NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 090351
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1051 PM CDT Wed Jul 8 2026

Updated aviation portion for 06Z TAF issuance

.KEY MESSAGES...

- Localized flooding is possible overnight in urban, low-lying,
  and poorly drained areas.

- Trends continue to be monitored for the excessive heat potential
  early next week.

&&

.DISCUSSION...
Issued at 112 PM CDT Wed Jul 8 2026

The latest RAP analysis and satellite/radar imagery show a cold
front stretching from west-central to north-central Wisconsin
early this afternoon. Morning showers and storms have exited over
northern Lake Michigan, giving way to partial clearing across
central and east-central Wisconsin where temperatures have warmed
into the lower 80s. Cooler temperatures in the lower to middle 70s
persist across the north where cloud cover and rainfall were more
widespread. Cloud cover is becoming more extensive again over
southern Minnesota in association with a remnant MCV. Focus of
this forecast remains on the severe weather and flash flooding
potential through this evening.

Severe Weather and Flood Outlook:  Destabilization is actively
taking place early this afternoon over central and east-central
Wisconsin where mixed- layer CAPE is climbing upwards of 1000
J/kg. With further solar heating, thunderstorms are expected to
redevelop in a buoyant airmass south of the front and across
central Wisconsin in the 18-20Z time frame. These storms should
track east through the afternoon before propagating southeast this
evening as a cold pool becomes established. Deep layer shear of
25 to 35 knots is expected in the area of greatest concern across
central and east- central Wisconsin. This shear profile will be
supportive of a few bowing structures and perhaps an isolated
supercell. Given the modest shear aloft, conditions will be most
favorable for damaging wind gusts rather than severe hail. High
freezing levels around 15,000 feet and poor mid-level lapse rates
do not favor large hail, except within the strongest rotating
updrafts. A weak, isolated tornado will also be possible, most
likely focused along an outflow boundary or lake breeze where low-
level vorticity is enhanced. The greatest period of concern is
from 3 to 7 PM before storms shift south and east of the forecast
area. Scattered shower and storm activity could persist into the
overnight period, but a stabilizing atmosphere should keep
intensities below severe levels.

Upper-level flow will be nearly parallel to the surface front
within a corridor of precipitable water values approaching 2.00
inches and high freezing levels. High rainfall rates of 2 to 3
inches per hour are expected in the strongest storms, which could
lead to localized flash flooding in vulnerable urban, low-lying,
and poorly drained areas.

Fog Potential Late Tonight:  After the rain winds down late
tonight into Thursday morning, there is a decent signal for fog
development, particularly across central to north-central
Wisconsin where clearing will occur first. Considerable
uncertainty exists regarding how long showers stick around into
Thursday. A moist boundary layer, weak cyclonic flow in the low
levels, and weak shortwave impulses aloft could keep light showers
lingering into the afternoon over central and east- central
Wisconsin.

Excessive Heat Outlook: An amplified upper air pattern featuring
a dominant upper- level ridge is expected to build northeast into
the region Friday through the weekend and persist into early next
week.

High pressure at the surface will slide across the area
Friday through the weekend. While minor signals for spotty shower
activity exist in some medium-range guidance, forcing is non-
existent beneath the building ridge, and a dry forecast has been
maintained.

The primary story in the extended period will be potential for
excessive heat. Very warm air aloft will accompany the building
ridge will argue for surface high temperatures climbing into the
upper 80s to lower 90s by Monday and Tuesday. Coupled with
humidities remaining high, minor heat- related impacts appear
possible at this time for those outdoors. Some relief from the
heat and humidity is expected towards the middle to end of the
next work week as the ridge begins to suppress southward.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1050 PM CDT Wed Jul 8 2026

Isolated to scattered showers and a couple storms will continue
overnight into Thursday morning as a cold front sags south across
the area. Main hazards will be heavy rain and lightning. Ceilings
and visibilities will drop through the night as low clouds and fog
spread in/develop, with IFR/LIFR conditions for much of the area.
Some VLIFR conditions are possible, especially across northern
WI. The fog will lift Thursday morning, with clearing skies
expected in the afternoon. Patchy/areas of fog is again expected
Thursday evening/night. Winds will remain under 10 kts.

&&

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

&&

$$

DISCUSSION.....MPC
AVIATION.......Bersch