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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Quoting texascoastres:
didnt mean for it to post twice

What do you think about ex-Fred?
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didnt mean for it to post twice
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umm.....did i kill the blog?
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the speed has increased from 10 to 15mph in the last 3-4hrs
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the speed has increased from 10 to 15mph in last 3-4 hrs
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Quoting btwntx08:

cause fred is blowing up which is not decreasing lol he got mixed up and idk about the pressure and he's wrong on the conditions they're favorable idk whats he's looking at lol

Avila doesn't mean the convection is decreasing- the speed is decreasing.

THIS ACTIVITY IS MOVING GENERALLY
WESTWARD AT ABOUT 15 MPH AND HAS BEEN GRADUALLY DECREASING.
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Quoting hydrus:
Both the tropics and the blog.


I still dont quite understand.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
or grand turks in about 50
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1197. hydrus
Quoting Weather456:


I dont understand, the tropics?
Both the tropics and the blog.
Member Since: September 27, 2007 Posts: 1 Comments: 20929
Hi everyone I will only be here for about 15 minutes.
Fred-->I think it has about 25~40% of redevelopment. What do you guys think?
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Quoting iceman55:
i hope i.m not kill blog :(


no not you becuz even in quiet times you contribute to the blog.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting hydrus:
It was quiet.


I dont understand, the tropics?
Member Since: July 24, 2005 Posts: 407 Comments: 19076
at the current speed the remnants of Fred will be at St. Martin in about 24hrs
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1191. hydrus
Quoting Weather456:
Jeeze I know the tropics are quiet but some people just seek in every attempt to kill this blog from tropical activity.
It was quiet.
Member Since: September 27, 2007 Posts: 1 Comments: 20929
1189. hydrus
Quoting iceman55:
Link


new models run
The NOGAPS persistently puts a storm in the S.W.Caribbean Sea.
Member Since: September 27, 2007 Posts: 1 Comments: 20929
Jeeze I know the tropics are quiet but some people just seek in every attempt to kill this blog from tropical activity.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
He seems to think so!
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1183. hydrus
Quoting texascoastres:
Thats funny Chris! I have a 16yr old named Chris
What a great name.
Member Since: September 27, 2007 Posts: 1 Comments: 20929
Thats funny Chris! I have a 16yr old named Chris
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Sorry, To far away can't help on the applejack maybe if you were closer. Have family in Lenore ( I think thats how its spelled) outside of Knoxville but they dont refine the better things
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1179. IKE
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 AM EDT THU SEP 17 2009

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

THE REMNANTS OF FRED....ACCOMPANIED BY DISORGANIZED SHOWERS AND
THUNDERSTORMS...ARE LOCATED ABOUT 450 MILES NORTHEAST OF THE
NORTHERN LEEWARD ISLANDS. THIS ACTIVITY IS MOVING GENERALLY
WESTWARD AT ABOUT 15 MPH AND HAS BEEN GRADUALLY DECREASING. SURFACE
PRESSURES ARE HIGH IN THE AREA AND THE UPPER-LEVEL ENVIRONMENT IS
NOT CONDUCIVE FOR RE-DEVELOPMENT.
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 AVILA



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1178. hydrus
Quoting texascoastres:
hydrus where are you from? didn't know muscadine was that commonly known
I was born in Florida, raised on Captiva Island. But I am in central Tennessee at this moment.
Member Since: September 27, 2007 Posts: 1 Comments: 20929
hi Chris nice to meet ya! Just hopin I dont become one of the newly lost(unemployed)
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1176. hydrus
Quoting texascoastres:
my name is Linda Thanks! As stated not typical of me. had very disharding day! Lost some good folks at work today!
Did you check the lost and found? Just foolin, I hope everything is o.k. If not, godspeed.
Member Since: September 27, 2007 Posts: 1 Comments: 20929
hydrus where are you from? didn't know muscadine was that commonly known
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1173. hydrus
Quoting texascoastres:
Have a relative that makes homemade his favorite is applejack
I would rather have the Applejack...My name is Chris.
Member Since: September 27, 2007 Posts: 1 Comments: 20929
1172. hydrus
Quoting Skyepony:
Aug numbers are out..

