The La Nina pattern that continues across the globe has been responsible for a myriad of weather events. The trade winds were much stronger this summer making conditions ripe for the very active hurricane season. The drought in Texas (one of the worst in its history) as well as the severe drought in the horn of Africa can also be linked to the ongoing La Nina. The National Oceanic and Atmospheric Association (NOAA) forecasts the current La Nina pattern to continue through the fall and upcoming winter (click here for story).
Washington Area La Nina Winters & Recorded Seasonal Snowfall:
La Nina Winters are characterized by a strong, active, northern branch of the Jet Stream:
- Storms will enter the Pacific Northwest bringing heavy rain and snow and will then cross the Rockies before ejecting into the Central Plains & Midwest. From there the storm track will likely move along the spine of the Appalachians before heading north into New England.
- Snowfall here in Washington will be heavily dependent on behavior of the North Atlantic Oscillation (NAO). If the NAO index enters a negative phase the storm track may shift more towards the coast delivering a Nor’easter. Otherwise, Washington will mainly be on the eastern side of the storm track this winter favoring more mixed precipitation events versus heavy snow.
Winter 2011-2012 Average Storm Track:
- The North Atlantic Oscillation fluctuates and is difficult to forecast more than a few weeks out… If the NAO tanks to its negative phase… the big cities could still dig out from a heavy snowfall.
- The Piedmont zone of the Mid-Atlantic will be more susceptible to some snow, sleet and freezing rain events this winter.
- The ski resorts of West Virginia, Maryland and Pennsylvania will likely receive the heaviest snowfalls.
- The Poconos, Sussex county NJ, Adirondacks, Catskills and northern New England have the greatest chance of receiving more snow than mixed events this winter.
What is the average seasonal snowfall across the Mid-Atlantic Region?
- Reagan National Airport’s “averaged snowfall” since records have been kept is approximately 17.5″
- Dulles International Airport and Baltimore-Washington-International Airport typically receive closer to 23″ a season
- In my opinion, the effects of planes taking off out of National Airport, heat trapping asphalt and it’s location right along the warmer Potomac River makes it one of the most scientifically ignorant places to collect weather data for DC. ** I have seen snow accumulate in North Arlington, Falls Church, Bethesda and wooded, upper Northwest Washington while the snow melts when hitting the ground at Regan National Airport. When you watch the media tell you how little snow falls in South Arlington (where DCA is located) — remember… it’s not called a ‘urban heat island‘ for nothing.
- An active northern branch of the jet stream will bring rapidly changing temperatures to the Northeast Megalopolis. I expect wide swings in temperatures with cold blasts followed by mild periods. December, January and February temperatures will be slightly below average (2 degrees below normal for the entire winter).
Tim’s Winter 2011-2012 Snowfall Forecast for the Washington Region: Downtown DC should see between 50 and 75% of its ‘average’ seasonal snowfall.
- Interstate 95 toward the beaches: slightly below to well below normal
- Western Suburbs: slightly below to near normal snowfall
- Mountains of WV, MD and PA: I think this is your year for above normal snowfall… last year’s snow drought will be a distant memory.