Bomb cyclone or dud cyclone?
Depending on who you ask, Wednesday’s storm once again met the relatively rare classification of earning the term “bomb cyclone.” But unlike March’s event, this month’s version is a bit more complicated.
The formal definition of a bomb cyclone, , is for the central pressure of a certain storm to drop 24 millibars in 24 hours. Traditionally, this is the threshold to determine whether “bombogenesis,” or a bomb cyclone, has officially taken place.
As of Wednesday afternoon, it did not appear that any location had achieved a 24 millibar drop in 24 hours, though it was close. The estimated pressure of Wednesday’s storm had dropped roughly 20 millibars in 24 hours, , an arm of the National Weather Service.
However, , a senior branch forecaster with the Weather Prediction Center, this storm is, in fact, a bomb cyclone. Roth’s argument is that due to Colorado’s latitude, the millibar threshold over a 24-hour time period lowers. He explained his rationale in a tweet on Wednesday.
The CO low’s central pressure has fallen to 988 hPa at 1500 UTC. Since its pressure has dropped from 1005 hPa at 1800 UTC yesterday, and the bomb equation calculates 17 hPa fall in 24 hours as satisfying criteria at 38N, the CO low has met bomb criteria with 3 hours to spare.
— David Roth (@DRmetwatch)
A reminder: Like the official definition of a blizzard, a bomb cyclone doesn’t have anything to do with the amount of snow a certain storm might or did produce. It has to do with the central low pressure of a storm, which is a general representation of the strength of a certain storm.
In addition, a so-called bomb cyclone is much rarer over a continental landmass like Colorado. Storms, particularly non-tropical ones such as this week’s, often use the vast temperature difference between oceans and land to strengthen. Since Colorado is hundreds of miles away from the nearest significant body of water, it’s much harder to get robust storms like this week’s over a continental location.
While this storm is certainly a strong one, it’s no March bomb cyclone, which produced the strongest wind gust ever recorded (96 mph) at the Colorado Springs airport, and an 80 mph gust in Denver.
Wednesday’s storm is expected to deliver strong winds and heavy snow, but it likely won’t quite get to last month’s level.
