MESOSCALE PRECIPITATION DISCUSSION 0091
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1041 PM EDT SAT MAY 16 2015
 
AREAS AFFECTED...TX 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 170240Z - 170840Z
 
SUMMARY...CONVECTION BEGINNING TO INCREASE IN COVERAGE ON THE
SOUTHERN END OF THE ELONGATED ORGANIZED CONVECTION OVER THE
SOUTHERN PLAINS.

DISCUSSION...CONVECTION EXPECTED TO CONTINUE TO INCREASE LATE
SATURDAY NIGHT INTO THE EARLY HOURS OF SUNDAY INTO SOUTH CENTRAL
TEXAS ALONG AND AHEAD OF THE WELL DEFINED DRY LINE.  MUCAPE VALUES
AS PER SPC MESO ANALYSIS AND LATEST RAP GUIDANCE SHOW VALUES IN
EXCESS OF 3000 J/KG AHEAD OF THIS CONVECTION---WHILE PWS IN THIS
AREA CONTINUE TO INCREASE AS PER LATEST GPS PW IMAGERY---WITH
VALUES UPWARD TO 1.5 TO 2 STANDARD DEVIATIONS ABOVE THE MEAN BY
EARLY SUNDAY MORNING. 

WHILE THE ELONGATED CONVECTION ACROSS THE CENTRAL TO SOUTHERN
PLAINS IS FAIRLY PROGRESSIVE FROM OKLAHOMA NORTHEASTWARD IN
RESPONSE TO THE NORTH NORTHEAST PUSH OF STRONG HEIGHT FALLS ACROSS
THESE AREAS---THE FORWARD SPEED IS EXPECTED TO BE LESS ON THE
SOUTHERN END ACROSS CENTRAL TEXAS WHERE LITTLE IN THE WAY OF
HEIGHT FALLS IS EXPECTED.  LITTLE MOVEMENT EVIDENT TO THE DRY LINE
AS PER LATEST SURFACE OBSERVATIONS OVER THE SOUTHERN PLAINS--WITH
THE STRONG CONVERGENCE AXIS ALONG THIS BOUNDARY NOT EXPECTED TO
MOVE APPRECIABLY OVER THE NEXT SEVERAL HOURS.  CONVECTION MAY
BECOME ORIENTED PARALLEL TO THE MOIST SOUTHWEST LOW LEVEL FLOW
ACROSS THIS REGION AND PARALLEL TO THIS DRY LINE--SUPPORTING
POTENTIAL FOR A PERIOD OF SLOW MOVING OR TRAINING OF CELLS IN A
SOUTHWEST TO NORTHEASTERLY DIRECTION.  THERE IS A CLEAR SIGNAL IN
THE LATEST HI RES GUIDANCE IN THE PERIOD FROM 0000 TO 1200 UTC FOR
LOCALLY VERY HEAVY RAINFALL AMOUNTS OF 2-4"+. THIS WILL INCREASE
THE RISK THIS PERIOD OF RUNOFF ISSUES ACROSS CENTRAL TEXAS IN
AREAS OF TRAINING.  

ORAVEC

ATTN...WFO...EWX...FWD...SJT...

ATTN...RFC...WGRFC...

LAT...LON   33289785 33219744 33079708 32849690 32309678 
            31439714 31329723 30669808 30179938 30330086 
            30330124 30350127 30520135 30800122 31550040 
            32459969 33119897 33269847