Some vaguely interesting DCA Snowfall stats

[Ender]

After reading mention of the "mid-Atlantic December 5th rule" I decided to take a look at historical DCA first .5" or greater snowfall dates and the implications for the ensuing winter. Here's what I found:

If the first such measurement was in the month of November (11 cases) then the winter averaged 17.1" with 13.7" falling after the first Nov snowfall.

If the first .5" or greater fell between 12/1 and 12/15 (17 cases) there Winter averaged 21.3" with 17.9" falling after the first event.

If the first .5" was between 12/16 and 12/31 (13 years) then Winter averaged 19.2" with 15.4" falling after that first snowfall.

If the first .5" was in the month of January (21 years) then the entire winter only pulled 12.1" with another 9.5" falling after the first snowfall.

Looking at the results from the angle of first snowfall depth was somewhat more interesting.

If the first snowfall was >4" then the season as a whole averaged 28.3" with 20.1" falling after the first storm. A total of 16 years met this criteria.

If the first snow was between 2" and 3.9" then the winter's total averaged at 11.5" with 8.75" falling after the first event.

In the 20 years where the first storm was between 1" and 1.9" the winter averaged 15.2" with 13.8" falling after that first snowfall.

A total of nine winters saw a first .5" or greater snowfall of between .5" and .9" and those winters only averaged 12.3" for the entire winter.

NOTE: I only considered a snowfall the "first snowfall" if the measurement was >=.5". So if .1" fell on 11/17 and .2" fell on 11/22 and .9" fell on 12/3 then as far as this "research" is concerned the first snowfall was the .9" event on 12/3.

The average of the entire data set (1945 - 2010) was 16.5".

[Kmlwx]

After reading mention of the "mid-Atlantic December 5th rule" I decided to take a look at historical DCA first .5" or greater snowfall dates and the implications for the ensuing winter. Here's what I found:

VERY interesting indeed. So if I read correctly, we want our first snow to be over 4 inches and right in the December 1-15 butter zone (ie Dec 5th). Interesting stuff thanks for this post!

[wxmeddler]

Interesting data for sure.