Oshkosh, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

826
FXUS63 KGRB 131758
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1158 AM CST Tue Jan 13 2026

Updated aviation portion for 18Z TAF issuance
and new information added to update section

.UPDATE...
Issued at 1142 AM CST Tue Jan 13 2026

Updated pops through Wednesday, with a main focus on providing
more definition during the strong frontal passage tonight. Also
added a chance of freezing drizzle with the frontal passage, as
there appears to be a couple hour window of opportunity at any
given location as mid-level moisture briefly shallows. Of course,
this will dependent on surface temperatures, so will only mention
a chance.

&&

.KEY MESSAGES...

- A light mix of rain, freezing rain, sleet and snow will result
  in hazardous travel across north central and northeast Wisconsin
  this morning. Icy conditions will impact the morning commute in
  the Northwoods.

- Accumulating lake-effect snow may cause additional travel
  concerns in far north central Wisconsin tonight into Wednesday.

- Widespread snow late Thursday afternoon through Friday, with
  additional chances for light snow through the weekend.

- Still mild today, then turning colder Wednesday through the
  weekend.

&&

.DISCUSSION...
Issued at 223 AM CST Tue Jan 13 2026

Active pattern continues through the week. Mixed precip to start,
then only snow as cold settles across the region. No heavy snow is
anticipated through the coming weekend, but a couple times of
widespread fresh light accumulations are likely, especially Thursday
afternoon through Friday.

Strong clipper low with MSLP of 989mb is over central Canada this
morning, just entering northwest Ontario. Strong warm air advection
over upper Mississippi river valley has been tempered by dry air
as seen on 00z MPX sounding. Result has been precip struggling to
build south over MN this morning, with only a few obs of light
rain and/or UP noted. Trends of models picking up on this,
showing main push of light precip eventually impacting areas
mainly north of highway 29. Ptype is a mess with initial warm air
advection giving way to wet-bulb cooling. Result is rain/freezing
rain (depending on sfc temps)/sleet mixing with snow eventually
if stronger saturation occurs. Not completely sold that will be
the case based on upstream trends, but models do point to better
coverage of precip toward 12z/6am and are beginning to see more
obs with precip upstream. Wondering though when precip makes it to
the 29 corridor if temps may be a bit too warm for any freezing
precip as readings are steadily coming up slightly above freezing
in the last couple hours. Overall, will keep the Winter Weather
Advisory as is and not expand it any farther south. Main icing up
to a few hundredths will be through mid morning over northern WI.
Then as colder air starts to arrive aloft, may see another round
of scattered rain/snow showers this afternoon north-central to
central WI.

Sharp trough axis aloft drops in overnight tonight dragging coldest
air aloft (850mb temps -18c to -20c) over WI. Retained the widespread
pops overnight into Wednesday morning for light snow. As the cold
air arrives behinds sharp sfc cold front, it will become blustery
and noticeably colder at the sfc, with readings by daybreak on
Wednesday around 10 above north, to near 20 Fox Valley to lakeshore.
Apparent temps will be below zero north and in the single digits
above elsewhere. It will feel like quite the change compared to
the recent mild weather. Lake effect expected into north-central
WI on Wednesday, with a few flurries at times elsewhere. Given the
dry airmass, clouds will begin to break up through the day in
downslope areas of central and eastern WI. Even with some sun,
temps and apparent temps will stay steady.

We`ll see brief ridging and warm air advection aloft late Wednesday
night into Thursday. Stronger shortwave trough arrives by Thursday
night, spreading light snow across the entire western Great Lakes
region into Friday. Probabilities for an inch of snow are higher
with the system (60+%), but chances for 2" are only 20-50% and
chances for 4" are 5-15%. Temps on Friday bounce back (mid
20s-lower 30s) as the system moves through, but become cold again
for the weekend. Highs will be in the teens and lows will be below
zero for parts of the area. Apparent temps could drop toward 20
below both Saturday night into Sun AM and again Sunday night into
Mon AM.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1142 AM CST Tue Jan 13 2026

Most of the precipitation has moved out of the forecast area at
issuance time and clearing has pushed into east central WI. Some
IFR ceilings lingered over NC WI, and MVFR ceilings were moving
into central WI. A cold front was moving into northern MN,
accompanied by light mixed precipitation. This front will reach
northern WI early this evening, then move out of the forecast area
during the overnight hours. A brief mix of snow and freezing
drizzle could accompany the front. Lake-effect should increase in
north central WI after the frontal passage, as cold north-
northwest winds flow across western Lake Superior. Some of these
snow showers will likely reach the RHI TAF site through much of
the night. MVFR conditions should improve to VFR in the southeast
half of the forecast area later tonight into early Wednesday, but
snow showers will continue north of RHI.

Gusty west winds are expected this afternoon and early evening.
Winds veer north-northwest and gust to 25 to 30 kts this evening
and overnight in the wake of the strong cold front. The strong
winds will persist through Wednesday. Pockets of LLWS will
continue across the region through much of the TAF period.

&&

.MARINE...
Issued at 223 AM CST Tue Jan 13 2026

Westerly winds reach Small Craft Advisory criteria today as
strong low tracks north of Lake Superior. Strong cold front tied
to the low moves through tonight. Stronger northwest winds, with
frequent gale gusts to 40 kts, are expected late tonight through
Wednesday evening. The strongest winds will be over the Lake
Michigan waters. Even with an offshore northwest wind direction,
waves will be higher and there will be moderate to at times heavy
freezing spray.

&&

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

&&

$$

UPDATE.........Kieckbusch
DISCUSSION.....JLA
AVIATION.......Kieckbusch
MARINE.........JLA