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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768. presslord
1:08 AM GMT on August 22, 2007
it's a blog, for Christs sake...it has its own personality...just like any other teacher, it has a few quirky traits...but it's a darned good teacher....
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767. raziorizzo
1:05 AM GMT on August 22, 2007
Central Florida got direct hits from Charlie,Frances and Jeanne
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766. Masquer08er
1:07 AM GMT on August 22, 2007
FlScienceTeacher, Google and bookmarks. ;-)
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765. bluehaze27
8:08 PM EST on August 21, 2007
taytay, what's bad about it? The point was that you don't need a cat 5 to do major damage. I think many forget that on this site when they hype up cat 5's. Dean may well cause more deaths if it does the same as erin and ride up north.
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764. bluehaze27
8:07 PM EST on August 21, 2007
Stoopid1, the atlantic storms come in cycles. two weeks of active, two weeks of dormancy. This is a generalization not set in stone of course, just an observation from past seasons.
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763. TayTay
1:06 AM GMT on August 22, 2007
It looks like the remnants of Erin caused more deaths than a cat 5 Dean

Bad comparison. Erin was over land for a much longer time and wasn't over a sparsely populated area. Erin had some devastating rain.
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762. FLScienceTeacher
1:03 AM GMT on August 22, 2007
there have been a number of people expressing there opinions on the lack of scienctific information coming off this blog... is it any different anywhere else?... if so where can people go to get the information without the drama, I know it can be entertaining but I just don;t have the time to read through the nonsense...
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761. SEFL
1:01 AM GMT on August 22, 2007
"Posted By: EyeWallReplacement at 12:05 AM GMT on August 22, 2007.
WPBHurricane05

My bust...

I meant Irene in 1999, not Iris.

I realized that as soon as I hit post.

So, that's Andrew, Irene, Frances, Jeanne, Wilma, and Katrina. 6 willy-willies in 15 years!

I get almost as much action as Cantore....."

I have lived in the same house in southeast Florida for 20 years. Jeanne and Frances passed just north of me and Wilma went right over the top of me. I was 50 miles north of Katrina and just had some wind and 80 miles north of Andrew and felt nothing. You must move around a lot to take DIRECT hits from all of those!
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760. Stoopid1
1:01 AM GMT on August 22, 2007
Tropics are soon to go back to hibernation mode

Doubtful. The conditions are still ripe for development. La Nina is in place. Weather patterns have been, for the most part, conducive for cyclogenesis. Just need some storms to get out in the Atlantic and GOM. We've already seen that the tropics are capable of being active, with Dean and Erin forming only a day aprat from each other. I still expect a decent amount of activity.
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759. juniormeteorologist
1:05 AM GMT on August 22, 2007
NaturalDisaster you got mail. Hey everyone I am off for a while. Going to work on my website. Anyway I think we could have are next tropical system once this wave off the coast of Africa emerges. See ya!
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758. Masquer08er
1:00 AM GMT on August 22, 2007
PBG, Humilty is a endangered species on this site. Obnoxious 'Casters are all too common.
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757. surfmom
1:02 AM GMT on August 22, 2007
caught some groundswell waves from Dean today on the Gulf coast SRQ - they were puny, but at least I got a few rides on the longboard. This swell came through the channel, perhaps more to come wednesday from the bay. The swell rolled in around 3:00 and lasted for about two hours. It was neat to watch flat - swell - then flat again
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756. bluehaze27
8:03 PM EST on August 21, 2007
It looks like the remnants of Erin caused more deaths than a cat 5 Dean (Cantori)
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755. snowboy
12:55 AM GMT on August 22, 2007
Dean is regathering strength, moisture and energy and starting to build..
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754. Stoopid1
12:57 AM GMT on August 22, 2007
Forget 92L!!!! The new African wave will be more of an issue and will develop into a much bigger problem! I'm no expert, but just sit back and watch:)

I wouldn't quite forget about 92L. I know it's been said before, but once the circulation gets in the GOM, it could develop. African wave looks decent, but it has to esacpe the 30kt wind shear it's in before it can do anything. Track should be similar to Dean, but a little more northerly with the possibility of entry onto the GOM. So... we COULD see 2 storms coming within the next week or so. Just keep watching.
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753. bluehaze27
7:59 PM EST on August 21, 2007
Hello all, the gfdl has dean crossing into the pacific and riding up the baja peninsula. Food for thought.Link
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750. Skyepony (Mod)
12:55 AM GMT on August 22, 2007
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749. SWFLGURU
12:42 AM GMT on August 22, 2007
Forget 92L!!!! The new African wave will be more of an issue and will develop into a much bigger problem! I'm no expert, but just sit back and watch:)
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748. katadman
12:46 AM GMT on August 22, 2007
It's an issue of compassion (or the gross lack of it, as in this case). I added him to my ignore list. I also make my living off of hurricanes and floods, but certainly don't wish them on anyone. Get a life.
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747. EyeWallReplacement
12:41 AM GMT on August 22, 2007
To MasterForecaster:

