Arctic Oscillations Will Determine Winter Weather

After a year of unprecedented warmth this summer, coupled by last winter's milder temperatures, the debate over whether Old Man Winter will make an appearance this year is the topic of discussion for many.

"It is difficult to predict exactly what will happen this winter in our area. I do not think it will be a particularly bad winter and may be milder than normal, but again, at this point it is really all speculative. The Climate Prediction Center in Washington DC is predicting warmer, and milder temperatures for most of the country," said Ted Jemba, meteorologist for the National Oceanic and Atmospheric Administration in Glasgow.

In fact, the only area predicted to experience cooler and wetter than normal temperatures is the west coast.

If a weak to moderate El Nino pattern develops, as expected, in the equatorial Pacific Ocean, this would create warmer temperatures across Montana beginning in October and potentially lasting through February.

However, much of our areas weather is influenced by air mass pushes coming in from Canada and the Arctic. This Arctic Oscillation is the most influential of determining factors for our winter conditions. This seesawing of atmospheric pressure between the Arctic and mild latitudes is always present and fluctuates between positive and negative phases.

Unlike an El Nino or La Nina, which are caused by temperature shifts in the Pacific Ocean, Atmospheric Oscillation refers to shifts in atmospheric pressure between the Arctic Circle and much of the Northern Hemisphere. In the positive phase, atmospheric pressure lessens over the Arctic Circle and increases in the southern latitudes. In the negative phase, just the opposite happens. Atmospheric pressure is higher over the Arctic Circle and lower in the south. What does that mean for us? It means that when the Atmospheric Oscillation is in a positive phase, low-pressure systems, which cause cold, stormy weather, stay trapped in the extreme north. In a negative phase, those low-pressure systems are forced southward, bringing frigid air from the polar region down with them.

Atmospheric Oscillations are difficult to predict and because of that, the Climatic Prediction Center doesn't factor them into their three month outlooks which is why this winter’s weather is still really anyone's guess.

The average temperature in the U.S. during the month of August was 74.4 degrees, 1.6 degrees above the long term average. This makes August of 2012 the 16th warmest on record. This, combined with the hottest July and a warmer than average June contributed to the third hottest summer on record since record keeping began in 1895, according to the National Climatic Data Center.

For those who look to the Farmer's Almanac for a glimpse into future weather predictions, the 2013 edition predicts the Midwest will experience "milder than normal temperatures with average precipitation," calling it a winter of contraries with winter returning to some, but not all areas. It predicts the eastern half will experience cold and lots of snow while the western half will have warm, dry conditions while the gulf experiences cooler, wetter conditions. The Great Lakes and Northeast will see a return of winter.

NOAA does not take the Farmer's Almanac predictions into consideration when figuring out weather patterns and predictions although both are predicting similar weather patterns across much of the United States.

 

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