Severe Thunderstorm Watch 27

Issued

Feb 18, 2012, 4:46 AM CST (10:46 UTC)

Expired

Feb 18, 2012, 10:00 AM CST

In force

5 hr

Issued by

the Storm Prediction Center

Largest hail expected

1.5 in

Strongest gust expected

60 kt

Counties Acadia Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, Jefferson Davis Parish, LA, Vermilion Parish, LA, Brazoria County, TX, Chambers County, TX, Fort Bend County, TX, Galveston County, TX, Hardin County, TX, Harris County, TX, Jackson County, TX, Jefferson County, TX, Liberty County, TX, Matagorda County, TX, Montgomery County, TX, Orange County, TX, San Jacinto County, TX, Wharton County, TX

The Houston radar (KHGX), 29 km from the middle of the area, began a volume at 10:50 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.

Two or more tornadoes

20%

One or more EF2 to EF5 tornadoes

5%

Ten or more severe wind reports

30%

One or more gusts of 65 knots or more

20%

Ten or more severe hail reports

30%

One or more hailstones of 2 inches or more

5%

Six or more combined severe hail and wind reports

70%

• Mesoscale Discussion 123Feb 18, 4:35 AM CST
• Mesoscale Discussion 124Feb 18, 8:29 AM CST
• Mesoscale Discussion 125Feb 18, 9:31 AM CST

529 
WWUS20 KWNS 181046
SEL7
SPC WW 181046
LAZ000-TXZ000-CWZ000-181500-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 27
NWS STORM PREDICTION CENTER NORMAN OK
450 AM CST SAT FEB 18 2012

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

       SOUTHWEST LOUISIANA
       SOUTHEAST TEXAS
       COASTAL WATERS

EFFECTIVE THIS SATURDAY MORNING FROM 450 AM UNTIL 900 AM CST.

HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 60
STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES NORTH OF PORT
ARTHUR TEXAS TO 25 MILES EAST SOUTHEAST OF PALACIOS TEXAS.  FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU7).

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.

DISCUSSION...A LINE OF INTENSE THUNDERSTORMS HAS DEVELOPED
ALONG/AHEAD OF SURFACE COLD FRONT SURGING EASTWARD ACROSS SOUTHEAST
TX.  THE SURFACE AIR MASS AHEAD OF THE STORMS IS ONLY MARGINALLY
UNSTABLE AT BEST.  HOWEVER...INCREASING MESOSCALE ORGANIZATION OF
THE LINE SUGGESTS SOME POTENTIAL OF DAMAGING WIND GUSTS REACHING THE
SURFACE.  OTHERWISE...HAIL WILL ALSO BE POSSIBLE IN THE STRONGER
CELLS.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM
MOTION VECTOR 25040.


...HART

Severe Thunderstorm Watches in Texas, 2012Severe Thunderstorm Watches in Louisiana, 2012Every severe thunderstorm watch in 2012

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.