NWS-Green Bay Forecast Discussion
FXUS63 KGRB 192309
AFDGRB
Area Forecast Discussion
National Weather Service Green Bay WI
609 PM CDT Fri Jun 19 2026
Updated aviation portion for 00Z TAF issuance
.KEY MESSAGES...
- Scattered showers and thunderstorms will bring a 50-75% chance
of rain this evening and tonight. Any storms will be capable of
producing hail. Strong, gusty winds are also possible.
- Scattered showers are expected Saturday afternoon, with a few
storms possible across far northeast Wisconsin, including Door
County.
- Near to below normal temperatures and comfortable humidity will
prevail through next week.
&&
.DISCUSSION...
Issued at 215 PM CDT Fri Jun 19 2026
Precipitation Chances...This afternoon's water vapor and radar
imagery showed a shortwave moving eastward over eastern ND and
northern MN, producing scattered showers and a few storms. As the
shortwave continues to track east, the forecast area will see these
scattered showers and isolated storms move across the area early
this evening through late tonight. When the precip reaches central
WI late this afternoon/early this evening, a corridor of SBCAPE of
500-900 J/kg, steep mid-level lapse rates of 6.5-7.5 C/km, and deep-
layer shear of 35-45 kts, will be present, leading to a marginal
risk for a few strong to severe storms. Given the present cooler
airmass, the freezing level will be lower, around 7000 ft, leading
to a hail threat. In addition, a few models indicate inverted-v
soundings, suggesting a marginal wind threat as well. As the storms
move eastward, the storms will become elevated, but the severe
threat will decrease as deep-layer shear and lapse rates lessen. Any
showers and storms will exit east after midnight.
Northwest/cyclonic flow will be in place following the departure of
the shortwave on Saturday. With low-level moisture in place and then
diurnally increasing during the afternoon, CAMs are indicating
isolated to scattered showers developing during the afternoon, and
dissipating in the evening as the sun sets. Cannot rule out a few
rumbles of thunder, mainly in far northeast WI, where a couple
hundred J/kg of CAPE will be focused during the afternoon.
On Sunday, a strong system will move across the Middle Mississippi
Valley. While models continue to show the system remaining south of
the forecast area, a few ensemble members indicate the far southern
portions of the forecast area may see some rain on the northern
periphery of the system; elsewhere should remain dry.
Quiet conditions look to prevail for the start of the work week with
the next chance for showers and storms arriving sometime midweek.
Temperatures...With a relatively unchanged northwest flow expected
through next week, very little variance in temperatures is forecast.
As such, both afternoon highs (mainly in the 70s) and overnight lows
(upper 40s to low 50s) will hover slightly below normal.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 609 PM CDT Fri Jun 19 2026
Coverage of showers and thunderstorms are expected to increase
this evening as a weak cold front moves across the region.
Potential for storms will be highest over central and north-
central Wisconsin prior to storms losing intensity as they move
east. Brief IFR visibilities, MVFR ceilings, gusty winds to 40-50
mph, and small to near severe hail are possible in any storms.
Added a tempo group at all taf sites as confidence is increasing
in coverage of the shower activity.
As the rain ends from late evening through early overnight,
confidence is lower in the flight conditions as guidance generally
disagrees in the development of low clouds and/or fog. Considering
winds and climatology, showed a mention of low end MVFR ceilings
at AUW/CWA/RHI late tonight into Sat morning. With heat of the
day, these ceilings should rise to VFR by late morning or early
afternoon.
Scattered showers will develop again on Saturday afternoon, but
confidence of coverage near the TAF sites is low enough to forego
a prob30 group.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION.....Kruk
AVIATION.......MPC