Winter 2010–2011 Forecast Summary

Over the past few weeks a variety of winter forecasts were released to the public, all of which are hinting at another season of extremes for the United States.

While the extremes of last winter will likely not be felt in the same regions, with this coming winter a new round of crazy weather could be in store for areas far removed from the 2010 blizzard-plagued mid-Atlantic and northeast.

To make it easier for you, here's a regional summary of pretty much every forecast released:

Pacific Northwest: Colder and wetter than average. La Niña often brings lower than average temperatures and increased mountain snow to the Pacific Northwest and western Montana during the winter months, which is good for the replenishment of water resources and winter recreation but can also lead to greater flooding and avalanche concerns.

Southwest: Warmer and drier than average. This will likely exacerbate drought conditions in these areas. All southern states are at risk of having above normal wildfire conditions starting this winter and lasting into the spring.

Northern Plains: Colder and wetter than average. Likely to see increased storminess and flooding.

Southern Plains, Gulf Coast States & Southeast: Warmer and drier than average. This will likely exacerbate drought conditions in these areas. All southern states are at risk of having above normal wildfire conditions starting this winter and lasting into the spring.

Florida: Drier than average, with an equal chance for above-, near-, or below-normal temperatures. Above normal wildfire conditions.

Ohio and Tennessee Valleys: Warmer and wetter than average. Likely to see increased storminess and flooding.

Northeast and Mid-Atlantic: Equal chances for above-, near-, or below-normal temperatures and precipitation. Winter weather for these regions is often driven not by La Niña but by weather patterns over the northern Atlantic Ocean and Arctic. These are often more short-term, and are generally predictable only a week or so in advance. If enough cold air and moisture are in place, areas north of the Ohio Valley and into the Northeast could see above-average snow.

Central U.S.: Equal chances of above-near-or below normal temperatures and precipitation.

Hawaii: Drier than normal through November, then wetter than normal December through February. Statewide, the current drought is expected to continue through the winter, with several locations remaining on track to become the driest year on record. Drought recovery is more likely on the smaller islands of Kauai and Molokai, and over the windward slopes of the Big Island and Maui.

Alaska: Odds favor colder than average temperatures with equal chances of above or below normal precipitation. The interior and southern portions of the state are currently drier than normal. A dry winter may set Alaska up for a greater chance of above normal wildfire conditions in the spring.

Courtesy NWS

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Winter 2010 Rewind: El Niño, NAO Convergence

This past winter was for many, absolutely epic! The rarest of events for big east coast cities unfolded between December and March, blanketing locations from Washington, DC to New York with record snowfall in the form of fierce blizzards and historic nor'easters.

As winter 2010 concluded I conducted two interviews with seasoned meteorologists having expertise in not only northeastern United States weather, but with nor'easters such as those that plowed through in months prior. In both my interviews with winter weather authority, Paul Kocin; and chief forecaster for AccuWeather, Elliot Abrams; the anomalies of two unique weather patterns converging was mentioned as the likely cause of that winter's wrath. Those anomalies were El Niño, the cyclic warming of the tropical Pacific, and the strong negative phase in a pressure cycle called the North Atlantic Oscillation (NAO).

Well alas... this week a new study appearing in the journal, Geophysical Research Letters, states that these two weather patterns did indeed converge along the east coast and are both responsible for the historic winter that unfolded. The study was conducted by a team of scientists at Columbia University's Lamont-Doherty Earth Observatory who analyzed 60 years of snowfall measurements to conclude that the negative NAO this particular winter made the air colder over the eastern United States, causing more precipitation to fall as snow. El Niño brought even more precipitation to the area, which when interacting with the NAO's presence, led to even more snow.

The last time the NAO experienced a strong negative phase was in the winter of 1995-1996. During that winter the east coast was also hammered with above average snowfall. This winter, the NAO was even more negative – a state that happens less than 1 percent of the time.

It is important to note, however, that while the heavy snow on the east coast dominated headlines this winter, the Great Lakes and western Canada (remember this?) actually saw less snow than usual – typical for an El Niño year. The arctic also experienced warmer weather than usual.

Finally, I'd like to once again showcase this radar rewind, courtesy of AccuWeather.com. You will see 22 major storms that doused the northeast in a four month radar animation from December 1 through March 30. AMAZING!

* Note: This video is best viewed in Firefox, Chrome, Safari or any web browser other than Explorer (go figure) and it's totally worth launching those browsers if you have one of them, because this is just awesomeness!



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