Sun Prairie, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

489
FXUS63 KMKX 181042
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
442 AM CST Sat Jan 18 2025

.KEY MESSAGES...

- Arctic air arrives into southern Wisconsin today, bringing
  frigid temperatures and bitterly cold wind chills through the
  first half of next week.

- Cold Weather Advisories have been issued from tonight through Monday
  evening in advance of the arriving Arctic air mass.
  Additional cold weather headlines are likely from Monday night
  into Tuesday.

- Heavy freezing spray is expected Sunday afternoon through
  Tuesday, particularly over southern Lake Michigan.

- Temperatures gradually trend back toward normal mid to late
  next week.

&&

.SHORT TERM...
Issued 442 AM CST Sat Jan 18 2025

Today through Wednesday:

Synopsis/Mesoanalysis: Breezy northwest winds and cold advection are
ongoing early this morning across southern Wisconsin, with
yesterday`s Arctic cold front now well southeast of the area. Said
winds will allow an Arctic air mass to settle into the region
through Sunday, with frigid temperatures and breezy northwest winds
supporting a prolonged period of wind chills at and below -10. The
Arctic air mass will remain entrenched through the day on Monday,
ultimately being reinforced by an even chillier pull of Arctic air
Monday night into Tuesday. Cold weather headlines have been issued
into Monday evening in this forecast package, with additional
headlines covering Monday night and Tuesday morning becoming
necessary in later forecasts. Winds will turn southwesterly during
the day on Wednesday, allowing the entrenched Arctic air mass to
begin breaking down. Dress warm if heading outdoors through the
beginning of the upcoming work week.

Rest Of Overnight: Given obs and radar trends over west-central
Wisconsin, can`t entirely rule out a few flurries to the north and
west of Madison through sunrise. Any such activity will be non-
impactful, with drying conditions in the low level shutting off any
flurry potential by sunrise.

Tonight Through Monday: The core of the incoming Arctic air mass
will settle into southern Wisconsin amid continued post-frontal CAA.
The arrival of said air mass will support overnight lows at or below
zero outside of far southeastern Wisconsin tonight, and areawide
Sunday night into Monday. Daytime high temperatures in the single
digits are expected both Sunday and Monday. The frigid air will be
accompanied by persistent, breezy northwest surface flow, which will
hold wind chills in the -10s and -20s through the entirety of this
time period. Wind chill readings will be at their coldest---and well
into the range of Cold Weather Advisory criteria---during the
overnight and morning periods, with brief "rises" above advisory
thresholds occurring during the afternoon hours each day. Rather
than chasing the periods of -20 to -29 wind chills with multiple
headlines, ultimately elected to issue a long-fused Cold Weather
Advisory from as early as 3 AM Sunday through 9 PM Monday, with the
understanding that there will be brief periods of sub-advisory level
wind chills during the afternoon periods. Did separate the advisory
into two different segments, given that sub -20 wind chills aren`t
forecast to reach far southeastern Wisconsin until Sunday evening.
Cold Weather Advisory thus runs between 3 AM Sunday and 9 PM Monday
outside of Milwaukee, Racine, and Kenosha Counties, and between 9 PM
Sunday and 9 PM Monday in Milwaukee, Racine, and Kenosha Counties.

Monday Night Through Tuesday: Even colder temperatures will arrive
into southern Wisconsin, resulting in the chilliest lows of the
period on Tuesday morning. Expect widespread lows in the double
digits below zero along/north of I-94 and US-18, with readings
approaching -10 further south. The even chillier air mass will
combine with still breezy northwest winds so support the coldest
wind chills of the upcoming Arctic outbreak. Cold weather headlines
will thus continue during this timeframe, with Extreme Cold Warning
level wind chills in the -30 to -35 range possible over central and
east-central Wisconsin on Tuesday morning. Should trends supporting
such wind chills continue to hold, a mixture of Extreme Cold
Warnings and Cold Weather Advisories will likely become necessary
during this portion of the period. Will monitor trends over the
coming forecasts, with headline decisions being made as this portion
of the period draws closer.

