Forecast Discussion for GRB NWS Office
FXUS63 KGRB 230429

Area Forecast Discussion
National Weather Service Green Bay WI
1029 PM CST Sat Feb 22 2020

Updated aviation portion for 06Z TAF issuance

.SHORT TERM...Tonight and Sunday
Issued at 203 PM CST Sat Feb 22 2020

During the early afternoon, skies were mainly clear and some high
clouds had started to drift into central Wisconsin. Temperatures
were mild, as readings at 1 PM ranged from 35 to 45 degrees,
leading to some melting snow across the area.

This evening, temperatures will fall below freezing which will
lead to refreezing of melted snow and the potential for slippery
spots on roads, especially secondary and untreated roads. Low
clouds and fog are also likely to redevelop, mainly across central
and northern Wisconsin, the Fox Valley east towards the lake
shore should remain mainly clear. Patchy dense fog is possible
across the Northwoods. The combination of low visibility and
slippery stretches on roads could lead to a period of hazardous
travel conditions late tonight and Sunday morning. Lows temps will
range through the 20s.

Sunday, fog should dissipate by mid-morning, with some scattered
clouds lingering through the midday. Most places should see some
sun during the afternoon, and then clouds will start moving back
into central Wisconsin as a cold front approaches the state. Highs
will top out in the upper 30s to lower 40s.

.LONG TERM...Sunday Night Through Saturday
Issued at 203 PM CST Sat Feb 22 2020

The main focus during the period will be winter storm moving
across the western Great Lakes region Tuesday into Wednesday.
For Sunday night and Monday, tranquil conditions are expected
as high pressure moves across the region. The system approaching
from the south will allow for clouds to increase during the day
Monday. Monday should continue the string of above normal
temperatures with highs in the middle to upper 30s.

For Monday night, there is a chance of light snow late across the
southern Fox Valley east to Manitowoc. Snow is expected to
gradually shift north during the day Tuesday. The heaviest snow
is expected to fall Tuesday night into Wednesday morning as the
low pressure system tracks northeast into lower Michigan. Central
into northeast Wisconsin would be in the favored location of the
heavy snow band. However, there is some concern that dry air is
lurking north of the area which may drop south across the area
Tuesday night which would limit snowfall amounts. Therefore,
confidence remains lows on snowfall amounts due to the dry air
filtering southward during this time frame. Gusty northeast/north
winds may  also result in blowing and drifting snow.

Also, increasing northeast winds and building waves may result in
the risk of coastal flooding along the Lake Michigan shoreline.
Ice shoves are also possible on the central Bay of Green Bay.
The snow should taper off and end across northeast Wisconsin
Wednesday night. Otherwise, fairly quiet conditions are expected
for the rest of the week, although temperatures are expected to
run below normal with highs mainly in the 20s.

.AVIATION...for 06Z TAF Issuance
Issued at 1026 PM CST Sat Feb 22 2020

The temperature and visibility at observing sites across Wisconsin
and Minnesota are behaving similar to yesterday evening,
suggesting persistence will be a good forecast. Will continue to
lean heavily in that direction with the 06Z TAFs. Continue to
expect FZFG and stratus to form again late tonight, especially in
central and north-central Wisconsin. LLWS will also be present
much of the time as fairly strong westerly flow continues above
the surface.



LONG TERM......Eckberg

NWS GRB Office Area Forecast Discussion