Tropical Depression Eight: the one to watch

By: Dr. Jeff Masters , 2:12 PM GMT on September 13, 2006

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Hurricane Florence is now a powerful extratropical storm passing along the south coast of Newfoundland. The storm still has winds of hurricane force, as evidenced by the sustained winds of 76 mph gusting to 93 mph reported at Newfoundland's Segona Island this afternoon. The QuikSCAT imagery from this morning shows an impressive storm with 55+ mph winds affecting a large swath of ocean near Canada.

Gordon is headed out to sea.
Hurricane Gordon became the third hurricane of the season last night, and is expected to remain a Category 1 hurricane for another two or three days until increasing wind shear and cooler waters weaken the storm. Gordon is headed northward out to sea, and is not a threat to land. I'm not going to talk about this storm very much.


Figure 1. Saharan Air Layer (SAL) analysis from 9Z (5am EDT) Sep 13, 2006. The bright orange layers show where very air air laden with Saharan dust lies. Note that TD 8 has to contend with some dry air from the SAL to its north and west, while Hurricane Gordon is in a moister, more favorable environment.

The one to watch: Tropical Depression Eight
The storm we really need to focus on is Tropical Depression Eight. This depression has the potential to grow into a major hurricane that may affect Bermuda or the U.S. East Coast next week. TD 8 is currently having difficulty organizing, due to the presence of dry air to its north and west (Figure 1), and about 20 knots of wind shear. TD 8 also has a very large circulation, and as we saw with Florence, it can take such storm a very long time to organize.

The computer track models all agree on a general westward motion the next five days, taking TD 8 into the middle Atlantic. It appears at this time that the storm will gain enough latitude to pass north of the Lesser Antilles Islands, since a trough of low pressure should pull the storm on a more west-northwesterly track 3-5 days from now. After that, the future track is uncertain. The long-range GFS model shows a more westerly track and an eventual threat to Bermuda late next week, and it is not out of the question that TD 8 could make it all the way to the U.S. However, the odds are against this. History shows that the large majority of tropical depressions that form in this part of the Atlantic end up recurving harmlessly out to sea. With the active jet stream pattern we've seen since early June expected to continue for at least the next two weeks, I expect TD 8 will recurve before reaching the U.S.

Research project studying TD 8
A new research tool is being used to study Tropical Depression Eight. The driftsonde is being used for the first time to aid in hurricane research. The driftsonde is a special high-altitude balloon that floats in the stratosphere at 70,000 feet and can launch special mini-dropsondes that float down on parachutes and radio back information on winds, pressure, temperature, and humidity as they fall to earth. The driftsonde will typically launch two mini-dropsondes per day, but can launch up to one per hour if special high density data is desired. The data from these mini-dropsondes (in theory) should be making it into the global computer models that forecast hurricanes, providing valuable data over data-void ocean regions that should help provide better forecasts. The tricky part is launching the driftsondes at the right time so that they drift from Africa to the Caribbean over a developing tropical cyclone. At least seven driftsondes have been launched since August 28. The research is being done as part of an international field project to help learn about the African Monsoon and hurricane formation called the African Monsoon Multidisciplinary Analysis (AMMA). Here's a sample of the status of some of the driftsonde missions, taken from the AMMA webpage. Note that the acronym AEW refers to "African Easterly Wave", meaning the tropical waves I talk so much about.

UPDATE:

MISSION #4 IS TERMINATED: Despite the tilted gondola, gondola #4 allowed the sampling of extra-tropical dry intrusions off the coast, west of Dakar and yesterday we dropped 4 sondes on the southeastern edge of tropical depression #7 (see attached document).

MISSION #5 IS AIRBORNE: Driftsonde #5 is flying over a streak of very moist air that we sample every three hours. It is now heading south and is located at about 11N and 41W.

MISSION #6 IS AIRBORNE: After sampling a weak trough of an AEW (1 sonde/3hrs), driftsonde #6 is heading to a more active area immediately off the coast where storm formation is predicted by different models (sampling strategy: 1 sonde/3hrs in the area). It should be over Dakar tomorrow and could be considered as a possible contributor to SOP-3.

MISSION #7 SHOULD BE LAUNCHED TODAY IF POSSIBLE: This driftsonde should be launched in the eastern part of a trough associated with an AEW (no possible launch the last two days due to strong wind and showers). Coordination with SOP-3 is possible with this driftsonde which should be over Dakar the day when SOP-3 begins (in 3 days).


Carolinas
Several of the computers models are forecasting that a tropical low pressure system might form off the Carolina coast on Friday, then scoot quickly northeastward out to sea. We'll have to watch the cold front expected to push off the East Coast Thursday to see if it spawns such a storm.

I'll be back with an update Thursday morning.
Jeff Masters

Surf's Up I (Royman)
Florence isn't anywhere near us, but she sure has kicked up our surf. This and the next two shots caught some surfers off Ruggles Ave., the good spot for the really good surfers. And I got soaked taking the pictures - the waves were hitting the sea wall so hard they were coming up on the Cliff Walk itself, and while I didn't mind getting myself wet, I had to keep drying the camera off.
Surf's Up I

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1459. HurryKaneKata
4:19 AM GMT on September 15, 2006


Hurricane Ioke Damage to Wake Island


The Central Pacific's biggest storm in a decade damaged 70 percent of the buildings on Wake Island when it slammed ashore last month, the U.S. Air Force said Wednesday.

Typhoon Ioke left the U.S. military research and refueling outpost without running water, and damaged power lines and a power grid. The buildings are being powered by generators, said Maj. Clare Reed, a spokeswoman for the 15th Airlift Wing.

The runway made it through intact, but it is missing its lights, the Air Force said.

