Alert archive / Texas / Severe Thunderstorm Watches in 2016

Severe Thunderstorm Watch 97

April 18, 201613 counties in Texas

The Storm Prediction Center issued this severe thunderstorm watch at Apr 18, 2016, 3:21 PM CDT for 13 counties in Texas. It was in force for 8 hr.

The area

The outline as issued.

The facts

Issued
Apr 18, 2016, 3:21 PM CDT (20:21 UTC)
Expired
Apr 18, 2016, 11:00 PM CDT
In force
8 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
60 kt

Counties Brooks County, TX, Cameron County, TX, Duval County, TX, Hidalgo County, TX, Jim Hogg County, TX, Jim Wells County, TX, Kenedy County, TX, La Salle County, TX, McMullen County, TX, Starr County, TX, Webb County, TX, Willacy County, TX, Zapata County, TX

The radar

The Corpus Christi radar (KCRP), 144 km from the middle of the area, began a volume at 20:20 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 SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes
10%
One or more EF2 to EF5 tornadoes
2%
Ten or more severe wind reports
40%
One or more gusts of 65 knots or more
10%
Ten or more severe hail reports
40%
One or more hailstones of 2 inches or more
30%
Six or more combined severe hail and wind reports
70%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Apr 18, 3:30 PM CDTSevere Thunderstorm WarningCRPWebb45 min
Apr 18, 3:55 PM CDTTornado WarningCRPWebb35 min
Apr 18, 4:21 PM CDTTornado WarningCRPWebb24 min
Apr 18, 4:44 PM CDTTornado WarningCRPWebb31 min
Apr 18, 5:05 PM CDTSevere Thunderstorm WarningCRPJim Wells, Kleberg, Nueces40 min
Apr 18, 5:15 PM CDTSevere Thunderstorm WarningCRPWebb35 min
Apr 18, 5:45 PM CDTSevere Thunderstorm WarningBROBrooks, Jim Hogg60 min
Apr 18, 5:48 PM CDTSevere Thunderstorm WarningBROHidalgo57 min
Apr 18, 5:51 PM CDTSevere Thunderstorm WarningBROStarr54 min
Apr 18, 5:51 PM CDTSevere Thunderstorm WarningBROStarr54 min
Apr 18, 6:31 PM CDTSevere Thunderstorm WarningBROStarr29 min
Apr 18, 6:47 PM CDTSevere Thunderstorm WarningBROHidalgo, Starr58 min
Apr 18, 7:21 PM CDTFlash Flood WarningBROStarr114 min
Apr 18, 7:46 PM CDTSevere Thunderstorm WarningBROHidalgo, Starr59 min
Apr 18, 8:40 PM CDTSevere Thunderstorm WarningBROCameron1 min
Apr 18, 8:45 PM CDTSevere Thunderstorm WarningBROCameron45 min
Apr 18, 9:34 PM CDTSevere Thunderstorm WarningBROZapata56 min
Apr 18, 10:14 PM CDTSevere Thunderstorm WarningBROCameron31 min
Apr 18, 10:14 PM CDTSevere Thunderstorm WarningBROZapata38 min
Apr 18, 10:45 PM CDTFlash Flood WarningBROCameron2 hr
Apr 18, 10:46 PM CDTSevere Thunderstorm WarningBROCameron44 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

Corpus Christi, TX (KCRP), launched 12:00Z, 8.4 hours before the alert went out and 157 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 2016-04-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2403 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 2016-04-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 60 square meters per square second.193958Sfc1 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
2403 J/kg
Mixed-layer CIN
-24 J/kg
Mixed-layer LCL
614 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
60 m²/s²
0-3 km storm-relative helicity
186 m²/s²
Significant tornado parameter
0.7
Supercell composite
3.2

Open this sounding in Storm Lab

The text

As transmitted.

051 
WWUS20 KWNS 182019
SEL7  
SPC WW 182019
TXZ000-190400-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 97
NWS STORM PREDICTION CENTER NORMAN OK
320 PM CDT MON APR 18 2016

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF 
  SOUTH TEXAS

* EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 320 PM UNTIL
  1100 PM CDT.

* PRIMARY THREATS INCLUDE...
  SCATTERED LARGE HAIL AND ISOLATED VERY LARGE HAIL EVENTS TO 2
    INCHES IN DIAMETER POSSIBLE
  SCATTERED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE

SUMMARY...THUNDERSTORMS ARE DEVELOPING ACROSS SOUTH TX IN A VERY
MOIST AND MODERATELY UNSTABLE AIR MASS.  A FEW OF THESE STORMS MAY
BECOME SEVERE...CAPABLE OF DAMAGING WINDS AND HAIL THROUGH THE LATE
AFTERNOON AND EVENING HOURS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 45
STATUTE MILES EAST AND WEST OF A LINE FROM 45 MILES NORTH
NORTHEAST OF LAREDO TEXAS TO 25 MILES SOUTHEAST OF MCALLEN TEXAS.
 FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU7).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

&&

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 29030.


...HART

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 17, 8:21 PM CDTMesoscale DiscussionSPCStarr, Zapata84 min
Apr 18, 12:02 AM CDTMesoscale DiscussionSPCHarris, Liberty, Montgomery, San Jacinto118 min
Apr 18, 4:29 AM CDTMesoscale DiscussionSPCKinney, Medina, Uvalde61 min
Apr 18, 5:10 AM CDTMesoscale DiscussionSPCFort Bend, Harris, Liberty95 min
Apr 18, 12:57 PM CDTMesoscale DiscussionSPCBrooks, Cameron, Dimmit, Duval, Hidalgo, Jim Hogg and 10 more2 hr
Apr 18, 5:54 PM CDTMesoscale DiscussionSPCBrooks, Cameron, Dimmit, Duval, Hidalgo, Jim Hogg and 10 more2 hr

Nearby

Severe Thunderstorm Watches in Texas, 2016Every severe thunderstorm watch in 2016

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.