Alert archive / Texas / Tornado Watches in 2002

Tornado Watch 675

September 7, 200222 counties in Texas

The Storm Prediction Center issued this tornado watch at Sep 7, 2002, 10:40 AM CDT for 22 counties in Texas. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Sep 7, 2002, 10:40 AM CDT (15:40 UTC)
Expired: Sep 7, 2002, 4:00 PM CDT
In force: 5 hr
Issued by: the Storm Prediction Center

All 22 counties

Austin County, TX, Brazos County, TX, Burleson County, TX, Chambers County, TX, Colorado County, TX, Fayette County, TX, Fort Bend County, TX, Galveston County, TX, Grimes County, TX, Hardin County, TX, Harris County, TX, Jefferson County, TX, Lee County, TX, Liberty County, TX, Milam County, TX, Montgomery County, TX, Orange County, TX, Robertson County, TX, San Jacinto County, TX, Walker County, TX, Waller County, TX, Washington County, TX

The radar

The Houston radar (KHGX), 109 km from the middle of the area, began a volume at 15:43 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.

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Sep 7, 1:38 PM CDT	Flash Flood Warning	HGX	Waller, Washington	3 hr

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 3.7 hours before the alert went out and 246 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: 301 J/kg
Mixed-layer CIN: -45 J/kg
Mixed-layer LCL: 917 m above ground
0-6 km bulk shear: 17 kt
0-1 km storm-relative helicity: 35 m²/s²
0-3 km storm-relative helicity: 62 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 071543
SEL5  
SPC WW 071540
TXZ000-CWZ000-072100-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 675
STORM PREDICTION CENTER NORMAN OK
1040 AM CDT SAT SEP 7 2002

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

   SOUTHEAST TEXAS                              
   COASTAL WATERS                     

EFFECTIVE THIS SATURDAY MORNING AND AFTERNOON FROM 1040 AM UNTIL
400 PM CDT.

TORNADOES...HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 55 STATUTE MILES NORTH AND
SOUTH OF A LINE FROM 45 MILES WEST SOUTHWEST OF COLLEGE STATION
TEXAS TO 20 MILES SOUTHEAST OF PORT ARTHUR TEXAS.

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 674.  WATCH NUMBER 674 WILL NOT BE IN EFFECT AFTER 1040 AM
CDT.

DISCUSSION...SCATTERED THUNDERSTORMS EXPECTED TO PERSIST/DEVELOP
INVOF WEAK WARM FRONT/SHEAR AXIS EXTENDING E FROM CIRCULATION
CENTER OF T.S. FAY...ATTM LOCATED ABOUT 50 E SAT.  UPPER LEVEL DRY
SLOT HAS ROTATED NNEWD ACROSS SHEAR AXIS.  THIS MAY ALLOW SURFACE
HEATING/DESTABLIZATION TO OFFSET GRADUAL WEAKENING OF T.S.
CIRCULATION...AND THEREBY MAINTAIN A THREAT FOR ISOLATED TORNADOES
OVER PARTS OF SE TX THROUGH THIS AFTERNOON.  

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 0.5 INCH...EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 60 KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. 
MEAN STORM MOTION VECTOR 12020.

...CORFIDI

310,0970 303,0934 285,0934 293,0970

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 6, 7:15 PM CDT	Tornado Watch	SPC	Austin, Brazoria, Chambers, Colorado, Fort Bend, Galveston and 9 more	5 hr
Sep 6, 11:35 PM CDT	Tornado Watch	SPC	Austin, Brazoria, Chambers, Colorado, Fayette, Fort Bend and 10 more	8 hr
Sep 7, 6:15 AM CDT	Tornado Watch	SPC	Atascosa, Austin, Bexar, Brazoria, Colorado, DeWitt and 11 more	6 hr

Nearby

Tornado Watches in Texas, 2002 Every tornado 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.