MESOSCALE DISCUSSION 0185
   NWS STORM PREDICTION CENTER NORMAN OK
   1216 PM CST SUN MAR 01 2009
   
   AREAS AFFECTED...PARTS OF NWRN NC THRU CNTRL VA
   
   CONCERNING...HEAVY SNOW 
   
   VALID 011816Z - 012115Z
   
   AN INITIAL BAND OF HEAVY SNOW IS EXPECTED TO GRADUALLY DEVELOP
   BETWEEN NOW AND 20-21Z...THEN LINGER INTO EARLY EVENING...WITH SNOW
   RATES IN EXCESS OF 1 INCH PER HOUR POSSIBLE.
   
   THE SOUTHEASTERN STATES DEEP CLOSED LOW IS NOW BEGINNING TO LIFT
   NORTHEASTWARD TO THE LEE OF THE SOUTHERN APPALACHIANS.  AS THIS
   PROCESS CONTINUES THIS AFTERNOON...TO THE SOUTHEAST OF THE DIGGING
   UPPER TROUGH ACROSS THE GREAT LAKES REGION...MODELS INDICATE THAT
   LOWER/MID TROPOSPHERIC FRONTOGENESIS WILL STRENGTHENING BENEATH
   INCREASINGLY DIVERGENT UPPER FLOW...FROM THE LEE OF THE CENTRAL
   APPALACHIANS THROUGH THE MID ATLANTIC SEABOARD.  THIS IS EXPECTED TO
   CONTRIBUTE TO STRENGTHENING DEEP LAYER UPWARD VERTICAL
   MOTION...INCLUDING THROUGH THE FAVORABLE MIXED PHASE REGION FOR
   LARGE DENDRITIC ICE CRYSTAL GROWTH.
   
   SOME UNCERTAINTIES EXIST CONCERNING THE CONTINUING PRESENCE OF
   SOMEWHAT MARGINAL LOW-LEVEL TEMPERATURES FOR SNOW REACHING THE
   SURFACE.  BUT...GUIDANCE...INCLUDING THE SREF...STILL INDICATE
   THAT...IF THERMODYNAMIC PROFILES ARE NOT ALREADY SUPPORTIVE...
   ENOUGH COOLING WILL PROBABLY OCCUR DURING THE ONSET OF PRECIPITATION
   TO SUPPORT SNOW...OR A QUICK CHANGEOVER TO SNOW...FROM THE
   NORTHWESTERN NORTH CAROLINA PIEDMONT THROUGH CENTRAL VIRGINIA.  THIS
   APPEARS MOST LIKELY NEAR OR NORTHWEST OF A DANVILLE/RICHMOND LINE BY
   THE 21-23Z TIME FRAME...INCLUDING LYNCHBURG...PERHAPS ROANOKE AND
   CHARLOTTESVILLE...BUT STILL SOUTH OF THE WASHINGTON D.C. AREA.
   
   IN GENERAL...MODEL FORECAST SOUNDINGS INDICATE STEEPENING MID-LEVEL
   LAPSE RATES THROUGH THE AFTERNOON...ATOP AN INCREASINGLY DEEP
   ISOTHERMAL LAYER NEAR OR JUST BELOW FREEZING.  THIS WILL BE VERY
   FAVORABLE FOR HEAVY WET SNOW...AND MID-LEVEL DESTABILIZATION MAY
   BECOME SUFFICIENT FOR STRONGER CONVECTIVE BURSTS...PERHAPS
   ACCOMPANIED BY ISOLATED LIGHTNING.
   
   ..KERR.. 03/01/2009
   
   
   ATTN...WFO...AKQ...LWX...RNK...
   
   LAT...LON   36168107 37478009 38027856 38237771 38227700 37707703
               36637877 36557982 36168107