Sun Prairie, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

481
FXUS63 KMKX 040217
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
817 PM CST Tue Dec 3 2024

.KEY MESSAGES...

- Scattered snow showers will be possible on Wednesday. These
  showers will be convective in nature and may feature some
  brief bursts of snow and low visibility. However,
  accumulations will be minor with any snow showers.

- Strong southwest winds tonight into Wednesday morning and
  northwest winds Wednesday afternoon into Thursday will bring
  gale conditions to Lake Michigan.

- The strong northwest winds Wednesday afternoon may exceed 45
  mph. Secure loose objects.

- Much below normal temperatures will return Wednesday night
  through Thursday night. Overnight wind chills will be in the
  negative single digits.


&&

.UPDATE...
Issued 817 PM CST Tue Dec 3 2024

Areas of low stratus have been developing this evening on the
leading edge of 925 mb warm advection. The fcst soundings were
showing the potential for this to occur, so would expect the
stratus to gradually shift newd with time. Do have higher
confidence for more widespread stratus after 12Z Wed with the
passage of a sfc trough that will shift swly winds to wly.

The arctic front is still on track for passage from 20-23Z Wed
with gusty nwly winds to 40-45 mph and sct snow showers.


Gehring

&&

.SHORT TERM...
Issued 256 PM CST Tue Dec 3 2024

Tonight through Wednesday Night:

Surface low pressure will strengthen as it tracks from Manitoba
to southern Quebec tonight through Wednesday. A potent clipper
system will impact southern Wisconsin and the rest of the Upper
Great Lakes region. We will see gusty southwest winds as the low
approaches tonight into Wednesday morning, and very strong
northwest winds and scattered snow showers in the wake of an
associated cold front Wednesday afternoon through Wednesday
night.

Southwest winds will steadily increase through late evening in a
warm air advection regime, peaking around midnight with the
strongest vorticity advection with a leading shortwave trough.
Winds will diminish a little Wednesday morning. The sudden cold
air advection with the passage of the 850mb cold front may bring
low clouds and possibly some drizzle. The low level temp profile
during this period looks too mild for ice crystal development.
Surface winds will be westerly during this time.

By 3 pm Wednesday afternoon, the surface cold front will arrive
in the northwest forecast area from the Dells to Madison and
then barrel across the rest of southern WI through 6 pm. The
biggest impact will be the strong winds. With the mixing
potential up to 800 mb (or higher for a few models), wind gusts
up to 39 kt/45 mph will be possible, which is the criteria for a
Wind Advisory. Not enough models suggest higher than this speed,
so we are not issuing a headline at this time.

As far as the snow showers go, it will be blustery with snow
falling, but amounts will be light. Forecast soundings are
consistent across the models with temperatures well into the
snow growth zone, and also with steep low level lapse rates.
What the models disagree on is the depth of the moisture and the
degree of the low level instability. With these uncertainties, I
am not really confident in getting intense snow showers that
would greatly reduce visibility and rapidly accumulate snow,
despite the strong winds. The meso model forecast reflectivity
usually can hint at the potential for stronger snow showers, and
they are not showing this scenario for tomorrow afternoon.
Visibility briefly down to 2 miles and a dusting of snow is
what we are thinking for now.

Temperatures will be "mild" tonight and Wednesday, but very
strong cold air advection will drop temps down to around 10F and
some single digits Wednesday night. With the wind gusts of
around 30 mph, the minimum wind chills will be in the negative
single digits.

Cronce

&&

.LONG TERM...
Issued 256 PM CST Tue Dec 3 2024

Thursday through Tuesday:

As low pressure continues eastward towards Maine and strong high
pressure travels southeastward from the Dakotas into Iowa on
Thursday, northwest winds with gusts upwards of 30 MPH continue,
with wind chills in the negative single digits early in the morning.
Mostly clear skies and dry weather expected Thursday, though
forecast soundings show some potential for a few cirrus and cumulus
clouds. Winds gradually decline in the afternoon and evening,
becoming light and variable Thursday night as high pressure passes
just south of our region. Overnight lows in the single digits to
teens.

Mostly calm, dry, and quiet weather expected Friday into the
weekend. Lingering high pressure in the eastern CONUS and low
pressure entering southern Canada will allow a southwest breeze to
gradually moderate air temperatures, trending slightly above
seasonal norms for the later half of the period. Early to mid
next week would be the next noteworthy chance for precipitation,
though it is too early to determine system track and precip
type.

Sheppard

&&

.AVIATION...
Issued 817 PM CST Tue Dec 3 2024

Areas of bkn010-019 stratus have been developing over srn WI
early this evening. Do not expect the coverage to change until
becoming widespread MVFR Cigs for the daytime hours of Wed.
Breezy swly winds tnt will become wly by late Wed AM then nwly
and even windier after 20Z Wed. Scattered snow showers along and
behind the arctic front may briefly drop vsbys to 1-2SM Wed
afternoon/early evening.


Gehring

&&

.MARINE...
Issued 256 PM CST Tue Dec 3 2024

There were no changes made to the Gale Warnings for the open
lake and Nearshore that are in effect.

Southwest winds will increase tonight as low pressure over
Manitoba deepens as it crosses Ontario tonight through
Wednesday. Southwest gales are expected from late this evening
through Wednesday morning as the low approaches.

A lull in the gusts will occur as a cold front crosses Lake
Michigan midday. Then a stronger period of high-end
northwesterly gales is anticipated from late Wednesday afternoon
into Thursday. Some isolated storm force gusts may occur,
especially over the eastern half of Lake Michigan early Thursday
morning. A Gale Warning is in effect for the whole lake to
cover both periods of gales tonight into Thursday.

Cronce

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 3 PM
     Wednesday.

     Gale Warning...LMZ643-LMZ644-LMZ645-LMZ646...3 PM Wednesday to
     9 AM Thursday.

     Gale Warning...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-
     LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 until noon
     Thursday.

&&

$$

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