MESOSCALE DISCUSSION 1254
   NWS STORM PREDICTION CENTER NORMAN OK
   0618 PM CDT THU JUN 16 2011
   
   AREAS AFFECTED...ERN AR...WRN TN...NRN/CNTRL MS...MO BOOTHEEL
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 485...487...
   
   VALID 162318Z - 170045Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
   485...487...CONTINUES.
   
   NUMEROUS TSTM CLUSTERS PERSIST ACROSS ERN AR IN ASSOCIATION WITH AN
   MCV DRIFTING E ACROSS N-CNTRL AR AND ALONG REMNANT OUTFLOW
   BOUNDARIES ACROSS THE LOWER MS VALLEY. ACTIVITY CONTINUES TO
   INCREASE IN COVERAGE SUGGESTIVE THE TSTM AMALGAMATION SHOULD LEAD TO
   SIGNIFICANT COLD POOL FORMATION AND ORGANIZATION INTO ONE OR MORE
   LINES. THIS PROCESS APPEARS TO BE UNDERWAY IN NERN AR/MO
   BOOTHEEL...AND IS MODELED TO SOME EXTENT BY 20-21Z HRRR SIMULATED
   REFLECTIVITY. WITH DOWNSTREAM SURFACE TEMPERATURES IN WRN TN HAVING
   RECOVERED INTO THE UPPER 80S TO LOWER 90S...WITH MIDDLE 60S TO
   MIDDLE 70S DEW POINTS...AN ORGANIZED QLCS COULD EVENTUALLY
   ACCELERATE EWD WITH A MORE PROMINENT THREAT FOR DAMAGING WINDS. IF
   THIS OCCURS...IT WOULD LIKELY NECESSITATE AN AREAL EXTENSION OF WW
   487.
   
   FARTHER S...A LARGE TSTM CLUSTER IN CNTRL MS CENTERED AROUND 50 NW
   MEI APPEARS TO BE GRADUALLY DEVELOPING SWD ALONG AN OUTFLOW BOUNDARY
   BISECTING NEWTON/JASPER COUNTIES INTO NRN GREENE COUNTY AS OF 23Z.
   ISOLATED DAMAGING WIND/MARGINAL SEVERE HAIL THREAT WILL REMAIN A
   SHORT-TERM THREAT WITH THIS CLUSTER. WITH CU FIELD DIMINISHING W OF
   THE OUTFLOW BOUNDARY...ADDITIONAL TSTM DEVELOPMENT IN THE WRN HALF
   OF WW 485 APPEARS UNLIKELY.
   
   ..GRAMS.. 06/16/2011
   
   
   ATTN...WFO...OHX...MOB...PAH...MEG...JAN...LZK...
   
   LAT...LON   34469188 35919047 36378997 36648968 36638896 36418839
               35998818 35198851 34598923 34108947 33458939 33048901
               32108860 31658859 31388880 31568905 32008968 32908984
               33409010 33749063 33729127 33899182 34469188