Notable Fort Collins Snowstorms

This entry posted 9:00 PM, Dec 27, 2006.

The recent holiday snow blast of Dec 21-22, 2006 officially dumped 19.7" of snow on Fort Collins (measured at the CSU weather station). Unofficial measurements taken around the city indicated up to 23" on the west side of town and 28" five miles SE of town (probably near I-25 and Harmony). This event seemed to be unusual, both for it's sheer magnitude, but also for the time of year in which it occurred - most of Fort Collins' heavy snowstorms occur in the Spring months of March or April. Occasionally a heavy storm occurs at the end of October of November, but December through February are often pretty dry. This piqued my curiosity to find out more about Fort Collins' heavy snow climatology, so I went on the web and did a bit of research - the results are posted below.

All of the following statistics are taken from the Climate Summary for Fort Collins Co-op Station 053005-4 - from the Western Regional Climate Center (WRCC). I believe this is the official cooperative data from the Fort Collins CSU Campus Weather Station. This data is maintained by the National Climatic Data Center (NCDC).

The Period of Record summary (there is a link near the very bottom left hand side of the page referenced above) is particularly interesting, as it lists the greatest daily snowfalls on each calendar day throughout the year. While this list is NOT a sure-fire way of picking off all the major snowstorms (especially ones which lasted more than a day), it is a reasonable way of getting an idea of what the largest daily snowfalls have been. Being the data lover that I am, I have compiled all the storms greater than 10" that are listed in that file (this method may miss some storms - if two 10+" storms happened to fall on the same calendar day only the greater storm is listed).

Current Record Single Day Snowfalls of 10" or Greater for Fort Collins, CO

(measurement taken at from 7 AM to 7 AM, sorted by calendar day)

14.5"    Jan 2, 1971

13.0"    Jan 8, 1962

10.2"    Jan 16, 1981

14.0"    Feb 27, 1918

10.0"    Mar 3, 1963

12.4"    Mar 6, 1990

12.7"    Mar 9, 1992

10.7"    Mar 10, 1988

15.5"    Mar 14, 1956

11.0"    Mar 15, 1928

18.0"    Mar 18, 2003    3rd-greatest single day snowfall for Fort Collins

14.2"    Mar 19, 2003

12.0"    Mar 21, 1944

12.8"    Mar 30, 1970

16.7"    Mar 31, 1988

19.7"    Apr 2, 1957    2nd-greatest single day snowfall for Fort Collins

10.5"    Apr 3, 1964

11.5"    Apr 4, 1983

13.5"    Apr 11, 1953

10.8"    Apr 14, 1945

11.8"    Apr 19, 1907

15.0"    Apr 24, 1942

11.5"    May 4, 1908

11.6"    May 5, 1978

15.9"    May 6, 1978

13.0"    Sep 17, 1971

10.3"    Oct 21, 1906

10.5"    Oct 23, 1942

12.1"    Oct 25, 1997

21.1"    Nov 20, 1979    Single day snowfall record for Fort Collins

10.1"    Nov 26, 1983

11.0"    Dec 7, 1988

14.0"    Dec 9, 1985

11.5"    Dec 12, 1958

18.0"?  Dec 21, 2006    I'm not sure what the calendar day total was for the recent storm

11.5"    Dec 22, 1941

11.2"    Dec 27, 1979

11.2"    Dec 31, 1975

By this method of compiling the data, there have been 39 days (including the recent storm) when the daily snowfalls greater than 10" since 1906. It is quote possible that a few days were missed. Note that two events had consecutive days of 10" daily snowfalls (March 18-19, 2003 and May 5-6, 1978). The number of snowstorms in which the total snowfall was greater than 10" of course is much higher, since storms often overlap at least one calendar day. To get a complete picture of heavy snowstorms, I will have to do a much more involved analysis with a more complete dataset. But this list gives a rough idea of when the largest events occurred. Counting up the total # of days with 10" or more daily snowfall by month gives an idea of the seasonality of heavy snowstorms in Fort Collins:

3 days in January

1 day in February

11 days in March (2 of these days were from the same storm)

7 days in April

3 days in May (2 of these days were from the same storm)

1 day in September

3 days in October

2 days in November

7 days in December 

Surprisingly November has only a handful of heavy snow days and December has more than I would have initially expected. This leads me to conclude that the timing of this storm isn't extremely unusual. But clearly, March and April are the peak time for heavy snowfalls in Fort Collins.

Summing up another way, 13 of days occurred during the early winter (Sep - Dec), only 4 days occurred in mid-winter (Jan - Feb), and the remaining 22 days occurred in the Spring months (Mar - May).

Being a cold time of the year, the recent storm did pile up an impressive amount of snow on the ground: 19"! To see how unusual this was, I compiled a list of the peak snow depths experienced in Fort Collins snowstorms.

Greatest Fort Collins Snow Depths

(period of record for snow depth starts Jan 1949 - it may also be a bit spotty in more recent times - for instance, there is no snowdepth data for the May 1978 storm).

23"    May 19, 2003

19"    Dec 21, 2006     2nd greatest snowdepth ??

18"    Nov 20, 1979

18"    Apr 2, 1957

17"    Mar 14, 1956

16"    Dec 10-11, 1985

15"    Apr 10, 1959 

14"    Dec 28-29, 1979 

Interestingly, this storm may have had the 2nd greatest snowdepth of any storm since the late 1940s or 1950s (snowdepth records seem to be missing prior to this time). It is also spotty or incomplete for some of the later years - the May 5-7, 1978 storm appears to be missing (or perhaps the snow didn't get very deep during that storm).

Greatest Fort Collins Snowstorms

32.2"  Mar 18-19, 2003  (daily snowfalls: 18.0", 14.2")

27.8"  May 5-7, 1978     (daily snowfalls: 11.6", 15.9", 0.3")

Eventually, I hope to obtain the full dataset and run a program to pick off the actual largest multi-day snowfall totals and all the 10+" snowfalls. When I do, I'll update these results.