MESOSCALE PRECIPITATION DISCUSSION 0549
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
337 AM EDT FRI AUG 12 2016
 
AREAS AFFECTED...SOUTHERN TO SOUTHEASTERN LA/SOUTHWESTERN MS... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 120736Z - 121136Z
 
SUMMARY...A QUASI-STATIONARY/PERSISTENT MID-LEVEL CIRCULATION HAS
ANCHORED ITSELF ACROSS SOUTHEASTERN LA EARLY THIS MORNING.
CONVECTION HAS BEGUN TO ERUPT NORTH OF THIS MID/UPPER LOW WITHIN A
VERY MOIST/UNSTABLE AIR MASS. HOURLY RAINFALL RATES APPROACHING 2
INCHES WILL BE POSSIBLE LEADING TO LOCALIZED AREAS OF FLASH
FLOODING.

DISCUSSION...THE 00Z RAOB FROM LIX SHOWED A TROPICAL AIR MASS IN
PLACE WITH PWATS NEARING 2.75 INCHES. A TALL/SKINNY INSTABILITY
PROFILE WAS OBSERVED WITH GENERAL 1000-700 MB WESTERLIES BEING
COUNTERED BY THE MID-LEVEL EASTERLIES ABOVE THIS LAYER. THE
RESULTANT CLOUD-BEARING FLOW SHOULD REMAIN VERY LIGHT. SUCH
MOTIONS HAVE ALREADY BEEN OBSERVED WITH ONE CELL CURRENTLY
QUASI-STATIONARY OVER ST. HELENA AND TANGIPAHOA PARISHES IN
EASTERN LA. WARM RAIN PROCESSES WILL DOMINATE AND BE QUITE
EFFICIENT WITH WET-BULB ZERO HEIGHTS APPROACHING 17 KFT. EXPECT
CELLULAR CONVECTION TO CONTINUE INTO THE EARLY MORNING HOURS WITH
AREAS OF FLASH FLOODING POSSIBLE.

WHILE NO SINGLE HIGH-RESOLUTION MODEL IS HANDLING THE ONGOING
CONVECTION PERFECTLY...THERE IS A REASONABLY STRONG SIGNAL THROUGH
12Z OF VERY HEAVY RAINFALL ACROSS SOUTHEASTERN LA. MANY SOLUTIONS
SHOW AROUND 3 TO 5 INCHES OF PRECIPITATION THROUGH 12Z WITH HOURLY
RATES EASILY APPROACHING 2 INCHES WITHIN SOME OF THE MORE
PRONOUNCED UPDRAFTS.

RUBIN-OSTER

ATTN...WFO...JAN...LCH...LIX...MOB...

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

LAT...LON   31319094 31178969 30428911 29788909 29378984 
            28869068 28739139 28909228 29369270 30269261 
            30949186