DENVER – We’re coming into Colorado’s severe weather season, which can bring heavy rain, thunderstorms, tornadoes, wildfire, flooding, and more.
In this series of videos, Denver7 Chief Meteorologist Mike Nelson breaks down Colorado’s weather patterns, how various types of weather develop and move into Colorado, and the threat across the state from the gamut of severe weather we face.
The Alberta Clipper and the Colorado Hooker: Where our storms begin
Where do our storms form? Denver7 Chief Meteorologist Mike Nelson shows us how storms begin, starting thousands of miles away in the Pacific Ocean and ending over the Rockies.
In Colorado, we get our main storm systems from three different areas.
Pacific cold fronts that come in off the Pacific coast, which oftentimes will bring Colorado heavy mountain snow but not much in the way of precipitation on the plains.
Alberta Clipper storms are low pressure systems that clip out of Alberta, Canada, and go to the north of Colorado generally don’t bring as much precipitation but create a lot of wind.
The Colorado hooker is when low pressure systems form over southeastern Colorado, which is also called an Albuquerque or Panhandle Low. Those swing a lot of moisture around the low-pressure system and bring us some of our heaviest snow and rain storms.
El Niño and La Niña also factor into Colorado’s weather patterns. El Niño is the warmer water in the equatorial Pacific more than 3,000 miles away, which changes the position of thunderstorms in the Pacific and eventually alters how the jet stream blows across the U.S.
Generally, El Niño would bring Colorado a lot of big, soggy storms in the wintertime and supercharges the summer monsoon in July and August. So El Niño tends to make a wetter weather pattern for Colorado.
But we’ve been in a La Niña for a while now, which involves cooler water in the Pacific and affects the energy balance of the atmosphere and jet stream. It tends to develop more of a northwesterly flow across the nation, from northwest to southeast.
In the wintertime that is great for Summit County and the northern mountains, but it comes at the expense of the San Juan Mountains in southwest Colorado. La Niña also typically means lots of wind across the eastern plains – which we’ve definitely seen so far this year!
What is the 'Denver Cyclone'? Colorado's topography and its impact on the weather, explained
Where am I? Denver7 Chief Meteorologist Mike Nelson explains the topographical map of Colorado and how it affects the weather patterns in our state.
The Palmer Divide plays into many of the weather patterns and events we see on this side of the mountains. During the cooler season, winds blow in from the northeast that forces air to rise over the Palmer Divide, which bring some of the heaviest snows to the southwest and southeast sides of Denver.
But in the summer, if there are southeasterly winds that blow over the Palmer Divide, a “Denver Cyclone” is created when air comes off the divide and curls back toward the Denver area.
If we get thunderstorms that develop in the mountains, they’re moving off the mountains. They run into air coming from the southeast, it creates a convergence line over the Denver area from around Castle Rock up to Denver International Airport and up into Weld County. Along that convergence line, we see tornadoes that form because the air coming together starts to spin.
Most of Colorado’s tornadoes occur east of I-25 – only about 10% happen west of the interstate.
Colorado weather in-depth: What kinds of tornadoes do we see and how do we spot them?
When is Colorado's tornado season? What different kinds of tornadoes do we see, and how can we spot them? Denver7 Chief Meteorologist Mike Nelson gives an in-depth explanation – from how tornadoes form in the clouds to storm-chasing advice.
Colorado hail season: When and why we see so much hail
Denver7 Chief Meteorologist Mike Nelson explains peak hail season in Colorado, where the elevation is higher than most other states because of the Rocky Mountains.
Since the storms are a little closer to the colder air, we see a lot of hailstorms in Colorado – especially in May, June and early July.
Colorado weather: Flooding threat, explained
Denver7 Chief Meteorologist Mike Nelson explains the threat of flood waters, and the time Colorado saw a year's worth of rain in a matter of days.
Tracking storms in Colorado: Useful weather resources
Denver7 Chief Meteorologist Mike Nelson introduces us to useful weather resources for tracking and measuring storms in Colorado, including the CoCoRaHS network.
Understanding climate change: What the science tells us, and how we move forward
Denver7 Chief Meteorologist Mike Nelson goes in-depth on a changing climate – what the science tells us, how long the research has been happening and what we can do to mitigate the impacts of climate change moving forward.
Click here to read more about climate change from Mike.
You can always get 24/7 weather updates anywhere in Colorado or across the country by watching the free Denver7+ streaming app.