NWS-Green Bay Forecast Discussion
FXUS63 KGRB 100346
AFDGRB
Area Forecast Discussion
National Weather Service Green Bay WI
946 PM CST Fri Jan 9 2026
Updated aviation portion for 06Z TAF issuance
.KEY MESSAGES...
- Accumulating snow is expected Saturday into Saturday night. Most
places should get between a half inch and 2 inches of snow, but
higher amounts are possible in the lakeshore counties and in
Vilas County.
- A weak clipper system will bring a chance of light snow
accumulations to northern Wisconsin Sunday night. A second
stronger clipper could produce light accumulations regionwide
late Monday night into Tuesday night, with additional snow
continuing over north central Wisconsin due to lake-effect on
Wednesday. Gusty north winds could occur on Wednesday.
- After a brief cool down over the weekend, temperatures will
rebound to above normal early next week, then fall again into
midweek.
&&
.DISCUSSION...
Issued at 345 PM CST Fri Jan 9 2026
Subsidence behind a departing short-wave and incoming high
pressure ridge, combined with downsloping northwest winds, have
caused low clouds to gradually erode over central and east central
WI this afternoon. Expect this trend to continue over northern WI
early this evening. WV imagery showed a northern stream short-wave
approaching from the eastern Dakotas, with a southern stream
upper low lifting northeast from the OK Panhandle.
After a quick drop in temperatures this evening, expect temps to
steady out overnight as thicker high/mid clouds arrive. Some
models were suggesting fog development over NC WI overnight, but
given the expected cloud trends, this should be patchy and not as
impactful as the previous few days. Light snow is expected to
develop in our western counties late tonight, as the clipper and
associated cold front arrives. A dusting could occur by daybreak.
Saturday and Saturday Night Snowfall... Uncertainty remains in
snowfall amounts due to significant differences in how the models
handle phasing of the northern and southern stream systems. Most
of the 12z models suggest that the northern stream clipper and
associated cold front will shift just east of the forecast area
before significant phasing occurs on Saturday. This would push
the more significant accumulations northeast of GRB CWA and into
the central U.P. and northern Lower Michigan, with perhaps some
decent snow amounts occurring over Door County. The ECMWF and
Canadian models continue to produce heavy snow over parts of
eastern WI. Will side with the less impactful solutions right now,
with most places only getting an inch or two of snow, with
locally higher amounts in Vilas and Door counties. Overall
confidence remains low, which is inherent with any phasing system.
Given this uncertainty, will hold off on any headlines this
afternoon, even though the current snowfall forecast supports an
advisory over Door County.
Forecast beyond Saturday Night...
A weak clipper system will brush through northern WI Sunday night,
and could bring light accumulations and slippery roads there. A
second stronger clipper arrives late Monday night and impacts the
region through Wednesday. Accumulating snow is expected over much
of the forecast area through Tuesday night, with additional
accumulations due to lake-effect expected over north central WI
on Wednesday. Another system arrives Thursday night into Friday,
but details are sketchy this far out.
Temperatures cool down a bit this weekend, then warm to above
normal again early next week. A decent surge of colder air and
gusty north winds follows the midweek clipper system, leading to
cooler temperatures for the latter half of the work week.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 945 PM CST Fri Jan 9 2026
Patches of MVFR clouds are hanging tough across far northeast WI.
Meanwhile, MVFR clouds are expanding and spreading north across
southeast WI. And a clipper system is producing a band of light
snow with IFR visibilities over Minnesota this evening.
Based on the trends above, trended earlier bringing in MVFR
ceilings to east- central WI overnight. Will start flight
conditions as MVFR at TAF start time as low clouds continue to
expand.
The clipper remains on track to bring light snow to the region,
starting around 11-12Z at the TAF sites. Flight conditions will
likely drop to IFR as this occurs, but a brief period of LIFR is
possible over east-central WI on Saturday morning. The heaviest
snow will be over the lakeshore where there is a 50-60% chance of
2 inches or more of accumulations.
The snow will diminish at most locations except for northern Door
county by midday Saturday. Periods of light snow and and flurries
will then move back into north-central and northeast WI from mid
to late afternoon and continue through the end of the taf period.
Northerly low level wind shear is forecast to develop across
north-central (RHI/AUW/CWA) TAF sites after 03Z Sun.
Light winds tonight will become northwest on Saturday, with gusts
to 20 kts in the afternoon and evening.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION.....Kieckbusch
AVIATION.......MPC
FXUS63 KGRB 100358
AFDGRB
Area Forecast Discussion
National Weather Service Green Bay WI
958 PM CST Fri Jan 9 2026
New Information added to update section
.UPDATE...
Issued at 958 PM CST Fri Jan 9 2026
Patches of low clouds are hanging tough across far northeast WI.
Where skies have cleared, patchy fog has developed. Meanwhile,
clouds with bases between 1500-2800 ft are expanding and spreading
north across southeast WI and northern IL. And a clipper system
is producing a band of light snow with 1-2 mile visibilities over
Minnesota this evening.
The inherited forecast remains largely on track based on the
latest model and observational data. Clouds are increasing in the
mid and upper levels, which will limit the fog potential up north
despite otherwise favorable conditions. Will continue to have
patchy fog in the forecast until late tonight.
