570
FXUS63 KGRB 230454
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1054 PM CST Sat Feb 22 2025

Updated aviation portion for 06Z TAF issuance

.KEY MESSAGES...

- A light wintry mix will be possible at times Sunday night
  through Wednesday. Main impacts will come from any potential
  icing creating slippery roads, bridges, and sidewalk.

- Temperatures warm this weekend through early next week. Highs
  ranging from the middle 30s to the lower 40s will be possible
  from Sunday through Wednesday.

&&

.DISCUSSION...
Issued at 211 PM CST Sat Feb 22 2025

Short Term...Tonight and Sunday

Skies were mostly sunny south of Highway 29 and mostly cloudy to
the north. Temperatures were in the 20s at most locations.

For tonight, skies should remain mostly cloudy through the night
north of Highway 29, while skies will become mostly cloudy to the
south. Lows tonight should fall to 10 to 19 degree range. On
Sunday, a weak 500mb trough will swing across the area. Bufkit
soundings indicated enough low level moisture that this feature
could trigger flurries in the morning into mid afternoon. Did add
a chance of flurries to the forecast. Trended lower than guidance
for highs across eastern Wisconsin where cloud cover will linger
longest. Across the north, this is the time of year with sunshine
temperatures can warm more than expected, thus stayed close to
guidance there.

Long Term...Sunday Night Through Saturday

Very unsettled pattern setting up for next week. Main forecast
concerns will be assessing several chances for mixed
precipitation, possibly bringing winter impacts, but details
remain hard to pin down. Temps will trend well above normal mid-
week, with uncertainty regarding how long the warmer temps will
stick around.

Precip Chances/Types: Progressive west/northwest flow aloft will
send the first in a parade of shortwaves into the area Sunday
night into Monday morning. Push of WAA and brief period of better
saturation will bring some light precip to the region, mainly
northern WI. Critical thickness thresholds, along with forecast
soundings showing a warm layer aloft, support freezing rain or
rain as the main precip types, depending on surface temps. And
due to the recent cold spell, any rain that falls could freeze
even with surface temps above freezing. Luckily only up to 0.05"
of QPF is expected due to limited moisture and lift. Some higher
amounts are possible, as the LFQ of an upper jet and shortwave
energy will try to co-locate for a time Monday morning, but this
is more likely in the U.P. at this time. Some minor icing on
roads/surfaces is possible over northern WI. Too much dry air
should keep locations south of Hwy 29 dry.

Next shortwave will move across the region Monday night into
Tuesday. Any narrow, heavier snow band looks to miss us to the
south, but some light precip (a hundredth or two) is possible, in
our area. Mainly liquid precip is expected over the south, with
mixed precip over the north, including possibly some drizzle or
freezing drizzle. Similar to the first system, due to the cold
ground, any falling liquid precip could lead to minor icing
issues.

The next fast moving system/shortwave is forecast to arrive on
Wednesday. This system is still on track to be stronger than the
first two, with heavier precip possible. However, still a lot of
uncertainty on the track. P-type will be tricky as critical
thicknesses hovering near the rain/snow thresholds. Chances for
1"+ of snow is still under 20%, but will be highly dependent on
the track of the system. Two additional systems are then forecast
to push across the Great Lakes Thursday into early Saturday, but
it is too early to assess any details.

Temps: Models in decent agreement showing temps trending warmer
early/mid week, with highs climbing into the 40s for much of the
area on Tuesday and Wednesday. Models then start to diverge late
in the week into next weekend, mainly due to when and how strong
a push of cold air will be behind the stronger low pressure
system at the end of the week. NBM 25-75 percentile spreads are
in the 10-15 degree range, with highs ranging from the 20s and low
30s on the colder guidance, to high in the 40s on the warmer
guidance. Models will hopefully get into better agreement on temps
trends into next weekend.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1042 PM CST Sat Feb 22 2025

MVFR ceilings in far NC WI should lift out of the area early in
the TAF period, followed by SCT-BKN mid-level clouds for the rest
of the overnight period. A weak short-wave trough will bring a
chance of flurries to the forecast area during the morning to
early afternoon Sunday, with partial clearing occurring as the
trough departs later in the day. There is some support for low
clouds (MVFR) redeveloping over NC WI Sunday evening, aided by
moisture from melted snow. Have added low clouds to the RHI TAF
site. There is a very small chance of a wintry mix at RHI toward
midnight Sunday night, but will hold off on adding it to the
forecast for now.

Light and variable winds will will become southerly on Sunday.
Wind should pick up a bit Sunday evening, and some LLWS will move
into NC/C WI mid to late evening.

&&

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

&&

$$

DISCUSSION.....Eckberg/Bersch
AVIATION.......Kieckbusch