DENVER — Earlier this month, the National Oceanic and Atmospheric Association released its latest El Niño Southern Oscillation forecast. This latest forecast projects current strong El Niño conditions will weaken to an ENSO-neutral pattern during the late spring or early summer. There are indicators suggesting a transition into a La Niña pattern by fall.
Sea surface temperatures peaked sometime in late November and have been slowly weakening ever since. Currently, SSTs in the Pacific are still in excess of 2 degrees Celsius above average. This puts us into the “ very strong” El Niño category as indicated by the graph below.
Notice the years we had strong El Niño conditions, then look at the months shortly thereafter. Every time, there is a sharp drop-off in sea surface temperature anomalies in the Pacific.
In each of the last three instances, La Niña conditions developed within a year of the peak El Niño conditions. Two of those strong El Niño patterns were followed by a moderate to strong La Niña within a year.
Models are also indicating a sharp drop-off in sea surface temperatures. Most of the models on the graph below are suggesting we’ll be in the midst of either a neutral pattern, or a weak La Niña pattern by the late summer/early fall. A few show a moderate to strong pattern on the way, while one model spits out the strongest La Niña on record ahead.
170°W). Figure updated 19 January 2016.
So what does this mean for Colorado weather?
Current forecasts don’t have El Niño conditions exiting until late spring and early summer. If you read Part 1 of our three-part series, you’ll recall El Niño conditions (on average) shift the jet stream to the south, which brings extra moisture to the southeastern United States, including southern Colorado.
The three-month outlook from the Climate Prediction Center matches that philosophy, and shows a good chance for above-average precipitation for southern Colorado through May.
Looking ahead into the summer and fall, the forecast get much hazier. If La Niña conditions do in fact develop, that likely means the jet stream will shift back to the north.
Copyright: NOAA
If this scenario plays out, it means a wet pattern for the Pacific northwest and plenty of snow through Washington, Idaho and Montana.
As far as Colorado is concerned, a La Niña pattern could mean a great ski season next year for the northern and central mountains of Colorado, with much less snow over the southwest corner of the state. Also, with drier conditions typically showing up over southern Colorado during these patterns, we could see a resurgence of drought conditions.
Remember ENSO is not the only driver of weather across the globe, or in Colorado. There are a slew of other factors that control weather on a daily basis. Keep in mind NOAA emphasizes while there is a lot of support to indicate a La Niña pattern isn’t far off, there is still plenty of uncertainty.
However, if these forecasts verify and averages hold up, we might be looking ahead at a dry pattern for at least part of the state to develop for the second half of 2016 and at least the beginning of 2017.