Alert archive / Iowa / Severe Thunderstorm Watches in 2017

Severe Thunderstorm Watch 214

May 15, 201730 counties in Iowa; Crawford County, Grant County, Richland County, Wisconsin

The Storm Prediction Center issued this severe thunderstorm watch at May 15, 2017, 5:11 PM CDT for 30 counties in Iowa; Crawford County, Grant County, Richland County, Wisconsin. It was in force for 9 hr.

The area

The outline as issued.

The facts

Issued
May 15, 2017, 5:11 PM CDT (22:11 UTC)
Expired
May 16, 2017, 2:15 AM CDT
In force
9 hr
Issued by
the Storm Prediction Center
Largest hail expected
2.5 in
Strongest gust expected
60 kt
All 33 counties

Allamakee County, IA, Black Hawk County, IA, Bremer County, IA, Buchanan County, IA, Butler County, IA, Calhoun County, IA, Cerro Gordo County, IA, Chickasaw County, IA, Clayton County, IA, Delaware County, IA, Dubuque County, IA, Emmet County, IA, Fayette County, IA, Floyd County, IA, Franklin County, IA, Grundy County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Howard County, IA, Humboldt County, IA, Kossuth County, IA, Mitchell County, IA, Palo Alto County, IA, Pocahontas County, IA, Webster County, IA, Winnebago County, IA, Winneshiek County, IA, Worth County, IA, Wright County, IA, Crawford County, WI, Grant County, WI, Richland County, WI

The radar

The Des Moines radar (KDMX), 154 km from the middle of the area, began a volume at 22:11 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
20%
One or more EF2 to EF5 tornadoes
2%
Ten or more severe wind reports
40%
One or more gusts of 65 knots or more
20%
Ten or more severe hail reports
30%
One or more hailstones of 2 inches or more
30%
Six or more combined severe hail and wind reports
80%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
May 15, 5:19 PM CDTSevere Thunderstorm WarningDMXCerro Gordo, Franklin, Hancock, Humboldt, Wright41 min
May 15, 5:40 PM CDTSevere Thunderstorm WarningARXChickasaw, Floyd, Howard, Mitchell65 min
May 15, 5:55 PM CDTSevere Thunderstorm WarningARXWinneshiek50 min
May 15, 5:58 PM CDTSevere Thunderstorm WarningDMXButler, Cerro Gordo, Franklin, Wright47 min
May 15, 6:24 PM CDTFlash Flood WarningDMXCerro Gordo, Franklin, Hancock, Wright6 hr
May 15, 6:31 PM CDTSevere Thunderstorm WarningDMXBremer, Butler44 min
May 15, 6:40 PM CDTSevere Thunderstorm WarningARXAllamakee, Chickasaw, Fayette, Winneshiek65 min
May 15, 6:41 PM CDTSevere Thunderstorm WarningDMXButler, Franklin34 min
May 15, 6:46 PM CDTTornado WarningARXWinneshiek44 min
May 15, 7:09 PM CDTSevere Thunderstorm WarningARXClayton51 min
May 15, 7:14 PM CDTSevere Thunderstorm WarningDMXBlack Hawk, Bremer, Butler45 min
May 15, 7:27 PM CDTSevere Thunderstorm WarningARXAllamakee, Clayton48 min
May 15, 7:52 PM CDTSevere Thunderstorm WarningDVNDubuque, Jackson38 min
May 15, 8:14 PM CDTSevere Thunderstorm WarningARXGrant29 min
May 15, 11:04 PM CDTSevere Thunderstorm WarningDMXHancock, Kossuth, Winnebago26 min
May 15, 11:29 PM CDTSevere Thunderstorm WarningDMXKossuth, Winnebago46 min

Discussions around it

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

The nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 10.2 hours before the alert went out and 210 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 2017-05-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 4 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 2017-05-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 136 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
4 J/kg
Mixed-layer CIN
-548 J/kg
Mixed-layer LCL
1538 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
136 m²/s²
0-3 km storm-relative helicity
125 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.1

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 15, 9:15 AM CDTMesoscale DiscussionSPCBuena Vista, Cherokee, Clay, Dickinson, Emmet, Lyon and 7 more90 min
May 15, 3:48 PM CDTMesoscale DiscussionSPCBuena Vista, Butler, Calhoun, Carroll, Cerro Gordo, Chickasaw and 16 more87 min
May 15, 5:52 PM CDTMesoscale DiscussionSPCDane, Green, Iowa, Jefferson, Lafayette, Rock and 1 more113 min

Nearby

Severe Thunderstorm Watches in Iowa, 2017Severe Thunderstorm Watches in Wisconsin, 2017Every severe thunderstorm watch 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.