Forecast Discussion for GRB NWS Office
000
FXUS63 KGRB 021110
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
510 AM CST Thu Feb 2 2023

Updated aviation portion for 12Z TAF issuance

.SHORT TERM...Today...Tonight...and Friday
Issued at 325 AM CST Thu Feb 2 2023

The latest RAP analysis and satellite/radar imagery show a strong
arctic cold front dropping southeast across South Dakota to
western Lake Superior early this morning. A band of light snow is
accompanying the front with visibilities dropping to 1sm across
northern Minnesota. This snow will likely be approaching far
north-central Wisconsin by 6 am this morning. Behind the front,
temps drop off quickly to below zero with wind gusts of 30 to 35
mph. As this front drops across the area, light snow accums today
followed by bitterly cold wind chills are the main forecast
concerns.

Today and Tonight...The strong arctic front will plow southeast
across the region this morning. Snow showers will be most
numerous across far northern WI where northwest winds and moisture
fluxes of Lake Superior will augment the snow shower coverage.
Amounts could reach up to an inch.  Isolated to scattered snow
showers and flurries will likely extend southeast across the rest
of the area this morning as well but with little to no
accumulations. As low level lapse rates steepen, northwest winds
will increase and become gusty as the arctic air arrives. Wind
gusts to 30 mph will be possible, which could lead to minor
blowing of any of the light snow. Temps will be falling this
afternoon despite increasing sunshine. As a result, highs will
likely occur by mid-morning across the north and midday elsewhere.

Wind chills will be falling to near advisory criteria (20 below) by
early this evening across north-central Wisconsin and by midnight
across northeast Wisconsin. Wind chills from 20 to 35 below are
likely by late tonight. Will consequently start the wind chill
advisory at 00z across north-central WI and 05z across northeast
WI.

Friday...Arctic high pressure will be sliding just southwest of
the region. The bitter cold wind chills will continue through the
morning hours before peaking at 5 below to 10 below zero in the
afternoon. With plenty of sunshine, highs will only reach in the
single digits above zero.

.LONG TERM...Friday Night Through Wednesday
Issued at 325 AM CST Thu Feb 2 2023

The main highlights from this forecast period revolve around small
chances for snow this weekend, chances for rain and snow early next
week, and above normal temperatures.

Friday night through Sunday...As a Canadian high exits the region
Friday night, strong WAA/isentropic lift surges across the region
via low-level southwest flow, bringing light snow to far north-
central and far northeast WI. By Saturday morning, only a couple
tenths of snow may accumulate. The remainder of Saturday will be dry
but warmer with high temperatures near normal in the 20s. A weak
clipper system will slide across the region sometime late Saturday
night into Sunday. Light snow showers or flurries are possible with
little to no accumulation for much of the region, except in far
north-central WI due to lake-effect. Sunday`s high temperatures to
be slightly above normal ranging from the middle 20s to low 30s.

Rest of the extended...As another clipper system, north of the
region, tracks east Monday into Monday night, it will phase with
shortwave energy over the Northern Plains/Upper Mississippi Valley
and bring chances for widespread precipitation to the region. Due to
warmer air in place, the precip would fall as a mix of rain and
snow. Some lake-effect snow may continue into Tuesday in far north-
central WI following this system as well.
&&

.AVIATION...for 12Z TAF Issuance
Issued at 509 AM CST Thu Feb 2 2023

-  A strong arctic cold front will move across the region this
   morning and usher in a bitterly cold airmass.

-  The front will be accompanied by MVFR ceilings and scattered
   snow showers north of a AUW to IMT line. VFR ceilings and snow
   flurries are expected further south.

-  Clearing skies are expected over all but far north- central
   Wisconsin this afternoon and evening.

-  Gusty northwest winds to 25 kts today will diminish somewhat
   tonight.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Wind Chill Advisory from 6 PM this evening to noon CST Friday
for WIZ005-010>012-018-019-030-035-036.

Wind Chill Advisory from 11 PM this evening to noon CST Friday
for WIZ013-020>022-031-037>040-045-048>050-073-074.
&&

$$

SHORT TERM.....MPC
LONG TERM......Kruk
AVIATION.......MPC

NWS GRB Office Area Forecast Discussion