MESOSCALE PRECIPITATION DISCUSSION 0120
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
524 AM EDT SUN MAY 24 2015
 
AREAS AFFECTED...EASTERN TX 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 240924Z - 241454Z
 
SUMMARY...A MATURE MCS WITH HOURLY RAIN RATES UP TO 2" COULD CAUSE
FLASH FLOODING OVER SATURATED SOILS.  AREAS NEAR SAN ANTONIO ARE
MOST AS RISK.

DISCUSSION...THE COMBINATION OF A MATURE MCS AND CONVECTION MOVING
ACROSS SOUTH-CENTRAL TX MAINTAINS A FLASH FLOOD RISK FOR THE
REGION.  HOURLY RAIN RATES UP TO 2" HAVE BEEN INDICATED BY RADAR
IN A REGION WITH PRECIPITABLE WATER VALUES NEAR 2", 30 KTS OF 850
HPA INFLOW (NEAR THE MAGNITUDE OF THE 850-400 MEAN WIND), AND
MUCAPES 1000-3000 J/KG.  THERMAL CONTRAST ALONG THE OUTFLOW
BOUNDARY TO ITS NORTHEAST IS DECENT, WITH ABOUT 15F OF CONTRAST.

THE WORRY IN THIS REGION IS THAT CONVECTION COULD FORM AHEAD OF
THE MCS AND ATTEMPT TO TRAIN, OR THAT THE BOW ECHO PATTERN COULD
EVOLVE INTO A LEWP/QLCS.  THE CONVECTIVE BOW HAS BEEN MOVING 30-35
KTS, WHICH HELPED DEFINE THE AREA ALONG WITH INPUT FROM
SAB/NESDIS.  SOUTH-CENTRAL TX, AN AREA SATURATED WITH RAINFALL
SINCE SATURDAY AFTERNOON, IS DEALING WITH A SIGNIFICANT FLASH
FLOOD THREAT ALONG THE BLANCO RIVER BASIN -- THIS RAINFALL COULD
MAKE THE SITUATION NEAR THE FLOOD WAVE WORSE.  THE 08Z HRRR AND
THE 12Z SSEO MEAN APPEARED TO BE HANDLING THIS SYSTEM'S FORWARD
PROPAGATION THE BEST.  THERE IS A SIGNAL IN THE MESOSCALE GUIDANCE
FOR LOCAL 3-5" MAXIMA.  KEPT THE CATEGORY OF THE MPD AS POSSIBLE
DUE TO HIGHER FLASH FLOOD GUIDANCE VALUES ACROSS SOUTHEAST TX.  

ROTH

ATTN...WFO...CRP...EWX...FWD...HGX...LCH...SHV...SJT...

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

LAT...LON   33119518 32939393 31349366 29919374 29609407 
            29349473 28809540 28469616 28439671 28969768 
            29439829 30539866 31689833 32739657