Snow Depth Days
of the Northeast

Traditionally, a winter's snowfall has been tracked as simply the total snow that falls during the season. While fine for several purposes, it doesn't really measure the impact of the snow on people. Suppose the total snowfall for a season is 100 inches. Near a coast where the ocean brings in warm, moist maritime air and rain, snow may not last for very long. Inland where arctic air dominates, the snow will last longer and the maximum snow depth can be much greater than near the coast.

The type of snow also has differing impacts. A foot of dry, fluffy snow will compress quickly with time (or with more snow) whereas an equal depth of wet snow presents more challenges to driving, shoveling, compression and melting.

Snow Depth Days

Snow Depth Days makes a better measure of impact a winter's snows. The depth days for a whole winter are simply the sum of the snow depth on the ground for each day of the winter. Storms that start with snow and change to rain count for less than storms that are all snow.

Two major blizzards in Massachusetts show the importance of the depth day metric. If you experienced both the Blizzard of '78 and the April Fool's Blizzard of '97, the 1978 storm wins hands down despite surprisingly similar snow distributions.  The key differences were the winds (1978 saw major coastal destruction), the weight of the snow (1997 took a heavier toll on tree limbs), and how long the snow remained. Massachusetts was shut down for a week in 1978, but the 1997 snow melted in days. 1997's storm brought far fewer depth days. A couple weeks earlier, Jan 20th, a storm left 22" of snow in Boston, a January record and 24 hour record. While a rain storm on Jan 26 melted most of the snow in Boston, snowbanks were still on the sides of the streets and sidewalks when the second storm hit on Feb 6th setting new 24 hour (23.6") and total storm records (27.5"). Boston and much of the rest of state simply had no place to put the new snow. Those storms brought the bulk of the snow that year, it would be fun to go back to the climatic records and compute the depth days for each month in 1978 and 1997.

Persistence Quotient

After tracking depth days for a few years, Jim Corbin realized that dividing a season's depth days by the season's snowfall, you get another interesting metric. The quotient is a number that tells you how many days an average inch of snow lasts. If two sites have the same number of depth days but a very different persistence quotient, the one with the higher value was colder than the one with the lower quotient. It didn't snow as much, but what fell stayed longer. I think depth days is the more important metric, but it's easy and worthwhile to track persistence too. Maybe we can find a correlation between it and average temperature.

Annual summaries

My collaborators and I have been tracking SDDs long enough to make it worthwhile to collect all the annual summaries together. Click on the column headings to see data for specific season. Caveat: data for the current season is season to date, all others are for the complete season. Some of the season pages will have data for partial seasons, I haven't included those here.

In each data box, the top number is the number of SDDs for the season, the lower box is the snowfall for the season. While it disagrees with the precision from the reports, I've recorded SDDs to the inch and snowfall to the tenth to make the data easier to read. To keep the table size down, I haven't included the Persistence Quotients.

Station Bold numbers are data for the whole season.
97/98 98/99 99/00 00/01 01/02 02/03 03/04 04/05 05/06 06/07 07/08 08/09 09/10 10/11
Collinsville CT SDDs:
Snowfall:
356
34.2		 1243
85.1		 111
30.0		 1109
94.6		 381
52.1		 673
79.1		 352
67.0		 245
29.7		 467
48.1


Ashland MA
61
24.0		 190
28.1		 544
70.5		 54
29.1

476
86.0		 199
48.0		 124
27.1		 330
54.5


S Attleboro MA 21
11.6		 50
23.4		 108
19.3		 260
48.2		 31
19.6








N Berlin MA




1386
98.5		 273
47.0		 868
108.2





Fairhaven MA 9
8.4		 63
33.4		 31
13.1		 98
44.0		 15
11.7		 270
60.1		 139
44.3		 525
92.7		 69
31.0		 16
13.1		 97
26.8		 152
35.6		 194
37.3		 178
30.8
Groveland MA







204
54.2		 364
2.3		 833
77.4


Manchester MA







82
16.3




Marlboro MA 294
41.8		 62
24.5		 247
30.3		 1106
89.3		 86
36.1		 888
87.3		 211
46.6		 685
96.7		 205
54.6		 184
32.5		 423
66.0		 530
54.5		 205
56.2		 461
54.6
Middleboro MA 18
41.5		 20
95.5











