Green Bay, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

811
FXUS63 KGRB 191504 CCA
AFDGRB

Area Forecast Discussion...CORRECTED
National Weather Service Green Bay WI
1004 AM CDT Sat Jul 19 2025

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Showers and scattered thunderstorms expected at times today,
  then pleasant conditions return tonight through Monday. Some
  storms could be strong to severe this afternoon across central
  and east-central Wisconsin.

- Smoke from the Canadian wildfires could reach the surface at
  times Sunday and Sunday night.

- An active pattern is expected during the middle of next week,
  with periodic chances of showers and thunderstorms. Strong
  storms and heavy rain will be possible at times.

&&

.DISCUSSION...
Issued at 408 AM CDT Sat Jul 19 2025

Short Term...Today...Tonight...and Sunday

An area of showers and isolated thunderstorms, associated with
weak mid level frontogenesis, will continue tracking through the
area this morning. Additional showers and thunderstorms will be
possible across central and east-central Wisconsin this morning
as a warm front lifts north over these areas with isentropic lift
providing the main forcing mechanism. A cold front pushing south
this afternoon could bring yet another round of showers and
thunderstorms as it sinks south. While these first few rounds of
convection should not be severe given the marginal instability in
place of a few hundred J/kg of MUCAPE, the activity this afternoon
could be strong to severe as SBCAPEs rise to 1000 to 1500 J/kg
along with 30 knots of bulk shear. The main concern is the
abundant cloud cover across the area with all these areas of
convection ongoing, which could limit the severe threat as the
expected amount of instability may not be fully realized. The
SBCAPE profiles are fairly long and skinny with a unidirectional
hodograph, which could also limit severe potential. Any strong to
severe storms this afternoon could produce gusty winds and hail.

High pressure brings dry and pleasant conditions tonight and Sunday.
Smoke from Canadian wildfires will push into the forecast area
Saturday night into Sunday. While the initial surge should be
aloft, there is some potential for surface-based smoke on Sunday.
Therefore, kept the increased sky cover a bit Saturday night into
Sunday per the previous forecast and added areas of smoke to the
forecast on Sunday.

Long Term...Sunday Night Through Friday

Models continue to trend towards no precip on Monday with surface
high pressure slowly drifting to the northeast and keeping
conditions dry. However, there could be some lingering smoke
making for hazy skies. Temps to remain near or a couple degrees
below normal on Monday.

The active pattern kicks in Tuesday with a zonal progressive flow
aloft and stagnant frontal boundaries at the surface. This will
create opportunities for rain and thunderstorms as various
shortwaves and upper jet streaks create broad lift, and
boundaries at the surface will also be a source for initiation. It
remains difficult to pin down details, as several complexes may
develop and move through or near the area next week, which may
also lay down and alter boundaries which will influence how storms
will track the next day. Strong to severe thunderstorm and heavy
rain leading to localized flooding are also on the table at times,
with daytime instability as high as 2000-3000 J/kg and pwats
around 2 inches. The greatest potential is in the Wed/Thu time
frame as these parameters peak and a cold front finally pushes
through.

Some agreement that drier weather would return Friday, with
greater uncertainty next weekend. Models are split on various
shortwaves and other features.

Temperatures trend above normal from Tuesday through the rest of
the forecast period. Wednesday is currently forecast to be the
warmest day, especially south of Hwy 29, where readings will
approach 90 and dew points will be in the 70s. Some heat index
values around 100 degrees are possible.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 654 AM CDT Sat Jul 19 2025

Cluster of thunderstorms continue to move across portions
of northeast Wisconsin this morning, with additional storms
possible this afternoon. Some of the storms could contain
low visibilities, gusty winds and hail.

At KOSH, scattered thunderstorms are currently well north of the
airport. Some of the mesomodels do develop convection over the
next few hours, thus have included in a tempo group. CIGS will
likely start out in the MVFR category later this morning and then
rise into the VFR category outside of thunderstorms. Additional
storms are possible this afternoon. Some of the thunderstorms
could produce torrential rain, hail and strong gusty winds.

&&

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

&&

$$

DISCUSSION.....Kurimski/KLJ
AVIATION.......Eckberg