
Snowfall accumulation from the Dec. 18-21, 2009 storm.
High resolution
To the surprise of no one affected by the Dec. 18-20, 2009 system that dumped heavy snow from the mid-Atlantic to southern New England, NOAA has rated the storm a Category 3 or “Major” winter storm on NOAA’s Northeast Snowfall Impact Scale, also known as NESIS.
NESIS characterizes and ranks Northeast snowstorms, using data calculated by NOAA’s National Climatic Data Center, based on the following factors: how much snow falls (must deposit at least 10 inches); the scale of the area impacted; and the population of the impacted area. NESIS ranks these storms on a five-tier scale ranging from Category 1 “Notable” to Category 5 “Extreme.”

“While snowfall from the December storm ranked in the top ten for Washington, Baltimore and Philadelphia, the storm only provided a glancing blow to the New York City and Boston metropolitan areas and overall affected a relatively small area. This led to it being classified as a Category 3,” said Louis Uccellini, director of the National Centers for Environmental Prediction – a division of NOAA’s National Weather Service – and co-developer of NESIS with Paul Kocin also with NCEP in Camp Springs, Md. Both Uccellini and Kocin are published winter weather experts.

Satellite image of the snowcover enlarged here.
"Last month's storm was one of only five in the past decade that ranked Category 3 or higher," added Kocin. The others being: December, 2002 (Category 3); February, 2003 (Category 4); January, 2005 (Category 4); February, 2006 (Category 3) and February, 2007 (Category 3).
Topping the NESIS scale - and the only storms rated Category 5 - are the “Superstorm” on March, 1993

followed by the “Blizzard of ’96” in January, 1996.

The scale, developed in 2004, catalogues storms dating back to 1888. End NOAA story.

Blockbuster east coast storms are favored in El Nino west QBO winters, the snowiest of all ENSO/QBO pairs in the eastern cities. The QBO was in transition from west to east at the critical level (45mb) in December.




New York City February 1969
Rank of 37 high-impact snowstorms that affected the Northeast urban corridor.
(click on hyperlinked dates for map of storm)
Rank |
Date |
NESIS |
Category |
Description |
1 |
Mar 12-14, 1993 |
13.20 |
5 |
Extreme |
2 |
Jan 6-8, 1996 |
11.78 |
5 |
Extreme |
3 |
Feb 15-18, 2003 |
8.91 |
4 |
Crippling |
4 |
Mar 2-5, 1960 |
8.77 |
4 |
Crippling |
5 |
Feb 2-5, 1961 |
7.06 |
4 |
Crippling |
6 |
Jan 11-14, 1964 |
6.91 |
4 |
Crippling |
7 |
Jan 21-24, 2005 |
6.80 |
4 |
Crippling |
8 |
Jan 19-21, 1978 |
6.53 |
4 |
Crippling |
9 |
Dec 25-28, 1969 |
6.29 |
4 |
Crippling |
10 |
Feb 10-12, 1983 |
6.25 |
4 |
Crippling |
11 |
Feb 14-17, 1958 |
6.25 |
4 |
Crippling |
12 |
Jan 29-31, 1966 |
5.93 |
3 |
Major |
13 |
Feb 5-7, 1978 |
5.78 |
3 |
Major |
14 |
Feb 12-15, 2007 |
5.63 |
3 |
Major |
15 |
Jan 21-23, 1987 |
5.40 |
3 |
Major |
16 |
Feb 8-12, 1994 |
5.39 |
3 |
Major |
17 |
Feb 17-19, 1979 |
4.77 |
3 |
Major |
18 |
Feb 18-20, 1972 |
4.77 |
3 |
Major |
19 |
Dec 11-13, 1960 |
4.53 |
3 |
Major |
20 |
Feb 22-28, 1969 |
4.29 |
3 |
Major |
21 |
Feb 12-13, 2006 |
4.10 |
3 |
Major |
22 |
Jan 18-21, 1961 |
4.04 |
3 |
Major |
23 |
Dec 18-21, 2009 |
4.03 |
3 |
Major |
24 |
Dec 23-25, 1966 |
3.81 |
2 |
Significant |
25 |
Feb 8-10, 1969 |
3.51 |
2 |
Significant |
26 |
Mar 18-21, 1958 |
3.51 |
2 |
Significant |
27 |
Feb 5-8, 1967 |
3.50 |
2 |
Significant |
28 |
Apr 6-7, 1982 |
3.35 |
2 |
Significant |
29 |
Mar 15-18, 2007 |
2.55 |
2 |
Significant |
30 |
Jan 24-26, 2000 |
2.52 |
2 |
Significant |
31 |
Dec 30-31, 2000 |
2.37 |
1 |
Notable |
32 |
Mar 31-Apr 1, 1997 |
2.29 |
1 |
Notable |
33 |
Mar 18-19, 1956 |
1.87 |
1 |
Notable |
34 |
Mar 1-3, 2009 |
1.65 |
1 |
Notable |
35 |
Feb 22-23, 1987 |
1.46 |
1 |
Notable |
36 |
Feb 2-4, 1995 |
1.43 |
1 |
Notable |
37 |
Jan 25-26, 1987 |
1.19 |
1 |
Notable |