Flash Flood Guidance
Issued by NWS

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000
AWUS01 KWNH 250433
FFGMPD
ALZ000-MSZ000-LAZ000-ARZ000-TXZ000-250902-

MESOSCALE PRECIPITATION DISCUSSION 0044
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1132 PM EST SAT FEB 24 2018

AREAS AFFECTED...SE AR...NRN LA...ERN TX...NRN MS / AL

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 250432Z - 250902Z

SUMMARY...HI-RES MODELS TRENDING TOWARD SUSTAINED MODERATE / HEAVY
PRECIPITATION HERE THROUGH 10Z. ONGOING FLOODING IN SOME AREAS AND
WET ANTECEDENT CONDITIONS IN OTHERS...MEANS SOME ADDITIONAL FLASH
FLOODING IS LIKELY.

DISCUSSION...A COLD FRONT WAS APPROACHING...BUT DEEP LAYER FORCING
HERE IN THE LOWER MISSISSIPPI VALLEY AND SOUTHEAST STATES WAS MORE
SUBTLE THAN THAT OCCURRING FARTHER NORTH. AT 0415Z RADAR AND
SATELLITE TRENDS INDICATED THAT CONVECTION WAS TAKING HOLD...WITH
AN INCREASE OF CONSISTENT COVERAGE AND SLIGHT UPTICK TO INTENSITY
FROM FAR EASTERN TEXAS TO NORTHERN MISSISSIPPI. THE 00Z 250 MB
ANALYSIS DEPICTS A SOMEWHAT DIFLUENT PATTERN...WHOSE INTENSITY IS
BOLSTERED BY STRONG JET WIND SPEEDS CLOSE TO 100 KNOTS IN THE
DISCUSSION AREA AND STRONGER TO THE NORTH. THIS DIFLUENT UPPER
PATTERN WAS SITTING ATOP MIXED LAYER CAPE VALUES OF AT LEAST 500
J/KG UP TO INTERSTATE 20 WITH A FEW HUNDRED J/KG EXTENDING INTO
NORTHEAST MS. CONVECTIVE INHIBITION PER THE SPC MESOANALYSIS WAS
NEAR ZERO...WHICH IS CORROBORATED BY ANOTHER IMPRESSIVE SET OF 00Z
SOUNDINGS AT KLCH...KSHV...WITH LOW LEVELS DEEPLY SATURATED YET
ALSO EXHIBITING MODERATE LAPSE RATES.

SEVERAL HI-RES MODELS...HRRR / WRF-ARW / GEM REGIONAL /
WRF-ARW2...TRENDED TOWARD WETTER SOLUTIONS...AND THE RAP MAINTAINS
UPPER DIFLUENCE OVER THIS REGION THROUGHOUT THE NIGHT. DUAL POL
ESTIMATES AND WRF-ARW HOURLY PRECIP OUTPUT SUGGESTS RAIN RATES
EXCEEDING AN INCH PER HOUR IN ISOLATED SPOTS...ESPECIALLY AS THE
DEEP LAYER FLOW WILL ALLOW BOUTS OF TRAINING...WITH THE LEADING
LINES PUSHING ONLY SLOWLY EAST AND SOUTH. THIS RAINFALL WILL
LIKELY RESULT IN RENEWED FLASH FLOODING FOR AREAS THAT HAVE BEEN
WET THE PAST FEW DAYS...WHICH DESCRIBES MOST OF THE DISCUSSION
AREA...BUT ESPECIALLY APPLIES TO NORTHERN MISSISSIPPI.

BURKE

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

ATTN...WFO...BMX...HUN...JAN...LZK...MEG...SHV...

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

LAT...LON   34888731 34648674 34068704 33298822 31999078
            31519299 31329447 31899398 32789270 33869150
            34419013 34498872



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