Alert archive / South Dakota / Heat Advisories in 2017

Heat Advisory 4, NWS Sioux Falls, SD

July 20, 201723 counties in South Dakota; 10 counties in Iowa; Rock County, Minnesota

NWS Sioux Falls, SD issued this heat advisory at Jul 20, 2017, 3:25 PM CDT for 23 counties in South Dakota; 10 counties in Iowa; Rock County, Minnesota. It took effect at Jul 21, 2017, 12:00 PM CDT. It was in force for 8 hr.

The area

The counties it named.

The facts

Issued: Jul 20, 2017, 3:25 PM CDT (20:25 UTC)
In effect from: Jul 21, 2017, 12:00 PM CDT
Expired: Jul 21, 2017, 8:00 PM CDT
In force: 8 hr
Issued by: NWS Sioux Falls, SD

All 34 counties

Buena Vista County, IA, Cherokee County, IA, Clay County, IA, Ida County, IA, Lyon County, IA, O'Brien County, IA, Osceola County, IA, Plymouth County, IA, Sioux County, IA, Woodbury County, IA, Rock County, MN, Aurora County, SD, Beadle County, SD, Bon Homme County, SD, Brule County, SD, Charles Mix County, SD, Clay County, SD, Davison County, SD, Douglas County, SD, Gregory County, SD, Hanson County, SD, Hutchinson County, SD, Jerauld County, SD, Kingsbury County, SD, Lake County, SD, Lincoln County, SD, McCook County, SD, Miner County, SD, Minnehaha County, SD, Moody County, SD, Sanborn County, SD, Turner County, SD, Union County, SD, Yankton County, SD

The radar

The Sioux Falls radar (KFSD), 38 km from the middle of the area, began a volume at 20:26 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, 8.4 hours before the alert went out and 324 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: 58 J/kg
Mixed-layer CIN: -429 J/kg
Mixed-layer LCL: 1266 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: -176 m²/s²
0-3 km storm-relative helicity: -172 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.1

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this heat advisory went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Sioux Falls, SD wrote its last area forecast discussion before this heat advisory went out at Jul 20, 12:36 PM CDT, 2 hours 49 minutes earlier.

Area forecast discussion, Jul 20, 12:36 PM CDT, 2 hours 49 minutes before

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Hazardous weather outlook, Jul 20, 5:11 AM CDT, 10 hours 14 minutes before

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The office that day

Everything else NWS Sioux Falls, SD issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 20, 12:25 AM CDT	Severe Thunderstorm Warning	FSD	Cottonwood, Jackson, Murray	50 min

Nearby

Heat Advisories in South Dakota, 2017 Heat Advisories in Iowa, 2017 Heat Advisories in Minnesota, 2017 Every heat advisory in 2017

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.