The Dee Snowstorm Scale

Category	Description	Average Snowfall Rates	Average Snowfall Accumulation	Minimum Visability	Winds
1	A weak storm, with light snowfall rates and minimal accumulation.  Travel is only impaired slightly.	Less than 1”   in 4 hours	Less than 2”	1.5-2 miles	0-20 mph
2	A marginal storm, but a burst of heavier snow sometimes occurs, reducing visibility’s temporarily.  Final accumulation is greater than with a Cat. 1.  Travel is impaired more significantly, especially during the heavier snow bursts, but still not difficult.	Less than 1” in 2  hours, with a brief period of 1”/hour snowfall.	2-4”	.75-1 mile	5-25 mph
3	A significant storm, with moderate snowfall rates occurring through about half the storms duration.  Travel at the onset of the storm is impacted and becomes difficult by the end of the storm.	1” per hour	3-8”	.30-.50 mile	10-30 mph
4	A significant storm, with moderate snowfall rates occurring through over half of the storm and a period of heavy snow also likely.  Travel is difficult only hours after the storm and very difficult by storms edge.  Blowing and drifting of snow is also significant.	1-1.5” per hour	4-10”	.25-.50 mile	20-45 mph
5	A major storm, with moderate snowfall rates through most of the storm and several peri9ods of heavy snowfall occurring.  Significant blowing and drifting of snow occurs.  Blizzard parameters are usually met by the storm.  Travel is very difficult soon after the onset of the storm and nearly impossible towards the end of the storm.	1-2” per hour	8-15”	.125-.50 mile	25-50 mph
6	A major storm, with moderate to heavy snowfall rates through most of the storm and periods of near whiteout conditions.  Severe blowing and drifting of snow, blizzard conditions occur through much of the storm.  Travel is basically impossible by the end of the storm.	1-4” per hour	1-2 feet +	0-.125 mile	30-60 mph+