Before this one, just 18 of 124 winters on record (back to 1887-88) witnessed 1.7” or less snow through the end of January. All of this year’s total came in January and it’s been characterized by many as the winter without a winter. But, will that continue?
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Fourteen of the 18 seasons in our current predicament, or worse, finished with a seasonal total of less than 10” of snow. That’s below normal by account of climatology and horrid in the eyes of a snow lover. One additional season finished with less than the current seasonal average of 14.5”, while three finished above to well above average.
Since some of the years in that sample had all of their snow after January, in attempt to balance a bit, I also examined seasons in which up to twice as much snow (3.4”) had fallen by the end January. That adds 10 to the sample for a total of 28 winters (3.4” or less). By this measure, the average portion of the seasonal snowfall accumulating in January and beyond is 75 percent.
Examining recent times
In recent history, the early 2000s have been marked by very little snow intermixed with copious snow. The copious snow years are of course easier to remember and much less numerous. 40.4” fell in 2002-03 including 28.8” from February till finish, and then there’s the record breaking 56.1” of snow in 2009-10 that included 32.1” in February alone.
Including those two years, five of the 10 Februaries have featured above average snow. Two of the ten featured above average snow in March. One (2007) even had accumulating April snow!
The 30-year norm for snowfall still to come in D.C. is 6.1”, 4.8” of which falls in February and 1.3” in March. Half of the seasons with 1.7” or less through January finished above that average (and half below). Four of the 18 seasons saw February snowfall greater than the current average of 4.8”, and 11 had March snowfall above the present day 1.3” norm.
Before the move to DCA, the average through March after a pathetic (1.7” or less) start was 8.3”. After the move, that average is 7”. Removing the high-snow outlier in each group, we get averages of 6” pre and 4.5” post. This, factored in with some evidence that La Ninas (particularly moderate ones) may tend to produce late in the season, could at least keep us watching a few weeks past this month, if warmth ever stays away for longer than a minute.
Baltimore and Dulles
Baltimore, whose record is a few seasons longer than D.C.’s, has seen only 11 years with equal to or less snow than this season’s 1.3”. Of those seasons, 84 percent of the winter total was still to come after January. Including snow totals up to double 1.3”, the average seasonal still to come is 76 percent. The 30-year average brings almost exactly half of the winter’s snow from February through April.
Dulles, where historical records are about half as long as D.C. and Baltimore, has seen five seasons with equal to or less than the 2.3” that has fallen through January. In those years, 78 percent of the seasonal total fell from February onward. Factoring in seasons with up to twice as much snow season-to-date brings a normal of 62 percent still to come. Like Baltimore. almost half of the seasonal total usually falls from February through April.
A guess on where we finish?
Now armed with a climatological basis for making an educated guess, it seems that the odds are historically poor to even top 10” on the season in D.C. Reaching average would be fantastic, and getting above might be akin to a mini miracle. It has happened though.
What do you think?
Disclaimer: There is no meaningful correlation between October through January snow and February through April snow when examining the entire set of years regardless of how they started. When examining the smaller subset of seasons, there is some correlation but it is still weak and impacted by outliers on both ends. This post is meant as historical in nature rather than predictive.