Flash Flood Guidance
Issued by NWS

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000
AWUS01 KWNH 300602
FFGMPD
MSZ000-LAZ000-TXZ000-301200-

MESOSCALE PRECIPITATION DISCUSSION 0170
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
201 AM EDT SUN APR 30 2017

AREAS AFFECTED...FAR EASTERN TX...WESTERN/CENTRAL LA

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

VALID 300600Z - 301200Z

SUMMARY...STRONG THUNDERSTORMS WITH INTENSE RAINFALL RATES OVER 2
INCHES/HR ARE EXPECTED OVER THE NEXT FEW HOURS. SOME FLASH
FLOODING MAY BE POSSIBLE.

DISCUSSION...RAPIDLY COOLING CONVECTIVE TOPS ARE NOTED ACROSS
AREAS OF FAR EASTERN TX AND INTO LA AS A COLD FRONT IMPINGES ON
THE AREA AND INTERACTS WITH A FOCUSED AREA OF STRONG
MOISTURE/INSTABILITY TRANSPORT THAT IS ADVANCING IN OFF THE
WESTERN GULF OF MEXICO.

THE 00Z GEM REGIONAL AND RECENT HRRR RUNS ARE SUGGESTING A FAIR
DEGREE OF CONVECTIVE ORGANIZATION ACROSS AREAS OF CENTRAL AND
WESTERN LA IN THE 06Z TO 12Z TIME-FRAME. GIVEN THE LATEST
CONVECTIVE TRENDS...THESE MODELS SEEM TO HAVE A SOMEWHAT BETTER
HANDLE ON THE CURRENT CONVECTIVE ENVIRONMENT. THERMODYNAMICAL
PROFILES ARE CONDUCIVE FOR AN INCREASE IN CONVECTIVE COVERAGE AND
INTENSITY...GIVEN A 40 TO 50 KT SOUTHERLY LOW LEVEL JET THAT IS
FOCUSING PWATS OF 1.8 TO 2 INCHES...AND MUCAPE VALUES OF 3000 TO
4000 J/KG ARE THE AREA. CONFLUENT LOW LEVEL FLOW AND THE
APPROACHING FRONT WILL FACILITATE THE ORGANIZATION OVER THE NEXT
FEW HOURS AND ALSO WITH AID OF A DIFFLUENT UPPER LEVEL LOW PATTERN.

EXPECT AS MUCH AS 2 TO 4 INCHES RAIN WITH ISOLATED HEAVIER AMOUNTS
THROUGH 12Z. SOME OF THESE RAINS WILL BE FALLING ON AREAS THAT DID
SEE SOME HEAVIER RAINS ON SATURDAY...AND SO THIS MAY RESULT IN
SOME RUNOFF PROBLEMS AND POSSIBLE FLASH FLOODING. WILL CONTINUE TO
MONITOR.

ORRISON

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

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

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

LAT...LON   33009218 32629135 31329153 30379220 29809303
            29789410 30299467 31319437 31809425 32539379
            32989316


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