Alert archive / Nebraska / Severe Thunderstorm Watches in 2017

Severe Thunderstorm Watch 452

August 15, 20177 counties in Colorado; 35 counties in Nebraska

The Storm Prediction Center issued this severe thunderstorm watch at Aug 15, 2017, 4:03 PM MDT for 7 counties in Colorado; 35 counties in Nebraska. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
Aug 15, 2017, 4:03 PM MDT (22:03 UTC)
Expired
Aug 15, 2017, 11:00 PM MDT
In force
7 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
60 kt
All 42 counties

Logan County, CO, Morgan County, CO, Phillips County, CO, Sedgwick County, CO, Washington County, CO, Weld County, CO, Yuma County, CO, Arthur County, NE, Banner County, NE, Blaine County, NE, Box Butte County, NE, Buffalo County, NE, Chase County, NE, Cherry County, NE, Cheyenne County, NE, Custer County, NE, Dawson County, NE, Deuel County, NE, Frontier County, NE, Garden County, NE, Garfield County, NE, Grant County, NE, Greeley County, NE, Hall County, NE, Hayes County, NE, Hooker County, NE, Howard County, NE, Keith County, NE, Kimball County, NE, Lincoln County, NE, Logan County, NE, Loup County, NE, McPherson County, NE, Merrick County, NE, Morrill County, NE, Nance County, NE, Perkins County, NE, Scotts Bluff County, NE, Sheridan County, NE, Sherman County, NE, Thomas County, NE, Valley County, NE

The radar

The North Platte radar (KLNX), 115 km from the middle of the area, began a volume at 22:07 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.

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
2%
Ten or more severe wind reports
40%
One or more gusts of 65 knots or more
20%
Ten or more severe hail reports
50%
One or more hailstones of 2 inches or more
30%
Six or more combined severe hail and wind reports
80%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Aug 15, 4:08 PM MDTSevere Thunderstorm WarningGIDSherman37 min
Aug 15, 4:12 PM MDTSevere Thunderstorm WarningGIDNance33 min
Aug 15, 4:20 PM MDTFlash Flood WarningGIDNance6 hr
Aug 15, 4:25 PM MDTSevere Thunderstorm WarningGIDMerrick, Nance50 min
Aug 15, 4:31 PM MDTSevere Thunderstorm WarningLBFCuster, Garfield, Loup44 min
Aug 15, 4:44 PM MDTSevere Thunderstorm WarningBOUWeld46 min
Aug 15, 4:44 PM MDTSevere Thunderstorm WarningGIDSherman24 min
Aug 15, 4:52 PM MDTFlash Flood WarningGIDSherman6 hr
Aug 15, 4:55 PM MDTTornado Warning Tornado observedCYSBanner45 min
Aug 15, 4:55 PM MDTFlash Flood WarningLBFCuster, Garfield, Loup6 hr
Aug 15, 4:57 PM MDTSevere Thunderstorm WarningGIDMerrick3 min
Aug 15, 5:13 PM MDTSevere Thunderstorm WarningLBFCuster47 min
Aug 15, 5:14 PM MDTSevere Thunderstorm WarningGIDGreeley, Howard, Nance46 min
Aug 15, 5:27 PM MDTSevere Thunderstorm WarningBOUMorgan, Weld53 min
Aug 15, 5:27 PM MDTSevere Thunderstorm WarningCYSBanner, Kimball33 min
Aug 15, 5:32 PM MDTFlash Flood WarningLBFLogan3 hr
Aug 15, 5:38 PM MDTSevere Thunderstorm WarningCYSBanner36 min
Aug 15, 5:40 PM MDTSevere Thunderstorm WarningCYSBox Butte, Dawes, Sioux50 min
Aug 15, 5:44 PM MDTTornado WarningCYSBanner, Cheyenne, Kimball46 min
Aug 15, 5:58 PM MDTSevere Thunderstorm WarningGIDHoward, Merrick, Nance47 min
Aug 15, 6:20 PM MDTTornado Warning Tornado observedCYSCheyenne40 min
Aug 15, 6:43 PM MDTSevere Thunderstorm WarningGIDMerrick, Nance47 min
Aug 15, 6:52 PM MDTSevere Thunderstorm WarningCYSCheyenne, Morrill34 min
Aug 15, 7:03 PM MDTSevere Thunderstorm WarningLBFGarden42 min
Aug 15, 7:51 PM MDTFlash Flood WarningLBFDeuel, Garden6 hr
Aug 15, 8:27 PM MDTFlash Flood WarningGLDKit Carson, Yuma3 hr
Aug 15, 9:43 PM MDTFlash Flood WarningLBFCuster8 hr
Aug 15, 10:35 PM MDTFlash Flood WarningGIDHall2 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

N. Platte/Lee Bi, NE (KLBF), launched 12:00Z, 10.1 hours before the alert went out and 101 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, N. Platte/Lee Bi, NE at 12:00Z on 2017-08-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 418 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, N. Platte/Lee Bi, NE at 12:00Z on 2017-08-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 62 square meters per square second.1939Sfc1 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
418 J/kg
Mixed-layer CIN
-256 J/kg
Mixed-layer LCL
763 m above ground
0-6 km bulk shear
29 kt
0-1 km storm-relative helicity
62 m²/s²
0-3 km storm-relative helicity
71 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.5

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 15, 2:52 PM MDTMesoscale DiscussionSPCLogan, Morgan, Phillips, Sedgwick, Washington, Weld and 1 more113 min
Aug 15, 11:33 AM MDTMesoscale DiscussionSPCAntelope, Blaine, Boyd, Burt, Cedar, Cuming and 15 more87 min

Nearby

Severe Thunderstorm Watches in Nebraska, 2017Severe Thunderstorm Watches in Colorado, 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.