MESOSCALE PRECIPITATION DISCUSSION 0374
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
303 PM EDT FRI SEP 12 2014
 
AREAS AFFECTED...SOUTHEAST TX...SOUTHWEST LA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 121855Z - 130030Z
 
SUMMARY...INCREASING COVERAGE OF INTENSE AND SLOW-MOVING SHOWERS
AND THUNDERSTORMS ARE EXPECTED THROUGH THE AFTERNOON AND EARLY
EVENING.

DISCUSSION...A FAIRLY COMPLICATED SCENARIO WILL BE UNFOLDING THIS
AFTERNOON AS A COLD FRONT SETTLING SEWD ACROSS TX/LA IS EXPECTED
TO INTERACT WITH A VERY MOIST/UNSTABLE BNDRY LAYER OVER THE TX/LA
COASTAL PLAIN. IN ADDITION TO THIS...A WELL LOW TO MID LVL
INVERTED TROUGH ASSOCD WITH AN EASTERLY WAVE IS SEEN ADVANCING
SLOWLY WWD. THE FRONT IS EXPECTED TO INTERACT WITH THE NRN PORTION
OF THIS WAVE AXIS THIS AFTERNOON AND EVENING.

AN EXPANSION OF SLOW-MOVING AND INTENSE SHOWERS AND THUNDERSTORMS
IS EXPECTED GIVEN THE INCREASE IN DEEPER MOISTURE/INSTABILITY AND
STRONGER LOW LVL CONVERGENCE/FORCING ASSOCD WITH THE FRONT AND
APPROACHING EASTERLY WAVE. THE HIRES MODELS...MOST NOTABLY THE 12Z
NAM-CONEST AND 12Z ARW SUGGEST POTENTIAL FOR LOCALLY VERY HEAVY
RAINFALL AMTS IN A SOMEWHAT LINEAR FASHION OVER PORTIONS OF SERN
TX AND SWRN LA. THE PWAT ENVIRONMENT BEING OVER 2 INCHES AS
INDICATED BY GOES-SOUNDER DATA WILL FAVOR VERY INTENSE RAINFALL
RATES. THIS COUPLED WITH SLOW MOVEMENT AND THE POTENTIAL FOR CELL
MERGERS WILL ENHANCE THE RISK FOR FLASH FLOODING. WILL CONTINUE TO
MONITOR.

ORRISON

ATTN...WFO...CRP...EWX...FWD...HGX...LCH...SHV...

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

LAT...LON   32229428 31879299 31019244 29889256 29589389 
            29199472 28669568 28169671 28049835 28779904 
            29789906 30669820 31329626