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  • 9 hours ago
AccuWeather's Geoff Cornish breaks down the definitions of both "bomb cyclone" and "blizzard," and what the snowstorm coming at the end of January has to do with both.
Transcript
00:00Here on the forecast feed we have a lot to talk about. We want to talk about the concept of a bombsite.
00:05A cyclone and a blizzard. We are likely to see both of these things take place in the-
00:10Mid-Atlantic and parts of the Northeast. I think I want to put the word parts of in Italian-
00:15Alex and bold and maybe underline it as well because this storm is not going to-
00:20It will bring some of you a flake but it will bring others significant snow and wind-
00:25And coastal flooding as well. First off, what is a bomb cyclone? Again, there are some of these phrases-
00:30In terms that get a lot of media attention and we use them here-
00:35As well because they are actually legitimate words, terms and-
00:40Phrases used by the American Meteorological Society. This is not just-
00:45A bomb cyclone is specifically a low pressure system-
00:50That goes through rapid strengthening and there is a standard to this. We are talking about 20-
00:5524 millibars of strengthening in 24 hours or less. So these are-
01:00There are storms that rapidly strengthen. Sometimes they are tropical systems, sometimes they are nor'easters and-
01:05Sometimes they are just regular low pressure systems that really wrap intensifying quickly-
01:10Wrap up and intensify very rapidly through parts of the Great Lakes region-
01:15Sometimes they are tropical systems-
01:16They typically occur over or near oceans because-
01:20Oceans-
01:20Oceanic heat content and the Gulf Stream, even in the winter, can be a huge drive-
01:25Never fuel for storms. This storm that we are going to be seeing-
01:30Develop over the next few days here. We are going to be taking you through some model graphics and so forth-
01:35Take you to the surface here. And here we have again what will become-
01:40An area of low pressure that initially-
01:43Let's go-
01:44We have to commit to-
01:45Let's go-
01:45Having to a model for this. Let's go-
01:46Let's go-
01:47Let's go-
01:48Let's go-
01:49Let's go-
01:50around, we're at one o'clock.
01:52You can see a closed contour for a baby area.
01:55You have low pressure, and it's not yet down to a full thousand millibars.
01:59It's around maybe 10 o'clock.
02:00There's a closed contour at 10 o'clock, maybe 1,001 millibars.
02:0510 o'clock, somewhere in that, but not deep enough to crank out a closed contour for
02:1010 for 1,000 millibars.
02:12As we take you forward in time, look at this.
02:15We're going to go from 1 p.m.
02:16Saturday, a little more than 1,000 millibars.
02:201 p.m. Sunday, we're strengthening it rapidly.
02:23In fact, it's...
02:25rapidly strengthened even before it goes off the map here.
02:28Only 18 hours into this,
02:30look at this.
02:31Here's 980 millibars.
02:33Four less than that.
02:35976, four less than that, 972.
02:37That's going to become a bomb cyclone in less...
02:40less than 24 hours, and then it goes off the map to the east.
02:43That's another part of this, the off the map to...
02:45the east is a consideration in this conversation.
02:47But overall, the bomb cyclone, it's going to verify...
02:50rapid strengthening, we've got the gulf moisture...
02:52or the gulf stream, I should say, the gulf stream.
02:55And that warmth, offshore, fueling this in a big way in contrast to...
03:00the really cold air, a loft.
03:02That's part of the storyline.
03:04So that's what...
03:05the bomb cyclone is, and this is going to be one of them.
03:07Let's go back to the graphics.
03:08This will probably...
03:10become a blizzard for some.
03:12And again, some is the key word there.
03:14So as we look back...
03:15at the definition of a blizzard.
03:17Is a blizzard about the amount of snow?
03:19No.
03:19We could...
03:20see an inch of snow in a blizzard.
03:22Sometimes in North Dakota, in Alaska, a blizzard warning.
03:25may verify as correct, even if you only get an inch or two of snow.
03:29What is...
03:30it's all about...
03:30it's all about blowing snow with wind frequently gusting...
03:35over 35 miles per hour.
