MESOSCALE PRECIPITATION DISCUSSION 0212
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
238 PM EDT SUN JUN 14 2015
 
AREAS AFFECTED...SOUTH-CENTRAL TX 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 141837Z - 142237Z
 
SUMMARY...A GROWING THUNDERSTORM COMPLEX OVER BEXAR COUNTY IS
BEGINNING TO PROPAGATE/GROW INTO AN AREA WHERE IT RAINED HEAVY
THIS MORNING.  FLASH FLOODING IS POSSIBLE.

DISCUSSION...AN OUTFLOW BOUNDARY FROM MORNING CONVECTION WAS SEEN
IN THE OBSERVATIONS ACROSS SOUTH-CENTRAL TX.  NEW CONVECTION HAS
FLARED ALONG ITS WESTERN FLANK, WHICH IS SHOWING SIGNS OF SHIFTING
SLOWLY EASTWARD AND/OR EXPANDING OUTWARD.  FORWARD PROPAGATING
CORFIDI VECTORS ARE LIGHT, WITH 1000-500 HPA THICKNESS LINES
INDICATING A SOUTHEAST TRAJECTORY BEING THE MOST LIKELY.  

INFLOW INTO THE REGION IS 20-25 KTS, AND PER RECENT RAP FORECASTS,
SHOULD REMAIN STEADY THIS AFTERNOON WHILE BECOMING MORE
SOUTHEASTERLY, WHICH SHOULD ALSO ALLOW THE THUNDERSTORMS TO SHIFT
MORE SOUTHEAST WITH TIME.  AN INVADING MCV CROSSING THE RIO GRANDE
COULD BE AIDING THIS COMPLEX'S DEVELOPMENT.  FLASH FLOOD GUIDANCE
VALUES (FFGS) SIGNIFICANTLY LOWERED AFTER THE MORNING CONVECTION
IN THIS AREA, WHICH DROPPED 6" OF RAIN LOCALLY.  PRECIPITABLE
WATER VALUES NEAR 2" SUPPORT HOURLY RAIN RATES UP TO 2.5", WHICH
WOULD EXCEED THE FFGS.  SOME OF THE LOCATIONS IN THIS AREA ARE
URBAN, WHICH WOULD NOT BE ABLE TO STAND RAIN RATES THIS HIGH. 
THERE IS A SIGNAL WITHIN THE MESOSCALE GUIDANCE FOR LOCAL AMOUNTS
OF 3-4" IN THIS REGION.  THE FLASH FLOOD RISK IS HEIGHTENED IN
THIS AREA.

ROTH

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

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

LAT...LON   30019816 29599736 28859665 28299725 28179827 
            28779902 29939910 
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