The primary change was to rework probability of precipitation for
Saturday. The band of snow that will arrive from the west has the
makings of a "high PoP, low qpf" event and increased snow chances
considerably. Also increased snow chances over eastern WI where a
transient but potentially intense fgen band will move across the
Fox Valley and Lakeshore during the morning. The 00Z is most
robust, generating 0.30-0.40 inches of QPF over Door County on
Saturday morning. This seems quite aggressive and is near the max
of all guidance in the LREF. Did raise QPF over the lakeshore,
but this was counteracted by lowering snow ratios with forecast
temps around 30-31 degrees. These changes put snowfall amounts in
the 2-3 inch range on Saturday over Door, or just below 3 inches.
A several hour break in the snow remains likely on Saturday
afternoon over Door County before light snow returns in the
evening. Given the transient nature of the snow band in the
morning, a sizable break in the snow in the afternoon, forecast
snow amounts and impacts don't seem sufficient for a Winter
Weather Advisory. If the break isn't as long on Saturday afternoon or
trends towards higher QPF continue, an Advisory may be needed.
&&
.KEY MESSAGES...
- Accumulating snow is expected Saturday into Saturday night. Most
places should get between a half inch and 2 inches of snow, but
higher amounts are possible in the lakeshore counties and in
Vilas County.
- A weak clipper system will bring a chance of light snow
accumulations to northern Wisconsin Sunday night. A second
stronger clipper could produce light accumulations regionwide
late Monday night into Tuesday night, with additional snow
continuing over north central Wisconsin due to lake-effect on
Wednesday. Gusty north winds could occur on Wednesday.
- After a brief cool down over the weekend, temperatures will
rebound to above normal early next week, then fall again into
midweek.
&&
.DISCUSSION...
Issued at 345 PM CST Fri Jan 9 2026
Subsidence behind a departing short-wave and incoming high
pressure ridge, combined with downsloping northwest winds, have
caused low clouds to gradually erode over central and east central
WI this afternoon. Expect this trend to continue over northern WI
early this evening. WV imagery showed a northern stream short-wave
approaching from the eastern Dakotas, with a southern stream
upper low lifting northeast from the OK Panhandle.
After a quick drop in temperatures this evening, expect temps to
steady out overnight as thicker high/mid clouds arrive. Some
models were suggesting fog development over NC WI overnight, but
given the expected cloud trends, this should be patchy and not as
impactful as the previous few days. Light snow is expected to
develop in our western counties late tonight, as the clipper and
associated cold front arrives. A dusting could occur by daybreak.
Saturday and Saturday Night Snowfall... Uncertainty remains in
snowfall amounts due to significant differences in how the models
handle phasing of the northern and southern stream systems. Most
of the 12z models suggest that the northern stream clipper and
associated cold front will shift just east of the forecast area
before significant phasing occurs on Saturday. This would push
the more significant accumulations northeast of GRB CWA and into
the central U.P. and northern Lower Michigan, with perhaps some
decent snow amounts occurring over Door County. The ECMWF and
Canadian models continue to produce heavy snow over parts of
eastern WI. Will side with the less impactful solutions right now,
with most places only getting an inch or two of snow, with
locally higher amounts in Vilas and Door counties. Overall
confidence remains low, which is inherent with any phasing system.
Given this uncertainty, will hold off on any headlines this
afternoon, even though the current snowfall forecast supports an
advisory over Door County.
Forecast beyond Saturday Night...
A weak clipper system will brush through northern WI Sunday night,
and could bring light accumulations and slippery roads there. A
second stronger clipper arrives late Monday night and impacts the
region through Wednesday. Accumulating snow is expected over much
of the forecast area through Tuesday night, with additional
accumulations due to lake-effect expected over north central WI
on Wednesday. Another system arrives Thursday night into Friday,
but details are sketchy this far out.
Temperatures cool down a bit this weekend, then warm to above
normal again early next week. A decent surge of colder air and
gusty north winds follows the midweek clipper system, leading to
cooler temperatures for the latter half of the work week.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 945 PM CST Fri Jan 9 2026
Patches of MVFR clouds are hanging tough across far northeast WI.
Meanwhile, MVFR clouds are expanding and spreading north across
southeast WI. And a clipper system is producing a band of light
snow with IFR visibilities over Minnesota this evening.
Based on the trends above, trended earlier bringing in MVFR
ceilings to east- central WI overnight. Will start flight
conditions as MVFR at TAF start time as low clouds continue to
expand.
The clipper remains on track to bring light snow to the region,
starting around 11-12Z at the TAF sites. Flight conditions will
likely drop to IFR as this occurs, but a brief period of LIFR is
possible over east-central WI on Saturday morning. The heaviest
snow will be over the lakeshore where there is a 50-60% chance of
2 inches or more of accumulations.
The snow will diminish at most locations except for northern Door
county by midday Saturday. Periods of light snow and and flurries
will then move back into north-central and northeast WI from mid
to late afternoon and continue through the end of the taf period.
Northerly low level wind shear is forecast to develop across
north-central (RHI/AUW/CWA) TAF sites after 03Z Sun.
Light winds tonight will become northwest on Saturday, with gusts
to 20 kts in the afternoon and evening.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE.........MPC
DISCUSSION.....Kieckbusch
AVIATION.......MPC