The Weather Outside Will Be Frightful

Break out the snow shovels! Meteorologists predict above average snowfall in the Northeast this winter and especially bitter cold in the Northern states. According to forecasters, that shakes out to least 6 inches more snow than usual in the New York City and Boston areas and high totals in the Great Lakes areas in Pennsylvania, Ohio and upstate New York. The Southeast should be warmer than normal, but with a risk of tornadoes, forecasters say. 

Overall, long range weather forecasters predict a wet winter in much of the country with temperatures colder than the last two years, but still higher than usual.  Indeed, the last two winters have been particularly warm. The 2015-16 winter in the United States was the warmest on record, and last winter was among the top ten warmest.  

Even so, it is worth remembering that even mild winters bring bitter temperatures and the threat of destructive snowstorms. That is one reason winter storms are the third largest cause of catastrophe losses, behind hurricanes and tornadoes. The 2015-16 winter was the warmest ever and it still caused more than $1.5 billion in insured losses and brought one of the heaviest snowstorms ever in several Eastern cities.    

Besides, snowfall during warmer temperatures produces wetter and heavier snow than snow at colder temperatures. Heavier, wetter snow causes more roof collapses and downed tree limbs than dryer, lighter snow that forms at more frigid temperatures.

Winters have been warmer on average in recent years due to climate warming but natural variability is the largest driver season to season.  A significant part of that natural variability stems from the La Nina / El Nino water temperature patterns in the Pacific Ocean. El Nino describes an extended period of unusually warm water around the equator in the eastern Pacific. La Nina is the opposite. It occurs when sea surface temperatures in that part of the Pacific are colder than normal.  

These temperature cycles in the eastern Pacific Ocean can be a major driver of weather in the continental United States. Even water temperature fluctuations of just a degree or two can have a huge impact. 

This year, meteorologists set the odds at 55% to 65% that a La Nina pattern develops in the eastern Pacific Ocean. If it develops, the La Nina pattern is likely to be relatively weak, forecasters say.  But even a weak La Nina can shape the winter for many of us. 

Historically, La Nina brings colder and wetter winters to the northern part of the U.S., and drier and warmer winters to the South. While forecasters look at other factors too (amount of snow on the ground in Siberia and extent of Arctic sea ice in the preceding months are other data points) predictions for the upcoming winter generally line up with the traditional La Nina effect.

That is a main reason that forecasters expect somewhat warmer temperatures across the Southern states and on the East Coast, but unusually cold temperatures and wetter conditions through the Northern states. Whatever the precise outcome this winter – ice, snow and plummeting temperatures are guaranteed!  

Posted by Jeffrey Gordon