Forecasting for a season is not an easy task
In late October meteorologists from NOAA’s Climate Prediction Center issued their forecast. The bottom line it doesn’t look good for many parts of the country. The problem with this upcoming winter is not simply that it looks colder than normal in the already coldest places, but drought stricken areas such as Texas are looking at a winter with less than normal precipitation. But the silver lining in this forecast is that it could be wrong since forecasting climate can be even more challenging than forecasting weather.
I’ve been forecasting weather for over 42 years (Ok, that’s a complete lie). Weather is organized chaos. One small change in the short term can snowball into something huge a week later. But the planet does at least give us signs of what’s to come. This upcoming winter we’ll have a La Nina pattern in the equatorial waters of the Pacific Ocean. This means colder than normal (just by a few degrees) sea surface temperatures near South America. That seemingly minor temperature difference causes weather patterns around the globe to adjust. Let’s look at what happened in Milwaukee for the last 3 moderate-strong La Nina’s. Stats are for December to March and compare to normal temperatures and snowfall.
2010-2011 Temp: -0.8° Snow: +15.8”
2007-2008 Temp: -0.9° Snow: +52.7”
1999-2000 Temp: +6.0° Snow: -14.3”
As Sesame Street taught us one of these things is not like the other. So we can’t depend strictly on La Nina or El Nino to make a prediction.
(Trying to send away the FOX6 Snowstick who’s anxious for this winter)
Other factors come into play and this winter NOAA thinks a “wild card” may trump La Nina. That card is the Arctic Oscillation. The AO is either positive or negative depending on whether high or low pressure sits over the Arctic Circle. When the AO goes negative, cold air from Canada surges south across the Great Lakes and other parts of the U.S. The problem with forecasting the + and – of the AO is strong phases typically last a only a few weeks and are hard to forecast well in advance.
So brace yourself for a long, cold, and snowy winter. While it’s no guarantee and we may luck into a few mild stretches it’s always better to be prepared and not scared. Because odds are Old Man Winter has his sights set on Wisconsin this season.
For a link to NOAA’s winter outlook, click here.