What is La Niña?
La Niña is a type of climate pattern that occurs when the trade winds become stronger and will pushes warmer water towards Asia. As this happens cold water is brought up to the surface closer to the west coast. This colder water will then push our jet stream further North. This can have a pretty big impact on our weather here in Colorado. It will also increase the risk for hurricanes in the Gulf of Mexico because there is less wind shear to break apart these storms.
How does this affect our winters in Colorado?
Since the jet stream is shifted northward, we tend to get more of a zonal or westerly flow. This means that the upper-level winds tend to flow directly over the mountains from the west to the east. These downsloping winds can create some pretty gusty conditions for us here in Southeastern Colorado as well as increased cloud cover and a greater number of valley fog days. Temperatures usually are either slightly above or just around normal.
In terms of snowfall, it will depend on where you are in the state. On the Western side of the Continental Divide, you will likely see more impactful snow storms because of these westerly winds.
What are the current conditions?
We are currently in an ENSO-neutral pattern, which means that sea surface temperatures are closer to normal or slightly below normal. The Climate Prediction Center has issued a La Niña watch, which means conditions are favorable for the development of La Niña conditions within the next six months. La Niña conditions will exist when we have at least one month of below average sea surface temperatures in the Pacific Ocean off the coast of South America.
What's the forecast?
We have already seen a slight shift in our jet stream, but again we aren't seeing La Niña conditions. The best chances for a La Niña pattern to emerge will be from November to February. Once we make it to the spring season, those chances start to go down and a more neutral pattern will be possible.
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