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Posted at 11:00 AM ET, 11/27/2009

Moderate El Niños often bring big snows

By Jason Samenow

* Windy and chilly, but gradually drying out: Full Forecast *

Our winter outlook, and several others that have been issued, are calling for better than average chances of a snowy winter because we're currently experience a weak to moderate El Niño event (an event characterized by warmer-than-normal sea-surface temperatures over the equatorial Pacific that can lead to shifts in weather worldwide). Our local National Weather Service Office in Sterling, Va. recently posted an article discussing the relationship between El Niño events and snow here. Here's an excerpt from the article along with a telling graphic:

dc-el-nino.jpgD.C. area snow during El Nino events compared to normal. Graphic courtesy National Weather Service.

On average, the stronger the El Niño episode, the warmer and wetter the winters have been. These findings can largely be linked to a stronger than normal sub-tropical jet that typically occurs during moderate to strong El Niño winters, which would favor more active storm systems from the south that draw warm, moist air northward as opposed to the drier Alberta clippers from the northwest. Seasonal snowfall averaged above normal for weak and moderate El Niño winters while below normal for strong El Niño episodes. During strong El Niño episodes, the bulk of the cold air remains north of the mid-Atlantic region, often resulting in precipitation falling as rain instead of changing to snow.

Interestingly, though moderate El Niños tend to produce above average snows for the season, slightly below average snow is characteristic of December during such events. When do you think we'll see our first accumulating snow?

By Jason Samenow  | November 27, 2009; 11:00 AM ET
Categories:  Local Climate, Winter Storms  
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Next: Forecast: Blustery Black Friday; weekend sun

Comments

At 1900 ft in the Blue Ridge Mtns, we actually already had some accumulating snow this past October. For DC, I'll guess December 7th.

Last night our low reached 33.3F. Currently 38.8, cloudy and blustery. Saw some snow flurries a little bit ago.

Posted by: spgass1 | November 27, 2009 11:47 AM | Report abuse

Asssuming you mean a trace or more, I will say December 17th.

Posted by: snowlover | November 27, 2009 12:21 PM | Report abuse

Just saw the first sleet pellets and snowflakes of winter 2009-2010 downtown!

Posted by: CapitalWeatherGang | November 27, 2009 12:29 PM | Report abuse

Still nothing in Columbia Heights West/Baileys Crossroads.

Some forecasters are predicting a winter like 1986/87. If that holds up we could be mild until mid-January, then we could see lots of snow thereafter. I'm still worried about a moderate/strong El Nino & a winter like the 1997/98 fiasco.

Posted by: Bombo47jea | November 27, 2009 12:54 PM | Report abuse

Weak 2 mod El Nino's have been predicted in the past & turned out 2 b stronger & last longer than forecast. I'll believe a weak 2 mod 1 when it actually occurs. First snow of 1" Jan 28. I don't consider a storm that starts out as snow & accum. an 1" or 2" b4 changing 2 rain a snow storm. Better 2 b skeptical & b surpised by a snowy winter than 2 get all excited about a predicted snowy winter & end up in disappointment.

Posted by: VaTechBob | November 27, 2009 2:02 PM | Report abuse

There was sleet in Goldvein on Veteran's Day.

My herding dogs are predicting a colder than normal winter. they have all put on more coat and undercoat. More acorns this year etc.

Posted by: vaherder | November 27, 2009 8:40 PM | Report abuse

The comments to this entry are closed.

 
 
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