Global Highlights

* The combined global land and ocean average surface temperature for August 2009 was 0.62°C (1.12°F) above the 20th century average of 15.6°C (60.1°F). This is the second warmest such value on record, behind 1998. August 2009 was the 31st consecutive August with an average global surface temperature above the 20th century average. The last August with global temperatures below the 20th century average occurred in 1978.
* The combined global land and ocean average surface temperature for June-August 2009 was the third warmest on record for the season, 0.59°C (1.06°F) above the 20th century average of 15.6°C (60.1°F).
* For the year to date, the combined global land and ocean surface temperature of 14.5 °C (58.3 °F) tied with 2003 as the fifth-warmest January-August period on record. This value is 0.55°C (0.99°F) above the 20th century average.
* The worldwide ocean surface temperature for August 2009 was the warmest on record for August, 0.57°C (1.03°F) above the 20th century average of 16.4°C (61.4°F).
* The seasonal (June-August 2009) worldwide ocean surface temperature was also the warmest on record, 0.58°C (1.04°F) above the 20th century average of 16.4°C (61.5°F).
* In the Southern Hemisphere, both the August 2009 average temperature for land areas, and the Hemisphere as a whole (land and ocean surface combined), represented the warmest August on record.
* A weak El Niño persisted across the equatorial Pacific Ocean during August 2009. Consequently, sea surface temperatures across the equatorial Pacific Ocean were between 0.7-1.0°C (1.3-1.8°F) above average during the month. According to NOAA's Climate Prediction Center, El Niño is expected to strengthen and last through the Northern Hemisphere winter 2009-2010.
If this is true, it should help the on going drought in a large part of the western U.S.
Member Since: September 27, 2007 Posts: 1 Comments: 20929
Have a relative that makes homemade his favorite is applejack
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my name is Linda Thanks! As stated not typical of me. had very disharding day! Lost some good folks at work today!
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1169. hydrus
Quoting texascoastres:
Usually about 2x a year have a few bottles that over the years have evaporated instead of being consumed
Yeah, we have some muscadine wine doing the same thing as we speak.I meant post.:)
Member Since: September 27, 2007 Posts: 1 Comments: 20929
1168. hydrus
Quoting texascoastres:
THanks Hydrus! unfortunately I am well above the legal limit And haven't had one since vacation in July
well enjoy, sit down and pull up a glass lady.
Member Since: September 27, 2007 Posts: 1 Comments: 20929
Usually about 2x a year. Have a few bottles that over the years have evaporated instead of being consumed
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1166. hydrus
Quoting jascott1967:
I'm a wishcaster, I'll admit it. I was born and raised in Houston, Texas and find the destruction and the subsequent economic aftermath to the island of Galveston a complete ignorance and arrogance of humans. And even more distressing is our disregard to the drudging and destruction to the natureal destruction of barrier wetland yet we turn our backs on the million a year+ deaths caused by malaria in poverious regions in the world.

Speed chess - ding, our turn.
I know J, what a troubled world we live in...Did you see what happened in Mayanmar? It taxes satisfactory verbal description....
Member Since: September 27, 2007 Posts: 1 Comments: 20929
THanks Hydrus! unfortunately I am well above the legal limit And haven't had one since vacation in July
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1162. hydrus
Quoting texascoastres:
That nightcap I had might have been a little stronger than normal!
thats fine as long as you are of age I guess.
Member Since: September 27, 2007 Posts: 1 Comments: 20929
I'm a wishcaster, I'll admit it. I was born and raised in Houston, Texas and find the destruction and the subsequent economic aftermath to the island of Galveston a complete ignorance and arrogance of humans. And even more distressing is our disregard to the drudging and destruction to the natureal destruction of barrier wetland yet we turn our backs on the million a year+ deaths caused by malaria in poverious regions in the world.

Speed chess - ding, our turn.
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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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