NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 230830
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
230 AM CST Tue Dec 23 2025

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Several rounds of wintry precipitation will be possible on
  Wednesday. The first round will be north of Hwy 29 Wednesday
  morning, with the second round south of Hwy 29 Wednesday
  evening.

- Above normal temperatures are expected throughout the work
  week, with highs expected to read above freezing.

- Confidence is increasing for a more widespread round of mixed
  wintry precipitation Thursday evening into Friday. Travel
  impacts will be possible.

&&

.DISCUSSION...
Issued at 221 AM CST Tue Dec 23 2025

Precip chances... Any remnants of drizzle/freezing drizzle have
exited to the east early this morning as drier air works in from
the west. Canadian high pressure then encroaches from the north
later this morning, offering us a brief dry spell. A ridge-riding
shortwave pulse then brings additional chances for freezing
drizzle/wintry precipitation on Wednesday, with signs pointing
toward another sneaky event. Two target areas are coming into
focus: the first round north of Highway 29 Wednesday morning in
conjunction with the shortwave and the second round south of
Highway 29 with better saturation. Snow will likely be the
dominant p-type across the north where temperatures stay below
freezing, whereas rain is favored for the southern activity.
Freezing drizzle will be prone to mix in near/around the Highway
29 corridor Wednesday evening as temps fall below freezing,
offering up a similar setup for yesterday's messy freezing precip
event.

Forecast concerns gradually shift to potential for a messy mixed
precip event Thursday into Friday, which would pose a hazard to
post-holiday travel. Warmer temperatures aloft would favor
predominantly liquid precip, though surface temperature behavior
would determine whether we see rain versus freezing rain. Driving
low pressure initially doesn't look too impressive as it treks
across the northern Plains late Thursday, with upper-level
dynamics somewhat lacking. Surface wave eventually reaches
Wisconsin early Friday morning, with ensemble cluster analysis
showing two axes of heavier QPF that split northeast Wisconsin to
the north and south. However, beginning to see a signal emerge for
an inverted trough setup early Friday morning, which would
enhance precip potential. As such, starting to see a trend toward
some QPF sneaking up into east-central Wisconsin Thursday night
into Friday. Probabilistic guidance offers a more pessimistic
scenario, showing a widespread 60 to 90% chance of receiving
frozen precip, mainly north of Hwy 29. Will have to see if this
trend holds over the next several forecast cycles.

Temperatures... Strong signal still present for above average
temperatures through at least the end of the work week as
positive height anomalies and mild Pacific flow usher in an above
freezing airmass. Highs will plateau in the mid to upper 30s
Friday and Saturday, with areas in/around the Fox Valley flirting
with 40 degrees. Dewpoints likewise rise above freezing beginning
Christmas Eve, which may result in widespread fog/low cloud
development. Post-holiday travel may be impacted as fog potential
lingers beyond Christmas Day, especially in areas that receive any
precip. Temperatures then crash on Sunday as an arctic cold front
passes over the Great Lakes.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1109 PM CST Mon Dec 22 2025

Patchy light drizzle and freezing drizzle will impact eastern WI
into the early overnight hours. Have included a mention at GRB/ATW
and MTW as observations are now indicating at least some drizzle
is reaching the ground.

MVFR cigs have developed late this evening. Expect these to last
through late tonight before scattering out. Brief IFR cigs may
occur over northern WI at RHI. On Tuesday, MVFR cigs over the
north will linger into the early afternoon. Otherwise, mid and
high clouds with VFR conditions will occur elsewhere through the
TAF period.

&&

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

&&

$$

DISCUSSION.....Goodin
AVIATION.......JLA