It's going to get very cold this weekend. The reason is interesting…giant weather patterns the size of our entire country combining together in a unique way.
The two most important patterns impacting us now are the Arctic Oscillation…or A-O, and the Pacific North-American Oscillation often shortened to the PNA. The technical name for these patterns is called a teleconnection…if you want to impress the weather enthusiast friends in your life.
The A-O shifts high and low pressure between the North Pole and Canada. When high pressure moves over the Arctic, cold air gets pushed south into the U.S. It's sending us the cold air.
The P-N-A shifts high and low pressure between the western U.S. and the Pacific Ocean south of Alaska. When high pressure is centered near Alaska... low pressure often forms over us. And low pressure often brings us storms.
The AO has been sending us cold air for a couple of weeks. It'll also send us this weekend's cold blast. The PNA is different though. It didn't matter for the last few weeks, but now it's also joining the party. It's going to bring low pressure to Colorado this weekend. It's the combination of the cold air …and low pressure…that are leading to the near record cold and storm potential here. That is what is making this weekend's cold event so potent.
This is a setup we don't see every year. Here's a look at the coldest low temperature in Colorado Springs in the last 30 years. Only in 11 years was the coldest low below negative 10... as forecast this weekend. So on average we only get this cold every three years. Only seven years have a coldest low of -14 or lower...meaning on average that occurs a little more than once every 5 years. Notably, when researching the data for this story, there is a clear upward trend in lowest low temperature between the beginning of the record in 1894 and today. For that reason - as cold as this weekend will be...it's not actually that historic. In the past, we saw cold like this more often. It's become a bit less common over time. One difference though is that in the past, it wouldn't necessarily require a polar air plunge for us to get a long duration deep freeze event.
So that's the science: massive weather patterns the size of our entire country - and that change on the scale of weeks to months - happen to be aligning perfectly to drive the cold and snow this weekend.
____
Have a question or story idea you would like the First Alert 5 Weather team to consider? Email: weather@koaa.com
Watch KOAA News5 on your time, anytime with our free streaming app available for your Roku, FireTV, AppleTV and Android TV. Just search KOAA News5, download and start watching.