Tornado Watch 315

Issued

May 20, 2011, 5:56 PM CDT (22:56 UTC)

Expired

May 20, 2011, 9:23 PM CDT

In force

3 hr

Issued by

the Storm Prediction Center

Largest hail expected

2 in

Strongest gust expected

60 kt

The Shreveport radar (KSHV), 128 km from the middle of the area, began a volume at 22:57 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

30%

One or more EF2 to EF5 tornadoes

20%

Ten or more severe wind reports

30%

One or more gusts of 65 knots or more

30%

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%

• Mesoscale Discussion 829May 20, 4:00 PM CDT
• Mesoscale Discussion 830May 20, 5:34 PM CDT
• Mesoscale Discussion 832May 20, 9:06 PM CDT

157 
WWUS20 KWNS 202255
SEL5  
SPC WW 202255
ARZ000-LAZ000-OKZ000-TXZ000-210500-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 315
NWS STORM PREDICTION CENTER NORMAN OK
555 PM CDT FRI MAY 20 2011

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

       CENTRAL AND SOUTHWEST ARKANSAS
       EXTREME NORTHWEST LOUISIANA
       EXTREME SOUTHEAST OKLAHOMA
       NORTHEAST TEXAS

EFFECTIVE THIS FRIDAY AFTERNOON FROM 555 PM UNTIL MIDNIGHT CDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 75 STATUTE
MILES EAST AND WEST OF A LINE FROM 25 MILES WEST NORTHWEST OF HOT
SPRINGS ARKANSAS TO 30 MILES SOUTH OF LONGVIEW TEXAS.  FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU5).

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.

OTHER WATCH INFORMATION...THIS TORNADO WATCH REPLACES TORNADO
WATCH NUMBER 312. WATCH NUMBER 312 WILL NOT BE IN EFFECT AFTER
555 PM CDT. CONTINUE...WW 313...WW 314...

DISCUSSION...SEVERAL STORM CLUSTERS AND ASSOCIATED CONVECTIVE
OUTFLOWS WILL PERSIST ACROSS THE ARKLATEX REGION FOR THE NEXT FEW
HOURS.  A RESERVOIR OF MODERATE-STRONG INSTABILITY AND RICH BOUNDARY
LAYER MOISTURE WILL MAINTAIN A RISK FOR STORMS CAPABLE OF PRODUCING
OCCASIONAL LARGE HAIL AND DAMAGING WINDS.  ADDITIONALLY...DESPITE
WEAK FLOW ALOFT...VERTICAL SHEAR IN THE LOW-MIDLEVELS WILL REMAIN
SUFFICIENT FOR ROTATING STORMS AND THE RISK FOR A TORNADO OR
TWO...ESPECIALLY WHERE STORMS INTERACT WITH THE PRE-EXISTING OUTFLOW
BOUNDARY IN AR.

AVIATION...TORNADOES AND 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
600. MEAN STORM MOTION VECTOR 24025.


...THOMPSON

Tornado Watches in Arkansas, 2011Tornado Watches in Texas, 2011Tornado Watches in Louisiana, 2011Every tornado watch in 2011

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.