Hurricane Dean--9th strongest hurricane on record

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

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 ( 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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317. intunewindchime
6:44 PM GMT on August 21, 2007
I am in Florida and was there a week before Katrina showing some children the city. I have not been back since. I just get upset when it seems people think we are over- reacting to a storm. Once you are in one, you WILL NOT take chances if another one is any where near the GOM. You can't. Too many times a storm has taken unexpected turns etc. As for some of the people of NOLA, well many had never witnessed a BIG storm and so could not even fathom it happening. Just like the guy in MX the other night asking us to tell his people to leave asap, because he did not think they would listen to just him. Also the people who were in Camiille in MS, they thought they had seen the WORST that could happen.... houses Camiile left parts of and were rebuilt, Katrina took away with a pinky finger....No one could imagine it......We have to get people to realize the unfathomable can happen.
The hurricanes are going to be bigger and stronger than we have seen within the life experiences of those people still living on the planet.
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316. extreme236
6:43 PM GMT on August 21, 2007
Posted By: Tazmanian at 6:41 PM GMT on August 21, 2007.

extreme236 where is that new wave going?

Let me check
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314. Tazmanian
6:42 PM GMT on August 21, 2007
AEApresident i been watching that wave has well
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313. KennerLA70065
6:31 PM GMT on August 21, 2007
As to Ms. Blanco, everyone who's job doesn't require them to listen to her is already ignoring her. She's announced that she is not running for re-election (which will be in a few months).

However, in her defense, the hurricane protection system in South Louisiana is still not fully recovered to what it was SUPPOSED to be pre-Katrina and some of it still hasn't recovered to what it ACTUALLY was for Katrina. It was fully prudent to take the early step that she did at that moment given the northward shifting of a few of the computer models, and the path that the storm would have taken to get to South Louisiana. Emergency crews need all the advanced prep that they can manage for this sort of thing.
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312. surfmom
6:37 PM GMT on August 21, 2007
Thanks Moonlightcowboy, I too enjoy Taz - He gets the best maps - he reminds me of the young buck wild horses I often come to know....alot of heart and potential, in time a really good horse --compliment & encourage the good, just ignore the ick -- remember our commonality here - it is our fascination weather
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310. cantoriesnumber1fan
6:32 PM GMT on August 21, 2007
Just keeping it real Taz, I have a very difficult time figuring out what the heck your talking about in any of your posts. Not trying to stir you up but maybe you should slow down a little so we can fully understand what your saying.
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308. Barkeep1967
6:40 PM GMT on August 21, 2007
Obviously most posters werent here during 2004-2005 season, especiially days, then hours before Katrina and Rita. This is so mild compared to then. Everyone stay calm and just respect other posters

Oh I was here. Remeber the tunnels idea ? Now that was funny.
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307. Tazmanian
6:40 PM GMT on August 21, 2007
extreme236 where is that new wave going?
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306. Thaale
6:20 PM GMT on August 21, 2007
The politics probably belong elsewhere.

But sometimes people are unfair to governors, presidents, and emergency managers. Nothing can be done in an instant. For instance, when a governor calls up the National Guard, those people have 72 hours to report. You can see why they have regular jobs and lives; theyre not robots kept on standby in a warehouse ready to be switched on.

Local officials bear the earliest and most responsibility, then state officials, then national ones. Nagin was more culpable than Blanco, and Blanco more culpable than Bush or Brown. Obviously its going to take several days for help to arrive from DC or out of state. Local officials are the first responders, just like 911 comes to your house before a special FBI investigative unit arrives from DC (though hopefully, neither ever has to!)

In Andrew, I dont remember that local officials did anything. Who was it, Steve Clark? Certainly nothing significant was accomplished by Dade before or after Andrew. Now what about Tallahassee? Chiles was a complete non-factor. It was left to the feds to finally step in, and we saw some help finally starting about Friday which is just what you would expect for a storm that hit on Monday.

The Andrew narrative that has taken hold is that is was Kate Hale who heroically got the feds to stop slumbering and start helping. But thats nonsense. Federal help was always going to come 3-5 days after a hurricane. Hales disgraceful sobfest neither sped that along nor hindered it. Thats why we have local emergency managers. Theyre supposed to BE the bleedin cavalry in those critical early days. Theyre not supposed to do nothing for three days, then go on television and CRY for some male to come and rescue them.

That was Hales way of dealing. She singlehandedly set women in crisis management back 15 years.
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305. moonlightcowboy
6:30 PM GMT on August 21, 2007
Hey now, in defense of Taz, he's one of the board's constant, ever-present blob watchers with a genuine concern for threatening danger.

