Appleton, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

326
FXUS63 KGRB 291803
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1203 PM CST Wed Jan 29 2025

Updated aviation portion for 18Z TAF issuance

.KEY MESSAGES...

- Record warmth is likely over much of the area on Thursday. Many
  locations from central to east central Wisconsin, including the
  Fox Valley, could see temperatures reach 50 degrees.

- A clipper system will impact Wisconsin during the second half of
  the weekend, bringing a chance snow and some rain. The greatest
  chances for more than 2 inches of snow (40-60%) and 4 inches of
  snow (20-30%) occur in far north-central and northeast
  Wisconsin.

&&

.DISCUSSION...
Issued at 412 AM CST Wed Jan 29 2025

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

Improving trend today in winds and any wintry precip as strong
low pressure exits across the northeast and high pressure drifts
across the region. A *much* weaker clipper low over western Canada
will track to Manitoba and across Lake Superior tonight into
Thursday. A bit of light snow may occur over far northern WI
overnight tonight, but main impact from this system will be the
warmer air to its southwest boosting temps to record territory for
much of our area on Thursday.

Winds gradually diminish...Pressure gradient still tight as cold
front drops across the region this morning. Soundings point to
northwest winds gusting to 25-30 mph this morning, with winds
dropping off to 15-20 mph this afternoon and to less than 10 mph
tonight.

Wintry precip today and light snow chances tonight...Last batch of
snow showers with rain mixed in have exited northeast WI. As temps
drop below freezing, any lingering moisture on untreated roads
could lead to a few icy spots, especially north where more precip
occurred last evening. Sufficiently cool temps and modest
inversions of 3-5kft will keep light lake effect and/or flurries
in the forecast north and northeast into early afternoon. Next
shot of very light snow arrives tonight, generally after midnight
over far northern WI. Warm air advection ahead of clipper is main
driver and mostly this focuses north, in Upper Michigan. Any snow
amounts in northern WI will be a coating to a half inch. Any
lingering snow will exit to the northeast by daybreak Thursday.

Record warmth on Thursday (1/30)...After a cooler night tonight with
lows in the teens north to low to mid 20s elsewhere, low-level southwest
flow steadily increases on Thursday. Lower inversion present with warm
air aloft, but it looks to be a mostly sunny day, so we should see
decent mixing, at least by late January standards. Winds do not look
near as strong as what we saw on Tuesday, but gusts may reach 25-35
mph most spots, with even some 30-40 mph gusts from Fox Valley to
the lakeshore. Mixing to top of inversion (900mb) supports high
temperatures reaching upper 40s to around 50 over all but northern WI.
ECMWF Extreme Forecast Index (EFI) and shift of tails (SOT) signal both
an unusual event and potential extreme event in terms of high
temps with regard to climatology. Given these factors, saw no
problem to side toward warmest guidance, which resulted in
forecast highs now into the lower 50s, if not even mid 50s from
parts of central WI to east central WI where no snowcover is
present. Record highs on Thursday are below 50 at all our primary
climate sites. Appears records will be established across the
board on Thursday. All time records for January do look safe, but
if highest end of guidance is reached, it could be close.

Jan 30 Record High..Year (Forecast High)
Appleton..........45..1989 (52)
Green Bay.........43..1989 (53)
Manitowoc.........47..1988 (50)
Marshfield........47..1919 (49)
Oshkosh...........45..1989 (51)
Rhinelander.......44..1999 (44)
Stevens Point.....43..2016 (51)
Sturgeon Bay......43..1988 (46)
Wausau............43..1999 (48)
Wisconsin Rapids..46..1974 (51)

Long Term...Thursday Night Through Tuesday

The main focus is on the precipitation associated with a clipper
system during the second half of the weekend. Models have a
general agreement on the timing, but are less settled on
location/track of the highest precip/snow. Initial warm advection
shows precip onset Saturday afternoon and evening, with continued
support from the upper jet and shortwave throughout Saturday
night and Sunday morning. A drop in forcing and moisture Sunday
afternoon will lead to the gradual end of precip. Exact details of
the precip are less clear. Ensembles show a wide range of forecast
snow amounts (for example, anywhere from 0 to 6" in Green Bay) a
result a differing tracks and temperature profiles. Nearly all
the high-end solutions come from the GFS which tracks the surface
low farther north across Ontario and has colder temps. The EC and
Canadian ensembles show similar QPF/snow forecasts and means--
which are lower than the GFS. Regardless of amounts, models do
focus on far northern and northeast WI as the location in the GRB
forecast area receiving the highest snowfall amounts, with the
probability of 3" or more around 40%. Lesser amounts are
anticipated farther south. Warming temperatures after sunrise
Sunday could result in rain mixing in as well, but the heaviest of
the precip may be ending at this time.

Temperatures Friday and Saturday will trend about 5-10 degrees
above normal, then about 10-15 degrees above normal Sunday with
highs in the mid 30s to low 40s. Readings look to be near normal
for the first part of next week.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1203 PM CST Wed Jan 29 2025

VFR conditions are expected through this TAF issuance. High
clouds will pass over the region this afternoon, with mid-level
clouds moving from southwest to northeast this evening and
overnight as a weak system and warm front moves over the region. A
few flurries may develop from within this mid-level cloud deck,
but should stay confined to far north-central WI. Skies will then
clear Thursday morning.

Lingering northwest winds will gust to 20 to 25 kts this afternoon
before subsiding this evening. Light southerly winds are expected
overnight, but a period of LLWS with winds from the southwest is
expected at all TAF sites Thursday morning, before surface winds
turn southwesterly and increase by the end of this TAF period.

&&

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

&&

$$

DISCUSSION.....JLA/KLJ
AVIATION.......Kruk