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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hey hydrus??
Thanks a LOT...now I got "hungry like the wolf" trapped in my head...
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Quoting Hurricane009:
Is it weakening or strengthening????


IMO, the cyclone remains almost steady but further analysis indicates the cloud tops have warmed some and the canopy have become somewhat ragged on the western flank.
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WV Loop with Dry Air Shaded,Last 12 Hrs

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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.
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Quoting hydrus:
You probably remember Duran-Duran also...:)


unfortunately, yes..
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802. HadesGodWyvern (Mod)
803
TCNA21 RJTD 170000
CCAA 17000 47644 CHOI-WAN(0914) 18203 11409 12314 265// 93309=

TY Choi-wan (0914) [System #18]
20.3N 140.9E
Current Dvorak Intensity: T6.5

----
weakening!!
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Swirl Watching - T Connection....
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Quoting Weather456:


upper diffluence/elevated convection

some of the moisture is also being pulled from the ITCZ.
If you want, check out post#-788 Some of the storms were not hurricanes but had some power, I am sure you will recognize the bad ones.
Member Since: September 27, 2007 Posts: 1 Comments: 22726
798. JLPR
Quoting Weather456:


upper diffluence/elevated convection

some of the moisture is also being pulled from the ITCZ.


ha! I see
also isn't it weird that in the middle of September this is the best tropical circulation in the Atlantic =P
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Atlantic,Caribbean,WV GOES-12 Ch-3 Loop
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Fred could be like a ZOMBIE, he doesn't know that he's really dead!!
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90S was given FAIR by the JTWC. I think wind shear and cooler SST led to its demise.

AOI near 5S 95E a LOW(10-25%) chance of tropical development in the next 72 hours.

This is based on current conditions

Wind shear and being too close to the Equator are probably the only limiting factors at this moment.


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Quoting JLPR:
So whats up with the convection left behind by the ULL?
is it going to dissipate or is it just going to sit there :|



upper diffluence/elevated convection

some of the moisture is also being pulled from the ITCZ.
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Quoting aquak9:
Blog is fairly quiet.

Fred must REALLY be dead now.
You probably remember Duran-Duran also...:)
Member Since: September 27, 2007 Posts: 1 Comments: 22726


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Evening, everybody....

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
Dude, where have u been..... good to see u in the blog.... I thought it was San Antone and points west that were suffering from the drought... Is this constant rainfall likely to cause serious flooding in the DFW area?

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.

I wonder where the Bahamas is on that list of "most hurricane strikes in the ATL" these days.... we've been at or near the top for a while. It would be nice to go back to having 5 year periods when we get bypassed....

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BurnAfterPosting or 456- well here goes...Inez -66, Doria -71, Agnes -72, Belle-76, David-79, Dennis-81, NoName-82, Kieth-88, Marco-90, Gordon-94, Jerry-95, Mitch-98, Gabrielle-00 or 01, Gordon00 or 01(again),Charlie, Fran, Jeanne, Wilma, I am sure I missed a couple. But that is all I remember now. the tropical depression we had in 92 is worth mentioning, 25 inches of rain in 4 days...1995 bad flooding also..numerous freak storms and squall lines over time also, some were very intense...
Member Since: September 27, 2007 Posts: 1 Comments: 22726
787. JLPR
So whats up with the convection left behind by the ULL?
is it going to dissipate or is it just going to sit there :|

Member Since: September 4, 2007 Posts: 36 Comments: 5223
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785. HadesGodWyvern (Mod)
aqua9k maybe.. have not seen a NHC Tropical Cyclone Guidance for "Fred" lately.
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Blog is fairly quiet.

Fred must REALLY be dead now.
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783. HadesGodWyvern (Mod)
you're welcome
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Quoting mobilegirl81:

Like the lottery, you never know.


