NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 150826
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
226 AM CST Mon Dec 15 2025

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- A strong winter storm moving across the Upper Midwest will bring
  a variety of impacts late Wednesday night into Friday. Hazardous
  travel is likely at times as this system will bring rain, snow
  or a wintry mix to the area along with areas of fog at times

- Temperatures above freezing are expected to turn sharply colder
  on Thursday, falling below freezing which may result in roads,
  bridges and sidewalks to become icy.

- Strong winds possible on Thursday and Thursday night (40-50%
  chance for gusts over 35 mph). Strong winds may result in
  isolated tree damage and power outages.

&&

.DISCUSSION...
Issued at 224 AM CST Mon Dec 15 2025

Compact short-wave, evident on WV imagery is working across northern
WI early this morning. Radar returns are picking up on light snow
falling out of high based clouds. However, as of 2AM have not had
any surface sites or web-cams report snow reaching the ground.
This is due to the robust dry layer from the surface up to just
above 700mb mb observed on the GRB 06Z RAOB. As southwest winds
advect low-level moisture into far northeast WI areas east of an
Iron Mountain to Sturgeon Bay line could see a few tenths of snow
accumulation this morning. High pressure will then build into the
region this afternoon allowing temperatures to warm into the upper
teens to low 20s at most locations. Tuesday highs are forecast to
reach the middle to upper 30s, which will be the fist time most
locations top freeze this month. All with the increase in
temperatures dew points are expected to rise near to slightly
above 32 degrees Wednesday night. This could lead to patchy areas
of locally dense fog.

Attention then turns to a strong pacific low pressure system that is
progged to move across northern MN and the UP late Wednesday night
through Thursday. Ensemble trends have slowed the arrival of this
system down slightly with most members now showing the onset of
precipitation overnight Wednesday into Thursday. Depending on surface
temperatures thermal profiles do show the possibility for a period
of freezing rain. However, strong WAA ahead of the low should
lead a transition to mainly rain for most locations Thursday,
except far northern WI where surface temps may be cold enough for
snow/sleet. A sharp cold front will then swing across the region
causing thermal fields to plumet. Forecast soundings suggest
precipitation should quickly transition to snow behind the front
late Thursday afternoon and evening. The sharp drop in
temperatures could also lead to freezing of any liquid water on
area road Thursday night. The finer details regrading p-type phase
changes still needs to be refined, so stay up to date with the
latest forecast updates.

Along with the precipitation chances with this system a period of
strong winds is also expected late Wednesday through Thursday. 01Z
NBM shows 40-50% probs for gusts greater than 35 mph during this
period. Isolated tree damage and sporadic power outages may be
possible.

Ensemble mean upper-level flow fields favor another clipper system
tracking across the Upper Midwest Friday into Saturday. At this
point thermal fields would support this being mainly a snow event,
however, total accumulations are still uncertain.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1027 PM CST Sun Dec 14 2025

VFR conditions will prevail overnight across much of the area.
The next clipper system will bring a chance of light snow to
portions of northeast WI late tonight into early Monday morning,
generally east of a line from KLNL to KMTW. A little uncertainty
if snow would make it to KGRB/KMTW; therefore, continued with a
PROB30 group to cover the possibility of some light snow in these
locations. LLWS has developed across the region with low level
winds from 220-240 degrees at 35 to 45 knots and will persist
through Monday morning. MVFR CIGS and VSBYs will be possible in
the areas of snow.

&&

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

&&

$$

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