Oshkosh, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

612
FXUS63 KGRB 180919
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
319 AM CST Sat Jan 18 2025

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- An arctic airmass arrives today, bringing a prolonged period of
  wind chills reaching 20 to 35 degrees below zero Saturday night
  through Wednesday morning. Wind chills as cold as 40 below will
  be possible early Tuesday morning.

- A Cold Weather Advisory goes into effect at 9 PM tonight,
  lasting through 9 PM Monday. An Extreme Cold Warning appears
  increasingly likely late Monday night/Tuesday morning.

&&

.DISCUSSION...
Issued at 319 AM CST Sat Jan 18 2025

Short Term...Today...Tonight...and Sunday

Winter returns today after the mild weather of yesterday. Cold
air advection is forecast through Tuesday, which will make for
colder high and low temperatures each of the next several days.
Arctic air is usually very dry, so other than a few snow flurries
little or now snow is expected outside of the lake effect snow
region of north central Wisconsin. Winds have too much of a
westerly component for significant snow in Vilas county, but there
could be an inch or so between now and Sunday.

Temperatures will fall across the area this morning, and then
level off in the afternoon before falling again tonight. Sub zero
air temperatures are expected tonight, with highs of 5 below to 5
above zero Sunday. Wind chills of 20 to 30 below zero are likely
by Sunday morning.

Long Term...Sunday Night Through Friday

Discussion for the extended will remain front-loaded on the
Monday morning through Wednesday morning period as we monitor the
necessity for Extreme Cold Warnings. On a lesser note, northwest
flow regime will continue to bring light lake effect snow chances
to the snowbelts through Monday afternoon. Northern Vilas county
may be able to pick up a few inches of light, fluffy snow during
this time.

Temperatures/wind chills... Arctic airmass is still on track to
dig down into the Midwest end of this week. 850 mb temperatures of
-30 to -32C (nearing the first percentile) will engulf the upper
Mississippi Valley, which, when paired with subsidence from high
pressure, will result in daytime highs Monday and Tuesday failing
to reach zero degrees for most. The last time a high temperature
below zero degrees was observed in the Green Bay area was in
January of 2019, which highlights the anomalous nature of this
setup when compared to climatology. This being said, no records
are currently in danger of being broken. Coldest timeframes look
to be early Monday and Tuesday mornings as stiff northwest winds
plunge wind chills between -25 and -35 degrees area-wide, locally
colder. Temperatures then moderate back to positive values on
Wednesday as surface ridging steers the arctic high off to the
east and WAA takes over.

Headlines... If guidance holds, which it likely will, the
entirety of the forecast area will be well within Extreme Cold
Warning territory early Tuesday morning. A similar story will
likely be true Monday morning, although the margin will be
slightly tighter. Regardless, expect a prolonged period of cold
weather headlines lasting through mid-week.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1045 PM CST Fri Jan 17 2025

A cold front had moved through the forecast area by late evening,
and low clouds between 2500-5000 ft AGL had overspread all but
the far southeast portion. Snow showers were ongoing over far NC
WI, and flurries were reported elsewhere. Northwest winds were
gusting to 20-30 kts.

Low clouds, with MVFR ceilings in parts of NC/C WI, will continue
across the region until clearing arrives Saturday morning/early
afternoon. The low clouds will persist longer north of RHI, and
lake-effect snow showers will likely continue in northern Vilas
County through Saturday evening. Gusty northwest winds will
continue through Saturday morning then diminish a bit during the
afternoon and evening.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Cold Weather Advisory from 9 PM this evening to 9 PM CST Monday
for WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074.
&&

$$

DISCUSSION.....RDM/Goodin
AVIATION.......Kieckbusch