Alert archive / Iowa / Mesoscale Discussions in 2018

Mesoscale Discussion 1470

September 17, 20189 counties in Iowa; 9 counties in Minnesota; 5 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at Sep 17, 2018, 3:05 PM CDT for 9 counties in Iowa; 9 counties in Minnesota; 5 counties in Wisconsin. It was in force for 115 min.

The area

The outline as issued.

The facts

Issued
Sep 17, 2018, 3:05 PM CDT (20:05 UTC)
Expired
Sep 17, 2018, 5:00 PM CDT
In force
115 min
Issued by
the Storm Prediction Center
Chance of a watch
5%
All 23 counties

Cerro Gordo County, IA, Chickasaw County, IA, Floyd County, IA, Hancock County, IA, Howard County, IA, Mitchell County, IA, Winnebago County, IA, Winneshiek County, IA, Worth County, IA, Dodge County, MN, Fillmore County, MN, Freeborn County, MN, Goodhue County, MN, Houston County, MN, Mower County, MN, Olmsted County, MN, Wabasha County, MN, Winona County, MN, Buffalo County, WI, Dunn County, WI, Pepin County, WI, Pierce County, WI, Trempealeau County, WI

The radar

The La Crosse radar (KARX), 126 km from the middle of the area, began a volume at 20:07 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 12:00Z, 8.1 hours before the alert went out and 142 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 12:00Z on 2018-09-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 400 joules per kilogram.LCLLFCEL10008507005003002001001 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 12:00Z on 2018-09-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 110 square meters per square second.19395878Sfc1 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
400 J/kg
Mixed-layer CIN
-276 J/kg
Mixed-layer LCL
1173 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
110 m²/s²
0-3 km storm-relative helicity
106 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

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Nearby

Mesoscale Discussions in Iowa, 2018Mesoscale Discussions in Minnesota, 2018Mesoscale Discussions in Wisconsin, 2018Every mesoscale discussion in 2018

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.