Flash Flood Guidance
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000
AWUS01 KWNH 250307
FFGMPD
MSZ000-LAZ000-ARZ000-250630-

MESOSCALE PRECIPITATION DISCUSSION 0050
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1106 PM EDT FRI APR 24 2015

AREAS AFFECTED...FAR NORTHERN LA...SOUTHERN AR...WESTERN MS

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

VALID 250300Z - 250630Z

SUMMARY...INTENSE QUASI-LINEAR BAND OF STRONG THUNDERSTORMS WILL
PERSIST THE NEXT FEW HOURS. ADDITIONAL LOCALIZED CONCERNS FOR
FLASH FLOODING REMAIN,

DISCUSSION...THE LATEST RADAR IMAGERY SHOWS A QLCS ORIENTED SW/NE
FROM NORTHEAST TX INTO SOUTHERN AR...WITH SOME DISORGANIZED BROKEN
CONVECTION DOWNSTREAM ACROSS PORTIONS OF NORTHERN MS. THE OVERALL
TREND HAS BEEN FOR THE CONVECTION TO BECOME BETTER ORGANIZED THE
LAST COUPLE OF HOURS...AND CLOUD TOPS TEMPS CONTINUE TO COOL WHICH
IS SUGGESTIVE OF STRONGER LARGE SCALE ASCENT.

LARGER SCALE DIVERGENT FLOW ALOFT AHEAD OF A SHORTWAVE TROUGH
EJECTING EAST OUT ACROSS THE CENTRAL/SOUTHERN PLAINS WILL HELP
FACILITATE LARGER SCALE LIFT OVERNIGHT ACROSS THE LOWER MS VALLEY.
THIS WILL COUPLE WITH AN ALREADY STRONG SWLY LOW LEVEL JET
REACHING UPWARDS OF 50 KTS AS PER KSHV VWP TO HELP SUSTAIN THE
CONVECTION WELL INTO THE NIGHT. THE LOW LEVEL JET IS INTERCEPTING
AND OVERRUNNING A WARM FRONT LIFTING NORTH AND IS TRANSPORTING A
POOL OF PWATS THAT ARE AS HIGH AS 1.7 TO 1.8 INCHES OVER THE LOWER
MS VALLEY. INSTABILITY IS FAIRLY MODEST WITH MUCAPE VALUES 1000 TO
2000 J/KG OVER EASTERN TX AND WESTERN LA...BUT WITH SUCH STRONG
LOW LEVEL JET FORCING AND LARGER SCALE LIFT...THE ONGOING
CONVECTION SHOULD PERSIST WELL INTO THE NIGHT.

HRRR OUTPUT SUGGESTS ADDITIONAL RAINFALL AMOUNTS OF 1 TO 3 INCHES
WITH ISOLATED HEAVIER AMOUNTS THROUGH 06Z. GIVEN SOME LOCALLY
HEAVIER RAINS EARLIER IN THE DAY ACROSS PORTIONS OF THE MPD
AREA...SOME CONCERN CONTINUES FOR FLASH FLOODING IN ASSOCIATION
WITH THE QLCS AS IT GENERALLY ADVANCES EAST.

ORRISON

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

ATTN...WFO...JAN...LZK...MEG...SHV...

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

LAT...LON   34439042 34268946 33428917 32978979 32629133
            32639317 32869401 33489396 33839349 34289164



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