Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 211502
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1002 AM CDT Thu Mar 21 2024

.KEY MESSAGES...

- Widespread snow accumulations are expected tonight into early
  Friday afternoon. The snow will impact the Friday morning
  commute, with a Winter Weather Advisory in effect. Localized
  higher snowfall amounts are possible, though there remains
  uncertainty with where the heavier snow bands will set up.

- Confidence is increasing in a prolonged period of wet weather
  later Sunday through Tuesday. Some uncertainty remains with
  timing, amounts, and initial precip type (snow vs rain).

&&

.UPDATE...
Issued 1002 AM CDT Thu Mar 21 2024

A quick look at incoming 12z guidance does not offer any major
surprises thus far. Many of the hi-res models are focusing in on
the tier of counties along the Illinois state line, coincident
with the band of strong frontogenesis that is expected to
develop late tonight. Some of the more broad regional and global
guidance (e.g., NAM and GFS) are focusing further north, along
and just north of I-94/US 18.

Past experience suggests that reality may well line between
these two solutions in terms of the location of the heavier band
of snow, as some of the higher resolution guidance tends to
place precipitation too far south in strong f-gen situations.
Will continue to evaluate guidance over the next few hours, but
right now trends are suggesting that locations along and just
south of I-94/US 18 have increasing potential for seeing that
higher band of snowfall late tonight and tomorrow morning.

The overall message of many locations seeing at least 3-5 inches
of snow, with an enhanced band of 6"+ has not changed, nor has
the fact that tomorrow morning`s commute will likely be messy.
It`s also worth emphasizing that impacts will largely be driven
by snowfall rates and timing, and less so by final
accumulations.

Boxell

&&

.SHORT TERM...
Issued 439 AM CDT Thu Mar 21 2024

Today through Friday:

Quiet weather is expected today, with increasing clouds through
the day ahead of the approaching low pressure system. Kept the
forecast dry today, but wouldn`t be surprised if a few flakes
make it through the dry low levels for flurries at times.

Confidence remains high in widespread accumulating snowfall
tonight into Friday afternoon. Most places should get at least 3
to 5 inches, so opted to issue a Winter Weather Advisory for the
entire forecast area. The lingering question will be where the
heavier bands set up due to strong frontogenesis and warm air
advection. Models have continued to shift southward overall
compared to the last 24-48 hours, which is reflected in the
latest storm totals. Totals could easily exceed 6 inches where
the stronger forcing sets up, but confidence isn`t high enough
to put a Winter Storm Watch out for any particular area. NBM
probs for 6"+ and 8"+ currently suggest this higher potential
would be across east-central portions of the forecast area,
generally from Madison eastward. If models show some consistency
going forward, confidence may increase enough to eventually
upgrade a swath of counties to a Winter Storm Warning.

The snow will be on the wetter side with snow ratios of 8-12 to
1 expected, the wetter snow towards the south. Snowfall rates
could reach 1-2 inches an hour for a time within the heavier
forcing. This snow is expected to impact the Friday morning
commute. The peak intensity may be just after rush hour based
on latest models, especially towards the east. Still some time
left to fine tune these details.

Snow should wind down from northwest to southeast late morning
into early afternoon.

DDV

&&

.LONG TERM...
Issued 439 AM CDT Thu Mar 21 2024

Friday night through Wednesday:

Clouds are expected to gradually clear Friday night, with
temperatures dropping to the upper teens to low 20s most places
behind the departing low pressure system. Temps will likely
struggle to get above the freezing mark on Saturday given the
expected snow cover along with the colder airmass in place.

A stronger low pressure system will move through the region early
next week. Models continue to remain largely west with the
arrival of the initial precip Saturday night into Sunday,
cutting back on the potential for additional accumulating
snowfall. Models have come into better agreement with the track
and timing of the low pressure system, though there remains
meaningful differences among solutions. These differences are
mainly impacting expected precip timing and totals along with
when the warmer temps arrive. Overall, it seems the biggest
impact from this system will be widespread rain Monday into
Monday night, with the precip winding down by early Tuesday.

High pressure will bring decreasing clouds and cooler temps on
Wednesday.

DDV

&&

.AVIATION...
Issued 1002 AM CDT Thu Mar 21 2024

VFR today will give way to rapidly decreasing flight conditions
tonight as snow begins to overspread the area. Winds today will
be light and variable, turning easterly by this afternoon and
tonight. IFR to LIFR conditions are likely late tonight and
through tomorrow morning at all terminals. Heavier snowfall
rates will occur with one or more bands of enhanced snowfall,
but these will be narrow and it`s difficult to determine if one
will directly affect a terminal area. Snow will end from west to
east tomorrow mid day to early afternoon.

Boxell

&&

.MARINE...
Issued 439 AM CDT Thu Mar 21 2024

High pressure will move over Lake Michigan today, with light
northerly winds eventually becoming east to southeast. East to
southeast winds will then pick up on Friday, as low pressure of
passes by to the south. A Small Craft Advisory may be needed
tomorrow for waves of 3 to 5 feet.

Breezy northerly winds Saturday will become easterly again on
Sunday. Winds may reach gale force at times Monday and Tuesday
as a stronger low pressure system moves through the region. At
the very least, a Small Craft Advisory will likely be needed at
times from Sunday night through Tuesday.

DDV

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-
     WIZ057-WIZ058-WIZ062-WIZ063-WIZ067-WIZ068...1 AM Friday
     to 1 PM Friday.

     Winter Weather Advisory...WIZ059-WIZ060-WIZ064-WIZ065-WIZ066-
     WIZ069-WIZ070-WIZ071-WIZ072...1 AM Friday to 4 PM Friday.

LM...None.
&&

$$

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