MESOSCALE PRECIPITATION DISCUSSION 0287
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
959 AM EDT THU OCT 31 2013
 
AREAS AFFECTED...SOUTHEAST TX...WESTERN AND CENTRAL LA...SOUTHWEST
MS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 311355Z - 311915Z
 
SUMMARY...THE THREAT FOR FLASH FLOODING CONTINUES TO SLOWLY SHIFT
FARTHER EAST INTO FAR SOUTHEAST TX AND SOUTHWEST LA.

DISCUSSION...PERSISTENT AND VERY SLOW-MOVING BANDS OF STRONG
CONVECTION CONTINUE ACROSS FAR SOUTHEAST TX AND EXTEND NEWD INTO W
CNTRL LA ATTM. LATEST SAT IMAGERY SHOWS VERY DIV FLOW ALOFT AND
EXTREMELY COLD CLOUD TOPS...WITH CLOUD TOPS TEMPS AS COLD AS -82C.
THIS IS INDICATIVE OF CONTINUED STRONG DEEP LYR ASCENT AND WITH
SUGGESTION OF THIS BEING SUSTAINABLE THROUGH AT LEAST THE EARLY TO
MID-AFTERNOON HOURS. THE VERY COLD CLOUDS TOPS COUPLED WITH AN
AXIS OF 2.2 TO 2.4 INCH PWATS AS PER LATEST
GOES-SOUNDER/GPS-DERIVED DATA SUPPORTS EXTREMELY HEAVY RAINFALL
RATES. ALREADY OBSERVED RAINFALL RATES OF 2 TO 3 INCH/HR HAVE BEEN
NOTED WITHIN THE BANDS AS THE LARGER SCALE CONVECTIVE MASS SHIFTS
GRADUALLY EAST OUT AHEAD OF A COLD FRONT AND ASSOCD UPPER LVL
TROUGH PUSHING THROUGH THE CNTRL/SRN PLAINS.

OVER THE NEXT SEVERAL HOURS...THE ALREADY INTENSE CONVECTIVE BANDS
WILL CONTINUE TO LOCALLY BACK-BUILD/TRAIN OVER THE SAME AREA WITH
LARGER SCALE FORCING PERSISTING AND TAKING ADVANTAGE OF EXTREMELY
MOIST AND MODERATELY UNSTABLE AIR ADVECTING IN OFF THE WRN GULF OF
MEXICO. THIS WILL SUPPORT ADDITIONAL INTENSE RAINFALL RATES...AND
ESP ACROSS EXTREME SOUTHEAST TX NEAR THE UPPER TX COAST NORTHEAST
INTO W CNTRL LA WHERE RADAR IMAGERY SUPPORTS AN AXIS OF MERGING
CONVECTIVE BANDS. THUS EXTREMELY HEAVY RAINS ARE POSSIBLE ACROSS
THIS AREA IN A VERY SHORT AMT OF TIME. AS A RESULT...FLASH
FLOODING WILL BE LIKELY.

ORRISON

ATTN...WFO...JAN...LIX...LCH...SHV...HGX...CRP...EWX...

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

LAT...LON   32719230 32789130 32269057 31109090 30559130 29439255
            28619390 27969560 27909659 28059720 28499744 29399711
            30179624 30959518 31669407 32719230