MESOSCALE PRECIPITATION DISCUSSION 0215
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
342 PM EDT TUE MAY 17 2016
 
AREAS AFFECTED...PORTIONS OF THE CENTRAL GULF COAST 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 171941Z - 172341Z
 
SUMMARY...AN INCREASINGLY AMOUNT OF THUNDERSTORM ACTIVITY WITH
HIGH RAIN RATES IS FORMING ACROSS THE CENTRAL GULF COAST.  HOURLY
RAIN RATES UP TO 2.5" COULD LEAD TO FLASH FLOODING, PARTICULARLY
WITHIN URBAN AREAS.

DISCUSSION...A FRONTAL WAVE IS MARCHING EASTWARD ACROSS SOUTHEAST
LA PER A 19Z MESOANALYSIS.  MLCAPES OF 1000-2000 J/KG EXIST ACROSS
THE REGION, WITH PRECIPITABLE WATER VALUES NEAR 2" ADVECTED IN BY
850 HPA INFLOW OF 20-25 KTS.  HOURLY RAIN RATES PER RADAR HAVE
MAXIMIZED IN THE 2.5" RANGE ACROSS SOUTHERN MS.

THERE ARE MIXED SIGNS FOR ORGANIZED THUNDERSTORM ACTIVITY AS 850
HPA INFLOW IS EXPECTED TO WEAKEN SOMEWHAT OVER THE NEXT SEVERAL
HOURS (A LIMITING FACTOR), THOUGH ENOUGH BULK SHEAR EXISTS IN THE
0-6 KM LAYER TO KEEP SOME ORGANIZATION.  CELL MOTION HAS BEEN
QUITE SLOW SO FAR -- ROUGHLY NORTHEAST AT 15 KTS -- THOUGH
ORGANIZED ACTIVITY WILL TRY TO MOVE EAST AT 20-25 KTS.  WITH CELL
MERGERS AND LIMITED CELL TRAINING POSSIBLE, FLASH FLOODING IS
CONSIDERED POSSIBLE, PARTICULARLY WITHIN URBAN AREAS.  THE
CAM/MESOSCALE GUIDANCE SHOWED A SCATTERSHOT AND INCONSISTENT
SIGNAL FOR LOCAL AMOUNTS OF 2-3"...BELIEVE AMOUNTS UP TO 5" ARE
POSSIBLE LOCALLY.  USED A FOUR HOUR HORIZON DUE TO THE UNCERTAINTY
IN THIS AREA.

ROTH

ATTN...WFO...JAN...LIX...MOB...TAE...

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

LAT...LON   31698790 31468575 30878508 30288569 30268689 
            30098830 29528886 29048882 28828932 29038957 
            28929038 29119113 30459072 31278976