Sun Prairie, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

309
FXUS63 KMKX 210250
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
950 PM CDT Fri Sep 20 2024

.KEY MESSAGES...

- Summer-like temps to continue one more day on Saturday, but
  cooler/near normal temps are expected into next week behind a
  weekend cold front.

- Additional showers and thunderstorms return Saturday night
  into Sunday with smaller chances afterward.

&&

.UPDATE...
Issued 950 PM CDT Fri Sep 20 2024

Forecast remains on track, with calm to light and variable winds
across the area. A few pockets of fog are possible in Sheboygan
County where dewpoints are higher, as well as in the Wisconsin
River Valley low-lying regions. Fog is not expected to be dense
or widespread.

MH

&&

.SHORT TERM...
Issued 231 PM CDT Fri Sep 20 2024

Tonight through Sunday:

A warm and drier airmass is now in place across srn WI which
will greatly limit the fog potential for tnt, despite high
pressure moving from IA into srn WI. Low temps mainly from
55-60F is forecast. Sly winds and warm, moist advection will
then begin Sat afternoon as a n-s sfc trough/cold front
approaches from the west. This front extends swd from a strong
upper wave and well developed sfc low over Manitoba and Ontario.
Sfc-850 mb dewpoints will surge back into the area from the sw
while PWs rise to 1.5-1.7 inches for Sat nt-Sun AM. Negative
showalter indices and marginal MLCAPE will develop by late Sat
afternoon and evening. South central WI may see initial shower
and storm development by mid to late afternoon, but with
increasing chances through the evening and overnight for all of
srn WI as the cold front passes. Continued or additional shower
and isold storm development is expected on Sunday on the cool
side of the exiting front via frontogenesis and the passage of a
shortwave trough across nrn IL and far srn WI. Overall 0.5-1.00
inches of rain is forecast with the highest potential for 1 inch
amounts toward the IL border.

Gehring

&&

.LONG TERM...
Issued 231 PM CDT Fri Sep 20 2024

Sunday night through Friday:

The passing cold front will stall along the Ohio Valley for
early in the week while a couple shortwave trough in wswly flow
move across the region. At this time it appears srn WI will be
on the nrn periphery of the upper dynamics and lower level
frontogenesis, hence just 20-40 PoPs at this time. The last
shortwave trough will exit Wed AM with 500 mb height rises to
follow as an upper ridge approaches from the nrn Great Plains.
The upper ridge and sfc ridging will then prevail over the nrn
Great Lakes for Thu-Fri. Temps will be near normal for this
period but will likely trend above normal late in the week.

Gehring

&&

.AVIATION...
Issued 950 PM CDT Fri Sep 20 2024

Calm to light and variable winds are expected through early
Saturday morning, with a few pockets of ground fog possible near
SBM through the same time frame. This fog is not expected to
become dense or long-lived, but may cause temporary reductions
in visibility. Saturday, southerly winds increase, with gusts
of 15 to 20 kt possible in the afternoon hours. Showers and
storms spread eastward ahead of and along a cold front late
Saturday afternoon into Saturday night. Reductions in
visibility, briefly gusty winds in the afternoon and early
evening hours, and lowered ceilings are expected with this
activity.

MH

&&

.MARINE...
Issued 231 PM CDT Fri Sep 20 2024

A cold front will continue across Lake Michigan this evening.
Thus light to modest southerly winds this afternoon will turn
westerly this evening into the overnight. Weak high pressure will
then move across the lake on Saturday with light and variable
winds in the morning becoming southerly in the afternoon and
evening. A Canadian cold front will then move across the lake
Sunday morning with winds shifting to modest northerly for the
afternoon, continuing into early next week.

Gehring

&&

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

$$

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