Flash Flood Guidance
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000
AWUS01 KWNH 221526
FFGMPD
MSZ000-LAZ000-222100-

MESOSCALE PRECIPITATION DISCUSSION 0366
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1125 AM EDT THU JUN 22 2017

AREAS AFFECTED...SOUTH-CENTRAL TO SOUTHWEST LA

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

VALID 221520Z - 222100Z

SUMMARY...BANDS OF HEAVY SHOWERS ASSOCIATED WITH T.D. CINDY WILL
CONTINUE TO BRING HEAVY RAINFALL OVER THE NEXT SEVERAL HOURS.

DISCUSSION...EXPERIMENTAL GOES-16 VISIBLE/0.64 MICRON MICRON
IMAGERY SHOWS THE LOW LEVEL CENTER ASSOCIATED T.D. CINDY
CONTINUING TO LIFT NORTH AND INLAND ALONG THE TX/LA BORDER. THE
SYSTEM OVERALL IS CONVECTIVELY VERY DISORGANIZED WITH A LARGE
AMOUNT OF MID LEVEL DRY AIR BEING ENTRAINED AND WRAPPED AROUND THE
STORM CENTER. THIS IS RESULTING IN A DISTINCT LACK OF INNER CORE
CONVECTION...WITH MOST OF THE EXISTING CONVECTION CHARACTERIZED BY
SOME RATHER FRAGMENTED AND SHALLOW-TOPPED BANDS AROUND THE EASTERN
AND SOUTHERN FLANKS OF THE STORM CIRCULATION.

HOWEVER...THERE WILL BE SOME PERSISTENCE AND POSSIBLE
INTENSIFICATION TO THE BANDED CONVECTION OVER AREAS OF SOUTHWEST
TO SOUTH-CENTRAL LA GOING THROUGH THE AFTERNOON HOURS AS DIURNAL
HEATING CONTRIBUTES TO AN INCREASE IN BOUNDARY LAYER INSTABILITY.
MEANWHILE THIS WILL BE COINCIDING WITH A FOCUSED AXIS OF SURFACE
CONVERGENCE WHICH WILL HELP KEEP STRONGER LOW LEVEL MOISTURE
TRANSPORT POOLED IN ACROSS THESE AREAS.

THE CURRENT ACTIVITY IS FOSTERING SOME LOCALIZED 1 TO 2 INCH/HR
RATES...AND WITH SOME MODEST STRENGTHENING OF THE CONVECTIVE
BANDS...SOME OF THE RATES MAY BEGIN TO EXCEED 2 INCHES/HR LOCALLY.
ASIDE FROM THE HEAVY RAINFALL RATES...THE CONCERN IS THE
REPEATING/TRAINING NATURE OF THE CONVECTION WHICH OVER THE NEXT 6
HOURS MAY RESULT IN ADDITIONAL RAINFALL TOTALS AS HIGH 3 TO 5
INCHES WITH ISOLATED HEAVIER AMOUNTS. THIS IS CONSISTENT WITH THE
LATEST HRRR GUIDANCE WHICH HAS ALSO TRENDED A LITTLE WETTER.
THEREFORE THE CONCERNS FOR RUNOFF PROBLEMS AND POSSIBLE FLASH
FLOODING CONTINUE.

ORRISON

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

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

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

LAT...LON   31069160 30929089 30339065 29739070 29279108
            29509170 29509215 29509249 29579285 29709306
            29709340 29739368 29929368 30169304 30639256
            30949219


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