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First, the numbers:

AVERAGE ANNUAL SNOWFALL

  • BWI Airport = 20.1"
  • Dulles Int'l Airport = 22.0"
  • Reagan National Airport = 15.4"

OUR SNOWFALL 4CAST (NOV-MAY)

  • Annapolis, MD = 29.2"
  • BWI Airport = 30.9"
  • Dulles Int'l Airport = 38.4"
  • Reagan National Airport = 27.6"

THOUGHTS ON SNOWSTORM MIX

  • 1 storm of 10" or greater
  • 2 storms of 6" or greater
  • 4 storms of 2" or greater
highest
lowest
novdec
janfeb
marapr
top 1 thru 3 day totals bwi
top 1 thru 3 day totals dulles
top 1 thru 3 day totals dc

SO...WHY SO MUCH SNOW?

We think that a warmer-than-average Pacific Ocean (El Niño conditions) will lead to a more active southern jet stream across the entire United States.  And that, in turn, we believe will translate into more storms coming into the DMV region from the SSW, some of which will turn into moisture-laiden Nor'easter-style snowstorms for the region, providing the snowfall totals we forecast above (as opposed to what the region saw last year: moisture-starved Alberta Clipper-style storms that originate in the Alberta province of Canada and "clip" the region with very light snowfalls).

Having said that, you can have all the storms you want from any direction and it doesn't automatically equate to snow.  Because Ingredient #1 for SNOW EVERYWHERE is cold air, and we're seeing a below-average temperature month on the whole so far in November - the first below-average temperature month in many months - so that's another good, early sign of the overall atmospheric set-up lending itself to snowfall.  Then comes Ingredient #2, which is the moisture (see: storms from the SSW!), and we think the DMV region will see plenty of moisture over the winter months from an active southern jet stream (did someone say moisture? seriously, what year has seen more moisture than 2018?!?).

As a result, in addition to the one winter event that already occurred in the DMV on 11/15/2018, which produced much more snow than we expected across the region but delivered a bit of everything as we had forecast in advance, we think all signs point to a winter to remember for Winter 2018-2019.

SO WHAT ABOUT THIS EL NIÑO?

Signs of an El Niño winter have been steadily building for months now across the Pacific (primarily in the form of elevated Sea Surface Temperatures, SSTs), especially across the central and eastern Pacific Ocean.  Combine that with a number of storms originating in the Gulf of Mexico region and moving up the east coast of the United States as coastal lows/Nor'easters (starting with the 7/21/2018 mid-summer Nor'easter the DMV region experienced + numerous storm systems of the same variety September-November 2018), and you get a (our!) very hopeful outlook for much snowfall ahead over the next 120 days. 

el4
el1
enso

DOES EL NIÑO GUARANTEE BIG SNOWS?

There are some correlations to be made when it comes to El Niño winters and overall snowfall in the DMV region, but there's no hard-and-fast connection that says "If A, Then B."

We can see that in many El Niño years, the DMV region has experienced a double-digit snowstorm/blizzard/Nor'easter (January 1987, almost officially March 1993, February 2003, December 2009/February 2010 x2, January 2016) but that such an event is not exclusive to El Niño years, and, in fact, sometimes happens in La Niña set-ups (cooler-than-normal Pacific Ocean waters) such as January 1996, January 2000, and almost officially February 2014 (more Dulles and west of DC than the rest of the DMV region). 

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IT'S HARD TO GET BIG SNOW TOTALS in the DMV!

If we look at the snow totals since the 1986-1987 winter season, we can see just how hard it is to get BIG SNOW TOTALS (above the season avearges of 15.4" for D.C., 20.1" for BWI and 22.0" for Dulles) in the DMV region.

For each of the three major airports in the DMV region that are the core reporting/climate data centers for the region, the frequency of above-average snowfall for any given year is only about 30%, give or take a few points.  And looking at the numbers, it's clear to see how the AVERAGE number is shaped: relatively low snowfall totals on a fairly consistent basis that are (somewhat) inflated (to 30-year averages) by "random" years that deliver BIG SNOW TOTALS!

BALTIMORE SEASONAL SNOW TOTALS
1986-1987 thru 2017-2018
KBWI, BWI Airport

bwitotals

DULLES SEASONAL SNOW TOTALS
1986-1987 thru 2017-2018
KIAD, Dulles Int'l Airport

dullestotals

D.C. SEASONAL SNOW TOTALS
1986-1987 thru 2017-2018
*KDCA, Reagan National

dctotals