Why storms in spring and fall beat storms in winter in southern Colorado

We usually get our biggest snowstorms in fall and spring. Case and point:

Here are the top ten 4-day snowfall totals in Colorado Springs since 1960. We have records going all the way back to the late 1800s, and the trends match... but many of our snowiest storms were early in that period, so I want to highlight more recent trends. Highlighted are the totals that fell in fall or spring. Nine of the ten storms... with last week's storm in fourth place.

In Pueblo, the trend is there but not as intensely. This is partly due to you being farther from the mountains than the Springs. Six of the ten snowiest four-day periods happened in either fall or spring. Two separate storms in November 1991 made the list.

So we see the trend for spring and fall. This is due to moisture and the jet stream. The Rockies block a lot of wet air that comes in from the west and north. Our best moisture comes from the south and east. The jet stream tends to be more wavy in fall and spring , letting more of that moisture in.

Finally, let's talk about overall patterns. Snow pack is currently above average statewide, and on average, we get more snow in December and January than all months other than March. Combined, this means we get our biggest storms in fall and spring, but they're hit or miss. We get more frequent but smaller storms during midwinter.

We've seen one of our biggest long-duration storm total snowfalls in southern Colorado weather history this November. To hit the monthly snowfall record, we need 6 more inches in the Springs. We need 18 in Pueblo... a tougher sell.