MESOSCALE PRECIPITATION DISCUSSION 0078
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
529 PM EDT MON MAY 11 2015
 
AREAS AFFECTED...SW TEXAS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 112129Z - 120230Z
 
SUMMARY...POTENTIAL FOR FLASH FLOODING INCREASING THROUGH EVENING
HOURS GIVEN ACTIVATING CONVECTION ALONG SIERRA MADRE...SEA BREEZE
BOUNDARY AND PRIOR EAST-WEST ORIENTED OUTFLOW BOUNDARY EVENTUALLY
MERGING INTO LARGER COMPLEX. 

DISCUSSION...SFC ANALYSIS...RADAR AND VISIBLE IMAGERY SHOWS RAPID
DEVELOPMENT OF DEEP CONVECTION ALONG THE EASTERN FLANKS OF THE
SIERRA MADRE UNDER GOOD MST CONVERGENCE DUE TO DAY TIME HEATING
ALLOWING FOR SFC PRESSURE FALLS AND ISALLOBARIC WIND FLOW FOR
CONTINUED MST FLUX INTO THE AREA.  ADDITIONALLY...GULF BREEZE HAS
PRESSED WESTWARD INTO VERY UNSTABLE AND MST ENVIRONMENT AS WELL AS
OLDER OUTFLOW BOUNDARY FROM MAVERICK TO MATAGORDA COUNTIES
DROPPING SOUTH AS WELL.  WITH SB CAPES IN THE 3500-4000 J/KG AND
TPWS IN THE 1.6-1.75" RANGE THIS WILL FEED THESE DEVELOPING
CONVECTIVE LINES... UNTIL EVENTUAL FORWARD PROPAGATION OF THE
BOUNDARY CONVECTION AND CELLS MOVING OFF HIGHER TERRAIN IN MEXICO
SHOULD LEAD TO MERGERS OF THE COMPLEX AND OVERALL LAYER
OVERTURNING ACROSS THE WESTERN PORTIONS OF EWX AND CRP CWAS BY
00-02Z.  RATES IN EXCESS OF 2-3"/HR ARE LIKELY WITH INCREASES TO
3-4" WHEN MERGERS OCCUR.  

THIS SOLUTION IN LINE WITH THE NAM_CONEST ARW AND NMMB THOUGH
WITHOUT CONVECTION FROM THE GULF BREEZE...LIKELY TO EXACERBATE
CONVECTIVE/VIGOR AS WELL AS FOCUS THE HIGHEST THREAT A BIT FURTHER
SOUTH... MORE IN LINE WITH THE 19Z HRRR 

ATTN...WFO...BRO...CRP...EWX...

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

LAT...LON   29600063 28989837 27759839 26569894 26569939 
            27279986 27820041 28360100 29300151