First Category 5 storm of the year is Choi-Wan

By: Dr. Jeff Masters , 1:38 PM GMT on September 16, 2009

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The remains of Hurricane Fred continue to generate sporadic bursts of heavy thunderstorm activity over the middle Atlantic Ocean. These thunderstorms were generating winds up to 30 mph, according to this morning's QuikSCAT pass. However, QuikSCAT also showed that the remains no longer have a surface circulation. Water vapor satellite loops show that ex-Fred has moved beneath an upper-level low pressure system. This low features dry air on all sides, and this dry air will interfere with any redevelopment of Fred. While wind shear is now moderate, 10 - 15 knots, and is expected to remain in the moderate range for the next five days, the presence of so much dry air will require at least three days for the remains of Fred to overcome and regenerate a surface circulation. Only the HWRF model redevelops Fred, predicting it will develop on Sunday as it approaches the Bahama Islands. NHC is giving ex-Fred a low (less than 30% chance) of developing into a tropical depression by Friday. Fred's remains will be near the Bahamas on Sunday, and near Florida on Monday night. It is possible that a strong trough of low pressure expected to develop over the eastern U.S. early next week will turn Fred's remains northwards into South Carolina/North Carolina on Monday/Tuesday.

This morning's QuikSCAT pass shows a surface circulation near 13N 32, with a small region of heavy thunderstorms to the north. This region is about 450 miles west of the Cape Verdes Islands, and is headed west at about 10 mph. Satellite imagery shows a decrease in the amount of heavy thunderstorm activity this morning, and high wind shear of 20 knots is interfering with development. A band of high wind shear lies just to the north of the disturbance, and will continue to interfere with the system's development over the next three days. NHC is giving the system a low (less than 30% chance) of developing into a tropical depression by Friday.

The GFS model is predicting development of a new tropical wave coming off the coast of Africa early next week.


Figure 1. The remains of Hurricane Fred (left) keep on chugging across the Atlantic. A tropical wave is 450 miles west of the Cape Verdes Islands (right). The thunderstorms of the Inter-Tropical Convergence Zone (ITCZ) are far to the south, off the coast of Africa.

Super Typhoon Choi-Wan hits Category 5 strength
This year's first Category 5 tropical cyclone is Super Typhoon Choi-Wan, which intensified into a Category 5 storm with 160 mph sustained winds yesterday afternoon. Choi-Wan is over the open ocean south of Japan, and is not expected to impact any land areas. It is unusual to have to the globe's first Category 5 storm form this late in the year. Indeed, global tropical cyclone activity as measured by the ACE index, which measures destructive potential, has been near historic lows over the past two years. Only one Category 5 storm was recorded in 2008--Super Typhoon Jangmi, which attained winds of 165 mph at 06 GMT on September 27, as it approached the north coast of Taiwan. The last time so few Category 5 storms were recorded globally was in 1974, when there were none.

We got a rare treat yesterday when the Cloudsat satellite caught a perfect cross section through Choi-Wan when it was a Category 4 super-typhoon with 150 mph winds (Figure 2). The CloudSat satellite, launched in 2006, carries the first satellite-based millimeter wavelength cloud radar. It is the world's most sensitive cloud-profiling radar, more than 1000 times more sensitive than current weather radars. It collects data about the vertical structure of clouds, including the quantities of liquid water and ice, and how clouds affect the amount of sunlight and terrestrial radiation that passes through the atmosphere. The satellite has a narrow field of view, so can image only a small portion of the planet each day. About once per year, CloudSat happens to slice through the eye of an Atlantic hurricane. This happened last month, when Cloudsat caught a remarkable view of Hurricane Bill.


