466
FXUS63 KGRB 212347
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
547 PM CST Thu Nov 21 2024

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- Breezy north/northwest winds will persist through tonight, with
  gusts between 25 and 30 mph.

- Light rain or snow is possible Sunday night through Monday
  evening. Central into north-central WI has a 20% chance of
  getting 1 inch of snow or more.

- Temperatures trend cooler starting Tuesday.

&&

.DISCUSSION...
Issued at 305 PM CST Thu Nov 21 2024

Short Term...Tonight and Friday

1002 mb low continued to book it south along Lake Michigan this
afternoon, resulting in a transition to rain as dominant ptype as
warm air continued to dig down from the north. This being said,
rain showers have continued to diminish in coverage and intensity
from north to south as mid-level dry slot wraps in around the
center of the low and dries the profile from the top down.
Temperatures have likewise rebounded into the upper 30s to low 40s
across the forecast area, effectively melting most of the snow
accumulation we saw from this morning. Winds have been a bit
sporadic/slow to get going, although northwest winds have
continued to ramp up early this afternoon under a tight pressure
gradient. Suspect that strong push of warm air advection acted to
hinder stronger winds at 2 to 3K ft from mixing down to the
surface earlier this morning.

Wind... Wind concerns quickly subside later this afternoon as 850
mb jet propagates to our south. CAMs seem to be in agreement, so
opted to let the Wind Advisory for east-central Wisconsin drop off
early. This being said, sub-advisory breezy conditions will
persist through tonight as rain continues to fall and mix the
lowest 3 to 5K ft of the atmosphere. Gusts from 25 to 30 mph will
remain in the forecast overnight, especially across east-central
Wisconsin where lake enhancement is possible.

Tonight/Friday... Low is progged to track south into the Ohio
River Valley by this evening, leaving cloud debris across most of
the state through tomorrow. Some light showers may linger along
the Lake Michigan side of the Door Peninsula late tonight,
although not expecting much in the way of lake effect due to warm
temperatures and weak forcing. Highs for tomorrow to read around
5 to 10 degrees above average, ranging from the upper 30s in the
far north to the mid 40s along and east of the Fox Valley.

Long Term...Friday Night Through Thursday

Quiet weather to start the long term forecast from 00/Sat to
00Z/Mon. High pressure axis will move across WI, but enough
moisture lingering in the mid-levels will keep some clouds around.
Temperatures this weekend will be near or a couple degrees above
normal. Highs Saturday and Sunday will range from the mid 30s to
mid 40s. Lows will range from the mid 20s to low 30s.

An approaching shortwave and surface low will bring a chance for
precip from Sunday evening through Monday evening. Cross sections
show it will take several hours for the low level to become
saturated enough for precip to begin, with onset timing as early
as 00Z/Mon, but likely not until around or after 06Z/Mon. East-
central Wisconsin will likely remain warm enough for all rain.
Northern and parts of central WI are more likely to see a
rain/snow mix or all snow. Amounts are currently forecast to
remain light, with only a 20% chance of getting 1" of snow or
more, with the exception of northern Vilas County which has higher
probabilities for getting 1-3" during this time frame.

A cooler airmass settles in behind this system, which will bring
in below normal temperatures starting Tuesday. High temps Tue-Thu
will range from the mid 20s in north-central WI to the mid 30s in
the Fox Valley and lake shore. Lows will will be in the teens to
mid 20s. An even cooler push of air is possible into next weekend.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 539 PM CST Thu Nov 21 2024

A lingering deformation band of light rain will persist over
eastern WI through the evening, then gradually exit the region.
Lake-enhanced rain showers will also persist over far north
central WI. Otherwise, expect an extensive area of MVFR low clouds
to remain across the forecast area through the TAF period.
Ceilings will be in the IFR category over NC WI tonight into
Friday morning, before rising to MVFR again in the late morning
and afternoon.

The very strong winds associated with the passing low pressure
system have subsided, but northwest winds will still continue to
gust to 20 to 25 kts at times into Friday.

&&

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

&&

$$

DISCUSSION.....Goodin/KLJ
AVIATION.......Kieckbusch