DC Snowfall Per Event

[RodneyS]

The Capital Weather Gang had an interesting article yesterday about DC standing for "Dusting Central" -- see http://www.washingtonpost.com/blogs/capital-weather-gang/post/some-snow-possible-for-pm-commute-washington-dc-is-dusting-central/2013/02/04/3d795d58-6eff-11e2-ac36-3d8d9dcaa2e2_blog.html?wprss=rss_weather_latest. However, I quibble with the article's definition of "event" because, for example, a Friday night/Saturday morning snowstorm should be defined as only one event, and not two. Last year, by my count, we had only three snow events, rather than the five listed in the article. Nonetheless, this season every daily snowstorm has been its own event, and so we have had six events so far. How does that compare historically? According to a table that Ian put together a while back, the average is about 7.5 snow events in DC per year. However, the historical average amount of snow per event in DC is about 2.4 inches. This year, that average has been about one-tenth of that -- 0.25 inches. The only lower seasonal averages than that were the winters of 1972-73 and 1997-98, when in each case there was only one 0.1 inch event. Other than that, the lowest average was 0.46 inches in 1926-27, when five events produced 2.3 inches.

Can we perhaps have two more events to exceed the seasonal average number of events, while maintaining the lowest average amount of snow per event (excluding the two one-event years)?

[Ian]

I'm actually working on an article about this for sometime this week.

[MN Transplant]

Good stats, Rodney, and I'm looking forward to Ian's article.

 

This year may top it, but setting aside Commutaggedon, I recorded 7 events of 1.5" or less in the 10/11 winter.  Sitting at six this year.  We can nickle and dime with the best.

[RodneyS]

I'm actually working on an article about this for sometime this week.

Awesome. I'm thinking that by winter's end, we'll have ten events totaling under two inches.

[Ian]

Awesome. I'm thinking that by winter's end, we'll have ten events totaling under two inches.

 

im actually wondering if it's a wasted effort. im starting to believe we'll get something in the next few weeks.

[RodneyS]

im actually wondering if it's a wasted effort. im starting to believe we'll get something in the next few weeks.

There have certainly been many years in DC when the overwhelming majority of seasonal snow fell from this date in February forward. However, it's difficult to find analogs where DC had six sub-half inch events at this point in the season, and then got significant snow. The closest I see off-hand is 1985-86, where DCA had received 2.8 inches in five events -- the largest of which was 0.9 inches -- through February 10th, then received 12.6 inches in five additional events during the remainder of February.

However, as I've mentioned before, I think the two most remarkable snow seasons in DC history may be 1913-14 and 1959-60. In both seasons, no measurable snow at all had fallen through February 12th. Then, in eerily similar fashion, a two-day storm ensued on February 13th-14th, and the snow gates opened wide. From that point through March 22nd in 1914, there were seven snow events totaling 28.6 inches; and from that point through March 16th in 1960, there were six snow events totaling 24.3 inches.

[Ian]

Here's the piece for CWG. I didn't get super in depth but could provide more here if anyone wants it

 

http://www.washingtonpost.com/blogs/capital-weather-gang/post/dc-snow-drought-its-worse-than-you-think/2013/02/06/1d889022-700d-11e2-8b8d-e0b59a1b8e2a_blog.html

[NoVaSnow]

Here's the piece for CWG. I didn't get super in depth but could provide more here if anyone wants it

 

http://www.washingtonpost.com/blogs/capital-weather-gang/post/dc-snow-drought-its-worse-than-you-think/2013/02/06/1d889022-700d-11e2-8b8d-e0b59a1b8e2a_blog.html

Nice and depressing!

[RodneyS]

Here's the piece for CWG. I didn't get super in depth but could provide more here if anyone wants it

 

http://www.washingtonpost.com/blogs/capital-weather-gang/post/dc-snow-drought-its-worse-than-you-think/2013/02/06/1d889022-700d-11e2-8b8d-e0b59a1b8e2a_blog.html

Good article. In the next few days, I'll try and better analyze whether there are analog years other than 1985-86 where DC received only a bunch of minor snow events through this time in February, but then received significant snow after that.

[Ian]

Good article. In the next few days, I'll try and better analyze whether there are analog years other than 1985-86 where DC received only a bunch of minor snow events through this time in February, but then received significant snow after that.

 

yeah ill try to look at some more stuff too. i was sort of rushed plus 1000 word articles seem to get less interest than shorter ones.. not to mention we might break the streak and the event avg thing still.

[gymengineer]

What's DC's longest streak between 3" snowstorms?

After what we've seen so far this winter, this 2" number doesn't mean that much to me anymore because many of us (especially Wes, lol) have seen ~1" or more a couple of times so far. So just getting an event with 0.5"-1" more than what we've seen isn't going to be some amazing moment. A 3" total on the other hand....

[RodneyS]

What's DC's longest streak between 3" snowstorms?

I believe it's February 12, 2006 to March 2, 2009 --1114 days. So, if that's right, we would have to go without a three-inch storm until Valentine's Day next year to break that record.

[mattie g]

I believe it's February 12, 2006 to March 2, 2009 --1114 days. So, if that's right, we would have to go without a three-inch storm until Valentine's Day next year to break that record.

