Most of October was very warm. In fact, it was the fourth warmest on record after the average temperature in Colorado Springs and Pueblo. We started seeing flakes flying right around Halloween. But now – just a week later – we live in a snow globe. So what gives? As with most weather models of this scale, a lot of it comes down to a weather concept called teleconnections. A teleconnection is a large-scale, semi-permanent weather pattern that changes slowly, leading to changes in storm tracks, temperatures, and more.

For us, a pattern near Alaska called the Pacific North American Oscillation (or PNA) is usually one of the most important. In this case it is a factor (and something to talk about another time)..but something less common also happens.

With this storm system… a pattern called the Madden-Julian Oscillation (MJO) is at play. The MJO is a pattern of higher precipitation and moisture that sometimes develops in the Indian Ocean…about 11,000 miles from us here in Colorado! This improved precipitation pattern then moves eastward over the Pacific Ocean for several months and eventually changes the shape of the jet stream over the US. That’s what’s happening now – and we’re getting more storms as a result. The complexity here is that the MJO is a tropical weather pattern. So it doesn’t directly increase precipitation and snow for us. Instead, it disrupts the large wind circulations that carry air from the tropics to the mid-latitudes… where we live. That’s how it ends up changing our jet stream — and in some cases increasing the storm’s energy in the middle atmosphere. Also adding to the fun: the MJO is not always active. It affects our weather a few times a year, but it is not a constant part of US weather science.

The second thing we need for a lot of snow is cold air from the Arctic. So let’s talk about another big weather pattern. Arctic Oscillation. AO… in short… measures whether the pressure over the Arctic is higher or lower than usual. Right now… it’s lower than usual. And when that happens…high pressure can sit over the eastern US, as it is now.

Putting these ideas together…our jet stream is very wavy right now…and we have a lot of energy coming in from the Pacific. As cold air rises south from the Arctic…low pressure pulls in moist air from the Gulf of Mexico…and high pressure over the central US piles up the works and keeps storms spinning over us. It’s a perfect recipe for lots of snow.

As of today… Colorado Springs is tied for second most snowfall in the first 10 days of November. To get the snowiest November on record, we need at least 26.3 inches of snow in the Springs. We will be running.

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