And, he's very knowledgeable, too. Get to know him a little bit. Sure, sometimes he get's a bit excited and sometimes a bit cranky; but, we all do. The "Taz speake" as many of us affectionately call it, is unique and colorful. Taz is "special" to the blog, so please, have a little understanding! TIA

...Taz, buddy, take things a little slower, man! You're alright, thanks for watching the tropics!
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304. PascagoulaGal
6:30 PM GMT on August 21, 2007
Obviously most posters werent here during 2004-2005 season, especiially days, then hours before Katrina and Rita. This is so mild compared to then. Everyone stay calm and just respect other posters
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303. extreme236
6:33 PM GMT on August 21, 2007
that new wave is in a low shear enviroment, it just needs to get out of the itcz
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301. Tazmanian
6:32 PM GMT on August 21, 2007
extreme236 ok how is wind shear for the wave dos it have a ch?
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300. gthsii
6:30 PM GMT on August 21, 2007
intunewindchime: good points, well taken. i just worry about the future and that people may not heed her warnings. thats all. not trying to pick a fight or call her a fool. i just know human nature, and human nature will show that people will be complacent if given even one little iota of reason to be.
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299. HurricaneGeek
2:32 PM EDT on August 21, 2007
When will that ENTIRE african wave be off the coast?
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298. weathers4me
6:31 PM GMT on August 21, 2007
So the question remains. Do we in FL have something that could bear watching in the next few days?
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297. extreme236
6:29 PM GMT on August 21, 2007
Taz, i know that wasnt part of 92L, but the nhc post that talked about a wave was 92L, now there are new waves though as i see now
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296. extreme236
6:26 PM GMT on August 21, 2007
Taz, the nhc post you posted this morning was 92L, with the low pressure. but i see they added new waves. although the convection still seems mostly associated with the itcz
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295. will40
6:26 PM GMT on August 21, 2007
Yes Taz i know but we just need to calm down a lil. You contribute a lot to WU.
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294. intunewindchime
6:28 PM GMT on August 21, 2007
The Louisianna Governor declared and emergency before hand for good reasons, not just a knee jerk reaction to an early forecast model. LA is already a crippled state in the south, add another disaster, and it would tragic for NOLA. There are actually people trying to get their act together there and rebuild... granted there is that criminal element.... and that along with the lawlessness and less than all the cops they need, well it would be anarchy. Not to mention being prepared was a smart thing for her to do. Not everyone in NOLA is a criminal, there are good people there also. I think she did the right thing when the models pointed her direction. At least it put her state on notice to get their act together in advance this time so they did not have another Katrina fiasco.
That was ridiculous to see buses underwater...At least she TRIED to get her state prepared to protect her people....
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291. Tazmanian
6:26 PM GMT on August 21, 2007
: moonlightcowboy that was the area i was pointing out and they said it was all part of 92L

well you no what it was not
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289. GoofOff
2:16 PM EDT on August 21, 2007
Storms sometimes have a nasty habit of doing whatever they feel like. In
2004, Jeanne was a fish storm heading north out in the Atlantic, did a 270 degree clockwise turn and slammed into the Treasure Coast in Florida. We still did get sufficient warning to get prepared for it but since it hit the same place as Frances 2 weeks earlier, it took a heavy toll on the area that was already damaged.
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280. gthsii
6:13 PM GMT on August 21, 2007
"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?"

in my view she was OVER-compensating. We have the NHC and their warning schedule for this very reason. She should have followed the NHC and not jumped the gun. I am sure her intentions were good, but her actions could, and I stress could, lead to complacency again when real trouble heads their way.
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276. hylas49er
6:15 PM GMT on August 21, 2007
Good afternoon. Thank you for all of the kind input and emails during our brush with Dean. We came through just fine and today is a beautiful day here in St. Martin. Have a look at the webcam by clicking here. Quite a difference now!

Due to the great emails and comments I got posting the webcam here I have decided to upgrade cameras to one that web users can pan, tilt, and zoom. This will take a few weeks but keep checking back.
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275. ebzz
2:13 PM EDT on August 21, 2007
Posted By: presslord at 2:12 PM EDT on August 21, 2007.
OK...this is a learning moment for me...and a teaching moment for those of you smarter than me...whcih includes pretty much everybody on the

aside from the fact that we all know it's gonna obliterate Florida...What,if anything, can be said with certainty about the wave coming off w/Africa now?

The chances of anything developing where dean started is slim because the waters still might be stirred up. Give it a few days and I'm sure a wave that comes off the coast will become an invest. The waters are VERY warm right now.
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273. bluehaze27
1:08 PM EST on August 21, 2007
boiredfish, I hope you aren't seriously going to make excuses for this administration. Bush's response was abyssmal in everyway. That is not to excuse the mayor or governor, but it is too say that given the knowledge that Bush had in ADVANCE as to what might happen in N'orleans, he could have actually shown some leadership and pressed Blanco to get off her ass. He didn't. His father let South Florida down as well. This isn't a republican or democrat issue. It is a HUMAN issue.
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272. snowboy
6:05 PM GMT on August 21, 2007
stronger winds aloft do not always mix down to the surface, and can be affected by surface elevation and roughness and the nature of the system. NHC applies a "rule of thumb" correction, which may or may not be entirely applicable for the storm in question..
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271. presslord
2:10 PM EDT on August 21, 2007
OK...this is a learning moment for me...and a teaching moment for those of you smarter than me...whcih includes pretty much everybody on the

aside from the fact that we all know it's gonna obliterate Florida...What,if anything, can be said with certainty about the wave coming off w/Africa now?
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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
Member Since: August 18, 2007 Posts: 5 Comments: 1807

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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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