Making sense of weather terminology: What is a bomb cyclone?
COLUMBIA - You may have heard these phrases bouncing around on the news and social media lately: cyclone, "bomb-cyclone", winter hurricane, polar vortex, "1000-year snow", "air colder than Mars", snow-pocalypse (we've heard that one in Columbia before).
This all comes along with the powerful winter storm impacting the eastern and northeast coast this week.
More commonly referred to as a nor'easter, these winter storms (like the so-called "bomb-cyclone" happening now) are exceptionally powerful and impactful to the New England coastal states due to the system's arctic-like air interacting with warmer Atlantic Ocean waters. Not only can snow from these systems approach 20+ inches, but winds can gust over 50 mph leading to blizzard-like conditions and coastal flooding.
The east coast experiences around 2-5 of these storm systems per year and can lead to major traffic and travel issues, especially airline travel.
What makes this storm system especially hazardous is the extreme cold we just experienced in Missouri and the Midwest will now move over these areas. Vermont and New Hampshire will be approaching -30F Sunday morning and many records may be broken.
Will the New England states actually be colder than Mars? Technically, yes. The temperature on Mars fluctuates rapidly due to its thin atmosphere. At its equator: 68F during the day falling to -67F at night, a 100 degree swing.
As for that "1000-year snowfall," this system will have to work very hard to produce a snowfall to match that which dumped 23.6" on Boston one February day in 2003. The highest snowfall from this system will occur in northern Maine with 15-20" of snow expected through Friday night.
A "winter hurricane" can not exist in terms of meteorological definitions. However, these powerful coastal storm systems do exhibit similar characteristics to those of a hurricane: very low surface air pressure, winds over 70 mph, storm surge causing coastal flooding, and copious amounts of precipitation.
A few of these peer-reviewed terms can be found in the Glossary of the American Meteorological Society.
- Low pressure - Sometimes called a depression, an "area of low pressure" refers to a minimum in atmospheric pressure. Used interchangeably with cyclone.
- Cyclone - An atmospheric cyclonic circulation, a closed "low" circulation (counter-clockwise in the northern hemisphere)
- "Bomb" (a.k.a. bomb-cyclone) - An extratropical surface cyclone with a central pressure that falls on the average of at least 1 millibar per hour for 24 hours
- Polar Vortex - It most commonly refers to a planetary-scale, mid to high-latitude circumpolar circulation, typically found above 500-mb and near the tropopause/lower stratosphere (well above 10,000ft). The tropospheric edge of this is generally between 40º and 50º latitude, where the stratospheric edge remains mainly north of 60º latitude. This circulation exists throughout the year, but is strongest during winter when the air within the polar vortex is the coldest.