Alert archive / Texas / Severe Thunderstorm Warnings in 1999

Severe Thunderstorm Warning 21, NWS Austin/San Antonio, TX

March 12, 1999Llano County, Texas

NWS Austin/San Antonio, TX issued this severe thunderstorm warning at Mar 12, 1999, 4:03 PM CST for Llano County, Texas. It was in force for 62 min. 1 report came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued
Mar 12, 1999, 4:03 PM CST (22:03 UTC)
Expired
Mar 12, 1999, 5:05 PM CST
In force
62 min
Issued by
NWS Austin/San Antonio, TX
Area
Whole counties

County Llano County, TX

The radar

The Ft Hood radar (KGRK), 124 km from the middle of the area, began a volume at 22:06 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 was reported inside it

TimeReportWhereRemark
Mar 12, 4:10 PM CSTHail 1.75Tow, TX

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Mar 12, 10:45 AM CSTTornado WatchSPC6 hr
Mar 12, 3:45 PM CSTTornado WatchSPC5 hr

The nearest sounding before it

Del Rio, TX (KDRT), launched 12:00Z, 10.1 hours before the alert went out and 255 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, Del Rio, TX at 12:00Z on 1999-03-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2301 joules per kilogram.LCLEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Del Rio, TX at 12:00Z on 1999-03-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 207 square meters per square second.1939587897Sfc1 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
2301 J/kg
Mixed-layer CIN
0 J/kg
Mixed-layer LCL
550 m above ground
0-6 km bulk shear
52 kt
0-1 km storm-relative helicity
207 m²/s²
0-3 km storm-relative helicity
328 m²/s²
Significant tornado parameter
4.5
Supercell composite
17.6

Open this sounding in Storm Lab

The text

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

999 
WUUS1 KSAT 122201 RRA
SVRSAT
TXC299-122305-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
403 PM CST FRI MAR 12 1999

THE NATIONAL WEATHER SERVICE IN AUSTIN/SAN ANTONIO HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  LLANO IN TEXAS

* UNTIL 505 PM CST

* AT 400 PM CST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM 10 MILES NORTH OF LLANO... MOVING EAST AT 20
  MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  TOW AT 420 PM

DAMAGING WINDS AND LARGE HAIL ARE LIKELY. GO INSIDE A STURDY
BUILDING AND STAY AWAY FROM WINDOWS

MSF

The office that day

Everything else NWS Austin/San Antonio, TX issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Mar 12, 11:09 AM CSTSevere Thunderstorm WarningEWXBurnet, Williamson41 min
Mar 12, 12:34 PM CSTSevere Thunderstorm WarningEWXVal Verde61 min
Mar 12, 12:39 PM CSTSevere Thunderstorm WarningEWXBurnet46 min
Mar 12, 1:15 PM CSTSevere Thunderstorm WarningEWXEdwards60 min
Mar 12, 1:47 PM CSTTornado WarningEWXEdwards, Val Verde63 min
Mar 12, 2:50 PM CSTSevere Thunderstorm WarningEWXEdwards, Kinney, Real, Val Verde60 min
Mar 12, 3:39 PM CSTSevere Thunderstorm WarningEWXBurnet61 min
Mar 12, 3:53 PM CSTTornado WarningEWXKinney42 min
Mar 12, 4:17 PM CSTSevere Thunderstorm WarningEWXUvalde58 min
Mar 12, 4:45 PM CSTSevere Thunderstorm WarningEWXBurnet60 min
Mar 12, 5:16 PM CSTSevere Thunderstorm WarningEWXUvalde59 min
Mar 12, 5:21 PM CSTTornado WarningEWXBurnet, Travis64 min
Mar 12, 5:35 PM CSTTornado WarningEWXMedina, Uvalde60 min

Nearby

Severe Thunderstorm Warnings in Texas, 1999Every severe thunderstorm warning in 1999

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.