Oshkosh, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

044
FXUS63 KGRB 111721
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1221 PM CDT Fri Apr 11 2025

Updated aviation portion for 18Z TAF issuance

.KEY MESSAGES...

- Patchy ground fog may lead to rapid reductions of visibilities
  under 1/2 mile over central and north-central Wisconsin this
  morning. A few slippery spots are possible on untreated roads.

- Dry and warmer today and Saturday, with high temperatures in
  the 60s inland from Lake Michigan on Saturday.

- Rain showers (30-70 percent chance) return Sunday into Monday.
  Some of the rain may mix with or change over to snow across the
  area on Monday night that could lead to minor accumulations.

- Strong winds to 40 mph (up to 50% chance) will be possible at
  times on Monday and Monday night.

&&

.DISCUSSION...
Issued at 158 AM CDT Fri Apr 11 2025

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

Surface ridge extending across northern Wisconsin from central
Minnesota along with temps cooling to around or below freezing
has resulted in patchy fog and freezing fog over central and
north-central Wisconsin early this morning. Any fog will linger
through daybreak before dissipating. The deposition from the fog
along with road temps near freezing could lead to slippery spots
early this morning.

Otherwise, skies will be partly cloudy through the day as shortwave
and 850mb thermal trough drop across the area to enhance cu and
strato cu clouds. Highs will warm into the 50s, but it will be in
the low to mid 40s near Lake Michigan with a lake breeze.

Skies will become mostly clear tonight as high pressure drifts
across the western Great Lakes. May be some patchy fog again,
though signal does not look as good as it does this morning.
Saturday will be warmer with highs commonly in the 60s inland
from Lake Michigan. SW winds will begin to stir and mid and high
clouds will be on the increase ahead of developing low pressure
over the plains that brings in some rain showers beginning later
Saturday night.

Long Term...Saturday Night Through Thursday

The medium range models show a fairly progressive pattern shaping
up for the Sunday through Thursday time frame. An upper low will
track near the Canadian border while amplifying across the Great
Lakes in the Sunday night through Tuesday period, and impacts from
this system are the focus of this forecast.

Precipitation chances: Ahead of the upper trough, a strengthening
surface trough will lift northeast from southern Minnesota at 1 pm
Sunday to Lake Superior by 1 pm Monday. While warm advection will
be increasing as early as Saturday night, precipitation chances
(50-60%) will mainly be confined to far northern Wisconsin within
a region of focused mid-level frontogenesis.

Chances for more widespread precipitation will increase on Sunday
afternoon and evening when elevated instability in excess of 200
j/kg (potentially upwards of 600 j/kg) moves into northern
Wisconsin just ahead of the surface low. Have therefore added a
chance of thunderstorms to the forecast. While guidance shows a
relatively low chance of precipitation greater than a quarter inch
(20-40%), isolated amounts up to a half inch look possible within
thunderstorms.

The dry slot will bring a period of lower chances of precipitation
late Sunday night into Monday morning before the comma head of the
cyclone brings a chance of rain and snow to areas mainly north and
west of the Fox Valley (60-60% chance) Monday night. Minor
accumulations of snow will be possible over the northwoods when
850mb temps cool to about -8C.

Strong wind potential: There is no shortage of dynamics moving
across the region on Sunday night and Monday. The strongest winds
will likely occur within the cold advection regime on Monday
afternoon and Monday night when gusts up to 40 mph appear
possible.

Temperatures: Mild temperatures in the middle 50s to lower 60s on
Sunday will cool in the wake of the cold front into the 40s. Then
readings will moderate somewhat mid-week.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1219 PM CDT Fri Apr 11 2025

Visible satellite showed broken low-level cu beginning to stream
across portions of northeast Wisconsin early this afternoon, with
bases at around 4 to 5k ft. Remnant cu will then scatter out by
this evening with the loss of daylight. Otherwise, VFR conditions
persist through the end of the TAF period. Light winds out of the
northwest gradually back to southwesterly later this evening and
overnight.

&&

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

&&

$$

DISCUSSION.....JLA/MPC
AVIATION.......Goodin