Hurricane Dean--9th strongest hurricane on record

By: Dr. Jeff Masters , 2:46 PM GMT on August 21, 2007

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Hurricane Dean powered ashore in Mexico's Yucatan Peninsula this morning as a Category 5 hurricane with 165 mph winds. The pressure of 906 mb measured by the Hurricane Hunters shortly before landfall at 4:30am EDT makes Dean the ninth strongest hurricane on record in the Atlantic. This is the third lowest pressure at landfall behind the 1935 Labor Day hurricane in the Florida Keys and Hurricane Gilbert of 1988 in Cancun Mexico. Dean is also the first Category 5 hurricane to make landfall in the Atlantic Basin since Andrew of 1992.


Figure 1. Dean at landfall, as seen by the Cancun radar. Image credit: Meteorological Service of Mexico.

Radar images at landfall (Figure 1) show that Dean came ashore just north of Chetumal, Mexico, a city of 130,000 people. Dean's center passed about 15 miles north of the city, and Chetumal missed the strongest Category 5 winds of the storm. The strongest winds from Dean were in the right front quadrant on the northern side, since the forward speed of the storm adds to the rotational speed of the winds there. It appears Chetumal was just at the edge of the southern eyewall, and probably experienced sustained winds of Category 3 strength, 115 mph. We don't know, since the weather station stopped reporting data long before the storm arrived. However, a wind analysis done by NOAA's Hurricane Research Division (Figure 2) supports this estimate. The coastal area north of Chetumal where Dean's greatest fury was unleashed has a cruise ship port and a stretch of beach front development, and this region probably suffered near-total destruction.


Figure 2. Dean's winds one hour before landfall. Winds are in knots, multiply by 1.15 to convert to mph. Locations of Chetumal and the Costa Maya Cruise Ship Port are marked. Winds of Category 1 strength (65 kt) are colored yellow, and winds of minimal Category 3 strength (100 knots) are colored pink. Image credit: NOAA/Hurricane Research Division.

Further north, it appears that Cozumel probably got sustained winds near tropical storm force, 39 mph. The weather station there stopped transmitting data before the storm arrived. Cancun's winds topped out at 29 mph, gusting to 54 mph. To the south, Belize City has had top winds of 23 mph, gusting to 35 mph, so far this morning. On the western side of the Yucatan Peninsula, the winds are starting to rise at Campeche. Dean's center will pass south of Campeche, and bring tropical storm or Category 1 hurricane-force winds to the city.

Dean is powerful enough to survive the crossing of the Yucatan as a hurricane, and I expect it will be a Category 2 hurricane with 100 mph winds when it pops out into the Gulf of Mexico later today. Hurricane Janet of 1955, which hit near Chetumal as a Category 5 storm with 170 mph winds, weakened to a Category 2 storm with 105 mph winds when it popped out into the Gulf of Mexico south of Campeche. Janet was moving at about the same speed Dean is, so I expect Dean will behave similarly. Once out over the warm waters of the Gulf of Mexico, Dean has time to intensify by perhaps 15 mph before it makes a second landfall near Poza Rica. Dean will finally dissipate in the mountains about 100 miles north of Mexico City, and could bring heavy rains to the Mexican capital. No hurricane has ever survived the crossing from the Gulf of Mexico to the Pacific over the wide, mountainous portion of Mexico.

Links to follow today:
Campeche, Mexico observations.
Radar from Cancun, Mexico.
Belize City observations.
Morphed microwave animation.

Disturbance 92L
An area of disturbed weather associated with a tropical wave, 92L, is a few hundred miles north of Puerto Rico. This disturbance is less organized than yesterday, despite some rather favorable upper-level winds. There is some dry air to the north that may be interfering with organization, and there is probably not enough turning motion available from this tropical wave to get 92L spinning. I don't expect significant development today given its current state of disorganization, but 92L deserves close scrutiny over the next few days. None of the reliable computer models develop the system.

My live appearance tonight on Internet Partnership Radio
I'll be the guest tonight on the Internet Partnership Radio (http://www.ipr365.com). Tonight's show is called "Center of Circulation", and consists of global severe, winter, and tropical weather news/topics with up to the minute advisories, watches and warnings, safety & preparedness info, and periodic special guests. The host is Charlie Wilson. I hope you can listen in!

I may do a short update this afternoon, and the next full update will be Wednesday morning around 10am EDT.

Jeff Masters

Dean 2007 (nickmini)
A roof dumped atop another house
Dean 2007

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268. fire831rescue
6:09 PM GMT on August 21, 2007
Not to start a new argument, but the models have been wrong, wait... very wrong before. Don't ever say it's not gonna happen until it hits land somewhere. I've seen these storm do a 180 degre turn before. Just my .02
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267. moonlightcowboy
6:08 PM GMT on August 21, 2007
Posted By: JFLORIDA at 6:07 PM GMT on August 21, 2007.
BTW hurricanes do not usually track so tamely, People worried about a change in course, even a drastic change have history to back up their concerns.


