Why Bomb Cyclone Causing Heavy Disruption is So Unusual: Explained
Bomb Cyclone or “weather bomb” as the term has taken off in the broader media is intensifying into a major storm along the East Coast. This might soon earn a place in the record books.
But, the first thing you should know about this bomb cyclone is that it’s just a name – unlike Sharknado, this is not the literal winter storm. Although it may seem like an obscure expression that meteorologists invented, the actual scientific definition describes this as a storm that suddenly strengthens with a rapid drop in the atmospheric pressure.
While “bombogenesis” is when the pressure for cyclone drops to 24 millibars in 24 hours. The results include furious winds that create coastal flooding and blizzard conditions.
What is a Bomb Cyclone: Explained
The “weather bomb” is not that rare of a phenomenon; as per meteorologists such storms only breakout in the Northern Hemisphere for 10 times a year. They also have other names such as mid-latitude cyclone and Nor’easter, and these are probably the reason why no one heard of these before Winter Storm Grayson dumped snow in Tallahassee on Wednesday.
This is the result when everything comes together, right or wrong. Winter Storm Grayson is expected to explode at the East Coast, starting from now and anytime by Friday. And while getting more intense, it will head out from Florida to Nova Scotia, blowing record building snowfall with a category 3 hurricane speed.
Ryan Maue, Meteorologist at Weather.us is posting on Twitter – this storm will be in the top 15 percent of all “bomb cyclones”, depending on the intensity. In general, the storm becomes stronger when the pressure gets lower.
“This storm is a synoptic meteorologist’s dream,”
says Paul Huttner, who watches the weather for Minnesota Public Radio.
“It’s a perfect alignment of the three things we look for.”
The first is a warm conveyor belt of tropical moisture, which the Gulf Stream is shuttling out of the Caribbean and right up until the Atlantic coast. That’s pretty normal for this time of year. What’s less normal is the huge subzero air mass that dipped down from the Arctic about 10 days ago, plunging the Great Lakes and Eastern US into a sustained deep freeze.
Every year, around this time, the sun stops shining above the Arctic Circle. No radiation means no heat, which means all that air gets real cold real quick. Most of the time, jet streams—the easterly flowing air currents near the upper reaches of the atmosphere—keep that cold air bottled up in the Arctic. But sometimes, upper airwaves shift, forcing a buckle in the jet stream and allowing all that air to spill southward.
“The coldest air on the planet just happened to slide over Northeast America,” says Huttner.
“And with this incredible moisture feed, we’ve now got a huge temperature contrast. By the time this thing gets up into New England we’re talking about a good 100 degrees of temperature contrast across the center of the storm. And generally speaking, the stronger the temperature contrast, the deeper the storm.”
Differences in temperature, you see, lead to differences in pressure. As the pressure drops, air rushes in. The faster it drops, the faster the air moves. And thus, a winter storm is born.
Unlike hurricanes, which slow down as they head north and get away from the moist heat of the ocean, bomb cyclones tend to reach their peak intensity when they hit New England. That’s where the maximum temperature contrast usually is. It’s also where the third thing meteorologists look for—a low-pressure trough in the upper levels of the atmosphere—happens to be occurring right now.
With weather communication, as well as science communication in general, it can often be difficult to engage a wide audience and make them aware of imminent risks. Pulling terminology from the scientific lexicon is a valid way to do that, provided that the terms match the phenomena being predicted.
A similar dynamic played out with the polar vortex winter four years ago, when an actual weather term was popularized for the first time and became part of popular culture seemingly overnight.
Right now, it’s bomb cyclone’s turn. Perhaps next to come will be tropopause fold, or gravity wave (both real things).