MESOSCALE DISCUSSION 2554
   NWS STORM PREDICTION CENTER NORMAN OK
   1118 PM CST MON DEC 20 2004
   
   AREAS AFFECTED...ERN UPPER MI/NWRN LOWER MI
   
   CONCERNING...HEAVY SNOW 
   
   VALID 210518Z - 211115Z
   
   HEAVIER SNOW AREA NOW MOVING ACROSS NORTHERN LAKE MICHIGAN SHOULD
   CONTINUE WITH MAXIMUM SNOWFALL RATES OF 1 TO 2 INCHES PER HOUR IN
   THE COUNTIES ON THE EASTERN SHORE OF LAKE MICHIGAN AND THE EASTERN
   MOST COUNTIES OF UPPER MICHIGAN.
   
   SURFACE WINDS ON THE EASTERN SHORE OF LAKE MICHIGAN HAVE BACKED PAST
   SEVERAL HOURS AHEAD OF AN ADVANCING UPPER SHORT WAVE.  SURFACE
   CONVERGENCE ZONE SHOULD INCREASE ALONG THE EASTERN SHORE OF LAKE
   MICHIGAN DURING THE NEXT 6 HOURS AS LES REACHES A MAXIMUM.  LOW
   LEVEL VERTICAL VELOCITIES ARE ALSO FORECAST TO REACH A MAXIMUM
   AROUND 09 UTC. 
   
   THE HEAVIEST SNOW SHOULD BEGIN TO DECREASE AFTER 09 UTC AS
   CONVERGENCE/SURFACE FLOW WEAKENS WITH  UPPER SYSTEM MOVING QUICKLY
   PAST.
   
   ..BOTHWELL.. 12/21/2004
   
   
   ...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...APX...GRR...MQT...
   
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