Alert archive / Texas / Tornado Watches in 2004

Tornado Watch 878

November 17, 200418 counties in Texas

The Storm Prediction Center issued this tornado watch at Nov 17, 2004, 10:05 AM CST for 18 counties in Texas. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Nov 17, 2004, 10:05 AM CST (16:05 UTC)
Expired: Nov 17, 2004, 4:00 PM CST
In force: 6 hr
Issued by: the Storm Prediction Center

Counties Austin County, TX, Brazoria County, TX, Brazos County, TX, Burleson County, TX, Chambers County, TX, Colorado County, TX, Fort Bend County, TX, Galveston County, TX, Grimes County, TX, Harris County, TX, Jackson County, TX, Liberty County, TX, Matagorda County, TX, Montgomery County, TX, San Jacinto County, TX, Waller County, TX, Washington County, TX, Wharton County, TX

The radar

The Houston radar (KHGX), 46 km from the middle of the area, began a volume at 16:09 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

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

Issued	Product	Office	Counties	Lasted
Nov 17, 10:13 AM CST	Tornado Warning	HGX	Chambers, Harris, Liberty	32 min
Nov 17, 1:31 PM CST	Tornado Warning	HGX	Liberty	29 min
Nov 17, 3:04 PM CST	Severe Thunderstorm Warning	HGX	Harris	26 min
Nov 17, 3:31 PM CST	Tornado Warning	HGX	Montgomery	29 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

Lake Charles Mun, LA (KLCH), launched 12:00Z, 4.1 hours before the alert went out and 210 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 801 m above ground
0-6 km bulk shear: 17 kt
0-1 km storm-relative helicity: 101 m²/s²
0-3 km storm-relative helicity: 117 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 171605
SEL8  
SPC WW 171605
TXZ000-CWZ000-172200-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 878
NWS STORM PREDICTION CENTER NORMAN OK
1005 AM CST WED NOV 17 2004

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

       SOUTHEAST TEXAS
       COASTAL WATERS

EFFECTIVE THIS WEDNESDAY MORNING AND AFTERNOON FROM 1005 AM UNTIL
400 PM CST.

TORNADOES...HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 65 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 65 STATUTE MILES EAST AND WEST
OF A LINE FROM 45 MILES EAST NORTHEAST OF COLLEGE STATION TEXAS TO
50 MILES EAST SOUTHEAST OF PALACIOS 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.

DISCUSSION...THREAT FOR A FEW TORNADOES IS EXPECTED TO INCREASE THIS
THROUGH EARLY-MID AFTERNOON AS THE LOW LEVELS DESTABILIZE AND STORM
COVERAGE INCREASES ACROSS SE TX.  LOW-LEVEL SHEAR WILL BE STRONGEST
ALONG A NW-SE ORIENTED WARM FRONT THROUGH THE HOUSTON AREA...WHERE
THE TORNADO THREAT WILL BE MOST FOCUSED FOR THE NEXT FEW HOURS. 
HOWEVER...ADDITIONAL WARM SECTOR STORMS SHOULD FORM THROUGH EARLY
AFTERNOON IN THE AREA BETWEEN HOU-VCT-CLL...WHERE A TORNADO OR TWO
AND ISOLATED DAMAGING WINDS WILL ALSO BE POSSIBLE.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 55 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500.
MEAN STORM MOTION VECTOR 20020.


...THOMPSON

304,0943 282,0942 282,0963 304,0964

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Nov 17, 1:11 AM CST	Mesoscale Discussion	SPC	Aransas, Bee, Calhoun, Goliad, Kleberg, Nueces and 3 more	94 min
Nov 17, 9:36 AM CST	Mesoscale Discussion	SPC	Aransas, Austin, Brazoria, Brazos, Burleson, Calhoun and 27 more	114 min
Nov 17, 12:26 PM CST	Mesoscale Discussion	SPC	Austin, Brazoria, Chambers, Colorado, Fort Bend, Galveston and 11 more	94 min
Nov 17, 3:10 PM CST	Mesoscale Discussion	SPC	Brazoria, Chambers, Fort Bend, Galveston, Hardin, Harris and 7 more	65 min

Nearby

Tornado Watches in Texas, 2004 Every tornado watch in 2004

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.