665
FXUS63 KGRB 081741
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1141 AM CST Wed Jan 8 2025

Updated aviation portion for 18Z TAF issuance

.KEY MESSAGES...

- Light snowfall will be possible from late Thursday night into
  Friday morning which could lead to slippery stretches on area
  roads. Probabilities of snowfall greater than 1/2 inch ranges
  from 20-30%.

- Snow is also possible on Sunday into Monday. Probabilities of
  greater than 1 inch ranges from 30-40%.

&&

.DISCUSSION...
Issued at 242 AM CST Wed Jan 8 2025

Short Term...Today...Tonight...and Thursday

A ridge of high pressure was situated over MN early this morning,
and continued cold northwest flow off Lake Superior was producing
low clouds and flurries over roughly the NE half of GRB CWA. WV
imagery showed a short-wave trough north of Lake Superior moving
toward NE WI.

Low-level winds will back to the west as the surface ridge
approaches this morning, so any lingering lake-effect will taper
off. Even so, flurries will likely continue in association with
lingering low clouds. The previously-mentioned short-wave trough
will move through NE WI later this morning and afternoon, and will
combine with mid-level FGEN to support flurries across much of the
region through the day. RH timesections show the best saturation
occurring over far NE WI/Door County later this morning/afternoon,
so will mention a chance of measurable snow there. Any lingering
light snow or flurries should end in eastern WI early this
evening. Partial clearing occurs tonight as the surface ridge
gradually shifts east. WAA occurs tonight into Thursday, but
moisture is lacking, so little precipitation is expected. An
approaching cold front could bring a few flurries to NC WI later
Thursday afternoon.

Highs for today will range from the middle teens to lower 20s.
Lows tonight should be in the single digits, with lower teens in
Door County. Milder temperatures are expected on Thursday, with
highs in the 20s to near 30.

Long Term...Thursday Night Through Tuesday

Forecast concerns revolve around the snow potential on
Thursday night into Friday and also late in the weekend.

Thursday night into Friday:  An amplifying shortwave will push a
cold front across the region on late Thursday night into Friday
morning.  Like last night`s models showed, moisture is about 120-
130% of normal, but there are indications that it splits around
Wisconsin to the north and south.  As a result, precip amounts
continue to look minor, with probabilities of snowfall greater than
1/2 inch are around 20-30%.  Expect low impacts for the Friday
morning commute.

Late in the weekend:  Dynamics look more potent on Sunday into
Monday when a series of shortwaves move across the region.  Models
are more aggressive showing a low pressure system crossing southeast
Wisconsin during this time period.  Precip chances and amounts have
increased on Sunday and Sunday night with probabilities greater than
1 inch increasing to 30-40%.

850mb temps will cool to about -20C behind the low pressure system
for Monday.  Think there is potential for high temps to be
considerably colder than the NationalBlend for Monday and Tuesday.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1141 AM CST Wed Jan 8 2025

Will continue to see a mix of VFR/MVFR cigs early this afternoon.
Light, scattered snow showers or flurries also persist on and off
across northeast and far northern WI (including KRHI, KGRB, KATW,
and KMTW TAF sites). Occasional vsbys drops to MVFR are possible
within a snow shower, otherwise vsby is greater than 6SM. Both
clouds and snow showers clear out this evening and overnight,
resulting in VFR conditions area wide. Winds will generally be
light and gradually back from NW to W to S.

&&

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

&&

$$

DISCUSSION.....Kieckbusch/MPC
AVIATION.......KLJ