A ‘bomb cyclone’ may be coming to Mass. this weekend. What is it?
You may have heard talk of a "bomb cyclone" snowstorm that could impact Massachusetts this weekend . But do you need to worry?
Here's a breakdown of what that term means and what forecasters are saying about the chances of one dumping snow on the state in the coming days.
What is a bomb cyclone?
A bomb cyclone is a storm that undergoes "bombogenesis," meaning it rapidly intensifies within a 24-hour period, according to the National Weather Service . The strengthening of the storm is represented by a drop in millibars — a measurement of pressure used in meteorology.
The level of intensification required to classify as "bombogenesis" varies by latitude, according to the weather service. At 60 degrees latitude north, which cuts through Scandinavia, Russia, Alaska, Canada and Scotland, the bar to clear is 24 millibars of pressure. At the latitude of New York City — approximately 41 degrees north — the required pressure drop is about 17.8 millibars.
Bombogenesis often occurs when a cold air mass collides with a warm air mass, according to the weather service. In the case of the bomb cyclone that might travel to Massachusetts this weekend, a cold air mass from Canada is meeting with warm ocean air off the coast of the southeastern U.S.
The resulting storm brings high-speed winds and heavy precipitation, according to the weather service. This means they often cause substantial damage when they travel near or on land.
Is a bomb cyclone coming to Mass.?
While there is a growing potential for accumulating snow and gusty winds on Cape Cod, the Islands and further west into South Shore and the I-95 corridor, as of Thursday afternoon, weather models suggest the rest of Massachusetts likely won't be significantly impacted by this weekend's bomb cyclone, according to National Weather Service Boston.
The weather service has issued a winter storm watch for the Cape and Islands that is set to go into effect late Saturday night and last through late Sunday night. During this time, communities in these areas could get 6 inches of snow or more and wind gusts up to 55 mph.
The snowstorm is expected to reach the state sometime on Sunday and last through the evening, so there is still a chance the storm could change its track, according to the weather service. If this were to happen, the bomb cyclone could wreak havoc on more of the state.
"Massachusetts is going to catch the western edge of this storm, but the path it takes will determine the strength and reach of the impacts," WCVB Meteorologist Cindy Fitzgibbon predicted Thursday morning . "A jog of 50 miles to the west or east, for example, could significantly change what we experience on Sunday."
Adam Frederick, an amateur meteorologist of over 20 years who is known for his New England Weather Guy social media page , said in a Thursday morning Facebook post that he is around 70% certain that the storm will stay a ways away from the coast and cause only "moderate coastal impacts."
Forecasters will become more certain of the storm's impacts — or lack thereof — as Sunday approaches. Small changes in conditions close to a weather event can lead to vastly different outcomes, forecasters say .
The further into the future forecasting models predict, the more variance there is between each individual model's prediction, according to forecasters. As you get closer to a weather event, the models begin to converge on a single prediction.
Forecasters say that, once a storm system is 24 to 48 hours away from reaching a location, they can feel confident in their predictions of which communities will be most impacted. But there's always a chance conditions could change and cause vastly different weather impacts than were predicted — even when a storm is just a few hours away.
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