MESOSCALE DISCUSSION 0247
   NWS STORM PREDICTION CENTER NORMAN OK
   0745 PM CST TUE MAR 05 2013
   
   AREAS AFFECTED...THE MIAMI AND WHITEWATER VALLEY AND W-CNTRL OHIO
   
   CONCERNING...HEAVY SNOW 
   
   VALID 060145Z - 060545Z
   
   SUMMARY...HEAVY SNOW WILL LIKELY IMPACT THE MIAMI AND WHITEWATER
   VALLEY AND W-CNTRL OH INTO THE OVERNIGHT HOURS. RATES OF 1 IN/HR
   WILL BE POSSIBLE.
   
   DISCUSSION...REPORTS FROM THE NSSL PRECIPITATION IDENTIFICATION NEAR
   THE GROUND -- PING -- PROJECT AND COORDINATION WITH THE WILMINGTON
   OH WFO INDICATE THAT HEAVY WET SNOW IS INCREASING IN COVERAGE AND
   INTENSITY ACROSS PORTIONS OF E-CNTRL INDIANA. THIS IS IN CONJUNCTION
   WITH THE CORE OF A NW/SE-SHEARED ZONE OF WAA-RELATED PRECIPITATION
   OVER THE OH VALLEY. THE PRECIPITATION WILL LIKELY CONTINUE OVER THE
   AREA INTO THE OVERNIGHT HOURS...AS A MID-LEVEL CYCLONE TRACKS
   SEWD/PARALLEL TO THE LONG AXIS OF THE ISENTROPIC ASCENT ZONE.
   LOW-LEVEL TRAJECTORIES INTO THE AREA EMANATE FROM A SOURCE REGION OF
   SUB-FREEZING WET BULB TEMPERATURES...WHICH WILL YIELD A PHASE CHANGE
   TO SNOW ACROSS THE ENTIRE AREA DURING THE NEXT COUPLE OF HOURS. THIS
   WILL ALSO SUPPORT AN INCREASE IN SNOW RATES THROUGH THE
   EVENING...WITH AMDAR DATA SUGGESTING EFFICIENT SNOW AGGREGATION
   OWNING TO NEARLY ISOTHERMAL LAYERS BETWEEN 850 AND 700 MB. RATES
   REACHING 1 IN/HR WILL BE POSSIBLE...POTENTIALLY IMPACTING THE DAYTON
   METRO AREA BETWEEN 0230Z AND 0600Z.
   
   TO THE E/SE OF THE MCD AREA ACROSS CNTRL OH...A LOW-LEVEL WARM
   SECTOR FEATURING ABOVE-FREEZING THERMAL PROFILES IS EVIDENT PER
   REGIONAL SFC OBS AND THE 00Z ILN RAOB. PROVIDED THE ENEWD TRACK OF A
   SFC LOW...AND STRONG EWD SURGE OF THE DEEPER COLD AIR TO THE S OF
   THE LOW...AT LEAST PARTIAL SECLUSION OF THE WARM AIR CURLING AROUND
   THE LOW MAY GREATLY DELAY A CHANGEOVER TO SNOW FOR COLUMBUS AND ITS
   VICINITY AND POINTS FARTHER E. RAIN MAY POTENTIALLY BE THE
   PREDOMINANT PRECIP TYPE THROUGH AT LEAST 06Z/07Z -- AS AFFIRMED BY
   THE CONSENSUS AMONG HIGH-RESOLUTION WRF GUIDANCE.
   
   ..COHEN.. 03/06/2013
   
   
   ATTN...WFO...CLE...ILN...IWX...IND...
   
   LAT...LON   40788331 40378330 39608419 39558494 40098511 40748475
               40948407 40788331