Oshkosh, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

263
FXUS63 KGRB 021616
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1116 AM CDT Wed Apr 2 2025

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

.UPDATE...
Issued at 1111 AM CDT Wed Apr 2 2025

Widespread precipitation has exited north-central and northeast
Wisconsin late this morning. While more precipitation is expected
to move in this afternoon, warming temperatures to above freezing
will mitigate the risk of additional snow and ice. Therefore, have
ended the Winter Weather Advisory.

&&

.KEY MESSAGES...

- Another wintry weather system is expected to impact our area
  through this evening. Accumulating snow, light icing, gusty
  winds, rain, and some thunderstorms are all possible with this
  system.

- Two to five inches of snow, up to a tenth of an inch of ice, and
  gusty east to southeast winds to 35 mph could create additional
  power outages and make the morning commute snow covered and
  slippery.

- There is a chance of thunderstorms late this morning through
  early this evening. A few strong storms capable of producing
  hail and gusty winds are possible, mainly in parts of central
  and east-central Wisconsin.

- Rainfall and runoff will likely lead to rises on area rivers,
  which may lead to minor flooding at a few locations late this
  week.

- The active weather pattern will abate once this system departs
  by Thursday morning across northeast Wisconsin.

&&

.DISCUSSION...
Issued at 310 AM CDT Wed Apr 2 2025

Short Term...Today...Tonight...and Thursday

Doppler radar indicates the small, but intense, band of snow
associated with mid level frontogenesis continues to lift north
early this morning. Ground observations indicate this initial band
is putting out a quick 1-2" of snow as it lifts north across the
region. Behind this initial band of snow, observations indicate
precipitation is more liquid as surface and upper level
temperatures increase ahead of an approaching warm front.

Precipitation will change from snow to a wintry mix and eventually
rain from south to north this morning as a warm front lifts
towards southern Wisconsin. Northern Wisconsin will be the last
areas to changeover to rain, which may take until midday.
Precipitation amounts continue to be difficult to pin down;
however, the best chance for higher amounts of QPF will be across
the areas that will most likely be rain (central and east-central
Wisconsin) instead of heavy snow or ice accumulations.

Snowfall accumulations are still on track from the previous
forecast, with 2 to 5 inches of snow, locally up to 6 inches, and
up to 0.10" of ice. The impact from the ice should be mitigated by
the snow falling first as well as sunrise, which can warm the
asphalt even though the surface temperature may be around or just
below freezing. The morning commute continues to be the biggest
concern, especially before the sun rises or just after sunrise as
the sun will not be high enough in the sky to assist in melting on
the pavement. The worst areas are expected to be across north-
central and northeast Wisconsin, where temperatures will be lower
and the affects of the previous ice storm are still ongoing. Gusty
winds may lead to additional power outages across the north,
despite the lack of significant additional snow or ice
accumulations. The current Winter Weather Advisories will continue
per the previous forecast.

As the warm front pushes north this afternoon, thunderstorms will
be possible across the region as elevated instability advects in
across the western Great Lakes. Despite MUCAPEs potentially
rising to as high as 1000 J/kg, depending on which model is used,
the potential for severe weather is generally low. Model
soundings indicate there will be steep low level inversion in
place, making it very difficult to push the gusty winds to the
surface. The best chance for severe weather would likely be hail
given the effective shear values of 60-70 knots if there is
sufficient instability. The main timing of any strong storms would
continue to be 2 to 7 pm and mainly across the southeastern CWA.

The surface low will push north towards western Lake Superior this
evening, which will bring drier air into the region as well as a
cold front. Rain showers across north-central Wisconsin will
change over to snow before tapering off late tonight with wrap
around moisture. The lack of deep moisture will keep any snowfall
accumulations tonight in check. High pressure will then keep the
region dry on Thursday as temperatures rebound into the 40s.

Long Term...Thursday Night Through Tuesday

Low impact weather is expected to end the week and through the
weekend. A southern stream trough lifting into the Ohio Valley
Saturday may initiate light rain showers across the Fox Valley and
central WI, but amounts should be light (10-20% for greater than
0.1"). Sunday into Monday there is also a chance (10-20%) for light
snow across northern WI as persistent northwest flow develops over
Lake Superior and a northern stream trough moves across Ontario.
Snowfall amounts are expected to remain under 1".

LREF ensemble members are in generally good agreement that a mostly
dry and cooler than normal patter will continue through much of next
week.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1111 AM CDT Wed Apr 2 2025

Poor flying conditions are expected to continue through Thursday
morning. Low pressure will be lifting northeast across the region
through the evening hours. While widespread precipitation will be
exiting for a time through early this afternoon, precipitation is
expected to become more widespread this afternoon mainly north and
west of the Fox Valley. Visibilities may fall for a time into MVFR
or briefly IFR within this precipitation.

After precipitation ends around mid to late evening, gusty west
winds will develop overnight into Thursday morning. Gusts from 30
to 35 kts will be possible at times. Some improvement to ceilings
is possible on Thursday morning.

Low level wind shear will also be an issue to flying at times
through Thursday morning.

&&

.HYDROLOGY...
Issued at 310 AM CDT Wed Apr 2 2025

Rivers continued to level off today from the recent precipitation.
Several locations along the Wisconsin River have fallen below
flood stage, while many others in east-central and far northeast
WI sat at bankfull. While there was improvement with some rivers
leveling off, additional rainfall expected today will cause
additional river rises. QPF amounts of a half inch to an inch are
forecast, with the highest amounts occurring in areas where
rivers are already seeing impacts.

Higher end QPF amounts up to 1.50" could lead to rivers over east-
central WI moving into minor flood stage. But probabilities of
any river reaching moderate stage is low.

&&

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

&&

$$

UPDATE.........MPC
DISCUSSION.....Kurimski/GK
AVIATION.......MPC
HYDROLOGY......Kurimski