MESOSCALE PRECIPITATION DISCUSSION 0206
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1043 AM EDT SAT JUN 13 2015
 
AREAS AFFECTED...CENTRAL LA & SOUTHWEST MS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 131442Z - 131842Z
 
SUMMARY...A BAND OF THUNDERSTORMS IS MOVING INTO AN AREA OF
LOWERING FLASH FLOOD GUIDANCE VALUES.  FLASH FLOODING IS
CONSIDERED POSSIBLE.

DISCUSSION...A CONVECTIVE BAND WITH A COUPLE EMBEDDED MESOSCALE
CIRCULATIONS HAS BEEN MOVING EAST AT ~10 KTS, PARALLEL TO THE
1000-500 HPA THICKNESS PATTERN IN THE REGION AND SLIGHTLY FASTER
THAN FORWARD PROPAGATING CORFIDI VECTORS SUGGEST.  HOURLY RAIN
RATES AS OF LATE HAVE BEEN 1-1.5".  TOTALS OVER A BROADENING AREA
OF SOUTHWEST LA ARE IN THE 2-5" RANGE, WITH LOCAL AMOUNTS UP TO 8"
PER LCH RADAR ESTIMATES.

WHILE 850 HPA INFLOW IS FORECAST BY RAP GUIDANCE TO WEAKEN TO
20-25 KTS OUT OF THE SOUTH- SOUTHEAST, THE LINE/BAND'S EASTWARD
MOTION SHOULD PROVIDE ENOUGH CLOUD BASE INFLOW TO MAINTAIN
ORGANIZATION.  ALSO OF HELP WOULD BE INCREASING MIXED LAYER CAPES
IN ITS PATH, BETWEEN 1000-2500 J/KG PER THE LATEST SPC
MESOANALYSIS.  PRECIPITABLE WATER VALUES REMAIN IN THE 2-2.2"
RANGE PER GPS INFORMATION, WHICH COULD SUPPORT HOURLY RATES UP TO
2.5" WHERE CELLS TRAIN.  OF THE AVAILABLE MESOSCALE QPF GUIDANCE,
ONLY THE 13Z HRRR APPEARS TO INDICATE THIS SYSTEM'S PRESENCE,
WHICH INCREASES FORECAST UNCERTAINTY, HENCE THE FOUR HOUR TIMING
AND POSSIBLE CATEGORY.  FLASH FLOODING REMAINS POSSIBLE.

ROTH

ATTN...WFO...JAN...LCH...LIX...SHV...

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

LAT...LON   32519179 32089101 31039076 30109084 29889090 
            29159123 29269145 29469145 29489159 29469176 
            29449195 29509215 29499240 29779317 30519292 
            31789284 32339262