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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Does Fred keep its name if it redevelops since it is a surface trough now.
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859. HadesGodWyvern (Mod)
Ameister12: 12:40 AM GMT on September 17, 2009
Choi-Wan is weakening.
Pressure has gone up to 918mb according to Navy.


Pressure was always 918 MB on the NRL as far as I know

15W CHOI-WAN 090916 1800 19.6N 141.4E WPAC 140 918
15W CHOI-WAN 090916 1800 19.6N 141.4E WPAC 140 918
15W CHOI-WAN 090916 1200 19.2N 141.9E WPAC 140 918
15W CHOI-WAN 090916 1200 19.2N 141.9E WPAC 140 918
15W CHOI-WAN 090916 1200 19.2N 141.9E WPAC 140 918
15W CHOI-WAN 090916 0600 19.0N 142.6E WPAC 140 918
15W CHOI-WAN 090916 0600 19.0N 142.6E WPAC 140 918
15W CHOI-WAN 090916 0600 19.0N 142.6E WPAC 140 918
15W CHOI-WAN 090916 0000 18.6N 143.4E WPAC 140 918
15W CHOI-WAN 090916 0000 18.6N 143.4E WPAC 140 918
15W CHOI-WAN 090916 0000 18.6N 143.4E WPAC 140 918
15W CHOI-WAN 090915 1800 18.2N 144.2E WPAC 140 918
15W CHOI-WAN 090915 1800 18.2N 144.2E WPAC 140 918
15W CHOI-WAN 090915 1800 18.2N 144.2E WPAC 140 918
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858. JLPR
Quoting caneluver:
Guys/Gals it looks as if Fred wants to outrun the ULL and be by himself. He is putting on some clothes again. What an amazing tropical system he has been. I don't think I have ever seen a system endure so much.


Fred doesn't exist anymore
its LLC is gone
waiting for the new quickscat to see if anything has changed =]
Member Since: September 4, 2007 Posts: 36 Comments: 5223
sure hope The Gecko doesn't see post 852
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Choi-Wan is weakening.
Pressure has gone up to 918mb according to Navy.
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Quoting Chicklit:
Check out the shear map.

ShearMap


The ULL interacting with Fred is not just weakening, but looks like Fred is moving away from it, need more time and info to back that up though.
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853. JLPR
Quoting Weather456:


Geographic size and location

Cuba large and tropical
Bermuda small and subtropical


Its hard to get a hurricane go directly over Bermuda


yeah
But even with its size Bermuda sure gets a lot of indirect hits :|
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Fred and Gone.
Link
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Quoting JLPR:


yep they are just too wide xD


Geographic size and location

Cuba large and tropical
Bermuda small and subtropical


Its hard to get a hurricane go directly over Bermuda
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Reminds me of a Jackson Pollock painting.



"Pollock's daring abstract work legitimized the convergence and mastery of chance, intuition, and control. Layered skeins of paint generate beauty and order out of seemingly random gestures."
Courtesy National Gallery of Art Washington.
Link
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Member Since: July 3, 2005 Posts: 424 Comments: 128282
845. JLPR
Quoting BahaHurican:
Cuba gets 'em from every direction.... N, S, E, W, and all of the lesser compass points.... lol... poor Cuba also seems to be in the recurve zone...


yep they are just too wide xD
Member Since: September 4, 2007 Posts: 36 Comments: 5223
...gecko...
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iceman... The Lightning man...
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Quoting hydrus:
Well that makes sense, it is also in the hurricane belt just like P.R. but has much more land area. And situated like it is...Sitting duck.
Cuba gets 'em from every direction.... N, S, E, W, and all of the lesser compass points.... lol... poor Cuba also seems to be in the recurve zone...
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839. HadesGodWyvern (Mod)
The original map came from Jakarta Tropical Cyclone Warning Center
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Fred Gwynne - HA! LOL..

That would work for FredEx...
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Check out the shear map.

ShearMap
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Quoting HadesGodWyvern:


wow I am terrible at making a graphic.


Where did the base map come from?

