MESOSCALE PRECIPITATION DISCUSSION 0083
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
314 PM EDT WED MAY 13 2015
 
AREAS AFFECTED...SOUTH TEXAS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 131910Z - 140000Z
 
SUMMARY...ADDITIONAL CLUSTERS OF HEAVY SHOWERS AND THUNDERSTORMS
WILL PERSIST INTO THE EARLY EVENING HOURS.

DISCUSSION...THE LATEST WV/GOES-RGB IMAGERY INDICATES A
WELL-DEFINED AND SHARP UPPER TROUGH CROSSING THE RIO GRANDE VALLEY
EARLY THIS AFTERNOON AND THIS ENERGY WILL BE LIFTING NORTHEAST
THROUGH THE EVENING HOURS ACROSS THE SOUTHERN PLAINS. STRONG
FORCING/UPPER LEVEL DIVERGENCE COUPLED WITH A MOIST AND A
PERSISTENT S/SE LOW LEVEL JET SHOULD HELP TO GENERALLY SUSTAIN A
LARGE AREA OF SLOW-MOVING CONVECTION ALREADY IMPACTING PORTIONS OF
SOUTH TEXAS. 

THE CONVECTION IS HELPING TO GENERATE A WELL-DEFINED COLD POOL
OVER PORTIONS OF THE TEXAS HILL COUNTRY...BUT WITH A LARGE POOL OF
MODERATE INSTABILITY CONTINUING TO FEED IN OFF THE WESTERN GULF OF
MEXICO AND UP THE LOWER RIO GRANDE VALLEY...CONVECTION NEAR THE
COLD POOL AND UP ALONG A STATIONARY FRONT IS EXPECTED TO CONTINUE
TO REGENERATE. THE STRONGER DYNAMICS ALOFT ASSOCIATED WITH THE
TROUGH ALOFT SHOULD BEGIN TO LIFT AWAY BY 00Z...AND SO THE
CONVECTION MAY TEND TO WANE IN ORGANIZATION BY THAT TIME.

THE 12Z ARW AND LATEST HRRR SUPPORT ADDITIONAL RAINFALL AMOUNTS OF
2 TO 4 INCHES WITH LOCALLY HEAVIER AMOUNTS THROUGH 00Z. GIVEN VERY
HEAVY RAINS OF LATE...SOIL CONDITIONS ARE EXPECTED TO BE SATURATED
AND SO ANY ADDITIONAL HEAVY RAINS SHOULD RESULT IN ADDITIONAL
FLASH FLOODING CONCERNS. WILL CONTINUE TO MONITOR.

ORRISON

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

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

LAT...LON   31359628 31039567 30299541 29519561 28969656 
            28479715 27659796 27479853 27779882 28619890 
            29039920 29080029 29340070 29660070 30019996 
            30599832 31269720