Alert archive / Nebraska / Severe Thunderstorm Watches in 2012

Severe Thunderstorm Watch 554

August 3, 201220 counties in Nebraska

The Storm Prediction Center issued this severe thunderstorm watch at Aug 3, 2012, 7:11 PM CDT for 20 counties in Nebraska. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
Aug 3, 2012, 7:11 PM CDT (00:11 UTC)
Expired
Aug 4, 2012, 2:00 AM CDT
In force
7 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
60 kt

Counties Antelope County, NE, Blaine County, NE, Boyd County, NE, Brown County, NE, Cedar County, NE, Custer County, NE, Garfield County, NE, Holt County, NE, Hooker County, NE, Keya Paha County, NE, Knox County, NE, Lincoln County, NE, Logan County, NE, Loup County, NE, McPherson County, NE, Pierce County, NE, Rock County, NE, Thomas County, NE, Wayne County, NE, Wheeler County, NE

The radar

The North Platte radar (KLNX), 82 km from the middle of the area, began a volume at 00:13 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
5%
Ten or more severe wind reports
70%
One or more gusts of 65 knots or more
30%
Ten or more severe hail reports
70%
One or more hailstones of 2 inches or more
20%
Six or more combined severe hail and wind reports
90%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Aug 3, 7:33 PM CDTSevere Thunderstorm WarningLBFBlaine, Brown, Cherry, Rock, Thomas57 min
Aug 3, 7:45 PM CDTSevere Thunderstorm WarningLBFBrown, Holt, Rock60 min
Aug 3, 8:29 PM CDTSevere Thunderstorm WarningLBFBrown, Holt, Rock47 min
Aug 3, 8:38 PM CDTSevere Thunderstorm WarningLBFBoyd, Holt26 min
Aug 3, 9:22 PM CDTSevere Thunderstorm WarningLBFArthur, Keith, Lincoln, McPherson38 min
Aug 3, 9:29 PM CDTSevere Thunderstorm WarningOAXKnox31 min
Aug 3, 10:02 PM CDTSevere Thunderstorm WarningLBFLogan, McPherson43 min
Aug 3, 10:32 PM CDTSevere Thunderstorm WarningLBFLincoln43 min
Aug 3, 11:07 PM CDTSevere Thunderstorm WarningLBFCuster53 min
Aug 3, 11:58 PM CDTSevere Thunderstorm WarningLBFCuster18 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

N. Platte/Lee Bi, NE (KLBF), launched 00:00Z, 0.2 hours before the alert went out and 131 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 00:00Z on 2012-08-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1191 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 00:00Z on 2012-08-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 28 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
1191 J/kg
Mixed-layer CIN
-104 J/kg
Mixed-layer LCL
2741 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
28 m²/s²
0-3 km storm-relative helicity
69 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.7

Open this sounding in Storm Lab

The text

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

370 
WWUS20 KWNS 040010
SEL4
SPC WW 040010
NEZ000-040700-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 554
NWS STORM PREDICTION CENTER NORMAN OK
715 PM CDT FRI AUG 3 2012

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

       NORTHERN AND CENTRAL NEBRASKA

EFFECTIVE THIS FRIDAY NIGHT AND SATURDAY MORNING FROM 715 PM
UNTIL 200 AM CDT.

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 40
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 35 MILES WEST
NORTHWEST OF NORTH PLATTE NEBRASKA TO 20 MILES EAST SOUTHEAST OF
YANKTON SOUTH DAKOTA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE
THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU4).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR 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. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

OTHER WATCH INFORMATION...CONTINUE...WW 553...

DISCUSSION...THUNDERSTORMS ARE INCREASING ALONG A BOUNDARY EXTENDING
FROM NORTH CENTRAL INTO NORTHEAST NEB.  THESE STORMS WILL SAG
SOUTHWARD ACROSS THE WATCH AREA DURING THE NEXT SEVERAL HOURS.
STRONG INSTABILITY...STEEP LOW LEVEL LAPSE RATES...AND SUFFICIENT
VERTICAL SHEAR WILL POSE A RISK OF LARGE HAIL AND DAMAGING WINDS IN
THE STRONGER STORMS.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 30025.


...HART

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 3, 7:33 PM CDTSevere Thunderstorm WatchSPCDakota, Dixon6 hr
Aug 3, 11:19 PM CDTMesoscale DiscussionSPCAntelope, Blaine, Boone, Cedar, Custer, Garfield and 10 more86 min

Nearby

Severe Thunderstorm Watches in Nebraska, 2012Every severe thunderstorm 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.