La NiÃ±a Could Limit February Snow
As January comes to a close, the DC area has seen only two snow events this winter. Dec. 5 and Jan. 17 combined to drop 4-8 inches of snow across the metro area, which is 20 to 40 percent less than the average for this far into the season. Are we headed for our fifth consecutive winter of below-average snowfall? The answer could be yes if La NiÃ±a has anything to say about it.
La NiÃ±a is a phenomenon in which sea surface temperatures in the equatorial Pacific ocean run one to two degrees Celsius below average. This is the opposite of the more widely known El NiÃ±o, when such temperatures run above average. Like El NiÃ±o, La NiÃ±a can influence weather patterns around the world, including on a regional scale. The ongoing La Nina has strengthened to levels not seen since the winter of 1988-89, and may dim prospects for a snowy February.
Since 1950 there have been 11 moderate to strong La NiÃ±a events during winter. Moderate to strong La NiÃ±as correlate strongly with mild Februarys in the DC area and little snowfall. This is because they are often associated with high pressure systems off the southeast U.S. coast that pump warm air into our region and fewer southern storms, which tend to be our big snow producers. During the 11 events in the sample, the metro area averaged only 30% of normal snow during February. And in the last five of these events, the DC area did not have a February snowfall of more than two inches.
We have to go back to Feb. 8, 1974, for our last significant February snow event during a moderate to strong La NiÃ±a, when 4-8 inches of snow fell across the metro area. However, those craving the white stuff can take solace in the fact that most of the area recorded at least some snow in all of the sample Februarys. So while not likely to be voluminous, we do stand a good chance of seeing at least some flakes stick in in the coming month. Moreover, the outlook is a bit more snowy for March, if snow lovers haven't lost all hope by then.
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