Flash Flood Guidance
Issued by NWS

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000
AWUS01 KWNH 040633
FFGMPD
MSZ000-LAZ000-041200-

MESOSCALE PRECIPITATION DISCUSSION 0785
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
131 AM EST SUN DEC 04 2016

AREAS AFFECTED...SOUTHERN LA AND SOUTHWEST MS

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 040630Z - 041200Z

SUMMARY...STRONG THUNDERSTORMS WITH VERY HEAVY RAIN WILL CONTINUE
THROUGH THE EARLY MORNING HOURS.  THERE IS AN ONGOING CONCERN FOR
FLASH FLOODING AND RUNOFF PROBLEMS FROM TRAINING CONVECTION.

DISCUSSION...RECENT IR SATELLITE TRENDS HAVE SHOWN SLIGHTLY WARMER
CLOUD TOPS OVER THE LAST HOUR.  HOWEVER, THERE IS STILL A PLETHORA
OF DEEP MOISTURE MOVING ONSHORE OVER SOUTHERN LOUISIANA.  RECENT
RADAR IMAGERY FROM THIS REGION CONTINUES TO SHOW A QUASI-LINEAR
CONVECTIVE LINE ORIENTED FROM SOUTHWEST TO NORTHEAST ACROSS
SOUTH-CENTRAL LOUISIANA.  ENHANCED  MOISTURE CONVERGENCE AND LARGE
SCALE ASCENT FROM THE RIGHT-ENTRANCE REGION OF AN UPPER LEVEL JET
AHEAD OF A LARGE CLOSED LOW OVER NORTHERN MEXICO ARE HELPING TO
SUSTAIN THIS HEAVY CONVECTIVE PLUME. IN ADDITION, THERE IS A POOL
OF NEARLY 2 INCH PWS JUST OFF THE COAST, WHICH WILL HELP INCREASE
THE RAINFALL EFFICIENCY OF THESE STORMS GIVEN THE NEARLY SATURATED
LOW TO MID LEVELS SEEN IN THE LATEST SOUNDINGS.  THIS IS
APPROACHING 2.5 STANDARD DEVIATIONS ABOVE THE MEAN.

THE LATEST HRRR GUIDANCE SUGGESTS A VERY SLOW EASTWARD PROGRESSION
OF THE THUNDERSTORM ACTIVITY OVER THE NEXT SEVERAL HOURS.
ADDITIONAL CONVECTION IS LIKELY BEHIND THIS MAIN CONVECTIVE PLUME
WITH THE AMOUNT OF ISENTROPIC LIFT IN PLACE NORTH OF THE FRONT.
EXPECT ADDITIONAL RAINFALL AMOUNTS OF 2 TO LOCALLY 4 INCHES
THROUGH 12Z, WITH THE HEAVIEST AMOUNTS LIKELY NEAR THE CENTRAL
LOUISIANA COAST.  FLASH FLOODING AND LOCALLY SIGNIFICANT RUNOFF
PROBLEMS WILL CONTINUE TO BE POSSIBLE.

HAMRICK

...PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT...

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

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

LAT...LON   31739069 31558985 30948976 29989002 29249038
            29119125 29329213 29549311 29669365 30169367
            30659349 30989255 31609170



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