MESOSCALE DISCUSSION 2572 NWS STORM PREDICTION CENTER NORMAN OK 0601 AM CST THU DEC 23 2004 AREAS AFFECTED...MUCH OF OH...SERN LOWER MI...FAR NWRN PA CONCERNING...PRECIPITATION TRENDS...WINTER PRECIPITATION VALID 231201Z - 231600Z HVY SNOW OVER NWRN OH/FAR SERN LOWER MI WILL CONTINUE TO MOVE NEWD AND SHOULD BEGIN TO DIMINISH OVER THE REGION BETWEEN 14-15Z. HVY SNOW WILL LINGER TO AROUND 18Z OVER THE THUMB REGION OF SERN MI...WHERE LAKE ENHANCEMENT WILL OCCUR. FARTHER SE...A LARGE AREA OF MOD-HVY FREEZING RAIN/SLEET WILL CHANGE OVER TO LIGHT/MOD SNOW THROUGH 15Z...BEFORE ENDING FROM WEST TO EAST ACROSS CENTRAL/ERN OH BY 17Z AND FAR NWRN PA BY 18Z. HOURLY ICE ACCUMULATIONS OVER 0.10 INCH WILL CONTINUE BEFORE PTYPE CHANGEOVER TO SNOW. STRONG DEEP LAYER DYNAMIC LIFT WILL CONTINUE TO MOVE NEWD INTO SERN CANADA AHEAD OF NEGATIVELY TILTED SHORTWAVE TROUGH MOVING ACROSS THE OHIO VALLEY. A PRONOUNCED DRY SLOT WILL ALLOW FOR A RAPID DIMINISHMENT IN THE INTENSITY OF PRECIP FROM WEST TO EAST ACROSS MUCH OF OH/WRN PA THROUGH 18Z. INCREASED LOW LEVEL COLD ADVECTION WILL ALLOW FOR A TIGHTENING THERMAL GRADIENT IN THE LOWER LEVELS AND CONTINUED DECREASE IN THE AREAL COVERAGE OF A SHALLOW ELEVATED ABOVE FREEZING LAYER OVER CNTRL/ERN OH THROUGH THE MID MORNING. THUS...EXPECT FREEZING RAIN OVER CENTRAL OH TO CHANGE OVER TO SLEET AND THEN LT/MOD SNOW THROUGH 14Z AND FREEZING RAIN/RAIN OVER ERN OH/NWRN PA TO CHANGE TO LIGHT/MOD SNOW BETWEEN 14-16Z. FARTHER NORTH OVER SERN LOWER MI...DEFORMATION/FRONTOGENETIC HVY SNOWFALL BANDS WITH HOURLY RATES AROUND 1 INCH WILL CONTINUE TO DEVELOP NEWD FROM THE DTW METRO AREA TOWARDS LAKE HURON THROUGH THE MID MORNING. AS UPPER TROUGH CONTINUES TO ACCELERATE NEWD. THUS SUPPORT FOR HVY SNOW SHOULD END OVER THE DTW METRO AREA BETWEEN 14-15Z. HOWEVER FARTHER NORTH...INCREASING NLY FLOW OVER LAKE HURON COUPLED WITH LINGERING DEFORMATION SYNOPTIC SCALE LIFT WILL AID IN HVY LAKE ENHANCED SNOWFALL RATES UP TO 2 INCHES/HR OVER THE ERN THUMB REGION THROUGH 17Z. AS WINDS BACK TO A MORE NWLY DIRECTION AND SYNOPTIC SCALE LIFT DIMINISHES...EXPECT HRLY SNOWFALL RATES OVER THE THUMB TO DIMINISH TO AOB 1 IN/HR AFTER 18Z. ..CROSBIE/CARBIN.. 12/23/2004 ...NOTICE... SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A SCHEDULED BASIS...FOUR TIMES A DAY...BETWEEN 00-01 UTC... 06-07 UTC...12-13 UTC...AND 18-19 UTC AS SIGNIFICANT SHORT RANGE WINTER WEATHER EVENTS UNFOLD. THIS SCHEDULE WILL BE USED FROM DECEMBER 1 THROUGH FEBRUARY 28. ATTN...WFO...PBZ...RLX...CLE...ILN...DTX...IWX...GRR... 42247976 41638011 40908060 39958157 39098263 38988372 39388404 40868438 41808451 42868409 44018325
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