NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 131730
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1230 PM CDT Sat Jun 13 2026

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Marginal (level 1/5) risk for isolated strong or severe storms
  over east-central Wisconsin this afternoon. Wind and hail would
  be the primary concerns, though trends show most areas remaining
  dry.

- Gusty west winds up to 25 kts will result in conditions
  hazardous to small craft along the Lake Michigan shoreline
  through this afternoon.

- Cool and showery pattern to take hold over the course of the
  next week. Temperatures to run around 5 to 10 degrees below
  normal.

&&

.DISCUSSION...
Issued at 1035 AM CDT Sat Jun 13 2026

This afternoon... CAMs remain unimpressed with storm potential,
let alone severe weather potential, for this afternoon as guidance
shows better convergence along the front off to our south. This
being said, modest instability (500 to 1,000 J/kg MUCAPE) continues
to build under mostly clear skies, which may be sufficient for
convective initiation over east-central Wisconsin within the next
hour or two. If a stronger storm were to develop, steepening lapse
rates, elongated hodographs, and 40+ knots of bulk shear would
support gusty winds and hail as the primary concerns. Window for
any stronger storms remains tight, with 20 to 30% PoPs going until
around 5 PM. Lack of upper support should prevent any storm
organization. All of this to say, odds are looking better for most
areas remaining dry throughout the afternoon.

Extended... Pattern shift to cooler and more showery takes place
over the course of the next week as closed upper low sitting and
spinning over the Hudson Bay puts us under northwesterly flow
regime. Result will be temperatures running around 5 to 10 degrees
below normal, with highs reading mainly in the upper 60s to mid
70s.

Several chances for showers then exist throughout the week as
multiple shortwaves migrate through the base of a broader longwave
trough. The first of these chances arrives in the vicinity of a
surface low Monday into Tuesday, though better chances for more
widespread rain will be Wednesday into Thursday as PWATs increase
into the 1 to 1.25" range. It is still too soon to explicitly
determine severe weather potential during this time, though a
cursory glance shows instability to be fairly weak.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1035 AM CDT Sat Jun 13 2026

VFR conditions prevail through the TAF period as high pressure
currently over the northern Plains shifts east. Cu field with
bases at around 4 to 5k ft has started to develop over most of
northeast Wisconsin early this afternoon. Though there is a
slight chance (< 20%) for a shower or storm over east-central
Wisconsin over the next several hours, have refrained from
including in the TAF due to low confidence. Otherwise, winds
continue to ramp up and veer to the northwest this afternoon, with
gusts to 25 knots possible at all terminals through this evening.
MVFR cigs may then develop across the north late this evening
into tonight, though uncertainty remains on whether or not the
lower cigs will make it down to RHI.

&&

.MARINE...
Issued at 1035 AM CDT Sat Jun 13 2026

Post-frontal winds continue to ramp up and veer to northwesterly
early this afternoon. As such, gusts to 25 knots will be possible
along the Lake Michigan shoreline through this evening, though
waves should be held down to generally 1 to 3 ft. Have opted to
hold onto the Small Craft Advisory, though marginal, due to warm
weather and weekend status. The Advisory remains in effect until 5
PM today.

&&

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

&&

$$

DISCUSSION.....Goodin
AVIATION.......Goodin
MARINE.........Goodin