a "bomb cyclone"--is this an official term?

[Jason Harris]

Just checking out the forecast discussion for the Sacramento area, and the local forecaster has some interesting things to say about a potent storm that might be rolling along Tuesday/Wednesday, so what about this term "bomb cyclone"--from the context it seems to just mean the intensification of the surface low is brief and rapid:

--
THE MODELS HAVE NOW FAVOR
A "BOMB CYCLONE" SOLUTION WHEREBY A SURFACE LOW RAPIDLY INTENSIFIES
(IN THIS CASE...THE SURFACE LOW IS CURRENTLY PROGGED TO DROP 25-30
MILLIBARS IN 24 HOURS) AS IT APPROACHES THE COAST. MUCH UNCERTAINTY
LIES WITH THE TRACK OF THIS STORM...THE NEWEST ECMWF BRINGS THE
SURFACE LOW INLAND NEAR MONTEREY WHERE THE NEWEST GFS BRINGS IT
INLAND CLOSER TO THE CALIFORNIA/OREGON BORDER. THESE NEWER SOLUTIONS
BRING A NEW CROP OF PROBLEMS TO THE FORECAST AREA. WHEREAS THE
CONCERN WITH YESTERDAYS MODELS WAS WIDESPREAD HEAVY RAINFALL...THE
CONCERN NOW SHIFTS TO A POSSIBLE STRONG WIND EVENT WITH MODERATE
RAINFALL AND A COOLER FORECAST. WOULD REALLY LIKE TO SEE BETTER
MODEL AGREEMENT BEFORE PINPOINTING THE FORECAST DOWN...BUT IT IS
LOOKING RATHER LIKELY THAT CHRISTMAS EVE AND INTO CHRISTMAS

 

[Matt Sellers]

what about this term "bomb cyclone"--from the context it seems to just mean the intensification of the surface low is brief and rapid:

Exactly - and while the term isn't "official", the forecast discussion defined it well in terms of surface pressure fall over time (30mb in 24h, in this case.) Within the lower 48, such rapidly-developing lows can form (and "bomb out" or become a "bomb cyclone") just about anywhere; however, they most commonly occur along the West Coast, alee of the Rockies as they move across the Plains, or along the East Coast (noreasters.)

The term can also apply to rapidly-intensifying tropical cyclones to describe the fast drop in their minimum pressure (and associated rapid increase in maximum sustained wind speed.)

 

[John Farley]

Ah, this brings back memories! I first heard this term from Dave Murray, a local TV met in St. Louis, who said the night before the March, 1993 superstorm that "bombogenesis" was about to occur. I had never heard the term before, but boy, was he right - first there was an outbreak of tornadoes in the Florida peninsula, then almost at the same time an outbreak of heavy snow and thundersnow that produced snow down to the gulf coast and heavy snows of 4-9 inches not far inland from the Gulf, and then eventually 2-3 feet of snow and blizzard conditions all up and down the east coast from Atlanta to Boston. More than half the states were affected. You can read more about this at:

http://wintercast.tripod.com/id24.html

True "bomb" cyclone development doesn't happen to often, but when it does, the results can be pretty spectacular. It will be interesting to see what happens with this West Coast system.

 

[mikegeukes]

NWS Glossary mentions this:
<dl><dt>Bomb</dt><dd>Popular expression of a rapid intensification of a cyclone (low pressure) with surface pressure expected to fall by at least 24 millibars in 24 hour.</dd></dl>

 

[Jason Harris]

Thanks for the insights folks. Interestingly one of the weather channel reporters this morning was talking about Maine and "bombogenesis" there for a system he alleged was forecast to drop about 40 mb in 18 hours. I took a look at a few of the Maine discussions but didn't see anything that specific, but did see the term "bombing out":
--
AS THE FAST FLOW YIELDS A SEEMINGLY ENDLESS PARADE OF STRONG
DISTURBANCES THIS PERIOD. THE FIRST SYSTEM APPROACHES FROM THE
MIDWEST ON SUNDAY WITH COASTAL DEVELOPMENT BOMBING OUT AS IT RACES
NORTHEASTWARD ALONG THE NEW ENGLAND COAST.
--
Meanwhile, the forecaster for Sacramento, Ca didn't seem as enthusiastic today about
the models for the low. Still something to watch.

 

[Adam Ball]

It's also been referred to as "explosive cyclogenesis".

 

[Steven Williams]

The term 'weather bomb' gets used in this country (New Zealand). The media certainly like it and I'm sure the local Meteorological Service use it as well for the big pressure falls.