Milford MA
96
57.0











Milton MA 71
26.1		 77
35.7		 182
28.6		 228
64.4		 28
26.6		 317
73.9







Milton-BHO MA



83
40.3		 682
95.3
521
94.2





Monson MA






328
55.8		 273
52.2




Newburyport MA




613
46.2







Pepperell MA


1287
101.6		 183
45.6		 1379
99.0		 430
52.3		 841
111.8		 348
65.6		 295
49.9		 1584
99.3		 978
85.8		 728
59.3		 352
47.9
Sterling MA 399
55.0
356
35.0		 1612
92.0









Sudbury MA




1369
95.2







E Walpole MA
67
23.8		 149
18.1		 229
28.6









Waltham MA 80
36.3












Poland Spring ME 556
63.9		 319
37.3		 472
56.9		 2358
111.1		 667
54.3		 1811
68.4		 290
55.9		 1394
104.3		 284
43.6		 878
77.8		 1729
123.6		 1220
95.2		 540
60.2		 404
44.6
Bow NH






1264
99.5		 428
62.5		 603
57.1		 2834
139.2		 1824
105.8		 830
70.3		 34
9.7
Derry NH 320
52.9		 120
24.1		 204
36.6		 1520
99.0		 176
42.0		 1344
98.8		 359
47.6






Penacook NH
474
43.0		 416
45.6		 1501
97.6		 226
45.0		 1511
84.0		 504
50.6		 778
74.6		 368
48.8		 354
48.5		 2565
129.5		 1282
80.8		 411
50.1		 394
46.0
Peterborough NH






807
124.0
5
2.5



Plymouth NH 1737
87.8












Wilton NY 1115
73.0












Charlestown RI 16
10.5		 50
32.9		 50
13.7		 177
37.6		 16
10.7		 255
59.8		 177
49.4		 405
75.4		 91
27.2		 21
14.1		 50
13.9		 254
49.8		 203
37.9		 253
40.5
Woonsocket RI 80
19.0
188
21.2		 456
57.0
576
74.5		 155
42.2		 479
89.9		 186
45.3		 42
20.7		 218
41.8		 384
59.1		 153
38.8		 436
54.5
Mt. Mansfield VT 10370
260.9		 8742
207.4		 9407
301.7		 12695
309.6		 7428
232.6		 10940
180.4		 11272
210.5		 8221
190.5		 8079
221.0		 7869
238.1		 11973
249.7		 10235
208.5		 9240
178.2		 2228
111.0
Mt. Snow VT




3894
178







Comments

Thirteen years of data isn't much, but they hold some interesting tidbits. Clearly, the 2000/2001 or 2002/2003 season was the biggest one for everyone. However, there was a general perception that 2001/2002 had the least in recent memory. That's not the case! The low snowfall for most locations was some other year, often 1997/1998 south of Boston, but often 1998/1999 north and west of there. 2007/2008 was mild, but parts of New Hampshire had huge snow amounts. Several events had sharp rain/snow lines, narrow snow axes, or were elevation events where hilltop terrain had quite different snowfall than locations a couple hundred feet lower. 2009/2010 was lackluster over most of the region, notable mainly for a rain and windstorm in February, but the southern track of the storm system brought record snow seasons and multiple storms to places from New York to Pittsburgh to Washington DC.

Here in Penacook, I had 43-46 inches of snow in the three low years, but the Snow Depth Days varied between 226 and 474. On the other hand, in Derry, 30 miles south, the snowfall range was 24-44 inches in the same years and SDDs varied between 120 and 204. I'm sure a closer look will show the rain/snow line was often between us. In the 2000/2001 season we each had about 100 inches of snow and 1500 SDDs, suggesting the rain/snow line stayed south of Derry. The 2004/2005 season wound up being a fairly average year in Penacook, but the storm track was so far south that everyone else had more snow. Eastern Massachusetts residents will long remember it for historic storms and a blizzard that paralyzed much of the area in January. 2007/2008 ranged from boring in southern New England to historic in northern New England. Concord NH nearly set a record for the most snowfall for a season.

Apparently Mark Twain didn't say "If you don't like the weather, wait a minute," though he has said quite a bit about New England weather. Perhaps we can add "If you don't like the weather, drive an hour."

Contact Ric Werme or return to his home page.

Last updated 2011 Feb 5