NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 031015
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
415 AM CST Tue Dec 3 2024

.KEY MESSAGES...

- Scattered snow showers (30-40% chances) will be possible on
  Wednesday. These showers will be convective in nature and may
  feature some brief bursts of snow and low visibility. While
  accumulations will be minor with any snow showers, gusty winds
  may cause blowing/drifting on roadways.

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

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

&&

.SHORT TERM...
Issued 341 AM CST Tue Dec 3 2024

Today through Wednesday:

Some pesky low stratus has lingered this morning, as has been
the story the past few days. CAMs do depict the stratus
dissipating, giving way to some high cloud cover by late
morning. CAMs then show a brief pinch of saturation on the
soundings this afternoon suggesting some scattered low clouds
could return for a few hours this afternoon.

Otherwise, models depict subtle 500mb height rises over the
Upper Great Lakes, suggesting weak WAA over the region today.
Temperatures will respond in kind, with highs slightly improving
into the upper 20s to low 30s by the lakeshore.

Tonight, the core of the WAA will drive a clipper system across
northern WI and the UP, into southern Michigan. We'll stay dry
tonight as the clipper passes, but winds will increase as an
LLJ builds over the region.

As the clipper dives south into Lower Michigan Wednesday, it
will drive a weak trough through the area Wednesday morning,
and then a much stronger arctic cold front through Wisconsin
Wednesday afternoon. The aggressive push of cold air behind the
arctic cold front will steepen low level lapse rates to almost 6
C/km from the sfc to 3km, helping us realize some weak CAPE and
helping us mix up to almost 700mb. With the deep mixing,
saturation in the DGZ, and weak CAPE, convective snow showers
will likely form on a scattered basis along and behind the
front. Model QPF is only a few hundredths with any snow shower
activity which roughly translates to a few tenths of an inch of
snow, but given the convective nature of the snow showers,
there may be brief bursts of snow that may restrict visibility.
The well mixed atmosphere will also help us tap into the frontal
jet, which may cause northwesterly gusts to 40 mph late
Wednesday afternoon, leading to some blowing/drifting on roads.

Cold advection will quickly dry out the atmosphere and snow
showers will largely be out of the area by 7pm. Wednesday night,
the high winds and cold air advection will cause overnight lows
in the low teens with wind chills in the negative single digits
to around -10.

CMiller

&&

.LONG TERM...
Issued 330 AM CST Tue Dec 3 2024

Thursday through Monday:

Synopsis: Arctic high pressure will migrate from the Northern Plains
into the Ohio River Valley during the Thursday-Friday time period,
keeping northwesterly surface flow entrenched across southern
Wisconsin. Chilly temperatures will thus continue through the
conclusion of the work week, with highs generally ranging between
the mid to upper 20s and lows in the teens. Changes to the surface
pattern arrive moving into the weekend, as the aforementioned area
of high pressure translates into the Mid-Atlantic. Said progression
will allow surface winds to turn out of the west-southwest locally,
resulting in advection of a milder air mass from the Plains into
southern Wisconsin Saturday through Monday. In the mid-upper levels,
northwesterlies will remain in place through Saturday, with a weak
clipper system passing largely north and east of the region Friday
night into Saturday. Said disturbance could bring a few flurries or
light snow showers to the far northeast, though the more appreciable
wintry precip will remain confined to the northeast of the area. Mid-
upper northwesterlies will trend zonal to perhaps even slightly
southwesterly by Sunday/the beginning of next week, allowing
initially split upper flow to phase from the Gulf Coast to the
Canadian Maritimes by Monday/the conclusion of the period. With the
aforementioned phasing occurring near and just east of the region,
additional chances for rain and snow return to the forecast from
Sunday afternoon through Monday, particularly over south-central and
southeastern Wisconsin.

Quigley

&&

.AVIATION...
Issued 330 AM CST Tue Dec 3 2024

High MVFR to low VFR stratus has lingered this morning and
anticipated to linger into the post dawn hours. Models depict
these clouds dissipating for a brief period during the late
morning giving way to high clouds. Some models depict some 3500
to 4500ft ceilings returning during the early afternoon, but
confidence is low that this will occur, so have left this out of
the TAFs for now.

Otherwise, light westerly winds will become southwesterly by
tonight and then become breezy overnight as a low level jet
intensifies ahead of an approaching cold front. LLWS is not
anticipated at this time.

CMiller

&&

.MARINE...
Issued 330 AM CST Tue Dec 3 2024

Modest northwest breezes will continue over the lake early this
morning as high pressure moves over the Middle Mississippi
River Valley. Through the morning and into the afternoon hours
today, winds will come around from northwesterly to
southwesterly, as the surface pressure ridge shifts east.
Tonight, southwesterly winds will reach gale force as a strong
pressure gradient moves over the lake between the high, and low
pressure over Manitoba.

These southwesterly gales will continue into late Wednesday
morning before slightly easing off in strength for a short period
as a cold front from the low pressure system passes over the lake
during the early afternoon. Following the cold front, a stronger
period of high-end northwesterly gales is anticipated from late
Wednesday afternoon into Thursday. Some isolated storm force gusts
may occur during this time, especially over the eastern half of
Lake Michigan. A Gale Warning has been issued for the whole lake
to cover both periods of gales tonight into Thursday.CMiller

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...6 PM
     Tuesday to 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...10 PM Tuesday
     to noon Thursday.

&&

$$

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