There are several reasons as to why our winter has been snowier and colder than average.  The main components involve a La Nina phase in the Pacific Ocean and a favorable/active Jetstream pattern.

For those that don’t know, La Nina is the cool phase of what's known as the El Nino Southern Oscillation (ENSO).  Water temperatures in the equatorial Pacific Ocean fluctuate every 3 to 5 years between the warm El Nino phase and the cool La Nina phase. The latest readings show that sea surface temperatures are about 1.4 degree Celsius cooler in much of the tropical Pacific.  La Nina has widespread impacts around the world by changing the movement of winds and high and low pressure systems, it can even enhance hurricane activity in the Atlantic.

For Missouri and much of the United States, the impacts of La Nina are most pronounced in winter. Typically La Nina winters lean toward being colder than average and can also trend snowier, especially when compared to El Nino winters like last year. We averaged a little more than 6 inches last year, compared to our roughly 43 inches this year. Our 30 year average is 23.3 inches.  This La Nina year has had a lot of help with bringing us colder temps and snowier storms.  There have been large blocking events in the Gulf of Alaska.  These blocking events redirect the polar jetstream and amplifies the pattern, meaning it’s able to send much colder air farther south.  When you combine this cold air with an active Pacific jetstream feeding moisture into the West Coast of the U.S. it sets up a favorable pattern to receive colder air and a snowier winter.

The thing to remember is that this is what statistically happens, it is not a guarantee.