Flash Flood Guidance
Issued by NWS

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000
AWUS01 KWNH 301215
FFGMPD
LAZ000-ARZ000-TXZ000-OKZ000-301543-

MESOSCALE PRECIPITATION DISCUSSION 0158
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
814 AM EDT SAT MAY 30 2015

AREAS AFFECTED...NERN TEXAS / SERN OKLAHOMA INTO SWRN ARKNANSAS /
NWRN LOUISIANA

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

VALID 301213Z - 301543Z

SUMMARY...FLASH FLOODING WILL REMAIN POSSIBLE OUT AHEAD OF A SLOW
MOVING MCV WITH HOURLY RATES AROUND 2 IN/HR EXPECTED. THE THREAT
APPEARS GREATEST JUST AHEAD OF THE MCV NEAR THE RED RIVER WHERE
ANTECEDENT RAINFALL HAS FLASH FLOOD GUIDANCE VALUES LESS THAN 2
IN/HR.

DISCUSSION...RADAR IMAGERY FROM KDYX AND KFWS AT 1145Z PLACED AN
MCV ASSOCIATED WITH A NOCTURNAL MCS OVER STEPHENS COUNTY...MOVING
ENE AT AROUND 25 KTS. CLOUD TOPS ON IR SATELLITE IMAGERY HAVE ONLY
SLOWLY WARMED WITHIN THE CORE OF THE MCS OVER THE PAST 2 HOURS AND
ARE CURRENTLY BETWEEN -65 AND -70 C...CO-LOCATED WITH HOURLY
RAINFALL RATES OF 2 TO 2.5 IN/HR PER DUAL-POL ESTIMATES OVER
DENTON AND COLLIN COUNTIES.

ESTIMATED INSTABILITY PER THE SPC MESOANALYSIS PAGE AND RAP
FORECASTS SUGGEST SUFFICIENT BUOYANCY IS PRESENT AND WILL REMAIN
OVER THE NEXT FEW HOURS TO SUSTAIN HOURLY RAINFALL RATES NEAR 2
IN/HR...IN THE VICINITY OF AN EFFECTIVE FRONTAL BOUNDARY EXTENDING
WSWWD ACROSS THE ARKLATEX. THE TRACK OF THE MCV IS EXPECTED TO
CONTINUE AN ENEWD PATH THROUGH 15Z...WITH ENHANCED LOW LEVEL FLOW
OUT AHEAD OF THE MESO LOW SUPPORTING OVERRUNNING OF THE EFFECTIVE
FRONTAL BOUNDARY AND A CONTINUED FLASH FLOOD THREAT. THE MCS IS
MOVING INTO A REGION THAT CONTAINS A RELATIVE MINIMUM OF RAINFALL
OVER THE PAST 7 DAYS...NEAR THE TX/OK/AR BORDER...BUT NOT SO ALONG
THE RED RIVER WHERE SOILS REMAIN SATURATED AND FFG VALUES ARE AS
LOW AS 1 IN/HR IN A FEW SPOTS. THE STRENGTH OF THE MCS AND FLASH
FLOOD THREAT REMAINS UNCERTAIN BEYOND 15Z...BUT THE SITUATION WILL
CONTINUE TO BE MONITORED.

OTTO

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

ATTN...WFO...FWD...OUN...SHV...TSA...

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

LAT...LON   34389576 34039418 33399353 32719417 32589604
            32679688 32959754 33669774 34219702



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