MESOSCALE DISCUSSION 1950
   NWS STORM PREDICTION CENTER NORMAN OK
   0710 AM CDT MON OCT 07 2013

   AREAS AFFECTED...ERN VIRGINIA...CNTRL AND ERN MARYLAND...ERN
   PENNSYLVANIA...SRN NEW YORK STATE

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 071210Z - 071415Z

   PROBABILITY OF WATCH ISSUANCE...60 PERCENT

   SUMMARY...SEVERE THUNDERSTORM POTENTIAL MAY INCREASE SUFFICIENTLY TO
   REQUIRE ONE OR MORE WATCHES...PERHAPS AS EARLY AS THE 13-14Z TIME
   FRAME.

   DISCUSSION...A NARROW ENHANCED CONVECTIVE BAND APPEARS TO GRADUALLY
   BE IN THE PROCESS OF EVOLVING ALONG A SIGNIFICANT SURFACE FRONT NOW
   CROSSING THE LOWER GREAT LAKES/UPPER OHIO VALLEY AND CENTRAL
   APPALACHIANS REGION.  FURTHER DEVELOPMENT AND INTENSIFICATION
   APPEARS LIKELY WHILE ACTIVITY SLOWLY PROGRESSES EASTWARD THROUGH THE
   REMAINDER OF THE MORNING...AS FRONTOGENETIC FORCING CONTINUES TO
   STRENGTHEN WITH THE APPROACH OF THE VIGOROUS UPSTREAM SHORT WAVE
   TROUGH.  THIS IS ALSO EXPECTED TO COINCIDE WITH SUBSTANTIVE
   STRENGTHENING OF SOUTHERLY PRE-FRONTAL LOW-LEVEL FLOW...WITH THE
   HIGH RESOLUTION RAPID REFRESH INDICATING 850 MB WINDS IN EXCESS OF
   50 KT IN A CORRIDOR ACROSS NORTH CENTRAL VIRGINIA THROUGH
   CENTRAL/EASTERN PENNSYLVANIA AND THE SOUTHERN TIER OF NEW YORK STATE
   BY THE 15-17Z TIME FRAME.

   INSTABILITY APPEARS THE PRIMARY LIMITING FACTOR CONCERNING THE
   SEVERE WEATHER POTENTIAL.  WITH CONSIDERABLE CLOUD COVER LIKELY TO
   INHIBIT SURFACE HEATING...AND COLDER AIR ALOFT CONTINUING TO LAG THE
   SURFACE FRONT...LOWER/MID TROPOSPHERIC LAPSE RATES WILL REMAIN WEAK.
    BUT MOISTURE CONTENT IS SEASONABLY HIGH...AND CONTRIBUTING TO
   SUFFICIENT CAPE THROUGH FAVORABLY COLD MID-LAYERS TO SUPPORT ONGOING
   THUNDERSTORM ACTIVITY ALONG AND TO THE LEE OF THE BLUE RIDGE
   MOUNTAINS.  THIS LIKELY WILL CONTINUE DEVELOPING NORTHWARD WHILE
   GRADUALLY SHIFTING EASTWARD DURING THE NEXT FEW HOURS.  IT MAY NOT
   TAKE MUCH CONVECTIVE INTENSIFICATION TO SUPPORT TO SUPPORT AT LEAST
   LOW PROBABILITIES FOR SEVERE WIND GUSTS ASSOCIATED WITH DOWNWARD
   MOMENTUM TRANSFER.  AS PRECIPITATION LOADING INCREASES...THE
   POTENTIAL FOR SEVERE WIND GUSTS PROBABLY WILL INCREASE THROUGH MID
   TO LATE MORNING.

   GIVEN THE HIGH BOUNDARY LAYER MOISTURE CONTENT...AND THE ANTICIPATED
   EVOLUTION OF RATHER LARGE CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS IN
   THE PRE-FRONTAL ENVIRONMENT...THE RISK FOR TORNADOES MAY NOT BE
   COMPLETELY NEGLIGIBLE.  HOWEVER...THIS THREAT SEEMS LIMITED BY THE
   LOW POTENTIAL FOR VIGOROUS DISCRETE STORM DEVELOPMENT.

   ..KERR/EDWARDS.. 10/07/2013


   ATTN...WFO...PHI...BGM...AKQ...CTP...LWX...RNK...

   LAT...LON   39957748 41487743 42637660 42227526 39567538 37547684
               36877792 36987908 37997828 39957748