I actually use this one

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835. HadesGodWyvern (Mod)
LOL Tropical Cyclone "Marty" is off the graphic image in that TC formation potential map
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Quoting Weather456:
Regarding the SSD flash loops, I dont really like them. The default speed of the Java loop was better, every time I open a loop I have to adjust the speed cuz the flash loops are to slow. They load faster but man I have been suing Java loops for years now, Its gonna sad to see it go.

All Java loops on the SSD site will be replaced with flash loops on 01/01/10.

If anyone knows any good java loops that self update let me know.

Thanks
Agreed. It was kinda weird to have to DOWNLOAD Java onto my Acer in order to use the NASA page....
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Dry air on Freddy's East and southern side is rapidly disappearing tonight, as he continues separating from the ULL to his southwest. There's still a good sized mid level circulation left, and while the chance is small, I'm amazed he has held on this long. Is this Destiny in the making?


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Quoting Weather456:
hydrus,

I think Florida has more strikes than us.

Georges was the reason. The other reason is that my country is only 2nd to Cuba for the Caribbean with the most hurricane strikes.
Well that makes sense, it is also in the hurricane belt just like P.R. but has much more land area. And situated like it is...Sitting duck.
Member Since: September 27, 2007 Posts: 1 Comments: 21199
i want to say a bad word about Choi-Wan.
hope it weakens before landfall. cripes.
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CATLoop
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827. HadesGodWyvern (Mod)


wow I am terrible at making a graphic.
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Quoting Chicklit:
Fredex is well...still not dead.
could be a zombie
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825. JLPR
Quoting Weather456:
hydrus,

I think Florida has more strikes than us.

Georges was the reason. The other reason is that my country is only 2nd to Cuba for the Caribbean with the most hurricane strikes.


yes Georges was my worst so far
it caused $1,907,026,374 in damage to PR =O
so yep bad one xD
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Regarding the SSD flash loops, I dont really like them. The default speed of the Java loop was better, every time I open a loop I have to adjust the speed cuz the flash loops are to slow. They load faster but man I have been suing Java loops for years now, Its gonna sad to see it go.

All Java loops on the SSD site will be replaced with flash loops on 01/01/10.

If anyone knows any good java loops that self update let me know.

Thanks
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Fredex is well...still not dead.
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Quoting aquak9:
hey hydrus??
Thanks a LOT...now I got "hungry like the wolf" trapped in my head...
HAHA! the eighties strike again, that wasnt such a bad song , you,ll live. If you do hate it, forgive me, I know how it feels.
Member Since: September 27, 2007 Posts: 1 Comments: 21199
Regarding FredEx ...

Perhaps we could give him a last name. I nominate Fred Gwynne. No I won't post an image. Please look it up yourself.

g'nite
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GOM 60 Hour Water Surface Temperature Forecast
Member Since: July 3, 2005 Posts: 424 Comments: 128282
One shot of lightening and we have Fredenstein!!!!!!!!!!!!!!!!!!!!!!!!!!
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Boy, the storm system over NE. Texas looks like a "Terracane".
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GOM 84 Hour Wave Forecast (using MIKE21)
Member Since: July 3, 2005 Posts: 424 Comments: 128282
Somebody used to keep a list of this stuff.... was it www.hurricanecity.com???

[goes to look]
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814. SLU
Quoting Weather456:


Georges was the reason. The other reason is that my country is only 2nd to Cuba for the Caribbean with the most hurricane strikes.

I have lived through

Hugo
Luis
Marilyn
Bertha
Georges (the costliest)
Lenny
Omar

Only Bertha wasnt a major when it passed.




Wow you've been through some pretty heavy stuff man.

I've experienced a few too at age 23 but mostly "weak" systems. I've been through one hurricane in my life and that was Dean in 2007. Very frightening to see coconut trees bend over at 45degress for the 1st time. I never saw so many fallen trees before either but the overall damage was light for a 100mph sustained wind hurricane ...
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Evening WunderHumans.
looks like there's still a whole lotta nuthin' goin' on.
Link
(at least in the western hemisphere)
Though the eastern Caribbean looks interesting to me anyway.

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hey hydrus??
Thanks a LOT...now I got "hungry like the wolf" trapped in my head...
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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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