412
FXUS63 KGRB 281948
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
248 PM CDT Sat Jun 28 2025

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Strong or severe storms are possible late this evening and
  overnight, with strong wind gusts the main risk across north-
  central and central WI. The storms are expected to weaken as
  they move into northeast Wisconsin late tonight.

- A cold front is expected to move across the region Sunday
  afternoon and evening, bringing additional chances of
  thunderstorms. Some of these storms could become strong or
  severe with damaging winds and large hail.

- Thunderstorms could bring locally heavy rainfall to the
  area through Sunday night, with rainfall rates of 1 to 2
  inches per hour resulting in localized flooding especially
  in urban areas.

- Temperatures and humidity will trend back above average this
  weekend, with near to above average temps continuing into next
  week.

&&

.DISCUSSION...
Issued at 248 PM CDT Sat Jun 28 2025

Short Term...Tonight and Sunday

The complexities of summer forecasting are in full swing this
afternoon as there are many differing solutions in the evolution
of thunderstorm development tonight. Current expectations are
for thunderstorms to develop across Minnesota and move east-
southeast into Wisconsin during the late evening and overnight
hours. The greatest risk of thunderstorms will be across north-
central and central Wisconsin as the models have the storms
weakening, and in some cases dissipating by the time they reach
northeast Wisconsin towards 12z. Bufkit soundings indicated
strong winds over 40 knots in the low levels on the Rhinelander
sites through 3 am Sunday, which the storms could tap. The GFS
sounding also indicated as least 1,000-2,000 J/KG and wet bulb
zero heights around 11,000 feet to support hail. Locally heavy
rainfall should also be expected. Lows tonight should fall into
the 60s.

On Sunday, the evolution of the overnight convection along with
outflow boundaries will impact the amount of heating during the
day. Some of the models have the early morning convection decaying
while other meso models lingered scattered showers and storms
through the morning. The cloud cover and rain could impact high
temperatures which will be in the 80s to lower 90s, warmest
readings across east-central WI where heat indices will reach
the middle to upper 90s. The threshold for a Heat Advisory is
100F. A cold front will move across the area Sunday afternoon
and evening, bringing an increased risk of severe storms. The
Storm Prediction Center Day 2 Outlook has much of the area in
a Slight Risk. Bufkit soundings off the GFS were showing
2,000 to 4,000 J/KG of CAPE although shear values were not
too impressive around 20 knots. Damaging winds is the main
risk, although some large hail can`t be ruled out.

Long Term...Sunday Night Through Saturday

Next week... Decaying low pressure and coincident trough will
bring our next chances for showers/storms, mostly diurnal in
nature, Monday morning and afternoon. Isolated storms will be
possible as modest instability and steep lapse rates build out
ahead of the cold front, although deeper moisture will struggle to
make it up into Wisconsin as high pressure builds over the
northern Plains. When paired with early morning FROPA and
subsidence behind the front, this should help keep storm coverage
at bay during the afternoon. This being said, a strong or severe
storm would not be out of the question Monday afternoon due to
favorable synoptic setup and sufficient deep-layer shear.
Inverted-V soundings and elongated hodographs would support gusty
winds and hail as the primary threats. Northwest flow regime then
sets up along the leading periphery of an upper-level ridge,
bringing a brief reprieve from wet weather to much of the Great
Lakes through mid-week. Some ridge rider activity then looks to
be possible toward the end of the week, although predictability
within the longwave flow regime remains challenging. Result ends
up being low-end PoPs with slight chance thunder during the
Thursday/Friday timeframe, although this is wont to change
throughout the week. Otherwise, steady-state temperatures in the
upper 70s and 80s prevail through the end of the work week,
ushering in a period of seasonable summer weather. Any deviation
to above/below average will likely hinge on frontal timing and
location, as well as cloud cover.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1217 PM CDT Sat Jun 28 2025

Some MVFR CIGS will linger into the early afternoon across
central and north-central WI as a cumulus deck developed
across the area. For this afternoon through Sunday evening,
the main story will be the timing of thunderstorms at the
TAF sites. Confidence is high there will be a round or
two of storms during the period, however confidence is
low on the timing. Current thinking is a round of thunderstorms
will move into north-central Wisconsin around 05-08z Sunday and
the spread into northeast Wisconsin after 10z. This complex should
dissipate Sunday morning with another round of storms expected
later Sunday afternoon into Sunday evening. Strong storms with
gusty winds and hail are possible with the storms, along with
the potential heavy rainfall that will significantly reduce
visibilities for pilots.

&&

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

&&

$$

DISCUSSION.....Eckberg/Goodin
AVIATION.......Eckberg