...true. Had just a couple of small things changed with Dean we could've been looking at a GOM landfall somewhere. However, it does also add validity to the NHC and their abilities-I say great job!
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266. indigenous
6:03 PM GMT on August 21, 2007
Thanks jflorida, for your comments. The worst scenario for cat 5 damage seems to be difficult to find as yet. Let's hope that this luck continues.
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264. extreme236
6:08 PM GMT on August 21, 2007
cmc doesnt develop 92L anymore, at least not on the 12z run
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263. MZT
6:07 PM GMT on August 21, 2007
Looks like Dean has pulled in a good amount of dry air to his north. I'm starting to think this will disrupt re-organization over the bay of Campeche, before he can hit the east coast of Mexico. It may not be that bad tomorrow.
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262. StormHype
5:59 PM GMT on August 21, 2007
What do you guys think about the CMC developing 92L once it hits the gulf side?? Looks like a TD on the east then it blows up in the gulf...

I think it's on CRACK as usual. CMC is a waste of computer cycles. Thanks for asking.
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259. genha
6:01 PM GMT on August 21, 2007
RE:

Gov Blanco is the governor of Louisiana. She declared a state of emergency when it was thought that Dean would possibly come their way.

The scary thing about crying wolf like this is the next time she does it, and say that it actually is warranted and verifies, who the heck is going to listen to her?

I'm no Blanco fan, in light of Katrina; I don't think it was a case of crying wolf; it's trying in some small way to compensate for the late..or lack of action she took prior to Katrina. Wasn't it Pres. Bush who had to make the emergency declaration FOR her three days before landfall?
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257. KennerLA70065
6:02 PM GMT on August 21, 2007
CAT 5 reports? Are there any damage that would be commensurate with a CAT3? Looking at the radar, and the wind field diagram, it appears that, unless there's anything on the peninsula with some elevation, or, someone was unlucky enough to get caught in one of those tight bands, there may not have been as much punch in the storm as many were expecting.

I don't want to minimize the possible human tragedy that may have occurred here, but, it appears that, recently (last decade) they've called a few storms as being very strong, and the damage that they left behind just didn't support such a name.
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255. bluehaze27
1:02 PM EST on August 21, 2007
I know Dean is not yet done, but I guess now the focus shift towards africa again.
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254. gthsii
5:58 PM GMT on August 21, 2007
Hey Solo: watch for numerous and frequent typos on this blog.
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252. gthsii
5:55 PM GMT on August 21, 2007
err...never mind...misread your comment
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250. indigenous
5:50 PM GMT on August 21, 2007
Thank you, Mishnook. Are there Cat.5 damage reports yet from Dean's landfall impact?
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249. boatdrinkz
5:46 PM GMT on August 21, 2007
any word about little caymen ??
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247. boiredfish
5:50 PM GMT on August 21, 2007
Question again.....do the HH's include forward speed in max. winds. or not? Storm winds vs. earth winds are two different things? Maybe Dr. M could answer.....thanks.
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246. bluehaze27
12:54 PM EST on August 21, 2007
twinkster , it doesn't matter where the convection is. It matters where the eyes goes. If the eye goes over water, the convection will follow.
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245. Solo
5:52 PM GMT on August 21, 2007
bluehaze27 - I thank you for the clarification, nothing came for 'blonco' in a google search.
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244. hosweather
5:48 PM GMT on August 21, 2007
extreme236 at 5:47 PM GMT on August 21, 2007.
hosweather, storms are unlikely to develop, matter of fact they are likely to form, but conditions would have to be favorable and according to models, it would go over land a second time just a day or so after coming off florida

Some of the models are taking the disturbance on a more southerly track into the Gulf which would give much more opportunity for development. I am not saying that the last CMC solution is likely to occur. I am only saying that this wave still has a lot of potential for development before it exits to the E Pac,
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243. Twinkster
5:53 PM GMT on August 21, 2007
I don't think it will form because most of thge convection is to the south and a Hurricane can't restrengthen unless it has room to breath on all sides. I think the center is to south into the bay of campeche to restrengthen. Unless it starts heading north.
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242. TXKiwi
5:53 PM GMT on August 21, 2007
TWC just reported Dean's position at 89.4 W.. given that it was at 89.6W at 11am, it seems it is now traveling East.... stupid people!
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241. gthsii
5:53 PM GMT on August 21, 2007
Gov Blanco is the governor of Louisiana. She declared a state of emergency when it was thought that Dean would possibly come their way.

