storms, supporting the
potential for heavy downpours & efficient hourly rainfall rates. The
favorable conditions will be partially offset by an environment
unfavorable for training storms, in addition to progressive storm
motions. Thus anticipate a similar additional rainfall forecast to
last night`s storms, with 0.5" or less in most locations and
localized 1-2" totals in areas directly impacted by storms. Said
totals would translate to at most minor (urban/small stream flooding
& ponding of water in low-lying areas) hydro impacts across the
area. Will nevertheless closely monitor trends through the overnight
& early morning hours, particularly if any more enhanced hourly
rates track across areas receiving heavy rain this weekend.

Tuesday Afternoon: Additional scattered storm development is
forecast along an encroaching cold front. Storm potential will be
greatest over the northwest half of the area, where the front will
arrive first and there will be more sunshine. Lower precipitable
water values will be funneling into the region with the front,
making heavy downpour potential lower in Tuesday afternoon`s storms.
Widespread severe weather is not anticipated, though an isolated
stronger storm with gusty winds and small hail is possible.

Quigley

&&

.LONG TERM...
Issued 330 PM CDT Mon Aug 11 2025

Wednesday through Monday:

An upper level ridge will begin to build in from the west Wednesday
bringing some dry weather and slightly cooler conditions. This upper
level ridge will be associated with a sfc high that will extend from
Canada and build into WI. This sfc high will push east heading into
Thursday. A shortwave trough will move through the larger flow aloft
and bring some low chance POPS for Thursday night into Friday. Areas
across northern and central Wisconsin will have the best potential
for any rain, as thats where the best lift from this weak shortwave
is. But southwestern and west central Wisconsin will have some POPs
around 10-15%.

This shortwave will precede a larger trough and low centered over
Saskatchewan. This low is expected to move northeast into the Hudson
Bay from Thursday into Friday night. Winds will turn to southerly
and temperatures will increase across southern Wisconsin as both the
trough and shortwave move east to northeast.
High temperatures will return to the mid 80s to low 90s for the
weekend. As temperatures and dewpoints climb again we will see some
low chance POPS for the weekend around 10-30%. For much of the time,
conditions will be unstable, hot and humid, but there wont be much
of a forcing mechanism for rain. So we could get an isolated shower
or storm, but many will likely remain dry. Now the better chance for
any rain this weekend looks to be Sunday when the trailing cold
front, that is associated with the Low in the Hudson Bay, finally
advances through the state. There is a lot of timing uncertainty
here so POPS still remain low around 40%. But this would be the one
area of forcing that could cause some more widespread rainfall.
Conditions are expected to cool off a bit again behind this front.

Patterson

&&

.AVIATION...
Issued 330 PM CDT Mon Aug 11 2025

CIGs have improved early this afternoon, allowing for the return of
VFR conditions at all southern Wisconsin terminals. Will be
monitoring TSRA/SHRA development over Iowa later today, as some
model solutions suggest the potential for impacts to southern
Wisconsin terminals this evening and tonight. Will continue to
monitor trends and make adjustments to forecasts as necessary. Given
the low to moderate forecast confidence in TSRA/SHRA impacts, have
thus addressed TSRA/SHRA potential with PROB30 groups at all
aerodromes. Should confidence increase further, prevailing TSRA/SHRA
groups may become necessary at some terminals. VIS reductions and
low cloud bases would be possible in any precip. Outside of any
TSRA/SHRA, broader CIGs are expected to fall across all of southern
Wisconsin by daybreak Tuesday, with VIS reductions and FG possible
along and west of I-39. Have accounted for this potential at all
sites. Similar to today, VIS and CIG reductions will gradually
improve following sunrise Tuesday morning.

Quigley

&&

.MARINE...
Issued 330 PM CDT Mon Aug 11 2025

High pressure is centered off the middle Atlantic coast this
afternoon, combining with 1002 mb low pressure over Manitoba to
support breezy southeast winds across the open waters of Lake
Michigan. Southeast winds will persist through the majority of the
day Tuesday, ultimately turning out of the northwest Tuesday night
into early Wednesday morning as a cold front moves across Lake
Michigan. Periods of showers and storms are forecast across
primarily the southern open waters this evening through Tuesday
morning, and once again Tuesday night along the passing cold front.
Widespread severe weather potential is low, though a few storms
could produce gusty winds across southern Lake Michigan this evening
through early Tuesday morning.

Patches of fog are possible in nearshore zones this evening. Dense
fog is not anticipated, though trends will be closely monitored in
the event that fog forms.

Quigley

&&

.HYDROLOGY...

Flood warnings remain in effect along portions of several metro
Milwaukee rivers & their adjacent tributaries in the wake of this
weekend`s flooding in southeastern Wisconsin. The Lower Fox River in
downtown Waukesha currently sits in moderate flood stage. Water has
reached the bottom of the Barstow Bridge in downtown Waukesha,
resulting in subsequent backup of water, river flooding, and several
road closures in the immediate vicinity of the river. The Milwaukee
River in Cedarburg currently sits in minor flood stage, with rises
into moderate flood stage possible overnight tonight. The Cedar
Creek in Cedarburg, Menomonee River in Menomonee Falls, Lower Fox
River in New Munster, and Root River in Franklin all remain in minor
flood stage. Ponding of water in areas immediately near each river
segment will be possible until each can fall below flood stage later
this week. Continue to heed any road closures in all impacted areas
until river stages recede further & Flood Warnings are allowed to
expire. Impacts of any overnight/early Tuesday rainfall at each
station will be closely monitored, with updates to existing Flood
Warnings being sent if necessary.

Quigley

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$

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