Friday, July 26, 2013

WATCHES: Severe Thunderstorm Watch Number 447

WWUS20 KWNS 262040
SEL7
SPC WW 262040
ARZ000-LAZ000-OKZ000-TXZ000-270400-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 447
NWS STORM PREDICTION CENTER NORMAN OK
340 PM CDT FRI JUL 26 2013

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
EXTREME SOUTHWESTERN ARKANSAS
NORTHWESTERN LOUISIANA
SMALL PART OF SOUTHERN OKLAHOMA
NORTH-CENTRAL AND NORTHEAST TEXAS

* EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 340 PM UNTIL
1100 PM CDT.

* PRIMARY THREATS INCLUDE...
SEVERAL DAMAGING WIND GUSTS WITH A FEW SIGNIFICANT GUSTS TO 75
MPH POSSIBLE
SEVERAL LARGE HAIL EVENTS WITH A FEW VERY LARGE HAIL EVENTS TO 2
INCHES IN DIAMETER POSSIBLE

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 55
STATUTE MILES EITHER SIDE OF A LINE FROM 30 MILES SOUTH SOUTHWEST
OF SHERMAN TEXAS TO 20 MILES EAST NORTHEAST OF SHREVEPORT
LOUISIANA. 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.

&&

DISCUSSION...TSTMS FCST TO EXPAND IN COVERAGE AND INCREASE IN
INTENSITY DURING REMAINDER AFTERNOON. MULTICELL CLUSTERS AND A
COUPLE OF SUPERCELLS ARE POSSIBLE...OFFERING MOSTLY DAMAGING GUSTS
AND OCNL HAIL. A TORNADO CANNOT BE RULED OUT...MAINLY INVOF
QUASISTATIONARY OUTFLOW/DIFFERENTIAL HEATING-BOUNDARY ARCHING FROM
LAKE TEXOMA AREA SEWD TO NEAR SHV. AIR MASS NEAR THAT BOUNDARY WILL
BE CHARACTERIZED BY SLY/SELY SFC FLOW...MAXIMIZING LOW-LEVEL
STORM-RELATIVE INFLOW AND DEEP BULK SHEAR. AIR MASS BETWEEN THAT
BOUNDARY AND COLD FRONT NOW APCHG METROPLEX WILL BE CHARACTERIZED BY
2000-3000 J/KG MLCAPE AND 35-50 KT EFFECTIVE SHEAR MAGNITUDES.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM
MOTION VECTOR 30025.


...EDWARDS

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