Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 181102
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
602 AM CDT Mon Mar 18 2024

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Except for Tuesday, below normal temperatures will continue
  into next weekend.

- Next chance for widespread snowfall is forecast to arrive
  Thursday afternoon. 20-40% chance for greater than 3" of snow
  south of a Wausau to Oconto line.

&&

.DISCUSSION...
Issued at 315 AM CDT Mon Mar 18 2024

Short Term...Today...Tonight...and Tuesday

Lake effect snow will come to an end across far north-central
Wisconsin this morning as a surface ridge tracks across the
western Great Lakes region. Additional snowfall amounts are
expected to be under an inch, mainly across Vilas County. The
surface ridge will also bring some drier air into the region, with
some breaks in the clouds across central and east-central
Wisconsin this afternoon as winds back to the west. The breaks in
the clouds and backing winds will bring slightly warmer
temperatures today, with highs expected to mainly be in the 30s.

A fast moving clipper system tracking across the northern Great
Lakes will bring another round of light snow and flurries to the
region this evening and overnight with the best chances across
north-central and northeast Wisconsin (20-30 percent) and lower
chances across central and east-central Wisconsin (10-20 percent)
where mainly flurries are expected. Snowfall amounts this evening
will be light due to the fast moving nature of this system and
lack of deep moisture and strong lift, with snowfall amounts of
less than an inch expected and highest amounts across the north.
Lows tonight are expected to range from the upper teens across the
north, with middle 20s across east-central Wisconsin and the
lakeshore.

Although most of the area will be dry behind the departing clipper
system on Tuesday, a vigorous mid level shortwave will bring a
slight chance for additional light snow/flurries/sprinkles to the
far north (10-20 percent). There could be some moisture
contribution from Lake Superior, which could bring a tenth or two
of snowfall accumulations across far north-central Wisconsin.
Winds will also increase on Tuesday, with blustery conditions
expected across the region as northwesterly winds gust to 25 to 35
mph. A well mixed boundary layer up to 800 mb will bring the
warmest temperatures of the week to the region as highs during the
afternoon range from around 40 across the north, to the upper 40s
across east-central Wisconsin.

Long Term...Tuesday Night Through Sunday

Highlights for the extended period are below normal
temperatures prevailing through this week behind a cold frontal
passage Tuesday. There are also a few chances for some snow across
the region later this week into next weekend as well as the
chance for light lake effect snow in far northern WI Wednesday.

Precipitation...Winds are expected to veer northwesterly behind a
cold front passage Tuesday night into Wednesday which along with
favorable lake surface to 850 mb delta Ts of 17-23 degrees could
allow for another round of light lake effect snow, mainly for
northern Vilas County where up to an inch looks possible (30-60%
chance). With a dry surface layer in place across the rest of the
CWA expect mostly dry conditions with a few flurries possible. A
more widespread chance for snow is progged to arrive Thursday
afternoon as a moist warm air advection regime sets up out ahead
of a disorganized low developing over the northern Plains.
Ensemble models have come into decent agreement with an area of
frontogenetic forcing setting up somewhere across central to SE WI
that could lead to some locally higher snowfall rates.
Additionally this may be augmented with upper-level support in the
form of a right rear jet quadrant. Hindrances to the snow
potential, especially across northern WI could be a dry boundary
layer air, RHs in the 25-50% range Thursday afternoon, as well as
the presence of a high over eastern Ontario. Probabilistic
guidance shows about a 30-50% chance for 1-3" of snow across the
CWA, and a 20-40% for greater than 3" south of a Wausau to Oconto
line by Friday afternoon. The finer details of this system will
need to be worked out over the coming days, but given current
trends expect at least some minor impacts Thursday evening into
Friday morning. As the aforementioned system shifts out of the
area Friday attention will then shift to another potentially more
organized system bringing another round of snow to the area next
weekend. Ensemble models are in broad agreement for lee side
cyclogenesis during this time.

Winds...Expect breezy northwest winds Wednesday morning and early
afternoon with gusts possibly reaching 25-35 mph. Strongest gusts
are currently expect in far NE WI as 925 mb winds show a core of
stronger 30-35 knot winds over this region. Gusts should diminish
fairly quickly Wednesday evening.

Temperatures...With mean northwesterly flow at the 500 mb level
through this week, become more flat by this weekend, expect
temperatures to trend about 5-10 degrees cooler than climatology.
Highs each day are expected to range from the low 20s to low 30s
across the north and low 30s to around 40 degrees in central and
east-central WI. Overnight temperatures are expected to drop well
below freezing each night with lows in the mid teens to low 20s
for most. The sandy soil region of northern WI may drop into the
single digits Tuesday and Wednesday if winds decouple.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 552 AM CDT Mon Mar 18 2024

Scattered snow showers and flurries should taper off in NE/EC WI
early in the TAF period, as an upper trough shifts southeast.
Lake-effect snow showers will persist in far north central WI
until later this morning, due to cold NNW flow off Lake Superior.
MVFR cigs have spread in across most of the area this morning,
with some LIFR cigs across far north-central Wisconsin. CIGs
should improve to VFR later this morning as drier air works its
way into the region in central and east-central Wisconsin, with
MVFR CIGs hanging on into the afternoon until the lake effect
cloud bases rise with the drier air. Any clearing will be short
lived as mid level clouds increase ahead of a clipper system
tracking through the northern Great Lakes region. This system will
bring isolated light snow or flurries across the region, with the
best chances across northern Wisconsin from the mid-evening into
the overnight hours.

Gusty north to northwest winds will gradually weaken and become
westerly late this afternoon. Winds will then back southwesterly
tonight and once again become gusty to around 20 knots. In
addition, increasing low level winds around 2k ft will cause LLWS
as westerly winds aloft gust to 40 knots late tonight.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION.....Kurimski/GK
AVIATION.......Kurimski


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