Every week, the blog introduces you to a technical term from the American Meteorology Society’s “Glossary of Meteorology”. Welcome to #WxGeekSpeak!
This weekend’s storm brought more than valley rain and mountain snow to Arizona.
Sunday afternoon, the National Weather Service in Phoenix received several reports of a funnel cloud over Scottsdale. While ominous looking, this funnel cloud did not touch the ground or cause any damage.
There’s good reason why it was harmless.
From a meteorological standpoint, this is considered a cold air funnel. All the ingredients were in play to have cold air funnel clouds develop this weekend: an mid or upper level low pressure center (to provide spin), a drastic temperature change from surface to the upper levels and rising air associated with nearby showers.
Cold air funnel clouds can be common during well-developed Winter storms. These funnel clouds rarely touch the ground, primarily because the funnel originates in high cloud bases. In the event a cold air funnel touches the ground, the subsequent tornado is very weak in intensity.
Full definition of cold air funnel: A funnel cloud or (rarely) a small, relatively weak tornado that can develop from a small shower or thunderstorm when the air aloft is unusually cold (hence the name). They are much less violent than other types of tornadoes.