MESOSCALE PRECIPITATION DISCUSSION 0219
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
232 AM EDT WED MAY 18 2016
 
AREAS AFFECTED...SOUTH TEXAS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 180625Z - 180930Z
 
SUMMARY...SHORT-TERM HEAVY RAINFALL THREAT CONTINUES. SOME
ADDITIONAL FLASH FLOODING IS POSSIBLE OVER THE NEXT 2 TO 3 HOURS.

DISCUSSION...A CLUSTER OF VERY COLD-TOPPED CONVECTION EXTENDING
FROM NEW BRAUNFELS TO SOUTHWEST OF SAN ANTONIO CONTINUES TO EDGE
GRADUALLY OFF TO THE EAST-SOUTHEAST AND IS BEING SUSTAINED BY A
VERY MOIST AND MODERATELY UNSTABLE AIRMASS POOLED OVER SOUTH
TEXAS. PWATS ARE NEAR 1.75 INCHES AS PER BLENDED-TPW IMAGERY...AND
THE LATEST RAP ANALYSIS SHOWS A POOL OF 2000 TO 3000 J/KG OF
MUCAPE.

THE HIRES GUIDANCE HAS BEEN INSISTING ON THIS ACTIVITY WEAKENING
OVER THE NEXT FEW HOURS AS AN INCREASE IN LOW LEVEL CINH AND
WEAKENING LOW LEVEL FLOW WORK IN TANDEM TO DISRUPT THE STRONG
CONVECTIVE UPDRAFTS THAT HAVE BEEN PERSISTENT WITH THIS CLUSTER OF
CONVECTION FOR THE LAST SEVERAL HOURS. THE GLD-EXPERIMENTAL
LIGHTNING DENSITY PRODUCT SHOWS VERY STRONG STRIKE ACTIVITY AND
THERE CONTINUE TO BE SOME OVERSHOOTING TOPS AS PER THE GOES-OTD
ALGORITHM. THESE SIGNALS REFLECT INTENSE FORCING AND THUS SOME
VERY INTENSE RAINFALL RATES.

CONFIRMED RAINFALL RATES OF 2 TO 3 INCHES/HR HAVE BEEN OCCURRING
WITH THIS ACTIVITY...AND THIS WILL CONTINUE TO FOSTER SOME FLASH
FLOODING POTENTIAL AS THE CONVECTION EDGES DEEPER INTO SOUTH
TEXAS. THE CONVECTION AS IT APPROACHES THE GREATER VICTORIA AREA
AND ADJACENT COASTAL PLAIN...WILL BE OCCURRING OVER SOME AREAS
THAT HAVE SEEN VERY HEAVY RAINFALL OVER THE LAST FEW DAYS...AND SO
THERE COULD BE SOME ELEVATED CONCERNS FOR RUNOFF PROBLEMS GIVEN
THE WET ANTECEDENT CONDITIONS OVER THESE AREAS BEFORE THE
CONVECTION WEAKENS TOWARD DAWN.

ORRISON

ATTN...WFO...CRP...EWX...HGX...

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

LAT...LON   29689776 29399653 28809609 28429638 28329702 
            28639828 28869881 29419872