Figure 2. Top: conventional visible satellite image of Super Typhoon Choi-Wan at 3:57 UTC Tuesday, 9/15/09 from Japan's MTSAT. Bottom: cross section through Choi-Wan's eye taken at the same time, from the CloudSat cloud radar instrument. The CloudSat pass occurs along the red line in the top image. The CloudSat pass runs from south (left side of CloudSat image) to north (right side of CloudSat image). At the time of the image, Choi-Wan was strengthening into a Category 4 Super Typhoon (150 mph winds, 928 mb pressure), and reached Category 5 strength fourteen hours after this image was taken. In the CloudSat image, one can see 6+ isolated towers, marking the positions of spiral bands on the south side of the center. The eye is remarkably well-defined, with symmetric "hot towers" extending up to 55,000 feet, sloping outward with height. The thin solid grey line at 5 km marks the 0°C temperature line. Ice particles falling inside the hurricane melt at an altitude just below the 0°C line, creating a "bright band" of orange echoes throughout most of the hurricane. This is one a few inner eye images CloudSat has captured of an Category 4/5 tropical cyclone. Image credit: NASA/Colorado State University/Navy Research Lab, Monterey.

Twenty years ago today
On September 16, 1989, Hurricane Hugo weakened slightly as it underwent an eyewall replacement cycle. The tight inner eyewall that we had flown through the previous day had contracted to the point where it became unstable and collapsed. A new eyewall formed out of an outer spiral band, and Hugo's highest winds dropped to 140 mph--Category 4 strength. As this was occurring, the storm began a more northwesterly path and slowed down, in response to a region of low pressure north of Puerto Rico. By midnight, Hugo was only an hour away from its first encounter with land--the Lesser Antilles island of Guadeloupe.

Back on Barbados, our one undamaged P-3 Orion Hurricane Hunter aircraft flew a mission into Hugo, while the crew of the damaged aircraft remained on the ground. Our plane was grounded until a team of experts from the mainland could fly out and perform a detailed x-ray analysis of the wings to determine if the high g-forces we endured had caused structural damage. This might take a week, so the plan was to fly us back to Miami on a commercial jet. However, Hugo had forced the cancellation of virtually every commercial flight in the eastern Caribbean that day, so we were stuck on the island. Most of us spent a frustrated day touring the island on rented mopeds, getting a look at Hugo from the ground. We got thoroughly drenched by one of Hugo's outermost spiral bands, but the hurricane was too far away to bring any winds more than 20 mph to the island.

That night, our already jangled nerves got a new jolt--a tropical depression had formed due east of Barbados, and was headed right for us. In two days time, it seemed likely that Tropical Storm Iris would be paying us a visit.


Figure 3. AVHRR visible satellite image of Hurricane Hugo taken on September 16, 1989. Image credit: Google Earth rendition of the NOAA HURSAT data base.

Jeff Masters

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Downtown Fort Worth, Texas
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Quoting caneluver:
No Floyd nor Ivan this year.. Thanks to the shear.
You cannot say that because the tropical wave in the atlantic is holding its own, imagine w hat a strong hurricanr can do. Shear is not really a problem
Quoting hydrus:
2004 Hurricane Season, makes my stomach turn every time.


Yeah, but it sure was a fun one for tracking purposes.
2004 Hurricane Season, makes my stomach turn every time.
Member Since: September 27, 2007 Posts: 1 Comments: 21741
Quoting weathermancer:


I find many SST sites on web are very diff from each other.
This one I check out allot. Dunno which is most accurate with their colours. lol.
http://magicseaweed.com/msw-surf-charts2.php?chart=20&res=750&type=sst&starttime=125305 9200


As good a site as any it would appear
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Choi-Wan sized Topical Update!

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Quoting Travler1414:
5 years ago today huricane Ivan made land fall near Pensacola, Fl.


I remember being up in Birmingham riding the storm out and I will never forget the sound from the clouds that day. Like a really pissed off animal growling as it came over Red Mountain (just a big hill but just the same). Will never forget the aftermath of that storm. Trees down in Birmingham and it looked like a bomb had gone off in areas of Pensacola. Blue roofs for months, in fact there are still a few here in PC. Life changing event, Ivan...
Member Since: Posts: Comments:
Quoting weathermancer:


The Beatles - "You're Going To Lose That Swirl"
McCartney/Jackson--The swirl is mine.
Quoting Floodman:


A little trip down memory lane: The Swirl from Ipanenma

1964. Gilberto..lol , Cleo, Dora, Isbell, Silverswirl???
Member Since: September 27, 2007 Posts: 1 Comments: 21741
well guys, its been real, and its been fun...
aww heck, its been real fun, but I have to go eat, so I'll catch you guys later!
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Another lead blocker cold front on the way by 9/23. If it(hurricane season 09)all boils down to gravy, there wouldn't be enough to cover a chicken fried steak**** This season hasn't existed from day 1.
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No Floyd nor Ivan this year.. Thanks to the shear.
Quoting hydrus:
Motley Crue--Swirls,Swirls,Swirls...Neil Young-Cinnamon Swirl..The list is long..


