ROCKFORD (WIFR) -- Sea surface temperatures off the coast of South America drive the phases of El Nino and La Nina. The cooler temperatures we've been seeing over the last three months indicate that a La Nina is on the way.

La Nina helps to stregthen the circulation in the Pacific Ocean allowing a huge ridge of high pressure to build off the east coast pushing the stregthen jetstream into Canada allowing for cooler air to settle into our area.

Storms systems ride the jetstream and with its placement under a typical La Nina, we can expect more frequent visits from low pressure increasing the amount of precipitation we normally see during the winter months.

The jetstream separates the cold dry air from the warm moist air making for a sharper contrast in temperatures. So we can see quick warming and cooling which supports the possibilites for severe weather. This is something we've seen during our last two La Ninas both last year with the Caledoina tornado and the Poplar Grove tornado back in 2008.

So get your snow blowers ready, prepare to dress warm, and remember severe weather doesn't only occur in the spring.