 

Good God, this area sucks at winter.

[RodneyS]

Good God, this area sucks at winter.

During the last seven years, DCA has had one remarkable snowy period, but little else. After the 3+ year 3-inch snow drought ended on March 1-2, 2009 with a 5.5 inch event, DCA had the following 3+ inch events during the winter of 2009-10:

December 18-19, 2009: 16.4 inches

January 30, 2010: 6.4 inches

February 2-3, 2010: 3.3 inches

February 5-6, 2010: 17.8 inches

February 9-10, 2010: 10.8 inches

The next -- and so far last -- 3+ inch event was January 26, 2011, when DCA recorded 5.0 inches.

[mattie g]

Thanks, Rodney.  We all know the reality of the situation, but the feast or famine scenario in the region is truly remarkable.

[gymengineer]

These futility records (2" and 3") within the past decade tells us we're in a new snow climate. Who knows how long this will last.

We didn't used to go multiple seasons in a row without a 2-4" snowstorm, even if those multiple seasons were all below average.

[RodneyS]

According to a table that Ian put together a while back, the average is about 7.5 snow events in DC per year. However, the historical average amount of snow per event in DC is about 2.4 inches. This year, that average has been about one-tenth of that -- 0.25 inches. The only lower seasonal averages than that were the winters of 1972-73 and 1997-98, when in each case there was only one 0.1 inch event. Other than that, the lowest average was 0.46 inches in 1926-27, when five events produced 2.3 inches.

I have now done a quick review of DC's yearly snow records, and divided them into events and average snowfall per event through February 10th and after February 10th. Among other things, I've discovered that the monthly snow records available here -- http://www.erh.noaa.gov/lwx/climate/dca/dcasnow.txt -- are not entirely accurate, at least based on the daily DC snow records that I have. For example, 3 inches -- rather than 1 inch -- of snow fell in December 1926, so that the five 1926-27 snow events actually produced 4.3 inches of snow -- rather than 2.3 inches -- for an average per event of 0.86 inches per event. Whoever compiled the above table apparently failed to add in a 2-inch snowfall on December 5, 1926. That, it turn, means that 1926-27 does not have the lowest average snow per event other than the single-event winters of 1972-73 and 1997-98. Rather, that distinction belongs to the winter of 1975-76, which had an average of 0.55 inches per event (four events produced 2.2 inches).

Regarding possible analog DC winters to 2012-13 in terms of only several minor events occurring through this point in the season and then significant snow occurring thereafter, the most interesting snow season for snow lovers may be 1941-42. That year, through February 10th, there were five snow events producing just 2.1 inches of snow, for an average of 0.42 inches per event. There was only one event after February 10th, but it was a memorable one: The Palm Sunday storm of March 29, 1942, which dropped a remarkable 11.5 inches of snow on DC. And that was only half of what Baltimore got; see http://articles.baltimoresun.com/2012-03-28/news/bal-wx-70-years-ago-a-snowstorm-took-baltimore-by-surprise-20120327_1_wet-snow-snowstorm-power-outages. As I previously mentioned, 1985-86 also produced little snow through February 10th (five events totaling 2.8 inches), but then five additional events occurred after that date, producing 12.6 inches. Many other winters started slow, but then came on strong. On average in DC's history, there have been 5.1 snow events totaling 11.6 inches of snow through February 10th, and 2.4 events totaling 6.4 inches of snow after February 10th. So, there is hope for snow lovers for significant snow for the rest of this winter . . . sort of.

[RodneyS]

1926-27 does not have the lowest average snow per event other than the single-event winters of 1972-73 and 1997-98. Rather, that distinction belongs to the winter of 1975-76, which had an average of 0.55 inches per event (four events produced 2.2 inches).

So, the DCA winter of 2012-13 is likely finalized at seven snow events producing all of 1.7 inches of frozen precipitation, for an average of 0.24 inches per event. If we should get one more event, we would need 2.7 inches or greater to fail to beat the 1975-76 low average record of 0.55 inches per event.

[RodneyS]

So, the DCA winter of 2012-13 is likely finalized at seven snow events producing all of 1.7 inches of frozen precipitation, for an average of 0.24 inches per event. If we should get one more event, we would need 2.7 inches or greater to fail to beat the 1975-76 low average record of 0.55 inches per event.

Assuming that DCA is finalized today at 1.4 inches, there have now been eight snow events there this season, totaling 3.1 inches, for an average of 0.39 inches per event. If you're an extreme snow optimist, another event this season totaling 1.9 inches at DCA would cause this season's average to surpass the 1975-76 low average record (minimum of two events) of 0.55 inches per event.

To put this year's snow per event average in historical perspective, in every prior year in DC's history where there were at least eight snow events, a minimum of 5.7 inches of snow was recorded (eight snow events produced 5.7 inches in 1988-89, for an average of 0.71 inches). At the opposite extreme from this season was 1982-83, when there were only three snow events, but they produced 27.6 inches, for an average of 9.20 inches. And, in DC's record high snow year of 2009-10, just nine events produced 56.1 inches, for an average of 6.23 inches.