I would rather win the lottery than get hit by a Hurricane.
Member Since: March 10, 2006 Posts: 0 Comments: 10815
Quoting HadesGodWyvern:
Fiji Meteorological Services - RSMC Nadi Tropical Cyclone Center


Thanks
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Quoting P451:
12HR WV


Fred and ULL



Caribbean ULL



Looking at it from that makes it look like 2 giant nor'easters are out there.
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Semenolesfan and Dikster.....now that's funny!
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Quoting seminolesfan:
How do I know he's guessing, Dikster? Is that what you're asking?

Like the lottery, you never know.
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Quoting Dakster:


semenolesfan - How do you know this? There are plenty of years without a CONUS Cane hit....
How do I know he's guessing, Dikster? Is that what you're asking?
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Hades,

Can I have a link to the Fiji Meteorological Service since the link I have is down.
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771. JLPR
Quoting Weather456:
JLPR,

I was just referring to major hurricanes. There is too much to list if we talk tropical storms too.


Then i will consider myself lucky :)
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Quoting Hurricane009:
This was his exact words: I expect we will get a hurricane strike somewhere in the Atlantic this season that will require a disaster response.


Ahh yes. I remember it now... Thanks for the exact wording!
Member Since: March 10, 2006 Posts: 0 Comments: 10815
Quoting hydrus:
your still here?......I would have thought you were stuck in a tree somewhere!! which was the worst??


In terms of winds, for where I live, Charley

Rainfall, Fay
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767. IKE
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT WED SEP 16 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE REMNANTS OF FRED...LOCATED ABOUT 600 MILES EAST-NORTHEAST OF THE
NORTHERN LEEWARD ISLANDS...ARE MOVING GENERALLY WESTWARD AT ABOUT
15 MPH. ALTHOUGH THE SYSTEM CONTINUES TO PRODUCE INTERMITTENT
SHOWERS AND THUNDERSTORMS...THE UPPER-LEVEL ENVIRONMENT DOES NOT
APPEAR TO BE CONDUCIVE FOR RE-DEVELOPMENT
...AND THERE IS A LOW
CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.

SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A BROAD AREA OF LOW
PRESSURE AND A TROPICAL WAVE LOCATED ABOUT 600 MILES WEST OF THE
CAPE VERDE ISLANDS HAVE DIMINISHED. DEVELOPMENT...IF ANY...OF THIS
SYSTEM IS LIKELY TO BE SLOW TO OCCUR AS IT MOVES WESTWARD AT AROUND
10 MPH. THERE IS A LOW CHANCE...LESS THAN 30 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER PASCH/BERG
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JLPR,

I was just referring to major hurricanes. There is too much to list if we talk tropical storms too.
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Quoting BurnedAfterPosting:


If that were the case I would be the head of the NHC lol

at 31, Ive seen

Gloria (1985)
Bob (1991)
Andrew (1992)
Erin (1995)
Jerry (1995)
Mitch (1998)
Floyd (1999)
Irene (1999)
Gabrielle (2001)
Charley (2004)
Frances (2004)
Jeanne (2004)
Wilma (2005)
Fay (2008)
your still here?......I would have thought you were stuck in a tree somewhere!! which was the worst??
Member Since: September 27, 2007 Posts: 1 Comments: 22726
Quoting hydrus:
and your only 20 or 21. they should give you a Met Degree based just on experience...j.k.


If that were the case I would be the head of the NHC lol

at 31, Ive seen

Gloria (1985)
Bob (1991)
Andrew (1992)
Erin (1995)
Jerry (1995)
Mitch (1998)
Floyd (1999)
Irene (1999)
Gabrielle (2001)
Charley (2004)
Frances (2004)
Jeanne (2004)
Wilma (2005)
Fay (2008)
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Quoting Hurricane009:
It was a couple of days ago.


If you say so... That just seems like a rather bold statement from Dr. Masters.
Member Since: March 10, 2006 Posts: 0 Comments: 10815
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.

and your only 20 or 21. they should give you a Met Degree based just on experience...j.k.
Member Since: September 27, 2007 Posts: 1 Comments: 22726

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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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