Alert archive / South Dakota / Severe Thunderstorm Watches in 2007

Severe Thunderstorm Watch 287

May 22, 200714 counties in Nebraska; 28 counties in South Dakota

The Storm Prediction Center issued this severe thunderstorm watch at May 22, 2007, 2:25 PM CDT for 14 counties in Nebraska; 28 counties in South Dakota. It was in force for 8 hr.

The area

The outline as issued.

The facts

Issued: May 22, 2007, 2:25 PM CDT (19:25 UTC)
Expired: May 22, 2007, 10:00 PM CDT
In force: 8 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

All 42 counties

Blaine County, NE, Boyd County, NE, Brown County, NE, Cherry County, NE, Garfield County, NE, Holt County, NE, Hooker County, NE, Keya Paha County, NE, Logan County, NE, Loup County, NE, McPherson County, NE, Rock County, NE, Thomas County, NE, Wheeler County, NE, Aurora County, SD, Beadle County, SD, Brown County, SD, Brule County, SD, Buffalo County, SD, Campbell County, SD, Charles Mix County, SD, Davison County, SD, Douglas County, SD, Edmunds County, SD, Faulk County, SD, Gregory County, SD, Hand County, SD, Hughes County, SD, Hyde County, SD, Jerauld County, SD, Jones County, SD, Lyman County, SD, McPherson County, SD, Mellette County, SD, Potter County, SD, Sanborn County, SD, Spink County, SD, Stanley County, SD, Sully County, SD, Todd County, SD, Tripp County, SD, Walworth County, SD

The radar

The North Platte radar (KLNX), 181 km from the middle of the area, began a volume at 19:25 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes: 10%
One or more EF2 to EF5 tornadoes: 5%
Ten or more severe wind reports: 30%
One or more gusts of 65 knots or more: 30%
Ten or more severe hail reports: 60%
One or more hailstones of 2 inches or more: 20%
Six or more combined severe hail and wind reports: 80%

Warnings issued inside it

9 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
May 22, 2:34 PM CDT	Severe Thunderstorm Warning	ABR	Hughes, Lyman	41 min
May 22, 3:04 PM CDT	Severe Thunderstorm Warning	ABR	Hughes, Hyde, Lyman	41 min
May 22, 3:46 PM CDT	Severe Thunderstorm Warning	ABR	Hand, Hyde	44 min
May 22, 5:02 PM CDT	Severe Thunderstorm Warning	ABR	Brown, Spink	43 min
May 22, 5:24 PM CDT	Flash Flood Warning	ABR	Brown, Spink	6 hr
May 22, 5:42 PM CDT	Severe Thunderstorm Warning	ABR	Brown	27 min
May 22, 7:55 PM CDT	Severe Thunderstorm Warning	LBF	Holt, Rock	40 min
May 22, 9:30 PM CDT	Flash Flood Warning	FSD	Charles Mix, Douglas	3 hr
May 22, 9:57 PM CDT	Flash Flood Warning	FSD	Davison	3 hr

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Aberdeen, SD (KABR), launched 12:00Z, 7.4 hours before the alert went out and 194 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: 729 J/kg
Mixed-layer CIN: -53 J/kg
Mixed-layer LCL: 668 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 121 m²/s²
0-3 km storm-relative helicity: 115 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 3.0

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 22, 2:08 PM CDT	Mesoscale Discussion	SPC	Brown, Cherry, Keya Paha	2 hr
May 22, 2:26 PM CDT	Mesoscale Discussion	SPC	Adams, Blaine, Buffalo, Custer, Dawson, Franklin and 17 more	2 hr
May 22, 3:04 PM CDT	Tornado Watch	SPC	Adams, Buffalo, Custer, Dawson, Dundy, Franklin and 16 more	8 hr
May 22, 6:36 PM CDT	Mesoscale Discussion	SPC	Buffalo, Custer, Dawson, Franklin, Frontier, Furnas and 7 more	84 min
May 21, 9:59 PM CDT	Mesoscale Discussion	SPC	Campbell, Edmunds, Hughes, Hyde, Jones, Lyman and 5 more	61 min

Nearby

Severe Thunderstorm Watches in South Dakota, 2007 Severe Thunderstorm Watches in Nebraska, 2007 Every severe thunderstorm watch in 2007

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.