MESOSCALE PRECIPITATION DISCUSSION 0366
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
939 AM EDT THU SEP 11 2014
 
AREAS AFFECTED...EXTREME NORTHEAST TX...EXTREME SOUTHEAST
OK...AR...WESTERN TN...NORTHERN MS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 111330Z - 111730Z
 
SUMMARY...ADDITIONAL TRAINING OF VERY HEAVY SHOWERS AND
THUNDERSTORMS EXPECTED OVER THE NEXT FEW HOURS. FLASH FLOODING
WILL CONTINUE TO BE A MAJOR CONCERN.

DISCUSSION...A BROKEN BAND OF HEAVY SHOWERS AND THUNDERSTORMS
CONTINUES TO BE ORIENTED SW/NE FROM PARTS OF EXTREME NERN TX NEWD
THROUGH CNTRL AR AND INTO WRN TN. A SIGNIFICANT AMT OF TRAINING
HAS BEEN NOTED THROUGH THE MORNING HOURS...AND THE LATEST
RADAR/SAT TRENDS SUGGEST THAT ADDITIONAL TRAINING WILL OCCUR FOR A
COUPLE OF MORE HOURS AT LEAST. IN FACT...THE LATEST IR IMAGERY
SHOWS SOME VERY COLD CLOUD TOPS WITH THE COLDEST TOPS NOTED OVER
EXTREME SWRN TN AND ALSO DOWN OVER SWRN AR.

THE CONVECTION IS OCCURRING OUT AHEAD OF A COLD FRONT AND IS
INTERACTING WITH VERY MOIST SWLY H85 FLOW OF 20 TO 30 KTS. DESPITE
VERY MODEST INSTABILITY ATTM...THE BAND OF CONVECTION IS OCCURRING
WITHIN A DIFFLUENT FLOW REGIME ALOFT COURTESY OF H25 RRQ JET
DYNAMICS.

GIVEN THE LARGE SCALE ASCENT ASSOCD WITH THE UPR JET AXIS AND WITH
A WELL-DEFINED OUTFLOW BNDRY HELPING TO PROVIDE LOW LVL
FORCING...CONVECTION WILL LIKELY CONTINUE TO DEVELOP/BACK-BUILD
AND ULTIMATELY TRAIN OVER THE SAME AREA. THE 00Z ARW AND 00Z NSSL
WRF SUPPORT THIS IDEA THROUGH ABOUT 18Z. THE 00Z NMMB DOES AS
WELL...EXCEPT ITS AXIS OF CONVECTION IS TOO FAR NORTH.

ADDITIONAL FLASH FLOODING WILL BE EXPECTED GIVEN THE CURRENT
SET-UP AND ESP WITH PWATS OF 2.2 TO 2.4 INCHES WHICH ARE FOSTERING
EXTREMELY HEAVY RAINFALL RATES.

ORRISON

ATTN...WFO...FWD...JAN...LZK...MEG...OHX...SHV...TSA...

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

LAT...LON   36448882 36138812 35448793 34828851 34348964 
            34059045 33829139 33649224 33529297 33379431 
            33459508 33659556 34069535 34379491 34969386 
            35379271 35729103 36079010 36308962