A little trip down memory lane: The Swirl from Ipanenma

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Quoting Floodman:
Weathermancer, it doesn't take very long...think about the '04 season when Frances and Jeanne made hits on nearly the same stretch of beach about 11 days apart...and Jeanne was stronger than Frances


I find many SST sites on web are very diff from each other.
This one I check out allot. Dunno which is most accurate with their colours. lol.
http://magicseaweed.com/msw-surf-charts2.php?chart=20&res=750&type=sst&starttime=1253059200
Member Since: Posts: Comments:
Quoting Travler1414:
5 years ago today huricane Ivan made land fall near Pensacola, Fl.
AND Floyd 10 years ago today
Quoting Floodman:


Foolish man, I was the Inquisition


You got me on that one. :-)
Member Since: March 10, 2006 Posts: 0 Comments: 10570
5 years ago today huricane Ivan made land fall near Pensacola, Fl.
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Quoting Dakster:


Ahhh. That explains alot. Since we are on the topic, how did you escape the spanish inquisition?


Foolish man, I was the Inquisition
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Quoting Floodman:


Oh, pretty much the ususal: obsidian knife to chest, remove still beating heart...the weather gods like their sacrifices whole though


Ahhh. That explains alot. Since we are on the topic, how did you escape the spanish inquisition?
Member Since: March 10, 2006 Posts: 0 Comments: 10570
Quoting hydrus:
McCartney/Jackson--The swirl is mine.


ha, good one!

This Swirl is Our Swirl
(ancient hippy kumbaya trance song - lol)

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Quoting weathermanwannabe:


This one shows my age; "Standing on the Corner, Watchin All the Swirls Go By....."
Motley Crue--Swirls,Swirls,Swirls...Neil Young-Cinnamon Swirl..The list is long..
Member Since: September 27, 2007 Posts: 1 Comments: 21741
Quoting Hurricane009:
your so mean..lol


Everyone has a mean streak, but unlike others, I embrace my meanness...use it as a strength
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Quoting Floodman:


Whata truly mean and vile thing to say...I like it LOL
your so mean..lol
Weathermancer, it doesn't take very long...think about the '04 season when Frances and Jeanne made hits on nearly the same stretch of beach about 11 days apart...and Jeanne was stronger than Frances
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Quoting jeffs713:

Lets see.. they are both cat 5 hurricanes. Of course they look very similar. In order for a storm to get that strong, it has to have optimal conditions and structure. And since very strong hurricanes have the same structure... they will look the same.

You can compare Choi-Wan with just about any other mature, Cat 5 hurricane, and they will look strikingly similar.


Choi-wan's the size of the southern USA. I can only compare Ike and Isabel in size to that beast.
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Quoting weathermancer:


The Beatles - "You're Going To Lose That Swirl"


This one shows my age; "Standing on the Corner, Watchin All the Swirls Go By....."
Member Since: Posts: Comments:
Quoting weathermancer:


The Beatles - "You're Going To Lose That Swirl"
McCartney/Jackson--The swirl is mine.
Member Since: September 27, 2007 Posts: 1 Comments: 21741
Quoting ElConando:


Tim Tebow?

*Wiping away tears as the office-mates look oddly at the laughing atmoaggie*
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Quoting Halyn:



Where is WS when you actually have a use for him ??


Whata truly mean and vile thing to say...I like it LOL
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Quoting hydrus:
Duran-Duran---Swirls on Film..


The Beatles - "You're Going To Lose That Swirl"
Member Since: Posts: Comments:
Quoting Dakster:
Hey Floodman - How did you do sacrifices back in the Mayan empire days?


