NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 061140
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
640 AM CDT Mon Jul 6 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Dry conditions through Tuesday morning. Shower and storm chances
  increase to 30-50% across the Northwoods Tuesday afternoon,
  increasing to 60-85% and becoming widespread Wednesday into
  Thursday, with a risk for heavy rain and flooding. A few storms
  may become strong or severe as well.

- Temperatures rising slightly above normal for the start of the
  work week. Humidity levels also slightly increase midweek.

&&

.DISCUSSION...
Issued at 240 AM CDT Mon Jul 6 2026

Quiet Today through Early Tuesday...A ridge of high pressure will
prevail over the area today through tonight, allowing for a dry,
pleasant summer day. Late tonight into Tuesday morning, some
guidance is indicating a weak shortwave causing a subtle breakdown
of the ridge, which may bring a few light showers/sprinkles to the
area Tuesday morning, but the moisture profile is rather lacking.
Increasing clouds in north-central WI will more likely be the
outcome. Therefore, anticipate the dry conditions to continue
through at least early Tuesday.

Heavy Rain/Thunder Tuesday Afternoon through Thursday...Following
the weak shortwave Tuesday morning, the pattern will become a more
zonal flow with embedded shortwaves and a stalled frontal boundary,
resulting in rounds of showers and storms. The frontal boundary will
set up over far northern WI starting Tuesday afternoon and bring the
start of the showers and storms. The boundary will then slowly move
southeast over the area throughout Wednesday, and exit the area on
Thursday. Widespread showers and storms will accompany the front as
it slowly sags over the area. With models still indicating PWATs
approaching 2" during the peak of the precipitation, and the
potential for repeated/training rounds of storms moving along the
east-west orientated boundary, there is an increased risk of heavy
rainfall and flooding. The highest probabilities (50-70%) for 1" or
more of rain are focused across the Northwoods/north-central WI,
with probabilities decreasing quickly across the remainder of the
area. There is still potential for this axis of heaviest rainfall to
shift, considering the GEFS has the greatest probs for 1" or more in
the areas mentioned above, but the latest EC ensemble has the
greatest probs even further north across far northwest WI/northern
Upper MI. Regardless, agree with the latest Excessive Rainfall
Outlook from WPC that still includes the majority of the area in a
Slight Risk (level 2 of 4), but anticipate this will change as
details become clearer. Due to the uncertainty in the frontal timing
and placement, it is still too early to determine the severe weather
potential. However, with bulk shear up to 35 kts and MUCAPEs likely
near 1000 J/kg, there is still a low-end chance of severe storms.

Rest of the Extended...Model guidance indicates high pressure will
move into the area Friday, bringing dry conditions back to the area.
There are also signs of a weak shortwave moving over the region for
the weekend.

Temperatures...Highs will be slightly above normal today with values
ranging from the low to mid 80s, but will rise a few more degrees on
Tuesday (highs in the mid to upper 80s) with warmer air lifting into
the area. Temperatures should return closer to normal from midweek
through the end of the week with the presence of the precipitation
and frontal passage. Dew points will be at comfortable levels for
much of the week with the exception of Wednesday and Thursday, when
values may rise into the mid to upper 60s.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 640 AM CDT Mon Jul 6 2026

VFR conditions are expected through this TAF period with mostly
sunny/clear skies. The exception may be a FEW/SCT cu field
developing this afternoon at the central and north-central WI TAF
sites. Mid-high clouds will then move over the central and north-
central WI TAF sites late this evening/overnight. Winds will
mainly be light and variable, but northeast winds up to 10 kts
are expected at the east-central WI TAF sites this afternoon.

&&

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

&&

$$

DISCUSSION.....Kruk
AVIATION.......Kruk