Picture Alaska: Cold air funnels and how they form
A cold air funnel was spotted over Bristol Bay late last week
ANCHORAGE, Alaska (KTUU) - Picture this! You’re standing outside under the overcast skies, enjoying the fleeting Alaskan summer, when in the distance you spot what looks like a rope emerging from the base of a cloud. It looks eerie and depending on its size, it can be terrifying.
But what is it? Are they rare? And how do they form?
This is a photo a viewer sent in to Alaska’s News Source depicting such a sight.
While they can spark a sense of danger or urgency, they are usually very harmless and rarely if ever reach the surface. They are most common in the spring, but sightings like this aren’t out of the ordinary. The most recent sighting can be attributed to the unsettled and cool weather pattern that has gripped the state.
Cold air funnels get their name because they typically form beneath showers or weak thunderstorms, when the air aloft is very cold. This creates instability in the atmosphere, which in turn leads to rising air.
In order for them to form, there is usually a strong area of low pressure associated with the event. Like all funnel clouds, there is circulation, although it is very weak. The circulation creates the thin rope-like funnel cloud, which is then stretched as if reaching for the ground.
Because of the weakness of these funnel clouds, they are usually short-lived and very rarely touch the ground. On the occasion that they do, they are comparable to a very strong dust devil and usually lead to weak trees knocked over and siding and shingles ripped off homes. When they do touch the ground, they become a landspout and are usually rated as an EF0.
While tornadoes are exceptionally rare in Alaska, funnel clouds aren’t that uncommon. They form all over the U.S. and Canada, with an overwhelming majority of them being very short-lived. It’s because of this that they are very hard to detect on radar and rarely if ever does the National Weather Service issue a product for them, outside of a special weather statement.
While the odds aren’t entirely zero that a cold-air funnel won’t make it to the ground, it can provide a picture-worthy moment, and a learning moment of the fluidity of our atmosphere.
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