Alert archive / Texas / Tornado Watches in 2015

Tornado Watch 520

October 24, 201515 counties in Texas

The Storm Prediction Center issued this tornado watch at Oct 24, 2015, 2:44 PM CDT for 15 counties in Texas. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: Oct 24, 2015, 2:44 PM CDT (19:44 UTC)
Expired: Oct 24, 2015, 10:00 PM CDT
In force: 7 hr
Issued by: the Storm Prediction Center
Largest hail expected: 0.5 in
Strongest gust expected: 55 kt

Counties Aransas County, TX, Brazoria County, TX, Calhoun County, TX, Chambers County, TX, Fort Bend County, TX, Galveston County, TX, Harris County, TX, Jackson County, TX, Kleberg County, TX, Matagorda County, TX, Nueces County, TX, Refugio County, TX, San Patricio County, TX, Victoria County, TX, Wharton County, TX

The radar

The Corpus Christi radar (KCRP), 119 km from the middle of the area, began a volume at 19:48 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: 50%
One or more EF2 to EF5 tornadoes: 20%
Ten or more severe wind reports: 20%
One or more gusts of 65 knots or more: 10%
Ten or more severe hail reports: 5%
One or more hailstones of 2 inches or more: 5%
Six or more combined severe hail and wind reports: 50%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Oct 24, 3:10 PM CDT	Flash Flood Warning	CRP	Aransas, Goliad, Nueces, Refugio, San Patricio, Victoria	3 hr
Oct 24, 3:25 PM CDT	Tornado Warning	HGX	Brazoria, Matagorda	35 min
Oct 24, 3:32 PM CDT	Tornado Warning	CRP	Nueces	13 min
Oct 24, 3:44 PM CDT	Tornado Warning	CRP	Aransas, San Patricio	31 min
Oct 24, 4:25 PM CDT	Flash Flood Warning	CRP	Kleberg, Nueces	2 hr
Oct 24, 5:14 PM CDT	Flash Flood Warning	HGX	Brazoria, Fort Bend, Jackson, Matagorda, Wharton	3 hr
Oct 24, 7:20 PM CDT	Flash Flood Warning	HGX	Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty and 3 more	3 hr
Oct 24, 8:18 PM CDT	Flash Flood Warning	HGX	Brazoria, Fort Bend, Jackson, Matagorda, Wharton	3 hr

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, 7.7 hours before the alert went out and 111 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: 1121 J/kg
Mixed-layer CIN: -4 J/kg
Mixed-layer LCL: 628 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 87 m²/s²
0-3 km storm-relative helicity: 140 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 3.8

Open this sounding in Storm Lab

The text

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

932 
WWUS20 KWNS 241941
SEL0  
SPC WW 241941
TXZ000-CWZ000-250300-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 520
NWS STORM PREDICTION CENTER NORMAN OK
240 PM CDT SAT OCT 24 2015

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* TORNADO WATCH FOR PORTIONS OF 
  COASTAL TEXAS
  COASTAL WATERS

* EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 240 PM UNTIL
  1000 PM CDT.

* PRIMARY THREATS INCLUDE...
  A FEW TORNADOES POSSIBLE
  ISOLATED DAMAGING WIND GUSTS TO 65 MPH POSSIBLE

SUMMARY...RISK FOR ISOLATED TORNADOES IS EXPECTED TO GRADUALLY
INCREASE OVER THE NEXT SEVERAL HOURS AS THE REMNANT CENTER OF
HURRICANE PATRICIA EMERGES INTO THE WESTERN GULF OF MEXICO.  THE
PRIMARY RISK WILL BE ALONG COASTAL COUNTIES...LASTING THROUGH THE
AFTERNOON AND INTO THE EVENING HOURS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 60 STATUTE
MILES EITHER SIDE OF A LINE FROM 45 MILES SOUTH OF CORPUS CHRISTI
TEXAS TO 45 MILES NORTHEAST OF HOUSTON TEXAS.  FOR A COMPLETE
DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
(WOUS64 KWNS WOU0).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

&&

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
600. MEAN STORM MOTION VECTOR 16020.


...GOSS

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Oct 24, 12:50 PM CDT	Mesoscale Discussion	SPC	Aransas, Brazoria, Brooks, Calhoun, Cameron, Galveston and 10 more	2 hr
Oct 24, 6:14 PM CDT	Mesoscale Discussion	SPC	Aransas, Brazoria, Calhoun, Chambers, Fort Bend, Galveston and 5 more	91 min

Nearby

Tornado Watches in Texas, 2015 Every tornado watch in 2015

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.