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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*stretches back, yawns...* Nothin' goin' on, eh?
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wu-stock 09 opener for Floodman
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Quoting alaina1085:


Hey, whatever helps the children learn! My 5th grade teacher was like that and I still remember tons of lessons from her.


It is a good idea ha

oh btw, I posted a new blog, your input is welcomed! thanks!
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting tornadodude:
Mitch and Choi-Wan have odd similarities


Ya there both cat 5, once a storm reaches cat 5, they all look a like, they all have very dense thunderstorm activity around the eye and very round characteristics.
Dean

Felix

Rita
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Quoting tornadodude:


haha that would be entertaining LOL


Hey, whatever helps the children learn! My 5th grade teacher was like that and I still remember tons of lessons from her.
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454. jipmg
anyone have a rainbow satellite of the entire atlantic?
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Quoting alaina1085:


;)



You could be like Jack Black on school of rock and play your guitar and make up songs as you teach the children about pink floyd! Sounds good to me!


haha that would be entertaining LOL
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting hurricanehanna:

LMAO!!!! Flood you are so dang funny!!!


Gracias...LOL
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Quoting Floodman:


LOL


;)

Quoting tornadodude:


haha yeah, I'm pretty torn right now, because I love weather, but I know I would be a good teacher too, I tend to be able to make things easier to understand


You could be like Jack Black on school of rock and play your guitar and make up songs as you teach the children about pink floyd! Sounds good to me!
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Quoting alaina1085:


NP, but you really need to figure out if you want to be a teacher or a meteorologist dont ya think? lol. Ohhh, you could do both and teach meteorology!! Im a genius.


haha yeah, I'm pretty torn right now, because I love weather, but I know I would be a good teacher too, I tend to be able to make things easier to understand
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting alaina1085:


NP, but you really need to figure out if you want to be a teacher or a meteorologist dont ya think? lol. Ohhh, you could do both and teach meteorology!! Im a genius.


LOL
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Choi-Won Floater - Funktop Color Infrared Loop
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Mitch and Choi-Wan have odd similarities
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting tornadodude:


yeah it is, thanks for asking tho!


NP, but you really need to figure out if you want to be a teacher or a meteorologist dont ya think? lol. Ohhh, you could do both and teach meteorology!! Im a genius.
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Quoting hurricanehanna:
So I have a burning question.....

Did we ever find out if JFB/WS became a dad???


WS JR NOOOOOOOOOOOOOOOOOOOOOOOOOOOO!!! He should have to file a certain document to the government, so they can debate the issue.
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Quoting Patrap:
Choi-Won JSL Image


unbelievable....can't even begin to imagine the power...
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Quoting alaina1085:


Well that's good.


yeah it is, thanks for asking tho!
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting ElConando:
i.e. has issues with the blog stretching out. This is one of a few sites I exclusively use Firefox for.


What is Blog Streching?
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Choi-Won JSL Image

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Member Since: July 1, 2008 Posts: 13 Comments: 7396
Quoting tornadodude:


haha not really, I emailed my professor tho, and he seems willing to help


Well that's good.
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Quoting Floodman:


LMAO...I hear them saying that in the Tropics Update:

Here's a little song I wrote
About the MJO down-stroke
Don't Worry
Be Happy!

The wind may be blowing hard outside
Your house is filling with the rising tide
Don't Worry
Be Happy!

LMAO!!!! Flood you are so dang funny!!!
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Quoting tornadodude:


Dryness where? You're welcome to all the rain we've been getting in NW Florida! Please take it off our hands for a few days!
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Quoting alaina1085:


Did you ever figure that homework out?


haha not really, I emailed my professor tho, and he seems willing to help
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Looks like Fred still has a low level circulation based on visible.
Member Since: July 1, 2008 Posts: 13 Comments: 7396
Quoting tornadodude:


oh, well kinda late :P I still kept the link, so one could click on it instead, thanks tho!


Did you ever figure that homework out?
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Neither of those should
"stretch" the blog perceptibly, unless the resolution for your browser is set unusually low
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Good Afternoon WU!!!

Looks like we have TS Marty to deal with...:)
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Quoting Floodman:


When you add an image you have two boxes that come up after the link box, height, and width.

This an image at 400x400:



And 800x600:




ok cool, thanks guys
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting tornadodude:


oh, well kinda late :P I still kept the link, so one could click on it instead, thanks tho!


When you add an image you have two boxes that come up after the link box, height, and width.

This an image at 400x400:



And 800x600:


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Member Since: June 28, 2006 Posts: 25 Comments: 8360
427. jipmg
Quoting BDAwx:
who was it that said Choi-wan was going to become a category 5 a few days ago...

whoever it was i give them a high-five.


me, it looked similar to wilma at one point (the eye was small) so I figured a 5 was possible
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Edit:removed
Reason:a day late and a dollar short.
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Raining at 11n 61w Trinidad since 9:00 am. First true "rainy season" day for the year.
Several thunderstorms passing through, and in Tobago (where I am) heavy rain and lightening now.
It is very nice.
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Quoting ElConando:
i.e. has issues with the blog stretching out. This is one of a few sites I exclusively use Firefox for.


Not, I use IE without any problems!
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Quoting jeffs713:

Instead of removing it, add width tags to the link. I usually set mine as "width=700". (add it in after the link to the image, but before you close the link tag)


oh, well kinda late :P I still kept the link, so one could click on it instead, thanks tho!
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting tornadodude:


ah ok, well I fixed it, just removed the pic and kept the link, we actually discussed Catarina in my EAS class today

Instead of removing it, add width tags to the link. I usually set mine as "width=700". (add it in after the link to the image, but before you close the link tag)
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i.e. has issues with the blog stretching out. This is one of a few sites I exclusively use Firefox for.
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419. BDAwx
a few days ago, someone said Choi-Wan would become a category 5...

whoever it was i give them a high-five.
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Quoting jeffs713:

I'm on IE6 here at work. Anything newer than that (or FF) will work fine.

It is an excellent pic of Caterina, though.


ah ok, well I fixed it, just removed the pic and kept the link, we actually discussed Catarina in my EAS class today
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting iceman55:


The dry air has been cut off from its source, now the dry should go away in a couple of days but if fred's remnants will still be around is a different one.
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Quoting tornadodude:


sorry :( it didnt stretch mine, weird

I'm on IE6 here at work. Anything newer than that (or FF) will work fine.

It is an excellent pic of Caterina, though.
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Quoting CaicosRetiredSailor:
THIS IS FRED:







THIS IS YOUR BRAIN ON FRED:






LMFAO
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Quoting jeffs713:

Holy blog stretching, batman!


sorry :( it didnt stretch mine, weird
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting tornadodude:


Cyclone Catarina was developed from an ULL


link

Holy blog stretching, batman!
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Quoting Hurricane009:
I commented on your blog. :)


Thanks! :)
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting OracleDeAtlantis:


I'm not looking for best case scenarios here, I'm looking for worst case scenarios, and hearing the Weather Channel say don't worry be happy, while I can see outflow developing rapidly, is contradicting my intuition. Also, this thing is moving through some of deepest warm water in the world.


LMAO...I hear them saying that in the Tropics Update:

Here's a little song I wrote
About the MJO down-stroke
Don't Worry
Be Happy!

The wind may be blowing hard outside
Your house is filling with the rising tide
Don't Worry
Be Happy!
Member Since: Posts: Comments:

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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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