What weather will the new year bring?
(Note: This was written on December 20th for the December 27th Wake Weekly and Butner-Creedmoor News due to early deadlines.)
December started with a bang as far as the weather was concerned. Colder-than-normal temperatures and frozen precipitation hinted at a long cold winter to come. Thankfully, this week is milder, and a short stretch of dry days is giving our soggy yards a chance to recover. So, what’s next? What will the rest of the winter be like?
As of this writing, all signs point to the rest of December being in the normal range, which means high in the lower 50s and lows in the lower 30s. Of course, there may be a colder or warmer day embedded in the next week, but on average, the forecast looks… well… average.
January doesn’t look as promising for those of us who prefer the milder weather. I’ve been following several long-range forecasters over the past few weeks. Based on the global patterns that affect the weather across the United States, it looks like most of the country, including the east coast, will be plunged into below-normal temperatures.
One of the things forecasters watch is called the Madden-Julian Oscillation, and it’s a complicated thing to explain. The gist of it is by watching where thunderstorms are firing over the Indian Ocean and western equatorial Pacific Ocean, meteorologists can make an educated guess at what the U.S. will experience about 14 to 15 days later.
The most famous pattern long-range forecasters consider is the El Nino/Southern Oscillation (ENSO) in the eastern equatorial Pacific. Warmer-than-normal sea surface temperatures in this area signal an El Nino year. Cooler-than-normal sea surface temperatures signal a La Nina year. When the temperature falls somewhere in between, it’s called ENSO neutral. As of this month, it looks like we should be experiencing an El Nino winter, but the air circulation patterns that normal accompany the warmer-than-normal sea surface temperatures have been slow to show up.
There is also an Arctic Oscillation, which affects the weather and climate on an annual to decadal scale. It’s not very well understood yet, so researchers are studying it in earnest. So far, it appears that a warmer Arctic region during the winter causes a weakening of the polar vortex, which leads to changes in the jet stream and causes winter storms to dip farther into the southern U.S.
These are just three of the factors that seasonal forecasters consider when predicting the weather for weeks to months out. Right now, they seem to be adding up to a cold and potentially stormy January.
I’ll add my usual disclaimer about long-range forecasts here: There are still so many factors that go into creating the weather we don’t fully understand or know how to reliably account for in computer models that it’s quite possible even the most trusted seasonal prognosticators could be wrong. Only time will tell.