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Winter Weather Advisory 21, NWS Green Bay, WI

December 9, 202517 counties in Wisconsin

NWS Green Bay, WI issued this winter weather advisory at Dec 9, 2025, 2:37 AM CST for 17 counties in Wisconsin. It took effect at Dec 9, 2025, 5:00 PM CST. It was in force for 13 hr.

The area

The counties it named.

The facts

Issued
Dec 9, 2025, 2:37 AM CST (08:37 UTC)
In effect from
Dec 9, 2025, 5:00 PM CST
Expired
Dec 10, 2025, 6:00 AM CST
In force
13 hr
Issued by
NWS Green Bay, WI

Counties Brown County, WI, Calumet County, WI, Door County, WI, Florence County, WI, Forest County, WI, Kewaunee County, WI, Langlade County, WI, Lincoln County, WI, Manitowoc County, WI, Marinette County, WI, Menominee County, WI, Oconto County, WI, Oneida County, WI, Outagamie County, WI, Vilas County, WI, Waushara County, WI, Winnebago County, WI

The radar

The Green Bay radar (KGRB), 58 km from the middle of the area, began a volume at 08:36 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Minneapolis, MN (KMPX), launched 00:00Z, 8.6 hours before the alert went out and 399 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Minneapolis, MN at 00:00Z on 2025-12-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Minneapolis, MN at 00:00Z on 2025-12-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 242 square meters per square second.1939587897117Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
500 m above ground
0-6 km bulk shear
43 kt
0-1 km storm-relative helicity
242 m²/s²
0-3 km storm-relative helicity
307 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The office that day

Everything else NWS Green Bay, WI issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Dec 9, 2:37 AM CSTWinter Storm WarningGRBBrown, Calumet, Kewaunee, Langlade, Lincoln, Manitowoc and 10 more29 hr
Dec 9, 3:06 AM CSTGale WarningGRB33 hr
Dec 9, 3:06 AM CSTSmall Craft AdvisoryGRB39 hr

Nearby

Winter Weather Advisories in Wisconsin, 2025Every winter weather advisory in 2025

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.