162
FXUS63 KGRB 040630
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
130 AM CDT Thu Jun 4 2026

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Scattered showers/storms return today, lasting into the weekend.
  Limited potential for strong storms this afternoon, with better
  chances for strong or severe storms Friday afternoon.

- Above normal temperatures persist for the next week. Chance for
  highs in the low 90s increases early next week, along with
  potential for heat-related impacts.

&&

.DISCUSSION...
Issued at 1226 AM CDT Thu Jun 4 2026

Rain/storm chances... Convection in the vicinity of the frontal
boundary over western Minnesota continues to trek along early
this morning, though it should diminish within the next couple of
hours as it outruns better instability and encounters drier air.
Re-development of scattered showers/storms will then be possible
later this morning into early this afternoon as better moisture is
drawn north by high pressure shifting off to the east. Remain
somewhat critical for severe potential this afternoon as cloud
shield from aforementioned convection will hinder better
instability from building. Also seems to be somewhat of a disjoint
between upper forcing and deep layer shear, so any stronger
storms will hinge upon upstream development. As such, wind looks
to be the primary threat with any stronger storms, though any
severe threat would be little to none.

Better chances for any strong/severe storms comes Friday afternoon
and evening as driving shortwave treks over the northern Plains
and FROPA makes it into Wisconsin. Mid-level convergence and
increasing deep-layer shear (35 to 40 knots) would provide a
stronger base for convective activity, as abundant moisture
interacts with instability reservoir (1,500 to 2,000 J/kg) near
the surface low. However, greatest uncertainty will once again
revolve around cloud cover from sub-severe morning convection,
and whether or not sufficient destabilization will be able to
occur. This being said, lingering boundaries/outflow from said
convection may provide enough surface lift to get a couple of
stronger updrafts going later Friday afternoon. In this scenario,
steepening lapse rates and pseudo inverted-V profiles would
support gusts to 60 mph and up to 1" hail as the primary hazards.
Accompanying the severe threat on Friday will be the potential
for heavy rain as PWAT axis reaches around 1.5 to 1.75" (90th
percentile) and dewpoints climb into the mid 60s. Probabilistic
guidance continues to show a fairly widespread 40 to 70% chance,
locally higher, for receiving 0.5" of rain, with a 30 to 50%
signal for 1". Would lean more pessimistic toward the higher
totals, as these would be more likely with training and/or slow-
moving storms. As it appears now, storm motion looks to be fairly
progressive.

Temperatures... Temperatures will remain above average over the
course of the next week as synoptic flow eventually re-amplifies
and building heat ridge/Hudson Bay high set us up under southerly
flow regime. Highs this afternoon will read several degrees higher
than yesterday, peaking in the mid to upper 80s from the Fox
Valley and up into far northeast Wisconsin. However, dewpoints in
the mid to upper 50s should hold down the overall heat risk to a 1
out of 4. Potential for heat-related impacts then drastically
increases during the early to middle part of next week, with
probabilities for 90-degree highs sitting at around 50 to 80%.
Ample moisture transport from an open Gulf will likewise cause
dewpoints to rise solidly into the 60s, which would put us under a
level 2 out of 4 (moderate) risk for heat-related impacts early
next week. Cursory glance indicates that a level 3 out of 4
(major) risk may be possible toward the end of next week, though
this is beyond the current forecast period.

Fire weather... Fire weather concerns will continue to diminish
with the arrival of scattered showers/storms later this morning
into this afternoon. A slower arrival of the rain may allow RHs to
dip down into the low to mid 30s across portions of far northeast
Wisconsin this afternoon, though critical thresholds are not
expected to be met.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1036 PM CDT Wed Jun 3 2026

VFR conditions will prevail overnight. Thursday conditions will
generally remain VFR, however, periods of MVFR conditions are
possible with a round of showers and thunderstorms moving into the
region.

As low and mid level moisture begins to advect into the region
tonight high based cigs will gradually start to lower Thursday
morning. A series of short-waves, currently over the Dakotas, will
arrive to the region late Thursday morning kicking off a round of
showers for the afternoon. Shower coverage will likely be isolated
to scattered through the afternoon. As any showers pass over a
terminal brief MVFR conditions will be possible. A few embedded
thunderstorms are also possible Thursday afternoon and evening,
mainly across central and norther WI where the strongest instability
is forecast to reside. Have framed out the best timing for any
thunderstorms at AUW, CWA, and RHI with PROB30 groups.

Southwest winds will increase on Thursday with gusts 15 to 20 kts
starting after 12-14Z.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Beach Hazards Statement from this afternoon through late tonight
for WIZ022-040-050.
&&

$$

DISCUSSION.....Goodin
AVIATION.......GK

NWS GRB Office Area Forecast Discussion