923
FXUS63 KGRB 171908
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
208 PM CDT Wed Jun 17 2026

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Rain and a few storms continue through this evening, with
  totals over an inch possible in central Wisconsin. Severe
  weather is not expected.

- Small Craft Advisory and Beach Hazards are in effect for areas
  south of Sturgeon Bay through tonight due to high waves and
  gusty winds.

- Below normal temperatures and comfortable humidity will prevail
  through next week.

&&

.DISCUSSION...
Issued at 207 PM CDT Wed Jun 17 2026

The latest RAP analysis and satellite/radar imagery show low
pressure tracking east across central Minnesota beneath a myriad
of shortwave energy traversing the northern Mississippi Valley.
Ahead of the low, widespread cloud cover along with a band of
light to moderate rain is spreading east across northern
Wisconsin. No lightning has been detected across northeast
Wisconsin so far today and mesoanalysis indicates little to no
instability present across the region. As the low moves across the
region, thunderstorm potential and marine hazards are the main
forecast concerns.

Rain and Thunderstorm Potential:  Periods of rain will continue
for the rest of the afternoon and evening as low pressure moves
southeast into southern Wisconsin. Rain will be most widespread
where mid-level frontogenesis is the strongest, across central to
east-central Wisconsin, just north of the low track. Sfc-based
instability is progged to remain south of Wood and Waushara
counties this afternoon, keeping the threat of strong and severe
storms out of our forecast area. However, local rain amounts may
reach over an inch, with the highest probabilities focused over
central Wisconsin. Most of the rain will end overnight, though a
few sprinkles could persist into the early morning hours along the
Lake Michigan shoreline. On Thursday, partial clearing in the
morning will allow sfc-based instability to build up to 500-750
J/kg beneath flat troughing and cold air aloft. With convective
temperatures in the middle to upper 60s reached by early
afternoon, weak shortwave impulses will provide large-scale ascent
for widely scattered afternoon storms capable of producing small
hail. Highs on Thursday will range from the upper 60s to lower
70s.

Long Term Outlook: Persistent upper troughing will encompass the
Great Lakes to New England region over the next week. With active
northwest flow aloft, this weather pattern will favor below normal
temperatures and comfortable humidity levels through the extended
period. The northwest flow will remain active, as several low-
amplitude shortwave impulses provide periodic rain chances from
this weekend into the middle of next week. Thunderstorm chances
will remain low, however, as the reservoir of instability will be
suppressed well south of the region. With precipitable water
values averaging around 25 percent of normal, overall
precipitation amounts look to be below normal despite the multiple
chances for rain.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1210 PM CDT Wed Jun 17 2026

Low pressure will be moving from south-central Minnesota to
southern Wisconsin this afternoon to the Lower Peninsula of
Michigan this evening. The surface low will bring periods of rain,
isolated thunderstorms across central and east-central WI, and
deteriorating ceilings and visibilities this afternoon and
evening. The ceilings and visibilities should bottom out in the
IFR category before improving flight conditions generally take
place late tonight into Thursday morning. Generally, flight
conditions should return to VFR in the 11Z-15Z time period,
though uncertainty is higher across far northern WI (RHI) and near
the Lake Michigan shoreline (MTW).

As the low traverses the region, winds will shift from the
southeast this afternoon, to the northeast tonight, then northwest
on Thursday. Gusts up to 20 kts will be possible at times.

&&

.MARINE...
Issued at 207 PM CDT Wed Jun 17 2026

Southeast winds are increasing over southern and east-central
Wisconsin early this afternoon. A Small Craft Advisory and Beach
Hazards statement remain on track to impact areas south of
Sturgeon Bay where waves of 3 to 5 feet will create dangerous
swimming and boating conditions through tonight. In contrast,
locations on Green Bay and north of Sturgeon Bay will see lighter
southeast winds around 10 to 15 knots and waves of 2 feet or less.
Adjustments were made to cancel the beach hazards for Door County
due to lower expected wave impacts and to end the marine
headlines early at 09Z tonight to match the latest wind and wave
forecasts as winds back to the northwest after midnight.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Beach Hazards Statement through late tonight for WIZ040-050.
&&

$$

DISCUSSION.....MPC
AVIATION.......MPC
MARINE.........MPC

NWS GRB Office Area Forecast Discussion