NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 131116
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
616 AM CDT Sat Jun 13 2026

.KEY MESSAGES...

- Low (level 1 of 5) risk for an isolated strong to severe storm
  this afternoon across far east-central Wisconsin with hail and
  strong winds the primary hazards. This risk is trending lower,
  though.

- Cooler, below average temps expected for the next week with
  additional periods of showers/storms for mid to late next
  week.

&&

.DISCUSSION...
Issued at 110 AM CDT Sat Jun 13 2026

Early today: Scattered showers/storms

A low-level jet interacting with a mid-level zonally oriented
baroclinic zone is producing fast-moving showers. Thunder is
quite isolated given the meager CAPE above the freezing level.
Despite the weak instability with MUCAPEs under 500 J/kg, gusty
winds of 35 to 45 mph could occur with any showers/storms. This
risk should diminish after sunrise as the low-level jet weak
weakens.

This Afternoon: Storm risk across east-central Wisconsin

A mid-level shortwave trough will drive a cold front southeast
across the area during the day today. Once again, strong mid-
level flow will support storm organization, with the frontal
timing and unstable sector limiting any risk to east-central
Wisconsin. However, modest low-level convergence and weak
synoptic forcing and the diffuse boundary swinging through much
of the area by late afternoon casts doubt on robust storm
development with only 20-30% chances for a storm in the 1 pm to
5 pm window across far east-central Wisconsin. Elongated
hodographs and steep mid-level lapse rates with MLCAPE forecast
around 1000 J/kg would support large hail with any storms, in
addition to strong, gusty winds.

Sunday-Friday: Cooler, intermittent shower/storm chances

In the wake of Saturday's frontal passage, a cooler airmass will
overspread the area. Broad mid/upper level troughing will remain in
place across the Great Lakes through the week, resulting in below
average high temps, mainly in the 60s and 70s.

Dry weather is expected for Sunday and Monday with shower/storm
chances returning for mid-week as a series of upper level shortwave
troughs rotate through the base of the broader trough. At this time,
the highest chances (50-80%) are focused on the Tuesday-Wednesday
period, although forecast details will be better resolved in
coming days. It's too early to assess severe weather potential,
but broadly speaking, instability looks to be fairly weak, given
the overall pattern.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 551 AM CDT Sat Jun 13 2026

Scattered showers/isolated storms will diminish quickly by mid
morning with winds becoming gusty from the west behind a front.
While there is a small (<30%) chance for a shower or storm
across east-central Wisconsin this afternoon, most areas will
remain dry beyond early this morning. Winds will diminish this
evening. Mainly VFR conditions are expected this afternoon into
tonight, although MVFR ceilings may develop across northern
Wisconsin late tonight.

&&

.MARINE...
Issued at 551 AM CDT Sat Jun 13 2026

Winds will become gusty from the west to southwest as a front
moves through. Although waves likely will mainly be in the 1 to
3 ft range through the day, highest along the Lake Michigan
shore, winds may occasionally gust to 25 kts, especially later
this morning through the afternoon. A Small Craft Advisory is in
effect for the nearshore Lake Michigan waters later this
morning through the afternoon.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
WI...None.
MARINE...Small Craft Advisory from 10 AM this morning to 5 PM CDT this
     afternoon for LMZ541>543.

&&

$$

DISCUSSION...JM
AVIATION...JM
MARINE...JM