STORM2K

MESOSCALE DISCUSSION 0410
NWS STORM PREDICTION CENTER NORMAN OK
0213 PM CDT WED APR 21 2004

AREAS AFFECTED...MUCH OF AR AND EXTREME SOUTH CENTRAL MO

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 211913Z - 212045Z

...THUNDERSTORMS ARE INCREASING ACROSS WRN/NWRN AR...

WARM ADVECTION ATOP CONVECTIVELY-COOLED LOW LEVEL AIRMASS OVER
CENTRAL AR HAS MAINTAINED SIGNIFICANT CLOUD COVER AND SLOWED
DESTABILIZATION. HOWEVER...MUCH OF WRN INTO NRN AR HAS DESTABILIZED
SIGNIFICANTLY OVER THE LAST FEW HOURS WITH VERY STEEP LAPSE RATES
NOW EVIDENT...SFC-3KM VALUES AROUND 8C/KM. IT APPEARS SYNOPTIC
BOUNDARY DRAPED INTO NWRN AR WILL PROVE SIGNIFICANT IN CONVECTIVE
INITIATION OVER THE NEXT 1-2 HOURS...WITH ADDITIONAL DEVELOPMENT
POSSIBLE INTO WRN-SWRN AR IN THE NEXT FEW HOURS. TORNADO WATCH MAY
BE ISSUED SHORTLY.

..DARROW.. 04/21/2004


ATTN...WFO...LZK...SGF...SHV...TSA...

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

MUCH OF ARKANSAS
EXTREME SOUTHEAST OKLAHOMA

EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 240 PM UNTIL
900 PM CDT.

TORNADOES...HAIL TO 3 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 85 STATUTE MILES EAST AND WEST
OF A LINE FROM 15 MILES NORTH NORTHEAST OF HARRISON ARKANSAS TO 15
MILES SOUTH SOUTHEAST OF EL DORADO ARKANSAS.

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...CONTINUE...WW 98...

DISCUSSION...AIRMASS OVER MUCH OF AR CONTINUES TO DESTABILIZE WITH
SBCAPE VALUES OF 1500-2500 J/KG. WEAK CAP AND FORCING ALONG SEVERAL
REMNANT BOUNDARIES WILL LIKELY RESULT IN SCATTERED STRONG/SEVERE
THUNDERSTORMS IN THE NEXT FEW HOURS. SUPERCELLS ARE LIKELY...WITH
THE THREAT OF ISOLATED TORNADOES IN STRONGER CELLS.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500.
MEAN STORM MOTION VECTOR 27030.


...HART