Alert archive / Kansas / Tornado Watches in 2012

Tornado Watch 157

April 12, 20129 counties in Colorado; 13 counties in Kansas; 7 counties in Nebraska

The Storm Prediction Center issued this tornado watch at Apr 12, 2012, 12:47 PM MDT for 9 counties in Colorado; 13 counties in Kansas; 7 counties in Nebraska. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
Apr 12, 2012, 12:47 PM MDT (18:47 UTC)
Expired
Apr 12, 2012, 8:00 PM MDT
In force
7 hr
Issued by
the Storm Prediction Center
Largest hail expected
3 in
Strongest gust expected
60 kt
All 29 counties

Cheyenne County, CO, Kiowa County, CO, Kit Carson County, CO, Logan County, CO, Phillips County, CO, Prowers County, CO, Sedgwick County, CO, Washington County, CO, Yuma County, CO, Cheyenne County, KS, Decatur County, KS, Greeley County, KS, Hamilton County, KS, Kearny County, KS, Logan County, KS, Rawlins County, KS, Scott County, KS, Sheridan County, KS, Sherman County, KS, Thomas County, KS, Wallace County, KS, Wichita County, KS, Chase County, NE, Dundy County, NE, Frontier County, NE, Hayes County, NE, Hitchcock County, NE, Perkins County, NE, Red Willow County, NE

The radar

The Goodland radar (KGLD), 72 km from the middle of the area, began a volume at 18:49 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
70%
One or more EF2 to EF5 tornadoes
20%
Ten or more severe wind reports
40%
One or more gusts of 65 knots or more
30%
Ten or more severe hail reports
80%
One or more hailstones of 2 inches or more
60%
Six or more combined severe hail and wind reports
95%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Apr 12, 2:31 PM MDTSevere Thunderstorm WarningBOULogan46 min
Apr 12, 3:07 PM MDTSevere Thunderstorm WarningBOUSedgwick53 min
Apr 12, 5:13 PM MDTSevere Thunderstorm WarningLBFKeith, Perkins47 min
Apr 12, 5:17 PM MDTSevere Thunderstorm WarningGLDHitchcock43 min
Apr 12, 5:30 PM MDTTornado WarningGLDHitchcock45 min
Apr 12, 5:39 PM MDTSevere Thunderstorm WarningGLDCheyenne, Rawlins66 min
Apr 12, 5:53 PM MDTSevere Thunderstorm WarningGLDCheyenne, Rawlins28 min
Apr 12, 5:55 PM MDTTornado WarningLBFPerkins35 min
Apr 12, 6:13 PM MDTSevere Thunderstorm WarningLBFFrontier, Hayes47 min
Apr 12, 6:15 PM MDTSevere Thunderstorm WarningGLDHitchcock30 min
Apr 12, 6:30 PM MDTSevere Thunderstorm WarningLBFLincoln, Perkins45 min
Apr 12, 6:32 PM MDTSevere Thunderstorm WarningGLDHitchcock, Red Willow40 min
Apr 12, 6:51 PM MDTTornado WarningGLDHitchcock24 min
Apr 12, 7:00 PM MDTSevere Thunderstorm WarningGLDCheyenne, Rawlins46 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

Denver, CO (KDNR), launched 12:00Z, 6.8 hours before the alert went out and 74 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, Denver, CO at 12:00Z on 2012-04-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 34 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Denver, CO at 12:00Z on 2012-04-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 201 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
34 J/kg
Mixed-layer CIN
-126 J/kg
Mixed-layer LCL
946 m above ground
0-6 km bulk shear
50 kt
0-1 km storm-relative helicity
201 m²/s²
0-3 km storm-relative helicity
121 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

964 
WWUS20 KWNS 121848
SEL7
SPC WW 121848
COZ000-KSZ000-NEZ000-130200-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 157
NWS STORM PREDICTION CENTER NORMAN OK
1250 PM MDT THU APR 12 2012

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

       EASTERN COLORADO
       WESTERN KANSAS
       SOUTHWEST NEBRASKA

EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 1250 PM UNTIL
800 PM MDT.

TORNADOES...HAIL TO 3 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 60 STATUTE
MILES EAST AND WEST OF A LINE FROM 50 MILES NORTHWEST OF IMPERIAL
NEBRASKA TO 45 MILES EAST SOUTHEAST OF LAMAR COLORADO.  FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU7).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

DISCUSSION...THUNDERSTORMS ARE EXPECTED TO INTENSIFY THIS AFTERNOON
OVER EASTERN CO AND TRACK EASTWARD INTO WESTERN KS/SOUTHWEST NEB.
THIS REGION IS WITHIN A CORRIDOR OF MODERATE CAPE AND STEEP LAPSE
RATES...ALONG WITH FAVORABLE LOW LEVEL AND DEEP LAYER SHEAR.  STORMS
ARE FORECAST TO QUICKLY BECOME SUPERCELLULAR WITH A RISK OF VERY
LARGE HAIL AND A FEW TORNADOES.  INCREASING WIND FIELDS THROUGH THE
LATE AFTERNOON AND EVENING WOULD SUPPORT A RISK OF STRONG TORNADOES.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 3 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
450. MEAN STORM MOTION VECTOR 27030.


...HART

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 11, 10:50 PM MDTMesoscale DiscussionSPCCrowley, Douglas, Elbert, El Paso, Jefferson, Pueblo and 1 more85 min
Apr 12, 12:24 PM MDTMesoscale DiscussionSPCPhillips, Yuma2 hr
Apr 12, 4:02 PM MDTMesoscale DiscussionSPCCheyenne, Kit Carson, Phillips, Prowers, Sedgwick, Washington and 1 more88 min
Apr 12, 1:28 PM MDTMesoscale DiscussionSPCGrant, Haskell, Meade, Seward, Stevens2 hr
Apr 12, 5:54 PM MDTSevere Thunderstorm WatchSPCBlaine, Buffalo, Custer, Dawson, Franklin, Furnas and 12 more6 hr

Nearby

Tornado Watches in Kansas, 2012Tornado Watches in Colorado, 2012Tornado Watches in Nebraska, 2012Every tornado watch in 2012

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.