MESOSCALE PRECIPITATION DISCUSSION 0285
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
347 PM EDT SUN AUG 17 2014
 
AREAS AFFECTED...NORTHEAST AR...MO BOOTHEEL...WESTERN/CENTRAL TN 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 171940Z - 180000Z
 
SUMMARY...TRAINING CONVECTION WILL SUPPORT THE POTENTIAL FOR FLASH
FLOODING THE NEXT FEW HOURS.

DISCUSSION...THE LATEST IR SAT IMAGERY SHOWS A W/E ORIENTED BAND
OF COLD-TOPPED CONVECTION STRETCHING FROM NERN AR INTO NWRN TN
ATTM. THE LATEST RADAR TRENDS INDICATE THIS BAND IS BEGINNING TO
TRAIN OVER THE SAME AREA AND AS A RESULT...THERE WILL BE A CONCERN
FOR VERY HVY RAINFALL TOTALS.

GOES SOUNDER PWATS ARE RUNNING AOA 2 INCHES IN THIS AREA AND SO
RAINFALL RATES WILL BE EXTREMELY HVY AND COULD APPROACH 3
INCHES/HR WITHIN THE DEEPEST CELLS AND WHERE OVERSHOOTING TOPS
OCCUR. IN FACT...THE LATEST GOES OTD ALGORITHM SHOWS A FEW
OVERSHOOTING TOPS JUST EAST OF KPHT.

THE CONVECTION WILL CONTINUE TO DEVELOP THROUGH THE AFTERNOON AND
TAKE ADVANTAGE OF A VERY UNSTABLE BNDRY LAYER AS EVIDENCE BY THE
LATEST RAP ANALYSIS WHICH SHOWS A NOSE OF SBCAPE EXCEEDING 4000
J/KG FROM CNTRL AR NEWD INTO WRN TN. ADDITIONAL FORCING ASSOCD
WITH A COLD FRONT SINKING SLOWLY SEWD SHOULD HELP TO SUSTAIN THE
CONVECTIVE THREAT INTO THE EARLY EVENING HOURS.

THE LATEST HI-RES MODELS ARE IN RATHER GOOD AGREEMENT ON LOCALLY
VERY HVY RAINS...AS THE 12Z NAM-CONEST...12Z ARW AND 12Z NMMB ALL
SHOW A SIGNAL FOR A W/E AXIS OF HVY RAINS WITH LOCALLY SEVERAL
INCHES POSSIBLE THROUGH 00Z.

FFG VALUES ARE HIGH ACROSS THE THREAT AREA...BUT GIVEN THE MEAN
LYR FLOW THAT IS NEARLY PARALLEL TO THE AFOREMENTIONED FRONT...THE
ENVIRONMENT IS CONDUCIVE FOR TRAINING CONVECTION AND A FEW CELL
MERGERS. THEREFORE...EXPECT FLASH FLOODING TO BE POSSIBLE THROUGH
00Z.

ORRISON

ATTN...WFO...OHX...PAH...MEG...LZK...

ATTN...RFC...LMRFC...NCRFC...OHRFC...

LAT...LON   35768694 35518851 35479017 35539168 35779257 36249274
            36439198 36389025 36398887 36568743 36518617 36098608
            35768694