NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 060630
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
130 AM CDT Thu Aug 6 2026

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Areas of fog, locally dense, will persist through late this
  morning, especially over eastern Wisconsin.

- There is a marginal (1/5) risk for severe weather on Friday.
  Several rounds of showers and storms then expected this weekend
  through early next week, though confidence in storm timing and
  severity remains low.

- Near normal high temperatures in the low to mid 80s through
  most of next week.

&&

.DISCUSSION...
Issued at 1216 AM CDT Thu Aug 6 2026

Fog... Patchy ground fog has already begun developing overnight
due to decoupling winds and clear skies, reducing visibilities to
1 SM or less in some areas. CAMs continue to show a strong signal
for areas of locally dense fog persisting through late this
morning, before dispersing within a few hours of sunrise. Will
continue to observe trends over the next few hours to determine
whether or not an advisory will be needed.

Rain/storm chances... Will continue to message potential for several
rounds of rain/storms late this week through early next week,
though the synoptic pattern remains volatile. However, details
continue to come into focus for storm timing and severity on
Friday as upper perturbation interacts with cold FROPA at the
surface during the afternoon and evening. Corridor of decent
instability (1,000 to 1,200 J/kg) builds just ahead of the front
during this time, with potential for storms to start off surface-
based. Gusty winds look to be the main hazard with any strong or
severe storms as bulk shear exceeds 30 knots and inverted-V
profiles tap into 35 to 40 knot winds at the top of the dry layer.
Severe threat decreases further south and east.

Beyond Friday, general story hasn't changed much as we remain on
the northern periphery of western ridge and more moist/unstable
airmass. As such, better chances for more organized convection
look to remain off to our south where better thermodynamics
reside. ML guidance continues to highlight southern Wisconsin,
northern Illinois, and even into the Ohio Valley for the greatest
severe threat. In our neck of the woods, multiple embedded
shortwaves riding the 500 mb wave train should be enough to kick
off several rounds of showers and non-severe storms this weekend
through early next week. Though predictability of timing and
coverage of showers/storms remains low this far out due to the
nature of the synoptic pattern, question that arises will be
excessive rainfall potential due to repeated rounds of precip.
Similar to the severe threat, better moisture looks to be holed up
to our south in proximity to the low, though some long-range
guidance suggests the boundary stalling out over southern
Wisconsin. Current thinking is that any heavy rain potential will
hinge on training storms and mesoscale processes. Will continue
to monitor in the coming days, as WPC begins highlighting a
marginal ERO for Day 5.

Temperatures/smoke... Temperatures to read near normal in the low
to mid 80s through the weekend as upper flow flattens out and
weakens. Humidity levels will be comfortable, with dewpoints
reading in the upper 50s to mid 60s. Another plume of elevated
wildfire smokes works its way into Wisconsin behind the front on
Friday, though significant impacts to visibility or air quality
are expected.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1016 PM CDT Wed Aug 5 2026

Skies have cleared across northeast Wisconsin this evening. High
clouds will invade the region after midnight, but doubtful they
will have a significant impact on temps.

Other than ground fog, good flying weather is expected through the
TAF period. There remains a good signal remains for fog
developing over eastern WI thanks to clearing skies and light
winds. Visibility less than 1SM in play at GRB/ATW/MTW, with 1-3SM
vsby possible at RHI/AUW/CWA. Fog will dissipate by 14Z-15Z on
Thursday.

Rest of day will feature FEW-SCT VFR fair weather clouds,
especially over eastern WI. Skies then clear again for Thursday
evening.

&&

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

&&

$$

DISCUSSION.....Goodin
AVIATION.......MPC