MESOSCALE PRECIPITATION DISCUSSION 0569
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
743 AM EDT FRI OCT 09 2015
 
AREAS AFFECTED...SW TEXAS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 091155Z - 091630Z
 
SUMMARY...MCS STARTING WEAKENING TREND BUT REMAINS FLASH FLOOD
THREAT FOR A FEW MORE HOURS.

DISCUSSION...SYNOPTIC SETUP IDEAL FOR MAINTENANCE OF MCS ACROSS SW
TX...WITH SLOW MOVING SW UPPER LOW WITH STRONG 80+ KT JET BECOMING
HIGHLY DIFFLUENT ACROSS NE MEXICO/TEXAS.  THE TRAILING EDGE/RIGHT
ENTRANCE OF THE NORTHERN STREAM 40 KT JET ALSO SUPPORTS FAVORABLE
UVV REGION PARTICULARLY OVER THE NORTHERN PORTION OF THE
DISCUSSION AREA.  AS SUCH A WELL EVOLVED MCV CAN BE SEEN JUST E OF
DFX RADAR.  COLD POOL REINFORCED NORTH-SOUTH BOUNDARY JUST W OF
HDO TO COT TO LRD IS ACTING AS ISENTROPIC SURFACE FOR REMAINING
25-30 KT 925-850MB WINDS...AND GIVEN REMAINING MODERATE LAPSE
RATES THAT HAVE NOT BEEN MODIFIED BY THE LATENT HEAT RELEASE
FURTHER EAST...500 J/KG MUCAPES REMAIN FOR CONTINUED WEAK
CONVECTIVE DEVELOPMENT...AND GIVEN AMPLE MOISTURE
ENVIRONMENT...SUPPORTIVE OF 1.5-2"/HR RATES. THIS SHOULD REMAIN
FOR MAYBE 1-3 MORE HOURS. THE THREAT HERE IS VERY SLOW EASTWARD
MOVEMENT AS MCV IS NEARLY STATIONARY WITH THE POTENTIAL FOR NNW
SLOW SHIFT GIVEN FORECAST CHANGE IN STEERING FLOW IN THE NEXT HOUR
OR SO... THIS WILL KEEP CELLS RELATIVELY STATIONARY BEFORE THEY
RAIN OUT OVER SE UVALDE AND ZAVALA COUNTIES.

FURTHER SOUTH...IR IMAGERY SHOWS CONTINUED BUT NARROWING APEX TO
THE CONVECTIVE WEDGE JUST ACROSS THE RIO GRANDE INTO MEXICO. 
BREAKS IN CLOUDS ON GOES SOUNDER AND RAP ANALYSIS INDICATES A
NARROW RIBBON OF UNCAPPED SBCAPES IN EXCESS OF 1000 J/KG. VWP
NETWORK INDICATES SLACKENING LOW LEVEL INFLOW FROM THE SE WHICH
WILL BE BACKING WITH TIME ALLOWING FOR AN AXIS OF LOWER THETA-E
AIR ALONG THE TEXAS GULF COAST TO ADVECT INTO THE COMPLEX.  THIS
WILL LEAD TO INCREASE OF FORWARD SPEED AND FRACTURING OF
CONVECTIVE LINE OVER THE NEXT 3-4 HOURS...DRAMATICALLY REDUCING
THE FLASH FLOODING THREAT.   STILL WITH AMPLE JET ENERGY FROM THE
SW...SOME POTENTIAL FOR BACKBUILDING REMAINS BUT LIKELY WILL BE
ALONG OR JUST WEST OF THE RIVER.  

GALLINA

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

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

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