MESOSCALE DISCUSSION 0043
   NWS STORM PREDICTION CENTER NORMAN OK
   0842 PM CST THU JAN 17 2013
   
   AREAS AFFECTED...SERN VA...FAR NERN NC
   
   CONCERNING...HEAVY SNOW 
   
   VALID 180242Z - 180645Z
   
   SUMMARY...A TRANSITION FROM RAIN OR A RAIN/SNOW MIX TO HEAVY
   SNOWFALL IS EXPECTED TO OCCUR WITHIN THE NEXT 1-2 HRS ACROSS SERN VA
   AND FAR NERN NC. A BURST OF WET...HEAVY SNOW...WITH RATES OF 1 INCH
   PER HR AND LOCALLY HEAVIER RATES APPROACHING 1.5 INCHES PER
   HR...WILL BE POSSIBLE.
   
   DISCUSSION...A LARGE SWATH OF PRECIPITATION /PRIMARILY RAIN OR A
   RAIN/SNOW MIX AT 02Z/ ASSOCIATED WITH A VIGOROUS UPSTREAM UPPER
   TROUGH IS EXPECTED TO CHANGEOVER TO MAINLY SNOW BY 04Z ACROSS THE
   COASTAL PLAIN OF SERN VA AND FAR NERN NC. SFC OBS FROM 02Z SHOW
   TEMPERATURES GENERALLY IN THE LOW-MID 30S F...BUT AS DYNAMIC
   COLUMNAR COOLING ASSOCIATED WITH INTENSE UPPER DIVERGENCE/DPVA
   ATTENDANT TO THE UPPER TROUGH OCCURS OVER THE AREA...SUB-FREEZING
   VERTICAL TEMPERATURE PROFILES WILL BECOME INCREASINGLY COMMON.
   SIMILAR TO AREAS W OF THE DISCUSSION AREA...HIGH MOISTURE CONTENT
   /PW NEAR 1 INCH PER 00Z SOUNDINGS/ AND A SUFFICIENTLY DEEP DENDRITIC
   GROWTH ZONE...COUPLED WITH INTENSE MIDLEVEL FORCING FOR
   ASCENT...WILL SUPPORT SNOWFALL RATES NEAR 1 INCH PER HR. 00Z PLOT
   DATA AND FORECAST MODEL GUIDANCE INDICATE THE UPPER WAVE IS
   ACCELERATING NEWD...AND SHOULD RESULT IN A CESSATION OF THE HEAVIEST
   SNOWFALL RATES BY 07Z...AS AN ATTENDANT DRY SLOT /NOTED ON WATER
   VAPOR LOOP/ RAPIDLY SPREADS N/NEWD INTO NERN NC AND SERN VA.
   
   ..ROGERS.. 01/18/2013
   
   
   ATTN...WFO...AKQ...RAH...
   
   LAT...LON   36967647 36527687 36397720 36347776 36487810 37167787
               37737758 37957700 37807656 37507630 36967647