298
FXUS63 KGRB 131827
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
127 PM CDT Wed May 13 2026

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- A Frost Advisory is in effect tonight for central Wisconsin.

- A chance of mainly light rain Thursday night into Friday.

- Gusty winds, warm temperatures, and low relative humidities will
  lead to elevated to near-critical fire weather conditions at
  times from Thursday through Saturday.

- Periods of heavy rainfall along with strong to severe storms are
  possible Sunday night through Monday night.

&&

.DISCUSSION...
Issued at 127 PM CDT Wed May 13 2026

High pressure will bring continued dry weather to the region
through Thursday. Skies will clear tonight along with decreasing
surface winds, which will allow temperatures to fall after sunset.
Overnight lows are expected to drop well into the 30s north and
west of the Fox Valley. While frost/freeze headlines have not
started across the north, central Wisconsin could drop low enough
for frost formation; therefore, will issue a Frost Advisory for
central Wisconsin tonight.

A cold front will bring the chance for showers to the region
Thursday night into Friday. The forcing and moisture window with
this front are fairly limited; therefore, a brief window of light
to possibly moderate rain is only anticipated as this system
tracks through the region. Partial clearing and daytime heating
should allow a few showers and isolated storms to redevelop as a
weak boundary moves through in the Friday afternoon.

After a brief dry period Friday night into Saturday evening, a
pattern change to southwest flow aloft will bring an increasingly
moist and unstable air mass to the region. The leading surge of
moist and marginally unstable air will arrive Sunday, bringing a
chance of showers and isolated storms to the region. Low pressure
developing in the central Plains on Sunday will lift northeast
along a slow moving cold front Sunday night through Monday night.
This system will generate periods of showers and thunderstorms,
and locally heavy rainfall, in an increasingly moist (PWATs of 1.2
to 1.7 inches) and unstable air mass. Probabilistic forecasts
show a 40-60% chance of 1+ inch of rain from Sunday through Monday
night, with a 20-30% chance of 2+ inches. Potential for severe
thunderstorms increases Sunday night, as increasing elevated
instability and steep mid-level lapse rates (7-8 C/km) support a
threat of large hail. Surface based instability increases to 1-3K
j/kg Monday afternoon and early evening, leading to potential for
surface-based severe convection, especially as the surface low, a
short-wave trough and a 50 kt low-level jet move into the region
in the late afternoon/evening. The surface low and cold front will
pull out of the region later Monday night, with drier conditions
arriving Tuesday into Wednesday.

Temperatures will remain below normal tonight, climb to above
normal late this week into early next week, then return to near
normal for the middle of next week.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1204 PM CDT Wed May 13 2026

VFR/MVFR stratocu was noted across the region early this afternoon
with bases slowly rising throughout the day. Bases should continue
to rise this afternoon, resulting in VFR bases everywhere at some
point this afternoon. Skies should scatter out later this
afternoon into early this evening as drier air works its way into
the region.

North-northwest winds of 15-15 knots were noted across the region
this afternoon with a few gusts approaching 30 knots at times
given the deep mixing. Winds should subside this evening with the
loss of daytime heating below 10 knots.

&&

.FIRE WEATHER...
Issued at 127 PM CDT Wed May 13 2026

Pine fuels have reached their peak volatility and fine fuels have
still not greened up over northern WI; therefore, several periods
of elevated fire weather conditions are expected during the next
few days.

Thursday...Elevated fire weather conditions are expected with low
relative humidities of 20-30% across much of north-central and
central Wisconsin. Temperatures will be cooler, with highs around
70 along with southerly winds of 10 to 20 mph.

Friday...Warmer temperatures are expected with highs in the 80s
along with southwesterly winds of 15 to 25 mph and relative
humidities of 20-30%. Critical fire weather conditions are
possible across Vilas County on Friday where the combination of
warm temperatures, strong winds, very low relative humidities, and
exceptionally dry fuels could create dangerous wildland fire
conditions. A Fire Weather Watch has been issued for Vilas County
on Saturday. Across the rest of the area elevated fire weather
conditions are expected.

Saturday...Elevated fire weather conditions are again expected
with highs in the upper 70s, relative humidity values of 20-30%
and westerly winds of 10 to 20 mph are expected. Conditions could
approach near-critical conditions on Saturday across much of
north-central Wisconsin.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Friday afternoon through Friday evening
for WIZ005.

Frost Advisory from 1 AM to 7 AM CDT Thursday for WIZ030-031-
035>037-045.
&&

$$

DISCUSSION.....Kurimski
AVIATION.......Kurimski
FIRE WEATHER...Kurimski

NWS GRB Office Area Forecast Discussion