987
FXUS63 KGRB 100842
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
242 AM CST Fri Jan 10 2025

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- A light dusting of snow could create scattered slippery spots
  on area roads and sidewalks this morning, and again in the late
  afternoon and evening.

- Confidence is increasing for hazardous travel on Sunday and
  Sunday night due to accumulating snow. There is a 70-90% chance
  of greater than 2 inches of snow across the area. Locally up to
  5 inches is possible over northern Door County due to lake
  enhancement.

- Wind chills may approach 20 below zero over central and north-
  central Wisconsin late Monday night into early Tuesday morning.

&&

.DISCUSSION...
Issued at 241 AM CST Fri Jan 10 2025

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

A cold front was moving through NC/C WI early this morning,
accompanied by a narrow band of light snow, with vsbys of 2-5SM.
WV imagery showed an upper level trough lagging well behind the
front, and moving through MN. Light snow and flurries were also
occurring in conjunction with this feature. Widespread stratus
covered the western Great Lakes region.

Have used a blend of meso-models to time the band of light snow
across the forecast area, before shifting it east into Lake
Michigan later this morning. Most places should only see a light
dusting with the frontal snow. Although models are not handling
this well, it appears there be another period of patchy light snow
or flurries associated with the upper trough passage later this
afternoon and evening. In addition, there should be an uptick in
lake-effect snow showers in Vilas County as low-level winds turn
NW and lake-H8 delta-t`s increase to 16-18 C. An additional
dusting of snow should occur in NC/C WI later this afternoon/
evening, with a half inch to an inch in northwest Vilas County. A
ridge of high pressure will move into western WI late tonight,
with low-level winds backing west and decreasing lake-effect over
NC WI. Partial clearing will occur as the upper trough shifts
east later tonight into Saturday morning, though clouds will
increase again during the afternoon.

Highs todays will be in the middle 20s to lower 30s. Lows tonight
should drop into the single digits and teens, except around 20 in
northern Door County. Highs on Saturday should be in the 20s.

Long Term...Saturday Night Through Thursday

Focus for the long-term remains on snowfall potential on Sunday and
Sunday night. Once the snow ends, attention then turns to bitterly
cold wind chills on Monday night through Tuesday night.

Snow Potential on Sunday and Sunday Night...Shortwave energy moving
across the northern Mississippi Valley into the western Great Lakes
will support a surface low tracking from west-central WI to the
central Upper Peninsula on Sunday to Lake Superior on Sunday night.
This track continues to trend north over the past 24 to 48 hours.
Moderate forcing (QG/warm advection) will accompany precipitable
water values upwards of 150% of normal to produce a large swath of
light to moderate snowfall.  Probabilities for snowfall amounts
greater than 2 inches have increased over the past 24 hours and now
sits at 70-90%.  While thermal profiles show a decent cross-hair
signature over northeast Wisconsin on Sunday morning, wind profiles
look more veered over Lake Michigan than they did in past model
cycles, most likely due to the northward track trend of the surface
low. If this trend continues, lake enhancement may not play as large
a role in snowfall amounts over northern Door County.

The latest snowfall forecast shows a solid 2 to 4 inches across the
area, with the lowest amounts over the southern Fox Valley and the
highest amounts over far northeast WI.  Northern Door County has
potential to see up to 5 inches thanks to lake enhancement. Because
the snow starts late on Saturday night and diminishes on Sunday
evening, impacts will be less than if the snowfall occurred on a
weekday.  In addition, snowfall intensities up to 1/2 inch per hour
and a light/fluffy consistency also do not indicate that impacts
from snow will be significant.

Temperatures/wind chills... After the snow departs, cold advection
will resume Monday into Monday night when a modified arctic airmass
slides into the region.  Temperatures have trended colder over the
past 24 hours on Monday night with lows below zero and wind chills
to 20 below at several locations.  While these temps are not cold
enough for a Cold Weather Advisory, wind chills this cold could
produce frostbite in the 30 minutes on exposed skin by Tuesday
morning. Wind chills moderate slightly to 15 below zero on Tuesday
night.

Temperatures will be below normal from Monday through Wednesday
before approaching normal on Thursday and Friday.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1025 PM CST Thu Jan 9 2025

A weak cold front will bring a period of MVFR conditions and light
snow or flurries through Friday morning. MVFR conditions should
then improve to VFR and clear out Friday afternoon and evening for
most areas except north-central Wisconsin where MVFR stratus will
linger. A clipper system could bring a few inches of snow to the
region Sunday.

&&

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

&&

$$

DISCUSSION.....Kieckbusch/MPC
AVIATION.......Kurimski