Tuesday Night Through Wednesday Morning: One more overnight period
of -10 to -20 wind chills is anticipated. Locally colder readings
are possible, particularly in east-central Wisconsin. Whether or not
additional headlines will be necessary during this portion of the
period remains uncertain, with trends being monitored over the
coming forecast cycles.

Quigley

&&

.LONG TERM...
Issued 442 AM CST Sat Jan 18 2025

Wednesday night through Friday:

Synopsis: Temperatures will gradually moderate toward normal thanks
to west-southwest surface winds. An upper disturbance is forecast to
track across the western Great Lakes Thursday night into Friday.
While precipitation is not currently expected with this disturbance,
trends will continue to be monitored over the coming forecasts.

Quigley

&&

.AVIATION...
Issued 442 AM CST Sat Jan 18 2025

Predominantly VFR flight categories prevail early this morning in
the wake of a departed Arctic cold front. The lone exception is at
KUES, where CIGs between FL025 and FL030 have been reported over the
last 60 minutes. Have inserted a TEMPO group through 11Z to account
for said obs, and will monitor trends for any potential TEMPO
insertions downstream at KMKE and KENW. Post-frontal northwest winds
and gusts will continue to increase through this morning, allowing a
much drier air mass to move into southern Wisconsin. The arrival of
drier low level air will scour out low level cloud cover by early
afternoon, with only FEW-SCT based near FL200 remaining by this
afternoon. Northwest winds & gusts will decrease slightly this
evening as high pressure builds into the Northern Plains.

Quigley

&&

.MARINE...
Issued 442 AM CST Sat Jan 18 2025

Gusty northwest winds are in-progress across the open waters this
morning in the wake of an Arctic cold front passage. Gusts at or
slightly above 30 kts will continue through daybreak, with a few
gale-force gusts possible over the northern half of the lake.
Northwest gusts will weaken slightly through today as 988 mb low
pressure moves into northern Quebec and high pressure of 1040 mb
moves into the northern Great Plains. Northwest gusts will increase
to or just above 25 kts Sunday afternoon, combining with elevated
wave heights and a frigid Arctic air mass to support freezing spray,
with moderate to heavy freezing spray expected over the southern
half of the open waters. The aforementioned freezing spray potential
will continue into the beginning of next week as a second, stronger
area of high pressure near 1048 mb progresses into the northern
Great Plains. A Heavy Freezing Spray Watch has thus been issued from
Sunday afternoon through Tuesday afternoon, with trends being
monitored for a possible upgrades to Heavy Freezing Spray Warnings
over the coming forecast cycles.

In nearshore zones, gusty northwest winds and elevated wave heights
will continue through this afternoon in the wake of the departed
Arctic cold front. A Small Craft Advisory remains in effect from
Sheboygan south to Winthrop Harbor through 5 PM CST this afternoon.
Gusts and wave heights are expected to weaken slightly below
advisory thresholds this evening, though they will continue to hover
just below advisory levels into Sunday. Will thus monitor wind/wave
trends closely over the coming forecast cycles, making any Small
Craft Advisory extensions if necessary.

Quigley

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Cold Weather Advisory...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-
     WIZ057-WIZ058-WIZ059-WIZ060-WIZ062-WIZ063-WIZ064-WIZ065-
     WIZ067-WIZ068-WIZ069-WIZ070...3 AM Sunday to 9 PM Monday.

     Cold Weather Advisory...WIZ066-WIZ071-WIZ072...9 PM Sunday to
     9 PM Monday.

LM...Heavy Freezing Spray Watch...LMZ080-LMZ567-LMZ669-LMZ671-
     LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-
     LMZ876-LMZ878...noon Sunday to 3 PM Tuesday.

     Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 5 PM
     Saturday.

&&

$$

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