714
FXUS63 KMKX 050415
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1015 PM CST Wed Dec 4 2024

.KEY MESSAGES...

- Gusty northwest winds up to 45-50 mph will continue tonight.
  A Wind Advisory remains in effect.

- West-northwest gales will persist into Thursday. Gale Warning
  remains in effect across Lake Michigan this evening into
  Thursday. Also cannot rule out a few brief storm force guest
  overnight/early Thursday morning.

- Well below normal temperatures will return tonight through
  Thursday night. Overnight wind chills will below zero (-5F to
  -10F) tonight. Then looking at a warm up for the weekend with
   highs creeping into the 40s.

&&

.UPDATE...
Issued 1015 PM CST Wed Dec 4 2024

Gusty northwest winds will continue tonight into Thursday
morning across southern Wisconsin. The cold polar air mass that
is moving in from the northwest is bringing in much drier air.
This drier air will limit the amount of flurries that continue
to make it to the ground. As the last of our mid level cloud
deck moves out that will bring an end to any of the light
snowfall. Any snow that does overcome the much drier air making
it to the ground will quickly be blown away with the strong
winds. Otherwise temperatures continue to drop across southern
Wisconsin with all areas in the teens and wind chills near or
below zero.

Patterson

&&

.SHORT TERM...
Issued 259 PM CST Wed Dec 4 2024

Tonight through Thursday night:

Concerning the snow showers this afternoon, we are realizing the
more broken/scattered activity along the cold frontal boundary
this afternoon. Also this activity is more offset from the
colder temps and strongest winds. However, a few of the
scattered convective snow showers are still producing localized
burst of snow and reduced visibility, along with some gusty
winds and even a flash or two of lightning. The leading line
have been moving into areas where the temperatures have
generally been hovering around or above freezing, so looking at
a bit wetter snowflakes with this afternoon activity and
limiting the impacts a bit more than if it was more aligned with
the colder airmass. Thus the higher reflectivity we are seeing
across Fond du Lac counties may be showing some signs of bright
banding.

Expecting to see this broken line of snow showers continue to
track east late this afternoon. The stronger cores remain across
east central WI, but may begin to see activity fill in south of
I-94 over the next hour or two. While still cannot rule out a
deeper snow shower or two to develop this afternoon into the
early evening hours for east-central and southeastern WI,
especially if the colder air/winds catch up with the line, the
mid to upper 30s temps ahead of the line continue to be a
limiting factor for us meeting the snow squall thresholds.
Nevertheless even with sub- squall line criteria, this snow
shower activity can still lead to travel impacts through the
afternoon commute with reduced visibility, localized burst of
snow, and a few slick spots. If traveling and you encounter a
burst of snow, slow down and give extra space between vehicles.
This initial line of snow showers are likely to clear east to
the lake by 23z-00z.

Behind the initial line of snow showers, expect the colder
Arctic airmass begin to settle in along with the stronger
northwesterly winds. Seeing gusts of 45 to 50 mph at LNR, MRJ,
and PVB. Additionally upstream radar in ARX and MPX indicates
some lingering lighter convective showers to fill in through the
evening/tonight. This activity is likely to bring some light
accumulations, but given the stronger winds may blow this drier
type snow around as well. Will gradually see this activity taper
off overnight as we loose the better forcing associated with
the cold front, but some light flurries may linger with any
cloud cover.

Otherwise, temps dip into the teens to single digits with below
zero wind chills (-5F to -12F). Gusty northwesterly winds will
linger into Thursday, but gradually weaken as the surface low
tracks up the St. Lawrence River Valley, while high pressure
builds in across the Dakotas. The high is progged to work its
way south-southeast through the day into the Mid-Mississippi
River Valley into Thursday night. With the Arctic airmass
settled over the region, looking at high temps on Thursday only
topping off in the low to mid 20s with another night of lows in
the teens to single digits. While winds chills will be colder
during this timeframe they are likely to remain above zero.

Wagner

&&

.LONG TERM...
Issued 259 PM CST Wed Dec 4 2024

Friday through Wednesday:

Northwesterly upper-level flow sets up over the area for Friday
with surface high pressure settling to our south across the
Ohio River Valley. Will start to see more westerly winds and a
small bump in temps for the end of the week. Meanwhile will be
watching two western troughs developing over the Southwest
CONUS/Baja of California and Pacific Northwest. As the two
system develop and track eastward into the weekend, the majority
of the mid range deterministic models along with their
associated ensemble suites (ENS, GEFS, GEPS) have the southwest
trough weakening to not much more than a shortwave as it lifts
across the Midwest quicker for the end of the weekend. While the
main northern trough remains slower and further west, there are
hints of another shortwave trough ejecting off ahead the main
trough and trekking across central Canada during the same time
and phase with the southern one. With this setup, looking at
temps to warm up into 40s through the weekend. NBM has 40-70%
chance of exceeding 45F on Sunday/Monday and even a 20- 30%
chance of exceeding 50F in our southern locations closer to the
WI/IL border.

Then the main trough deepens into early part of next week
dragging the accompanying surface low across Upper Midwest with
additional precip chances. While the there continue to be
difference in timing and track of the system there is a signal
for southern WI to remain in the warm sector of this system.
Then a cold front front is progged to sweep through Tuesday into
the middle of next week bring cooler temps and less activity
pattern for midweek onward.

Wagner

&&

.AVIATION...
Issued 1015 PM CST Wed Dec 4 2024

Largely VFR conditions are expected to persist through the
period. The last of the mid level cloud cover around 3-4 kft has
begun to scatter out. Clear skies are expected once the
remainder of these clouds move out of the area. Northwest winds
will remain gusty into Thursday afternoon across southern
Wisconsin. The strongest of the northwest winds are expected to
be prior to and around midnight with guts of 30-40 knots.
Heading into early Thursday morning gusts will dwindle a bit
with gusts closer to 30 knots. Terminals along Lake Michigan
will see these stronger gusts linger into Thursday morning.
Winds will start to taper off quicker late Thursday morning into
the afternoon.

Patterson

&&

.MARINE...
Issued 259 PM CST Wed Dec 4 2024

Low pressure continues to track eastward across Ontario/Quebec
dragging a cold front across Lake Michigan and northwestern
gales will become more prevalent heading through the
evening/tonight. No major changes to the headlines at this time
as gusts up to 45 knots are looking likely tonight. Still
thinking there may be a few storm force gusts, especially across
the eastern side of the lake overnight into Thursday morning.
Additionally with the colder Arctic airmass moving over the the
lake there will be a window for some moderate freezing spray
concerns overnight into Thursday morning as well for the
southern two-thirds of the lake. Stronger northwesterly winds
will continue into Thursday before weakening below gale
conditions through the afternoon as the low pushes further east
and high pressure begins to build across the Upper Midwest.
Lighter, but still gusty west-northwesterly winds persist
through the end of week before the high pressure drift southeast
into the Ohio river Valley for the weekend. Then we can see
southwestern winds increase through the weekend.

Wagner

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Wind Advisory...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-WIZ057-
     WIZ058-WIZ059-WIZ060-WIZ062-WIZ063-WIZ064-WIZ065-WIZ066-
     WIZ067-WIZ068-WIZ069-WIZ070-WIZ071-WIZ072 until midnight
     Thursday.

LM...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.

     Gale Warning...LMZ643-LMZ644-LMZ645-LMZ646 until 9 AM Thursday.

&&

$$

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