MESOSCALE PRECIPITATION DISCUSSION 0556
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
702 AM EDT SAT AUG 13 2016
 
AREAS AFFECTED...CENTRAL/SOUTHERN LA...SOUTHWEST MS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 131100Z - 131700Z
 
SUMMARY...EXTREMELY HEAVY RAINFALL WILL CONTINUE THIS
MORNING...WITH DANGEROUS AND POTENTIALLY LIFE-THREATENING FLASH
FLOODING EXPECTED.

DISCUSSION...A VERY SLOW-MOVING LOW TO MID LEVEL LOW CENTER WEST
OF NATCHEZ MS CONTINUES TO DRIFT EVER SO SLOWLY TO THE
WEST-NORTHWEST THIS MORNING...AND CONTINUES TO FOCUS EXTREMELY
HEAVY RAINFALL ACROSS PORTIONS OF CENTRAL AND SOUTHWEST LA WITH
THE PERSISTENCE OF MULTIPLE WELL-DEFINED CONVECTIVE BANDS.

AREAS OF SOUTHWEST LA IN PARTICULAR ARE SEEING A SET-UP CURRENTLY
OF A WELL-DEFINED FETCH OF DEEP MOISTURE AND INSTABILITY OUT OF
THE NORTHWEST GULF OF MEXICO AND SOUTHEAST TX WHERE THE LOW LEVEL
FLOW IS QUITE CONFLUENT. MLCAPE VALUES ARE ALREADY OVER 1500 J/KG
IN SOME CASES AND COINCIDING WITH A DEEP TROPICAL AIRMASS OVER THE
REGION. PWATS EMBEDDED WITHIN THE BROADER LOW CIRCULATION REMAIN
VERY HIGH WITH VALUES GENERALLY ABOVE 2.5 INCHES.

THE BEST FORCING SHOULD REMAIN AROUND THE SOUTHWEST FLANK OF THE
LOW CIRCULATION AND THIS WOULD FAVOR PORTIONS OF CENTRAL AND
SOUTHWEST LA SEEING EXTREMELY HEAVY RAINS PERSIST. TRAINING
CONVECTIVE BANDS WITH HOURLY RAINFALL RATES OF UP TO 3 INCHES/HR
WILL FAVOR VERY HIGH RAINFALL TOTALS THROUGH MIDDAY.

EXPECT ADDITIONAL RAINFALL AMOUNTS OF 4 TO 8 INCHES WITH THE
HEAVIEST FOCUS GENERALLY NEAR AND JUST EAST OF A LINE FROM
ALEXANDRIA TO OAKDALE TO LAKE CHARLES. FARTHER SOUTHEAST OVER
TOWARD BATON ROUGE AND LAFAYETTE...THE RAINS HERE WILL BE MODERATE
TO HEAVY AS WELL...BUT WITH LOWER RAINFALL RATES.
NEVERTHELESS...EVEN THESE ALREADY SEVERELY HARD HIT AREAS WILL SEE
THE POTENTIAL FOR ADDITIONAL AMOUNTS OF 2 TO 4 INCHES.

DANGEROUS AND POTENTIALLY LIFE-THREATENING FLASH FLOODING WILL
REMAIN LIKELY ON THE ADDITION OF THESE VERY HEAVY RAINS AND
ESPECIALLY OVER AREAS OF SOUTH-CENTRAL LA WHERE STORM TOTALS ARE
BEGINNING TO EXCEED 20 INCHES FOR THE EVENT IN SOME AREAS.

ORRISON

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

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

LAT...LON   31639257 31369191 31269128 31179060 30859025 
            30489022 30179036 29799067 29469123 29389169 
            29489261 29749344 30509379 31239357 31609316