Oh, pretty much the ususal: obsidian knife to chest, remove still beating heart...the weather gods like their sacrifices whole though
Member Since: Posts: Comments:
"Twenty years ago today
On September 16, 1989, Hurricane Hugo weakened slightly as it underwent an eyewall replacement cycle. The tight inner eyewall that we had flown through the previous day had contracted to the point where it became unstable and collapsed. A new eyewall formed out of an outer spiral band, and Hugo's highest winds dropped to 140 mph--Category 4 strength. As this was occurring, the storm began a more northwesterly path and slowed down, in response to a region of low pressure north of Puerto Rico. By midnight, Hugo was only an hour away from its first encounter with land--the Lesser Antilles island of Guadeloupe.



The damage from HUGO is STILL visible on Nevis today. The entire island of Monteserrat was in the eye.
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Quoting JupiterFL:


I bought an F-150 from Grand Prairie Ford a few years back. Nice owners.


small world
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Quoting Tejano72:
Tornado: Originally from WV, that's while I don't smile with my teeth showing. Don't have many. I whistle when I sneeze, but hey, my family can still make our own ethanol. Here in FT Worth, TX now. Just billies without hills here. (picking teeth with straw..)
Where do you live exactly??? like what area?? I used to live in Saginaw,.
Quoting tornadodude:


haha oh ok, well I live in Indiana now, but my grandparents live in Grand Prairie


I bought an F-150 from Grand Prairie Ford a few years back. Nice owners.
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Tornado vortex signature passing over Socorro, New Mexico.
Member Since: August 9, 2009 Posts: 10 Comments: 5074
Quoting Tejano72:
Tornado: Originally from WV, that's while I don't smile with my teeth showing. Don't have many. I whistle when I sneeze, but hey, my family can still make our own ethanol. Here in FT Worth, TX now. Just billies without hills here. (picking teeth with straw..)


haha oh ok, well I live in Indiana now, but my grandparents live in Grand Prairie
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Quoting aquak9:
You're showing your age, hydrus...
how? I,m just a puppayyyy!
Member Since: September 27, 2007 Posts: 1 Comments: 21741
Tornado: Originally from WV, that's while I don't smile with my teeth showing. Don't have many. I whistle when I sneeze, but hey, my family can still make our own ethanol. Here in FT Worth, TX now. Just billies without hills here. (picking teeth with straw..)
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Quoting weathermancer:
wow!
This CloudSat data is reeeeeaalllll interesting.
Nice to see a vertical slice of the planet's most powerful storm.
Yes, the slicing of massive hurricanes and typhoons is very cool..
Member Since: September 27, 2007 Posts: 1 Comments: 21741
You're showing your age, hydrus...
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Quoting Halyn:



Where is WS when you actually have a use for him ??


ROFL
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I'm in the VI's and no there are none..

Last quickscat shows south winds just NW of Trini..so are there any Northerly winds in the missing section?
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wow!
This CloudSat data is reeeeeaalllll interesting.
Nice to see a vertical slice of the planet's most powerful storm.
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Quoting Floodman:


Wuith very few exceptions, hydrus, the same holds true for me...and hell, they could be lying too
Quoting JupiterFL:


"Swirls Gone Wild"
Duran-Duran---Swirls on Film..
Member Since: September 27, 2007 Posts: 1 Comments: 21741
ok im off check back in later
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613. DDR
Good evening
2 inches of rain,flash floods,in Trinidad
Good old unreliable itcz action this afternoon.
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Quoting Tejano72:
As we begin our 11th consecutive sunless day and our 10th inch of precipitation, I'd like to posit: "If this was over the GOM, what would it be?" - Signed, Damp in DFW

Nice "eye" over Texarkana...

Link

Wow! That's very cool.
Member Since: August 9, 2009 Posts: 10 Comments: 5074
Quoting Ameister12:
The eye of Choi-Wan looks very similar to Katrina's eye.







Lets see.. they are both cat 5 hurricanes. Of course they look very similar. In order for a storm to get that strong, it has to have optimal conditions and structure. And since very strong hurricanes have the same structure... they will look the same.

You can compare Choi-Wan with just about any other mature, Cat 5 hurricane, and they will look strikingly similar.
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Quoting JLPR:


There is no closed circulation anymore

-
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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.