019
FXUS63 KGRB 261923
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
223 PM CDT Fri Jun 26 2026

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Dry with near normal temperatures and tolerable humidity
  Saturday.

- Next chance of thunderstorms will be Sunday afternoon and Sunday
  night. Some of the storms could be strong or severe with large
  hail and damaging winds.

- Prolong period of heat and humidity will result in heat-
  related impacts next week.

- There are periodic chances of thunderstorms next week. The
  weather pattern would support that some of these storms
  could become strong or severe.

&&

.DISCUSSION...
Issued at 222 PM CDT Fri Jun 26 2026

Skies were partly to mostly cloudy this afternoon. Temperatures
were in the middle 60s to lower 70s, which is several degrees
below normal for late June. Tranquil conditions expected to
continue through Saturday night as high pressure is in place. High
temperatures on Saturday will be closer to normal with readings
around 80 with tolerable humidity levels.

Late Saturday night, a warm front will approach Wisconsin from the
southwest and then move across the state Sunday and Sunday night.
There are still many questions in how quick the convection will
break as southerly low level winds increase during the afternoon
and Sunday night. Bufkit soundings indicated 700/500mb lapse rates
of 7.5-8.5 C/KG, CAPE values increasing to 1,000 to 2,000 J/KG
and 0-6 km shear values of 30 knots would support strong to severe
thunderstorms. The models are depicting scattered convection
across northeast WI during this time frame. Most of the convection
should exit the area late Sunday night or early on Monday
morning. The current Day 3 Outlook from SPC has a Marginal Risk
into Vilas and Oneida counties.

On Monday, it will be hot and humid as there will be capped as the
convective temperatures for the afternoon will be close to 100F.
High temperatures in the 90s, combined with dewpoints in the lower
to middle 70s will result in the heat index climbing to 100-105F.
We will be flirting Heat Warning Criteria (105F) for a few hours
during the afternoon. Heat headlines are likely.

700mb temperatures peak at 15C on Monday which supports little
chance any convection would get going. By Tuesday, the 500mb
ridge is expected to be centered across the Ohio Valley with the
western Great Lakes region in the ring of fire. Models continue to
differ on timing/how far south into the ridge for convection
moving across the area, with the GFS keeping most of the activity
north of Wisconsin. This would result in several days of hot temps
and heat index values reaching advisory or warning criteria.
Yesterday, Tuesday was a potentially a busy day with a complex of
storms. The Canadian model has moved away from this solution while
the ECMWF depicts a complex across the area Tuesday which would
significantly impact high temperatures and maximum heat index
values. For the rest of the week, there are periodic chances of
thunderstorms. With all the heat and humidity in place, the
potential exists for strong or severe storms at times. Timing and
location of MCS complexes this far out is difficult at best.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1157 AM CDT Fri Jun 26 2026

VFR conditions should prevail through Saturday afternoon. The
only exception may be for some patchy MVFR VSBY between 07z-13z
Saturday due to light fog. Othewise, east-southeast flow expected
through Saturday afternoon. The next chance of storms will be on
late Sunday afternoon and Sunday night. Hot weather is expected
at times next week with highs in the 90s across much of the area
away from the bay and Lake Michigan.

&&

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

&&

$$

DISCUSSION.....Eckberg
AVIATION.......Eckberg

NWS GRB Office Area Forecast Discussion