Alert archive / Nebraska / Tornado Watches in 2007

Tornado Watch 86

March 28, 200722 counties in Nebraska; 5 counties in South Dakota

The Storm Prediction Center issued this tornado watch at Mar 28, 2007, 8:32 PM MDT for 22 counties in Nebraska; 5 counties in South Dakota. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Mar 28, 2007, 8:32 PM MDT (02:32 UTC)
Expired: Mar 29, 2007, 1:05 AM MDT
In force: 5 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

All 27 counties

Arthur County, NE, Blaine County, NE, Brown County, NE, Chase County, NE, Cherry County, NE, Custer County, NE, Dawson County, NE, Frontier County, NE, Furnas County, NE, Gosper County, NE, Grant County, NE, Hayes County, NE, Hooker County, NE, Keith County, NE, Keya Paha County, NE, Lincoln County, NE, Logan County, NE, Loup County, NE, McPherson County, NE, Perkins County, NE, Rock County, NE, Thomas County, NE, Bennett County, SD, Jackson County, SD, Mellette County, SD, Todd County, SD, Tripp County, SD

The radar

The North Platte radar (KLNX), 73 km from the middle of the area, began a volume at 02:36 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: 30%
One or more EF2 to EF5 tornadoes: 10%
Ten or more severe wind reports: 40%
One or more gusts of 65 knots or more: 20%
Ten or more severe hail reports: 60%
One or more hailstones of 2 inches or more: 30%
Six or more combined severe hail and wind reports: 70%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Mar 28, 8:52 PM MDT	Severe Thunderstorm Warning	LBF	Arthur, Keith, McPherson	38 min
Mar 28, 8:56 PM MDT	Severe Thunderstorm Warning	LBF	Hayes	49 min
Mar 28, 10:18 PM MDT	Flash Flood Warning	LBF	Chase, Hayes, Keith, Perkins	6 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 00:00Z, 2.5 hours before the alert went out and 162 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: 1774 J/kg
Mixed-layer CIN: -4 J/kg
Mixed-layer LCL: 816 m above ground
0-6 km bulk shear: 56 kt
0-1 km storm-relative helicity: 222 m²/s²
0-3 km storm-relative helicity: 244 m²/s²
Significant tornado parameter: 2.5
Supercell composite: 10.8

Open this sounding in Storm Lab

The text

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

000
WWUS20 KWNS 290234
SEL6  
SPC WW 290234
NEZ000-SDZ000-290900-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 86
NWS STORM PREDICTION CENTER NORMAN OK
935 PM CDT WED MAR 28 2007

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

       LARGE PART OF WESTERN AND CENTRAL NEBRASKA
       PART OF SOUTHERN SOUTH DAKOTA

EFFECTIVE THIS WEDNESDAY NIGHT AND THURSDAY MORNING FROM 935 PM
UNTIL 400 AM CDT.

TORNADOES...HAIL TO 2 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 55 STATUTE
MILES EAST AND WEST OF A LINE FROM 85 MILES NORTH OF VALENTINE
NEBRASKA TO 40 MILES EAST SOUTHEAST OF IMPERIAL NEBRASKA.  FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU6).

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.

OTHER WATCH INFORMATION...THIS TORNADO WATCH REPLACES TORNADO
WATCH NUMBER 81. WATCH NUMBER 81 WILL NOT BE IN EFFECT AFTER 935
PM CDT. CONTINUE...WW 82...WW 83...WW 84...WW 85...

DISCUSSION...STRONG SHEAR PROFILES REMAIN IN PLACE WITH AND AHEAD OF
ACTIVE SUPERCELLS THAT EXTEND ALONG WRN EDGE OF WATCH.  ALTHOUGH THE
THREAT FOR TORNADOES EXPECTED TO SLOWLY DIMINISH WITH LOSS OF
HEATING...A CONTINUED THREAT FOR LARGE HAIL AND ISOLATED TORNADOES
WILL CONTINUE SEVERAL MORE HOURS.

AVIATION...TORNADOES AND 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 21035.


...HALES

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 28, 8:06 PM MDT	Mesoscale Discussion	SPC	Arthur, Chase, Cherry, Dawson, Deuel, Dundy and 17 more	114 min
Mar 28, 10:07 PM MDT	Mesoscale Discussion	SPC	Blaine, Brown, Cherry, Custer, Dawson, Frontier and 14 more	113 min
Mar 28, 10:51 PM MDT	Tornado Watch	SPC	Furnas, Hitchcock, Red Willow	4 hr
Mar 29, 5:51 PM MDT	Mesoscale Discussion	SPC	Arthur, Dawson, Frontier, Furnas, Garden, Gosper and 9 more	2 hr

Nearby

Tornado Watches in Nebraska, 2007 Tornado Watches in South Dakota, 2007 Every tornado 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.