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Posted at 10:32 AM ET, 02/21/2013

Can D.C. dream the impossible dream of breaking the snow drought this winter?


March 2, 2009 — Snow falls in Glover Park. This was the last 2 inch or greater snowstorm on this date or later for D.C. It dropped roughly 4-8” in the immediate area, though some places well west got less and well east got more. (Ian Livingston)

Through today, we’re now at 757 days in a row without a 2 inch or greater snowfall in D.C. (and at Dulles as well as much of the immediate area). The streak rolls on, and our historical odds of experiencing a 2 inch storm will soon drop below 50 percent.

When we first brought you news of this painful record for snow lovers in early January, it was noted that over 80 percent of our average snowfall was to come. Fret not, we said.

With a week left in February, should we now be concerned we’re going to run this record well past 1,000 days?

Before getting too far... Based on our snow history, we should have seen an area-wide 2 inch or greater snowfall by now.

The lack of snow has been astounding. The combined snowfall of the last two and three winters could easily finish lowest on record.

An unprecedented few years of snow futility.


2 inch or greater snow events by decade at Washington, D.C. So far, there have been none in the 2010s, but the past three decades brought about a 50% shot of such. (Ian Livingston)

Anyway, the 2 inch or greater snowfall drought...

Our raw odds of “breaking the streak” from here out are not fantastic, as intimated by D.C.’s typical last accumulating snow event happening around the 24th of February. Of course, we do also average 2.7” from today through the end of March.

How can we have an average last snow before the end of our average snow?

Late-season tends to have more outlier events than other times in the cold season, due to still readily available cold air to the north coupled with increasing moisture and warmth of early spring.

Some years (like last year), we flip the switch early and winter is effectively canceled by now. In others (like this year?), the pattern seems to be as supportive for snow as it’s been all winter.


*A majority (7.6”) of this snow fell on the 20th. **This may be two separate events (I was not here). Looking at re-analysis of the setup as well as obs, it appears to primarily be one continuous events (with breaks) that produced this snow. If we only include the main body on the first two days, the total is 4.8”. 3/19-21/1958 and 3/30/1964 also reached that mark at DCA and would be included in the top events if the 2003 one was lowered. (Ian Livingston)

Big late-season snows happen. We’ve had one as recently as March 1-2, 2009 when 5.5 inches fell in the urban oven of D.C. They’ll happen again. Maybe even one before this winter of the dusting closes?

Since snowfall records began in the late 1800s, 5 storms overall have produced 10 inches or more snow on February 21 or later. That’s about 10 percent of all 10 inches or greater storms in the record. The biggest of these storms dropped 12 inches... waaaay back on March 27-28, 1891. At National Airport, since 1946, only one 10 inch or greater storm has happened post February 21 - the 10.3 inches on February 22-23, 1987.

Our climate current normals are drawn from 1981-2010 data. In that timeframe, D.C. has seen 15 storms drop 2 inches or more on this date or later. That works out to a nice simple average of every other year -- though two years had two, and gaps are noted. From 1999 to 2009 they did come every other year.


(Ian Livingston)
If we make it through February without a 2 inch or greater snowfall, as it seems we have a good chance of doing based on the current forecast, the odds fall to about 20 percent.

We’ve only seen one 2 inch or greater storm in March since 2000.

Even though this winter (and, seemingly, winter in general) has progressed pretty badly if you’re yearning to spend the day sledding, the right pattern can still produce significant snowfall for a bit longer.

We’re down, but we’re not out. Not yet.

Related: Does the “less snow, more blizzards” global warming theory hold up in Washington, D.C.?

. . . .

Disclaimer: In late-season events, the disparity between National Airport or the urban center of D.C. and elevated areas north and west can be extra large.

Two examples other than the March 1993 Superstorm include: March 14-15, 1999, when 5.4” fell at Dulles compared to 0.3” at National; and March 29, 1984 when 4.2” fell at Dulles and only a trace was recorded at National. (h/t Headful of Snow).

The difference can also be seen in the snowfall average at Dulles for March. It’s more than twice as high as National, with the locations “expecting” 2.8” and 1.3” respectively. Dulles even has a paltry (0.3”) snow average in April, though a majority of recent years feature no measurable April snow there.

Go further north and west/higher in elevation and your late-season snow odds increase a little with each step. However, in many years, the final notable snow event to impact one location is also the final to impact others locally.

By  |  10:32 AM ET, 02/21/2013

Categories:  Latest, Local Climate, Winter Storms

 
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