July 13, 2012|By Scott Dance
Severe weather has quieted, so there's not much else for meteorologists to chat about but a few guessing games. And AccuWeather severe weather blogger Henry Margusity's hunch is that there is a link between this month's heat waves across the U.S. and the climatic phenomenon known as the North Atlantic Oscillation.
The NAO, which measures the atmospheric pressure difference between the typical low pressure system near Iceland and high pressure south of the Azores, hit its lowest point since 1950 in June, an AccuWeather reader pointed out to Margusity.
The question that poses is, did a developing El Nino cause the drop in the NAO? El Nino forms when surface water temperatures in the Pacific warm, and it can cause changes in the jet stream's flow direction that affect weather patterns.
If so, it could mean a blocking pattern that would feed the eastern U.S. with "snow up to our chins" this winter, as Margusity puts it.
Read more on AccuWeather's website.
It's just one more hypothesis and piece of the puzzle when it comes to explaining climate patterns predicting El Nino.
The El Nino/La Nina Southern Oscillation remains under "neutral" conditions since April, when a La Nina pattern ended. Meteorologists in June called the odds of an El Nino forming by the end of the year at 50 percent. But in September and October, the probability rises to about 65 percent, according to a July 9 update from the Climate Prediction Center.
El Nino last began three years ago, in June 2009, and it lasted until May 2010.
The impact an El Nino can have on Maryland depends on its weakness or strength. Generally, Marylanders can expect a cold winter with more snow than normal. The National Weather Service office in Sterling, Va., lays out the possibilities in charts looking back at past El Nino years.
Have a weather question? E-mail me at sdance@baltsun.com or tweet to @MdWeather.