03:37It doesn't have to be sustained necessarily.
03:38It could be frequent gusts.
03:39It could be...
03:40sustained at 25, but frequently gusting to 38 for three or more hours.
03:44So that's the stipulation.
03:45The toughest part of this to verify is that.
03:47And then you need to have a quarter mile visibility...
03:50not because of fog, but because of snow being lofted into the air.
03:52Where could we see that with this storm?
03:55We're looking at two areas.
03:57And again, we have concerns about how much...
04:00snow is going to fall in Atlantic City.
04:01It's going to be a close call there.
04:03But we do expect...
04:05to see a blizzard down into parts of Southeast Virginia, Northeast...
04:10North Carolina, strong winds closest to the coast, stronger winds.
04:13There's less friction over water.
04:15And we have some question marks.
04:16When we're honest with you, we want to be transparent and honest.
04:18We do have question marks.
04:20We want to emphasize what we're sure of, but we need to be honest about the uncertainty
04:23of the Jersey Shore forecast here with...
04:25And we're also likely to see a blizzard in Cape Cod, Nantucket, North Carolina...
04:30versus Vineyard, maybe Block Island, maybe Montauk, and...
04:35And perhaps into Boston.
04:37I suspect it's more likely in Boston than it is in the...
04:40Jersey Shore, and I'll show you why.
04:41Our forecast is, again, we're on the ragged edge of this...
04:45storm system if you're in the Jersey Shore.
04:47So the pieces of the puzzle come together.
04:49We've got a strong...
04:50strong low-pressure system that strengthens aloft and at the surface.
04:53I want to take us just to the...
04:55the GFS model.
04:56All four of these in this tab are the GFS.
05:00Here is the most recent one.
05:02I'm going to hone in on the 7 a.m. Sunday.
05:04This is the...
05:05most recent GFS is the 12Z run on the 28th.
05:08That's Wednesday.
05:09Let's go back.
05:10A little earlier in the morning, six hours earlier.
05:12Didn't change a whole lot.
05:14I've looked at the placement.
05:15What I'm looking at here is the placement of this center of low pressure.
05:19Not...
05:20much change in the past six hours.
05:22Let's go back 12 hours earlier.
05:25If anything, maybe it was a nudge closer, and now it may be a small, small, small...
05:30step farther east.
05:30Not a big change.
05:32And then you go back 24 hours ago, 18...
05:35I should say, 18 hours earlier.
05:37This was the 18Z run from Tuesday.
05:39It actually...
05:40was a little farther offshore.
05:41So again, over an 18 to 24 hour window, maybe it's...
05:45a little farther west, but still, it's...
05:48they're forecasted sometime...
05:50meteorologists make, and man, you don't sleep easy, and then you wake up the next morning
05:54to see how you...
05:55Yeah, you did.
05:55And this is a very, very much a nail-biter here for New York City and for New Jersey.
05:59Look at this.
06:00Here's the GFS.
06:01All that snow.
06:02Painfully close.
06:03If you love snow and you're in Philly, you don't...
06:05don't see a flake.
06:05It's a tough one.
06:06If you are in...
06:07Here's the European.
06:09Very...
06:10Very close.
06:11Some snow for the Jersey Shore.
06:12Heavy snow in a blizzard in Cape...
06:15Here's the European AI.
06:17A little farther east.
06:18Disappointing for the snow fans at...
06:20Coastal New Jersey.
06:21Decent snow in Cape Cod.
06:23Not in Boston.
06:24The GFS...
06:25FSAI.
06:26It brushes the coast with some snow.
06:28Nothing in Philly.
06:29Here's the...
06:30Canadian.
06:31It's a little more robust there at the Jersey Shore.
06:33Not much.
06:34Two counties.
06:35West of New York City.
06:36And the UK meant way out to sea.
06:38So what do we do with all this?
06:39We have to...
06:40make a forecast.
06:41So I'm going to close with this.
06:42And again, we're most confident...
06:45in Cape Cod.
06:46And this portion of the map.
06:47Big questions in between.
06:50And so...
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