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 Click on season header for a detailed page for that season.
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 11/12 12/13 13/14 14/15 15/16 16/17
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





617
58.9
1102
67.3


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
259
40.2
29
15.2
183
46.9
173
49.6
924
80.4
127
35.0
65
37.7
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
1188
81.7
64
24.4
484
77.5
656
71.1
1476
94.9
124
37.0
182
44.9
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
1153
81.7
117
38.0
698
92.9
1019
80.4
1604
113.4
172
43.2
417
66.4
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
1514
98.0
305
65.0
676
81.5
1068
76.5
1539
96.8
229
30.7
884
88.5
Bow NH






1264
99.5
428
62.5
603
57.1
2834
139.2
1824
105.8
830
70.3
1833
88.3
337
63.9
1086
95.4
1928
95.7
1789
99.7
318
35.0
896
71.8
Bristol NH











547
54.6
1561
92.2
271
54.3
531
80.8
1686
94.4
1520
91.1
234
29.0
1021
64.9
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
414
50.1
1465
90.4
170
49.6
505
74.5
1398
76.1
1215
79.7
146
22.5
600
54.7
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
487
49.4
21
14.2
270
53.4




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
1008
68.9
25
16.6
306
69.9
384
59.1



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
10167
181.1
5507
126.2
7723
141.9
8301
170.2
9386
174.5
3651
102.8
5263
152.0
Mt. Snow VT




3894
178














Penacook Monthly Summary

This spreadsheet image shows the monthly data from my home in Penacook. The color shading shows the top two maximum distinct values (i.e. it ignores ties) and the minimum that is not zero. Note how the 2007/2008 remains the most exceptional season. Pretty much all seasons have flagged entries. The one that doesn't, 2009/2010, is the only season that had no snowpack for the entire month of March.

Sub-zero Days by season

I've often commented that a winter without a sub-zero low temperature is a waste. Here in New Hampshire that's generally not a problem. While 2006 never went below zero, the neighboring months came through so both the 2005/2006 and 2006/2007 seasons had sub-zero weather. On the other hand, some winters are just plain cold. I added this section during the historic month of February 2015.

SeasonDecemberJanuaryFebruaryMarchTotal
03/04 3 11 3  17
04/05  8  1 9
05/06 2    2
06/07  3 1 4 8
07/08  2 1  3
08/09 1 6 1 1 9
09/10  1   1
10/11  6 2 1 9
11/12  3   3
12/13  3   3
13/14 1 6 4 4 15
14/15  7 12 2 21
15/16   4  4
16/17 4 2   6

Comments

Twenty years of data is becoming respectable and holds some interesting tidbits. Clearly, the 2000/2001 or 2002/2003 season was the biggest one for everyone in southern New England. 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, 2015/2016 was the most spectacularly low snow season. I don't expect to see 22.5" of snow and 146 SDDs again. I had 43-46 inches of snow in three typical 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. In 2015/2016 storms several storms missed us and we wound up with the least snowfall and SDDs in my data. Eastern Massachusetts residents remembered 2005 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. 2011/2012 is memorable for a crippling October snowstorm in some areas and record low snowfall and SDDs just about everywhere during the rest of the season. Late January and most of February 2015 featured another assault on Eastern Massachusetts made everyone forget 2004/2005. There the story was snow and cold, but everywhere was cold and snow was slow to melt.

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 2017 Mar 4