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Mesoscale Discussion 802

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SPC MESOSCALE DISCUSSION 0802 FOR SWRN OK/EXTREME NWRN TX
CONCERNING...HEAVY RAINFALL...

VALID 192215Z - 200200Z

RAINFALL AMOUNTS UP TO 2 INCHES PER HOURS WILL POSSIBLE ACROSS
PORTIONS OF SWRN OK/EXTREME NWRN TX FOR THE NEXT FEW HOURS. 

OUTFLOW BOUNDARY EXTENDS FROM S OF CDS TO NEAR SPS AT 22Z. THE AIR
MASS IS VERY MOIST AND UNSTABLE SOUTH OF THIS BOUNDARY WITH MLCAPES
IN EXCESS OF 4000 J/KG. THE BOUNDARY IS MOVING SWD AT 20 KT...BUT
THE INCREASING SWLY FLOW ALOFT AND APPROACHING SHORTWAVE TROUGH
FROM SWRN TX SHOULD SLOW THE SWD MOTION IN THE NEXT HOUR OR SO. THE
CONVERGENCE ALONG THE OUTFLOW BOUNDARY IS EXPECTED TO PROVIDE A
FOCUS FOR CONTINUED CONVECTIVE INITIATION. STRENGTHENING SWLY FLOW
BETWEEN 2-6 KM IS SPREADING NEWD AND WILL CAUSE THE STORMS TO MOVE 
NORTH OF THE BOUNDARY ACROSS THE SAME GENERAL AREAS.  THE GREATEST
THREAT OF VERY HEAVY RAINFALL WILL OCCUR JUST NORTH OF THE BOUNDARY
FROM NEAR CDS EWD TO NEAR LTS AND NORTH OF SPS. THE HEAVY RAIN
THREAT WILL LIKELY SPREAD NORTH AND EAST DURING THE EVENING AS THE
LOW LEVEL JET INCREASES THE ISENTROPIC LIFT NORTH OF THE BOUNDARY.

..IMY.. 05/19/01

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