Alert archive / Texas / Tornado Watches in 1997

Tornado Watch 804

December 20, 199729 counties in Texas

The Storm Prediction Center issued this tornado watch at Dec 20, 1997, 5:30 PM CST for 29 counties in Texas. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Dec 20, 1997, 5:30 PM CST (23:30 UTC)
Expired
Dec 20, 1997, 11:00 PM CST
In force
6 hr
Issued by
the Storm Prediction Center
All 29 counties

Atascosa County, TX, Bastrop County, TX, Bee County, TX, Bexar County, TX, Blanco County, TX, Burnet County, TX, Caldwell County, TX, Comal County, TX, DeWitt County, TX, Frio County, TX, Gillespie County, TX, Goliad County, TX, Gonzales County, TX, Guadalupe County, TX, Hays County, TX, Karnes County, TX, Kendall County, TX, La Salle County, TX, Lee County, TX, Live Oak County, TX, Llano County, TX, McMullen County, TX, Medina County, TX, Milam County, TX, Refugio County, TX, San Patricio County, TX, Travis County, TX, Williamson County, TX, Wilson County, TX

The radar

The Austin/San Antonio radar (KEWX), 63 km from the middle of the area, began a volume at 23:32 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

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

IssuedProductOfficeCountiesLasted
Dec 20, 5:32 PM CSTSevere Thunderstorm WarningEWXFrio43 min
Dec 20, 5:46 PM CSTSevere Thunderstorm WarningEWXAtascosa44 min
Dec 20, 6:17 PM CSTFlash Flood WarningEWXBurnet, Williamson3 hr
Dec 20, 8:31 PM CSTFlash Flood WarningEWXTravis119 min
Dec 20, 8:52 PM CSTFlash Flood WarningFWDMilam3 hr
Dec 20, 9:11 PM CSTTornado WarningFWDMilam64 min

The nearest sounding before it

Corpus Christi, TX (KCRP), launched 12:00Z, 11.5 hours before the alert went out and 188 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, Corpus Christi, TX at 12:00Z on 1997-12-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 393 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, Corpus Christi, TX at 12:00Z on 1997-12-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 177 square meters per square second.1939587897117Sfc1 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
393 J/kg
Mixed-layer CIN
-3 J/kg
Mixed-layer LCL
593 m above ground
0-6 km bulk shear
45 kt
0-1 km storm-relative helicity
177 m²/s²
0-3 km storm-relative helicity
206 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.2

Open this sounding in Storm Lab

The text

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

794 
WWUS9 KMKC 202307
SEL4  
MKC WW 202307
TXZ000-210500-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 804
STORM PREDICTION CENTER NORMAN OK
507 PM CST SAT DEC 20 1997

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

   CENTRAL AND SOUTH CENTRAL TEXAS                              

EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 530 PM UNTIL
1100 PM CST.

TORNADOES...HAIL TO 1 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 80 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 40 MILES SOUTHWEST OF BEEVILLE TEXAS TO 55 MILES
NORTH NORTHWEST OF AUSTIN 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...LINE OF THUNDERSTORMS IS INCREASING AHEAD OF COLD
FRONT AND IN ASSOCIATION WITH STRONG UPPER SYSTEM. STRONG HEATING
TODAY HAS LED TO MODERATE INSTABILITY WITH SURFACE BASED CAPES OF
1500 J/KG. WIND PROFILES ARE BECOMING INCREASINGLY FAVORABLE FOR
SEVERE THUNDERSTORMS...INCLUDING SUPERCELLS AS MID LEVEL JET MAX
MOVES ACROSS THE AREA.


AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 1 INCHES.  EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 70 KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 480. 
MEAN STORM MOTION VECTOR 24030.


...VESCIO

275,0991 310,0990 310,0965 275,0970

Nearby

Tornado Watches in Texas, 1997Every tornado watch in 1997

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.