The scary thing about crying wolf like this is the next time she does it, and say that it actually is warranted and verifies, who the heck is going to listen to her?
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240. surfmom
5:39 PM GMT on August 21, 2007
Surfer information. So far no ground swell is really reaching the gulf coast coast - least by SRQ. If you are looking for waves on this side I'd keep checking buoy 42003 to see when /if the swell comes through. The east wind may also keep things flat. What is VERY interesting was watching the effect Dean had on low tide. I saw the beach go from happy go lucky to panic! (Life guards made two rescues in a matter of minutes once the tide started pulling out) As the tide went out, probably due to Dean, the rip current went from none existent to SEVERE, So I'd like to alert every one that Dean is be very strong and just sucking up the water, from as far as the gulf coast. I expect that all our beaches will be feeling this and we should be alert that RIP TIDES will occur and be very strong

more swell hopefully Wednes
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239. extreme236
5:51 PM GMT on August 21, 2007
Posted By: Twinkster at 5:49 PM GMT on August 21, 2007.

is it possible that dean doesn't even go over the bay of Campeche and stays over Mexico. Especially after you look at the satellite imagery Weather456 just posted


It will go in the bay of campeche, the center is in the far northern part of dean, so it will go in the bay
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238. bluehaze27
12:51 PM EST on August 21, 2007
Gov Blanco is the governor of Louisiana. She declared a state of emergency when it was thought that Dean would possibly come their way.
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237. strangesights
5:46 PM GMT on August 21, 2007
With all the jokes, Dean is in fact moving a bit north of the projection. Of course Dean will likely "correct" itself soon ... and I presume it will ... but I will be watching to verify.
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236. gthsii
5:49 PM GMT on August 21, 2007
dont call out dodabear...just report his inane comments
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234. Solo
5:50 PM GMT on August 21, 2007
Posted By: groundswell:
I would wait and make sure Gov Blonco doesn't declare an emergency before writing off 92L.

Who is Gov Blonco and what does he (or she) govern? Thank you...
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233. Twinkster
5:48 PM GMT on August 21, 2007
is it possible that dean doesn't even go over the bay of Campeche and stays over Mexico. Especially after you look at the satellite imagery Weather456 just posted
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232. extreme236
5:49 PM GMT on August 21, 2007
there is a low pressure center but it is very weak, only 1014mb
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231. extreme236
5:49 PM GMT on August 21, 2007
and sorry hosweather, i typed that wrong so i edited it
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230. bluehaze27
12:46 PM EST on August 21, 2007
Hosweather, any low level center that ever was with92l will most certainly be destroyed when it comes over Florida. I don't even think there is a low level center anywhere in that mess. Besides, upper level winds are becoming way to unfavorable.
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229. extreme236
5:46 PM GMT on August 21, 2007
hosweather, im not saying storms are unlikely to develop, matter of fact they are likely to form, but conditions would have to be favorable and according to models, it would go over land a second time just a day or so after coming off florida
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227. bluehaze27
12:45 PM EST on August 21, 2007
Dean now a cat 1
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226. extreme236
5:44 PM GMT on August 21, 2007
It could reform in the eastern pacific. the LLC would be gone and it would have to redevelop that but the upper lvl feature would still be intact so if Dean could get into a favorable enviroment in the pacific, then he could redevelop and perhaps earn the name Gil
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225. mishnook
5:44 PM GMT on August 21, 2007
Indigenous, Cantori was way, way to the North of the storm. Well out of the danger zone. I'd guess they picked their location becuase it was a resort with 1) stronger buildings in case it came closer; and 2) better margaritas.
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224. hosweather
5:43 PM GMT on August 21, 2007
extreme236 at 5:42 PM GMT on August 21, 2007.
Posted By: bluehaze27 at 5:41 PM GMT on August 21, 2007.

hosweather, it is NOT way to early to write 92l off. It is cooked. It is done. Stick a fork in it.

92L is done right now, and even if it got in the gulf it wouldnt have much time to organize unless it practically stalled


Are you saying that tropical storms are unlikely to develop in the Gulf?????
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223. Weather456
5:17 PM GMT on August 21, 2007


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221. indigenous
5:40 PM GMT on August 21, 2007
"Allowed HTML." Does anyone know what this means? I keep getting "modified comments." I am on Firefox.
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220. SouthSound
5:40 PM GMT on August 21, 2007
Can someone explain why when Dean then a cat 3 passed over the NOAA buoy south of Puerto Rico it registered a max wind speed of about 40 something mph and why Kingston Jamaica was getting winds at 30 feet above sea level of about 15 to 20 mph whereas at 600 feet there was major damage to vegetation and property?

Is it possible that NOAA registers high level winds that don't always make it to the ground? I believe this happens with rain but don't know if it applies to wind also.
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219. mishnook
5:38 PM GMT on August 21, 2007
This may be a dumb question, but what are the chances of Dean re-forming in the Pacific basin. According to the forecast track cone, it could be over 2/3rd accross central Mexico and still be a tropical depression.

If it does, when was the last time this occurred. I would think it would be rare, and even rarer still for a tropical cyclone to survive two landfalls, and to emerge in a new ocean.
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218. bluehaze27
12:42 PM EST on August 21, 2007
Dean is the third strongest landfalling storm in the atlantic basin history according to MSNBC at 906 mb
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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