The winter of 2013-2014 was unusually cold for the eastern 2/3 of the continental United States. Iowa endured the 9th coldest in 142 yrs. What might we expect for this coming winter? To help answer that question, the scientists at the Climate Prediction Center published their latest outlook on November 20. It is an interesting read at this link. I will summarize.
The Jet Stream is a huge river of air in the upper atmosphere. It guides weather systems around the globe. Colder Arctic air is kept north of the Jet in the northern hemisphere. Warmer air is to the south of it. One type of flow is called zonal where the Jet tends to travel in a general west to east direction across the globe like this first image below from January 31, 2014.
Notice Alaska is north of the Jet in the cold air. It enters the California coast and sweeps across the country. Entering the coast, it tends to bring needed moisture from the Pacific. The eastern states are in a normal zone of cold, some snow, and clouds. In the summer months, the zonal flow is farther to the north across Canada giving more of the U.S. warm temperatures and pleasant weather.
Another type of flow is amplified. An amplified pattern creates a wavy arrangement like this from January 27, 2014. Four important observations should be mentioned about this pattern.
- The pattern was persistent for much of the past winter.
- The Jet entirely missed the western states leaving them dry.
- Most of Alaska was in a warm air mass south of the Jet.
- A polar vortex, swirl, of very cold air was delivered to the eastern states.
This amplified pattern worsened the drought in the western states, gave the eastern states their unusually cold winter, and gave Alaska record warmth.
The temperature hit 62 degrees at Port Alsworth, on Lake Clark, on Monday, tying the highest January temperature ever recorded in the state, the National Weather Service reported. Nome peaked at 51 degrees, topping the city’s warmest January with a temperature typical of early June, forecasters said. In Anchorage, snow continued melting Tuesday in the latest of 15 consecutive days with temperatures at 32 degrees or above. As of Monday, it was the city’s fourth warmest January ever recorded.
What might be expected this winter?
It is expressed in probabilities based upon the output from several models and the behavior of El Niño. The temperature probabilities look like this. White is a very uncertain region. There are equal chances for below, near, and above normal temperatures. The predictions don’t favor any of them. Darker blue favors below normal. Darker orange favors above normal. The west coast and all of Alaska are orange.
Precipitation probabilities look like this. The darker green across southern California and the Gulf states favors more precipitation than normal, but not by much. The California region really needs this to come true. Alaska could see more coastal precipitation, but less in the interior.
So there you have it. Wait and see what happens. Good luck in your region.