I think 92L has about a zero percent chance of developing before it hits FL. Based on the current westward speed of about 15-20 mph, and wind shear of about 20 kts, it would hit FL in about 24 hours...very little time to go from no organization to a Trop Storm. Plus it would seem the "mother ship" circulation is much further south - near Hispanola - moving toward Cuba.....interference from these land masses will also keep this from developing.

But watch what Wall Street does with oil prices on Thurs once this thing gets into the Gulf...that's when the real action could occur.
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746. PBG00
12:48 AM GMT on August 22, 2007
There is nothing wrong with people thinking it was going to go north..but it was against everything, and some of those people were down right obnoxious about it.
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745. bobcane
12:45 AM GMT on August 22, 2007
By the way, my hat is off to a job well done by the NHC. They were tops all the way through on Dean. I am sure those in peril appreciated their extra effort to stay on top of the storm even though it was not going to affect the CONUS. Damn good I have to say. They are under appreciated in this blog.
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744. fire635
12:46 AM GMT on August 22, 2007
Evening all... does anyone think 92L will bring more than a typical thunderstorm to west/central florida? It would be nice to get at least 2 or 3 inches of rain.
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743. fatcat475
12:42 AM GMT on August 22, 2007
i was wrong about Dean going north
wasn't the first time and want be the last
for me or a lot of other folks including the experts
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742. Masquer08er
12:42 AM GMT on August 22, 2007
Bob, anyone can learn what to do and what not to do; what they did right and what they did wrong.

This is regardless of the outcome.
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741. raziorizzo
12:40 AM GMT on August 22, 2007
Central Fl will probably get some much needed showers from 92L thats about it
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740. Stoopid1
12:39 AM GMT on August 22, 2007
If Vegas put odds on Hurricane Dean, EWR would have lost a lot... If you don't know, read his blog. Whats next Mr. Expert?
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739. juniormeteorologist
12:39 AM GMT on August 22, 2007
NaturalDisaster you got mail. Also guys I think 92L may develop over the next two days or so, but to me looks like the African wave that is about emerge has a better chance when it gets over water. Any thoughts are appreciated.
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738. MasterForecaster
12:37 AM GMT on August 22, 2007
good evening guys and gals, whats going on?

quick question? whats the most anyone sees 92l developing into after it enters a more favorable environment? any shot at a tropical storm or minimal cane by friday?

katrina went over the same spot that this thing is forecast to go over, and it seemed like katrina became a hurricane in like 2 days...from what i remember here in miami.
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737. bobcane
12:28 AM GMT on August 22, 2007
You know, I was onboard with the north path and there are those that are saying the north wishcasters were sooooooo wrong. It's okay. I was wrong and I still am and I'll take my lumps for it. But I will also go back through all of the data over the next year to find out where I was wrong. I'll learn from being wrong. Those that went along with the models and are now saying how right they were will just say they were right and never look back. I'll be smarter for it in the end and will learn something from this storm. Then I will be on the Dean's list. I been wrong before I'll be wrong again...man, a bad Bushism just popped into my head...I won't be fooled again.
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736. Skyepony (Mod)
12:13 AM GMT on August 22, 2007
Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 22nd day of the month at 00:34Z
Aircraft: Air Force Aircraft (Last digit of aircraft registration number is 306)
Storm Number: 04
Storm Name: Dean (in the North Atlantic basin)
Mission Number: 16
Observation Number: 05

Mandatory Data...

Observation Time: Wednesday, 00:33Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 21.6N 90.1W (View map)
Location: 53 miles (85 km) to the NW (324°) from Mérida, Yucatán, México.
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 7,320 meters
Flight Level Wind: From 120° at 52 knots (From the ESE at ~ 59.8 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: -14°C
Flight Level Dew Point: -23°C
Weather (within 30 nautical miles): Scattered clouds (trace to 4/8 cloud coverage)
400 mb Surface Altitude: 7,590 geopotential meters
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734. Masquer08er
12:33 AM GMT on August 22, 2007
WPB, It looks like you could superimpose it over the actual track. I had a hard copy this afternoon. WOW
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732. NeverPanic
12:33 AM GMT on August 22, 2007
juniormet,
Doesnt look to have any circulation comming off the coast EUMETSATor here
QUIKSCAT
But then again its an impressive push....never say never. Always have to keep an eye out this time of year.
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731. WPBHurricane05
8:29 PM EDT on August 21, 2007
Has anyone commentd that NOGAPS nailed the track on August 17 (maybe before)?

