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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IIRC, nuetral years are the ones most likely to produce powerful storms and high ACE.....
Member Since: Posts: Comments:
Quoting iceman55:
2004 was El Nino


not a classic one though
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Quoting BurnedAfterPosting:
Hurricane009 you just contradicted yourself lol

you said it had a very good chance but it wasnt likely lol

so which one is it?


hmmm *scratches head*
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The CFS has predicted shear very well in 2009.
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Hurricane009 you just contradicted yourself lol

you said it had a very good chance but it wasnt likely lol

so which one is it?
Quoting BahaHurican:
Source, please?
Wikipedia but I have read it other places also. Give me a few minutes and I will tell you where else.
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good evening all
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Over 3.5" today on my patio in Tampa.....
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Quoting JLPR:


was 2005 a La niña year?


neutral
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Quoting JLPR:


was 2005 a La niña year?


No it was neutral
Quoting stormwatcherCI:
The Cayman Islands have the dubious honor of having experienced the most hurricane strikes in history. Due to the proximity of the islands, more hurricane and tropical systems have affected the Cayman Islands than any other region in the Atlantic basin (brushed or hit every 2.23 years).[4]
Source, please?
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Quoting BahaHurican:
Didn't someone spot Karen earlier this season?


became Erika
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894. JLPR
Quoting CybrTeddy:


I personally think that might not come to reality, because they were showing earlier an La Nina..


was 2005 a La niña year?
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Quoting aquak9:


Sorry, but Karen already ran that route.
Didn't someone spot Karen earlier this season?
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hi patrap
any chance for that ull south of P RICO for development??????thanks
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Quoting iceman55:
reedzone hey :)


Hi Iceman
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Notice the dip of ULL winds to the east of Fred, this is why I believe Fred is escaping the ULL. I might be wrong, it also appears on here that the ULL has weakened, again.. I could be wrong.

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887. HadesGodWyvern (Mod)
Quoting Yalahaman: 12:50 AM GMT on September 17, 2009
First one to say "Fred is dead" will get a nasty flick to the ear! Also , the CloudSat image is awesome! Puts these storms in a whole new perspective!


Freddy has been dead since February, just kidding. I am using the Australia cyclone name earlier this year.
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Fred might be moving away from the ULL according to CIMMS. It's also starting to "look" more organized, but lets see if it persists. It is currently in favorable wind shear.

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Quoting aquak9:


Sorry, but Karen already ran that route.


Fred is Karen......
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Quoting Magicchaos:
Does Fred keep its name if it redevelops since it is a surface trough now.


Debatable. They're still calling it the remains of fred and as long as it can be tracked as the remains of fred they may stick with fred.

If it was to interact with another area of convection/another disturbance then they probably would give it a new name.
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881. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #39
TYPHOON CHOI-WAN (T0914)
9:00 AM JST September 17 2009
=========================================

SUBJECT: Category Four Typhoon near Ogasawara Shoto

At 0:00 AM UTC, Typhoon Choi-wan (925 hPa) located at 20.3N 140.9E has 10 minute sustained winds of 100 knots with gusts of 140 knots. The typhoon is reported as moving north-northwest at 8 knots

RSMC Dvorak Intensity: T6.5

Storm-Force Winds
=================
120 NM from the center

Gale-Force Winds
================
270 NM from the center

Forecast and Intensity
=======================
24 HRS: 23.4N 139.3E - 100 knots (CAT 4/Very Strong Typhoon)
48 HRS: 28.4N 141.1E - 100 knots (CAT 4/Very Strong Typhoon)
72 HRS: 35.7N 147.1E - 85 knots (CAT 4/Very Strong Typhoon)
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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.
The Cayman Islands have the dubious honor of having experienced the most hurricane strikes in history. Due to the proximity of the islands, more hurricane and tropical systems have affected the Cayman Islands than any other region in the Atlantic basin (brushed or hit every 2.23 years).[4]
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Quoting iceman55:




I personally think that might not come to reality, because they were showing earlier an La Nina..
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Quoting weathermancer:


Fred will circulate around the globe for a few months (as a swirl) and then re-animate for the 2010 season, possibly hitting land.



Sorry, but Karen already ran that route.
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First one to say "Fred is dead" will get a nasty flick to the ear! Also , the CloudSat image is awesome! Puts these storms in a whole new perspective!
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875. JLPR
Quoting Ameister12:

I think so.


yep I think so too
a new LLC would mean a new system
Member Since: September 4, 2007 Posts: 36 Comments: 5223
874. amd
Quoting Weather456:
amd,

the official forecast is for El Nino to continue into Spring of '10


true. I was commenting on the possible upswing in the El Nino that MAY occur in April of 2010 according to iceman's post.
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Quoting aquak9:
Blog is fairly quiet.

Fred must REALLY be dead now.


Fred will circulate around the globe for a few months (as a swirl) and then re-animate for the 2010 season, possibly hitting land.

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872. HadesGodWyvern (Mod)
presslord, LOL
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Quoting Chicklit "Jackson Pollock painting" - at a glance that reminded me of an aerial photo of the Gulf Coast after a major hurricane.
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gecko is my pet name for JFVWS
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amd,

the official forecast is for El Nino to continue into Spring of '10
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Quoting Magicchaos:
Does Fred keep its name if it redevelops since it is a surface trough now.

I think so.
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864. HadesGodWyvern (Mod)
915 MB is the pressure from JMA
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863. HadesGodWyvern (Mod)
hmm presslord you must want gecko on the naming list for cyclones.. huh =P
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Quoting HadesGodWyvern:


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

I thought its was 915mb. Oh well.
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861. amd
Quoting iceman55:




looks like El Nino may not want to fade so quickly in 2010.

It's been 15 years since the last multi-year El Nino (1991-1994), and considering other multi-year El Nino's occurred in 1982-1983, and 1986-1987, we are more than overdue for a multi-year El Nino. JMHO.
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Does Fred keep its name if it redevelops since it is a surface trough now.
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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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