438
FXUS63 KGRB 090306
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1006 PM CDT Sat Aug 8 2026

Updated aviation portion for 06Z TAF issuance

.KEY MESSAGES...

- Showers and storms return on Sunday morning. Small risk of gusty
  winds and heavy rain south of highway 10. Main severe risk over
  southern WI.

- Additional rounds of showers and storms Sunday night through
  middle of next week, though confidence in storm timing and
  severity remains low.

- Slightly cooler in the 70s on Sunday with rain and clouds. High
  temperatures in the low 80s early to mid next week, followed by
  a cooling trend late next week.

&&

.DISCUSSION...
Issued at 1236 PM CDT Sat Aug 8 2026

Near term Through Sunday...
Quiet and less humid this afternoon with brief intrusion of high
pressure. Fair weather cu as high temps peak in the upper 70s to
lower 80s. Late tonight, attention will be west over southern MN
where convergence on nose of low- level jet and warm air advection
occurs on the edge of steeper mid-level lapse rates/MUCAPEs.
Complex of showers/storms is signaled to occur on nose of the LLJ
as it shifts into WI late tonight/Sunday morning.

Based on probabilities of 0.01/0.05 inch of 6hr QPF from
ensembles, expect the main bulk of showers/storms to track over
southern WI closer to gradient of instability. However, additional
showers and isolated storms will occur farther north into our
area. Will have to watch to see if the complex is slower to
develop as that would open door to intensification as it moves
into especially our southern areas, south of highway 10 late
Sunday morning. If that occurred, there would be at least a small
risk for gusty winds and/or heavy rain. A couple of the CAMs point
to this idea. Another area of showers will be present over far
northern WI closer to upper level jet and sfc front. Highs on
Sunday will be held down due to the clouds and rain, mainly in the
70s. If rain ends up more widespread, could even see some
locations staying in the lower 70s. Not going that cool yet
though.

Rain/storm chances rest of the forecast...
No big changes to going forecast as prevailing northwest flow
results in several embedded shortwaves that bring at least the
opportunity for chances of showers/storms through the better part
of next week. Now appears main focus for rain on Sunday night and
Monday morning could end up farther south, though with building
instability on Monday afternoon, will see slight uptick in
shower/storm potential over central and east-central WI as sfc
trough crosses the region even as main front will be over southern
WI/northern IL into lower MI. Pops not all that high though at
15-30%, so probably just looking at isolated activity. Shear would
be sufficient to have some severe weather risk though. SPC
currently has the Day3 Marginal (level 1 of 5) to our south and
WPC slight risk for excessive rainfall is also south.

Next potential for rain would be later Monday night into Tuesday
morning, though with low-level jet and frontal boundary farther
south, imagine greatest chances for storms of consequence will be
farther south as well. Similar to Monday though, if enough instability
materializes during peak heating, could see smaller chances for storms
on Tuesday afternoon. That pattern could repeat yet again on
Wednesday before the frontal boundary moves far enough south to
bring dry weather in for late this week.

Temperatures...
Beyond the cooler readings Sunday, high temperatures Monday
through Wednesday should be as warm as the lower 80s, though any
morning convection these days could alter those expectations. Late
next week, northwest flow and troughing increases leading to
cooler temps in the lower to middle 70s for most locations. Low
temperatures could drop into the 40s over northern WI by late next
week.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1004 PM CDT Sat Aug 8 2026

VFR conditions are expected through early Sunday morning as an
elevated smoke layer and high clouds spread across the region.
Fine-tuned the onset of the showers and included TEMPO groups when
vsbys will drop within the heavier showers to IFR for the central
and east-central WI TAF sites mid Sunday morning into early
Sunday afternoon. It appears the showers will reach the RHI TAF
site, but vsbys appear to be less impactful (MVFR). MVFR cigs are
anticipated within the area of showers and will follow for a few
hours after the shower activity ends into Sunday afternoon.
Additionally, since the better signal for storms appears to be
further south, continued to not include TS at this time. VFR
conditions will return Sunday evening, but there is a potential
signal for fog development late Sunday evening/night.

&&

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

&&

$$

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

NWS GRB Office Area Forecast Discussion