Once the NOGAPS has a handle on things, it becomes a very reliable model.
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730. WxKIDD
12:27 AM GMT on August 22, 2007
Posted By: Weather456 at 10:29 PM GMT on August 21, 2007.
Upper level lows are some of the features that play a role in the genesis of tropical cyclones and i saw that when an ull spawn a surface low/circulation after interacting with a tropical wave. That storm would grew to become Tropical Storm Erin a week ago.


no disrespect, but upper level lows play no role in tropical storm formation, you want an upper level HIGH above a sfc tropical low to get cyclogenesis, if anything ULLs inhibit tropical formation.
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729. Masquer08er
12:27 AM GMT on August 22, 2007
Has anyone commentd that NOGAPS nailed the track on August 17 (maybe before)?
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728. StormJunkie
12:27 AM GMT on August 22, 2007
ovr, much of the time, NOT ALL OF IT, is folks in here trying to learn how to discuss that info.

Ok, I do Med-Rare. See y'all later before they are well!
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727. ovrrxn
12:21 AM GMT on August 22, 2007
Storm -- I do appreciate the response and the link! So much time is wasted poring through the much of the junk posted, so what you provided will be helpful for me to make my own interpretations and decisions.
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726. WxKIDD
12:15 AM GMT on August 22, 2007
Posted By: BahaHurican at 9:18 PM GMT on August 21, 2007.
WxKIDD,

I remember hearing the mayor on TV pleading with people to evacuate between 12 and 18 hours before that storm hit NOLA. The real tragedy of NOLA and Katrina is that I believe almost no one expected the damage to be so severe. It had been quite a while since Betsy had flooded the city so thoroughly. And it seems to me that NOLA residents have a cocky optimism and faith in the levee system that seems almost temeritous given that system's history of breaches over the years. I never got the impression that emergency management leaders were emotionally prepared for the worst.
Meanwhile the intrepid nature and steady heads of many private citizens in that crisis did much to mitigate the loss of lives.


Look I dont want to really get into this all that much, but you simply cannot evacuate any major metropolitan area in 12 to 18 hours, it is simply impossible. The logistics alone are a nightmare....busses, cars, roadways, nevermind hospitals...where to take the patients, what to do with those that cant be moved...

the reality is, hurricane preparation must begin long before the storm on a multitude of levels, especially for a place like NOLA.

1. The government must ensure the levees are properly built and maintained (they werent, remember, NOLA was only hit by Cat 2 winds)

2. The emergency response must begin to be gotten into order the moment the risk to a city becomes even remotely possible...this means coordinating on a local, state, and federal level...knowing the role of each part of government and having FEMA preposition resources just outside the expected impact zone (they werent).

3. The citizens have to act responsibly...its hard because of the periodicity between major events and the numerous close calls as well as the beliefs that people have "survived" storms when in fact the core of a storm may have passed 100mi to your south. Some people cannot leave (particularly the urban poor with no transportation or MONEY or PLACE to go, in case of emergency.

4. The emergency rescue and rehabilitation must begin immediately upon the winds dying down (again, didnt really happen with the notable exception of the La Wildlife and fisheries and the Coast Guard)

I could go on, there is so much more, but i dont feel like writing a novel or rehashing the entire event. The thing i will say is this is in no way political, this is just what happened, everyone was caught with their pants down, democrat, republican, black, white, purple, everyone. And that is not to take away from the many heroes that did do great things before, during, and after the storm, but on a macroscopic level, it was a huge failure.
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725. StormJunkie
12:25 AM GMT on August 22, 2007
EWR, I see you can not muster a response to any of my points :~)
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723. StormJunkie
12:23 AM GMT on August 22, 2007
I am with you on that press.
Been an odd night in here...lol

Oh well, I got some steaks on the grill and I am off to enjoy.

See y'all later
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720. juniormeteorologist
12:22 AM GMT on August 22, 2007
NaturalDisaster you got mail. Also the wave the is coming off the coast of Africa looks pretty impressive. Any thoughts on it.
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718. NeverPanic
12:19 AM GMT on August 22, 2007
WOOOW.
Havent been on this blog for a day or so and from the sound of things you would think Dean is drawing his last breath.
He's still out there and going to cause more trouble to those in his path.
Not trying to be a a$%h*le but instead of arguing about who is better or done more or seen more then the other......FOCUS on whats in front of you or others. Dean is still a threat to some and I'm sure some are here to do what you do best. Warn those in the path.
BOUY42055


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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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