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+