Alert archive / Wisconsin / Mesoscale Discussions in 2015

Mesoscale Discussion 256

April 9, 201512 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at Apr 9, 2015, 4:46 PM CDT for 12 counties in Wisconsin. It was in force for 89 min.

The area

The outline as issued.

The facts

Issued: Apr 9, 2015, 4:46 PM CDT (21:46 UTC)
Expired: Apr 9, 2015, 6:15 PM CDT
In force: 89 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

Counties Calumet County, WI, Columbia County, WI, Dane County, WI, Dodge County, WI, Fond du Lac County, WI, Green Lake County, WI, Iowa County, WI, Marquette County, WI, Ozaukee County, WI, Sauk County, WI, Sheboygan County, WI, Washington County, WI

The radar

The Milwaukee radar (KMKX), 44 km from the middle of the area, began a volume at 21:46 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 47Apr 9, 5:15 PM CDT

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 9.8 hours before the alert went out and 244 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 101 J/kg
Mixed-layer CIN: -154 J/kg
Mixed-layer LCL: 614 m above ground
0-6 km bulk shear: 55 kt
0-1 km storm-relative helicity: 323 m²/s²
0-3 km storm-relative helicity: 253 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.4

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 9, 1:48 PM CDT	Tornado Watch	SPC	Green, Jefferson, Kenosha, Milwaukee, Racine, Rock and 2 more	9 hr
Apr 9, 5:15 PM CDT	Severe Thunderstorm Watch	SPC	Columbia, Dane, Dodge, Fond du Lac, Green Lake, Iowa and 6 more	4 hr
Apr 9, 6:04 PM CDT	Mesoscale Discussion	SPC	Green, Kenosha, Rock, Walworth, Waukesha	86 min

Nearby

Mesoscale Discussions in Wisconsin, 2015 Every mesoscale discussion in 2015

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.