Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 151845
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
145 PM CDT Fri Mar 15 2024

Updated aviation portion for 18Z TAF issuance

.KEY MESSAGES...

- A system dropping south out of Canada will bring a few chances
  for snow showers this weekend, mainly for the snowbelt region of
  northern Wisconsin.

- Northwest winds may gust to 25 to 35 mph on Saturday, strongest
  across central and far northeast Wisconsin, and east of Lake
  Winnebago.

- Temperatures remain 5 to 10 degrees above normal through
  Saturday before falling to more seasonable readings Sunday into
  Monday.

&&

.DISCUSSION...
Issued at 310 AM CDT Fri Mar 15 2024

Short Term...Today...Tonight...and Saturday

Dry weather is expected across northeast Wisconsin today as a
ridge of high pressure sinks south across the western Great Lakes
region. Highs today are expected to range from around 50 across
the north, to the lower 50s across central and northeast Wisconsin
with middle 40s near Lake Michigan.

A low pressure system tracking through southern Canada tonight
will bring an increased pressure gradient along with a cold front
slated to sink south across northeast Wisconsin later tonight.
Much of the area will remain dry despite the passage of this cold
front and associated mid level shortwave as model soundings show a
dearth of moisture associated with this system. However, a bit
better moisture across the north means there will be a chance
(20-30 percent) of precipitation across that area, mainly after
midnight. Precipitation will mainly be in the form of rain;
however, some snow could mix in at times. The lack of deep
moisture means snowfall accumulations will be de minimis. The
increased pressure gradient will bring an uptick in wind speeds
tonight with south to southwest winds of 20 to 30 mph expected
after midnight. Lows tonight are expected to range from the lower
30s across the north, to around 40 across east- central Wisconsin.

Saturday will continue to be blustery or windy behind the cold
front as a tight pressure gradient remains in place across the
western Great Lakes with west to northwest winds gusting to 25 to
35 mph. Although much of the region will remain dry, cyclonic flow
will combine with some lake moisture from Lake Superior and mid
level shortwaves to continue the chance (20-30 percent) across
north-central Wisconsin. Model soundings show a colder column in
place for Saturday along with a bit deeper moisture, meaning snow
will be the predominant precipitation type. Snowfall amounts on
Saturday will be light, with at best around a tenth or so of snow
possible across the far north. Highs on Saturday are expected to
range from around 40 across the far north, to the lower 50s across
east-central Wisconsin.

Long Term...Saturday Night Through Thursday

Primary focus of the long term period is continued chances for
lake effect snow Saturday night through Monday across the snowbelt
region of northern WI. Additionally, gusty northwest winds are
expected to remain through Sunday with gusts to 30-35 mph possible
during the afternoon.

Precipitation...Continued cold air advection and northwest flow
on the backside of a Canadian cyclone will keep the chances for
lake effect snow Saturday night through mid-day Monday. Lake
surface to 850 are expected to remain in the favorable 13 to 17
degrees range during this period. Probabilistic guidance gives
the northern WI snowbelt region a 30-60% chance for greater than
1" of snow accumulation by Monday afternoon. For the rest of the
CWA a secondary cold front, with support from upper level jet
dynamics is progged to swing across the region Sunday afternoon
creating small (10-20%) chances for scattered flurries. However,
forecast soundings are showing a dry surface layer which may
prevent much if not all snow from reaching the ground. As the
cyclonic flow shifts off to the east Monday ensemble guidances
shows a mean northwesterly flow pattern setting up across the
north-central CONUS for the middle of next week. A few short wave
impulses and jet streaks may pass through creating chances for
light precipitation, however, models are not in good agreement
with the timing, so left NBM PoPs for the middle of next week.

Winds...While northwest winds Sunday are not expected to be as
strong as Saturday a tight surface pressure gradient and mixing of
strong winds just off the surface will keep gusts of 30-35 mph
possible. Strongest gusts are expected generally across central
and northern WI.

Temperatures...Behind a cold temperatures Sunday and Monday are
expected to trend near or slightly below normal with highs each
day in the mid 20s across the north to the upper 30s in the Fox
Valley. Low temperatures Sunday and Monday are expected to drop
into the mid teens to mid 20s. Temperatures are then expected to
trend slightly warmer for the remainder of next week with highs
back in the upper 30s to mid 40s across the region.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 145 PM CDT Fri Mar 15 2024

Patchy VFR based stratocu will slowly cross this afternoon. Brief
cigs over central WI terminals. As a cold front approaches the
region tonight, mid-clouds will arrive over northern Wisconsin in
the evening and the rest of northeast Wisconsin later tonight.

Westerly surface winds less than 10 kts will back to the southwest
tonight and increase to 10 to 15 kts with gusts of 15 to 25 kts.
Increasing low level southwesterly winds of 35 to 45 knots at 2k
ft will cause LLWS beginning this evening, lasting through at least
daybreak on Saturday.

By daybreak Saturday the cold front will finish crossing the area.
A few light rain and snow showers could occur closer to the Upper
Michigan border as the front passes. Expect partly to mostly
cloudy skies on Saturday behind the front (mainly VFR though some
MVFR possible from RHI to the north) with some occasional light
snow showers over north-central WI at times, including RHI. The
main story Saturday will be the strong and gusty northwest winds
occurring at all terminals with winds 15-20 kts and gusts 25-30
kts.

&&

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

&&

$$

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


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