Alert archive / Texas / Severe Thunderstorm Watches in 2002

Severe Thunderstorm Watch 686

September 18, 2002Beckham County, Oklahoma; 22 counties in Texas

The Storm Prediction Center issued this severe thunderstorm watch at Sep 18, 2002, 5:00 PM CDT for Beckham County, Oklahoma; 22 counties in Texas. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Sep 18, 2002, 5:00 PM CDT (22:00 UTC)
Expired: Sep 18, 2002, 10:00 PM CDT
In force: 5 hr
Issued by: the Storm Prediction Center

All 23 counties

Beckham County, OK, Armstrong County, TX, Briscoe County, TX, Castro County, TX, Childress County, TX, Cochran County, TX, Collingsworth County, TX, Crosby County, TX, Dickens County, TX, Donley County, TX, Floyd County, TX, Garza County, TX, Hale County, TX, Hall County, TX, Hockley County, TX, Lamb County, TX, Lubbock County, TX, Lynn County, TX, Motley County, TX, Randall County, TX, Swisher County, TX, Terry County, TX, Yoakum County, TX

The radar

The Lubbock radar (KLBB), 34 km from the middle of the area, began a volume at 21:59 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.

The nearest sounding before it

Amarillo Airport, TX (KAMA), launched 12:00Z, 10.0 hours before the alert went out and 142 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: 49 J/kg
Mixed-layer CIN: -471 J/kg
Mixed-layer LCL: 2468 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 0 m²/s²
0-3 km storm-relative helicity: 52 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

000 
WWUS20 KWNS 182202
SEL6  
SPC WW 182200
TXZ000-190300-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 686
STORM PREDICTION CENTER NORMAN OK
500 PM CDT WED SEP 18 2002

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

   WESTERN AND NORTHWEST TEXAS                              

EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 500 PM UNTIL
1000 PM CDT.

HAIL TO 1 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 65 STATUTE MILES
EAST AND WEST OF A LINE FROM 50 MILES SOUTH SOUTHWEST OF LUBBOCK
TEXAS TO 55 MILES EAST NORTHEAST OF AMARILLO TEXAS.

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 684...WW 685...

DISCUSSION...THUNDERSTORMS DEVELOPING ALONG THE NM/TX
BORDER...ALONG WRN-MOST COLD SURGE ASSOCIATED WITH STRONG TROUGH
CROSSING THE 4 CORNERS REGION...EXPECTED TO INTENSIFY AS ACTIVITY
CONTINUES NEWD.  LARGE TEMPERATURE/DEW POINT SPREADS...MODERATE
DEEP SHEAR AND LARGE SCALE ASCENT APPEAR SUPPORTIVE OF BANDS OF
STORMS WITH HIGH WINDS AND SOME HAIL.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 1 INCH EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS. 
A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500.  MEAN STORM MOTION
VECTOR 24035.

...CORFIDI

353,0993 330,1010 330,1031 353,1015

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 18, 3:30 PM CDT	Severe Thunderstorm Watch	SPC	Alfalfa, Beckham, Blaine, Caddo, Canadian, Comanche and 18 more	6 hr

Nearby

Severe Thunderstorm Watches in Texas, 2002 Severe Thunderstorm Watches in Oklahoma, 2002 Every severe thunderstorm watch in 2002

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.