Hurricane Dean--9th strongest hurricane on record
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
A roof dumped atop another house
Reader Comments
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Thanks 456, you are one of the few who I really trust with their posts.
The monsoon trough is a convergence zone between the northeast trade winds and the southwesterlies. During summer months this trough moves so far north that the southeast trade winds cross the equator and turn to the southwest hence southwesterlies.
Now the ITCZ is very simple...a convergence zone between the southeast trade winds and the northeast trades.
Look at this Quikscat pass, the monsson trough is easily picked out. Look for the northeasterlies or easterlies then the southwesterlies and where they converge is the monsoon trough.
Thanks for your posts.
Link
Weather456 - now I'm a bit confused - not an unfamiliar feeling. :-) my met courses were so long ago that I'm finding I need to relearn some concepts. Do you have a link to more info ? I can always google, but you might have a good link.
Thanks for your posts.
sure
http://en.wikipedia.org/wiki/Monsoon_trough
WHY ARE THE PORN IMAGES STILL HERE?!?!?!?!?
Unbelievable!!Thank God the kids went back to school today..My oldest loves weather and she usually peeks when I am lookinh at the posts! I hope they banned that idiots ip...
Get a survey and skip the possible inaccuracies of some internet map. If you insist on relying on maps, get a topographic map of your area. I had a survey done two years ago for $300.
Topo maps are produced by a gov. agency - mine are old and were produced by US Geological Survey. Perhaps someone can give an update. There are also tidal surge maps by the army corp (I believe).
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