MESOSCALE DISCUSSION 2144
   NWS STORM PREDICTION CENTER NORMAN OK
   1141 AM CDT TUE SEP 06 2011
   
   AREAS AFFECTED...NERN SC/NWRN-CENTRAL AND ERN NC/FAR SRN VA
   
   CONCERNING...TORNADO WATCH 845...846...847...
   
   VALID 061641Z - 061745Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH
   845...846...847...CONTINUES.
   
   A NEW WW WILL BE NEEDED BY 18Z TO REPLACE MUCH OF WW 845 WHICH IS
   SCHEDULED TO EXPIRE AT THAT TIME.
   
   THREAT FOR TORNADOES AND DAMAGING WINDS IS EXPECTED TO PERSIST
   THROUGH THE AFTERNOON ACROSS MUCH OF CENTRAL AND ERN CAROLINAS INTO
   PARTS OF FAR SRN VA. 
   
   LATE MORNING SURFACE ANALYSES SHOWED THE PRIMARY SYNOPTIC LOW
   REMAINING GENERALLY STATIONARY OVER FAR NWRN GA...WHILE A
   SECONDARY...SUB-SYNOPTIC LOW WAS LOCATED OVER FAR NERN TN /JUST S OF
   TRI/.  COLD FRONTS TRAILED SWD FROM EACH OF THESE AREAS OF LOW
   PRESSURE...WITH THE ERN COLD FRONT MARKING THE WRN EXTENT OF THE
   SEVERE WEATHER THREAT.  AT 16Z...THIS BOUNDARY EXTENDED...INITIALLY
   SSEWD FROM NERN TN THROUGH FAR WRN NC INTO CENTRAL SC /INVOF
   CAE/...AND THEN SWD ALONG THE GA COAST THROUGH NRN FL TO OFF THE WRN
   FL COAST.  COUNTIES CAN CONTINUE TO BE CLEARED FROM THE WRN TWO
   TORNADO WATCHES /846 AND 847/ WITH THE FRONTAL PASSAGE.
   
   MEANWHILE...ISENTROPIC ASCENT ATOP A BAROCLINIC ZONE EXTENDING WSWWD
   FROM THE FAR SRN EXTENT OF THE DELMARVA PENINSULA /S OF WAL/ THROUGH
   FAR SERN VA TO NORTH CENTRAL NC...AND THEN WNWWD INTO FAR SWRN VA IS
   CONTINUING TO REINFORCE A RAIN-COOLED AIR MASS N OF THIS BOUNDARY
   WHICH IS ACTING A NRN DELIMITER TO SEVERE WEATHER.  SLOW SWD
   MOVEMENT HAS BEEN NOTED...WHILE THE SERN VA PORTION OF THIS FRONT
   APPEARS TO BE BECOMING QUASI-STATIONARY GIVEN THE LACK OF SHOWER
   ACTIVITY N OF THIS AREA. 
   
   GIVEN THE NWD TRACK OF THE UPPER LOW...DEEP LAYER MERIDIONAL FLOW
   WILL LIMIT THE ERN EXPANSION OF THE SEVERE WEATHER THREAT INTO FAR
   ERN NC.  SUFFICIENT DEEP LAYER AND LOW LEVEL SHEAR COMBINED WITH
   MODERATE INSTABILITY FROM ERN SC INTO CENTRAL NC AND SERN VA WILL
   SUSTAIN THE ONGOING SEVERE WEATHER THREAT AND THE NEED FOR A NEW WW
   BY 18Z.
   
   ..PETERS.. 09/06/2011
   
   
   ATTN...WFO...AKQ...MHX...RAH...ILM...RNK...CAE...GSP...
   
   LAT...LON   33667762 32987891 33517996 34408004 35588019 36038043
               36108136 36518130 36878028 37147868 36947755 37047696
               36897588 36537586 35837621 35257687 34717758 34477755
               34307735 33667762