On Monday, an Air Force response team that set sail by Navy ship from Guam reached the island and cleared the runway for planes to land, enabling a C-17 to fly to the island from Hawaii with 60 airmen and military contractors who have started assessing what repairs the facilities will need, Reed said.

The Category 5 storm passed almost directly over the 2.5-square mile atoll on Aug. 31 with sustained winds of up to 155 miles per hour and gusts of up to 190 mph. All 188 residents, mostly military contractors and Air Force personnel, were evacuated.
1458. stormybil
4:15 AM GMT on September 15, 2006
wow i left here at 2pmthere was only 8 pages you guys posted up 22 pages in 8 hours good job

notice they have ts helene going further west at this point are the models stiill calling for a north turn .?
and at what latitude this will begin thanks . the high might be very stong and hold helene south right . :)
1457. AllyBama
1:53 PM GMT on September 14, 2006
Ricderr..yes I would like to know too why Freddy picked Mobile..
Member Since: August 3, 2006 Posts: 132 Comments: 20635
1454. AllyBama
1:49 PM GMT on September 14, 2006
lol-Rand!!
Member Since: August 3, 2006 Posts: 132 Comments: 20635
1452. Oreodog
1:47 PM GMT on September 14, 2006
Did you know I counted 23 Waffle Houses between Houston and Baton Rouge on I-10? To make this weather related, 5 were shut down (Beaumont, Orange and Lake Charles) because of Rita.
1450. AllyBama
1:46 PM GMT on September 14, 2006
..well for you smokers that means cost of cigs will go up,up,up...
Member Since: August 3, 2006 Posts: 132 Comments: 20635
1449. ricderr
1:46 PM GMT on September 14, 2006
ok.......assignment america time...what made frederick move west....and what are the similarities or descrepancies to Helene...a free waffle house wishacasting breakfast to the answer
Member Since: June 27, 2006 Posts: 673 Comments: 21581
1448. mermaidlaw
1:45 PM GMT on September 14, 2006
I am going to get breakfast now, since you guys made me hungry! LOL! Be back later.
Member Since: July 23, 2006 Posts: 20 Comments: 8800
1446. PensacolaDoug
1:43 PM GMT on September 14, 2006
Morn'n all. Looks nice and peacable here this morning.

Everyone is getting along. Makes me feel all warm and fuzzy!
Member Since: July 25, 2006 Posts: 0 Comments: 556
1445. AllyBama
1:43 PM GMT on September 14, 2006
well..nothing is WRITTEN IN STONE and neither is the track of Helene...yesterday was 27th anniversary of Hurricane Frederic and HE obviously missed a trough! lol
Member Since: August 3, 2006 Posts: 132 Comments: 20635
1444. ricderr
1:43 PM GMT on September 14, 2006
76 million dollars in crop damage estimated in NC tobacco?
Member Since: June 27, 2006 Posts: 673 Comments: 21581
1442. robinvtx
1:41 PM GMT on September 14, 2006
saddlegait,did u get an answer? i havent found it if you did,thanks
1440. thelmores
1:40 PM GMT on September 14, 2006
76 million dollars in crop damage estimated in NC from Ernesto..... which dumped 8-12 inches in the area.....
Member Since: September 8, 2005 Posts: 0 Comments: 3805
1439. AllyBama
1:39 PM GMT on September 14, 2006
good morning Mermaid and ClearH20FL..
Member Since: August 3, 2006 Posts: 132 Comments: 20635
1436. i12BNEi
1:36 PM GMT on September 14, 2006
Morning all! Are there going to be any landfalling canes this year or what....maaan.It does seem that if all these "fish storms" weren't that,We would have been pretty busy here in fl.
1433. ClearH2OFla
1:32 PM GMT on September 14, 2006
Good Morning all!!! Well it appears from all indications that the great sucking sound we have heard for the last two weeks will continue as Helene should follow the path of flo and Go.
1432. mermaidlaw
1:31 PM GMT on September 14, 2006
Good morning Gulf, Rand, Thel, saddle, littlefish,Bama, Ricderr, and everyone else!
Hope you are all having a GREAT morning. Helene Could go anywhere, at this point?? Am I right?
Member Since: July 23, 2006 Posts: 20 Comments: 8800
1429. AllyBama
1:27 PM GMT on September 14, 2006
Thelmores - your pic of Helene looks better than the one a saw of TWC a few minutes ago...maybe Helene doesn't look so bad afterall..
Member Since: August 3, 2006 Posts: 132 Comments: 20635
1427. moonlightcowboy
1:27 PM GMT on September 14, 2006
Good morning, all!

Looks like Helene is going through the "John Wayne Effect" -- Circles of convection scattered like indians circling a wagon ...and all moving West in a fast fury!

Whoa--when she all comes together, likely to be one helluva shootout.
Member Since: July 9, 2006 Posts: 184 Comments: 29598
1426. AllyBama
1:26 PM GMT on September 14, 2006
you got that right GS!!
however, laying out by the pool with cool beverages would make the heat a little more tolerable.. :)
Member Since: August 3, 2006 Posts: 132 Comments: 20635
1425. WSI
1:26 PM GMT on September 14, 2006
"thus..a forecast...can be made made with an expected degree of success...based on knowns and probabilities"

Well said! I agree 100%.

Yes, wobbles and strength and unexpected ULL's can be a problem. However we do have SOME idea of what will happen.
1424. AllyBama
1:23 PM GMT on September 14, 2006
GS - if that happens then you and I are in the clear! OB Laden would send anything direcly course to DC in attempt to wipeout Bush!
Member Since: August 3, 2006 Posts: 132 Comments: 20635
1423. thelmores
1:23 PM GMT on September 14, 2006


HELENE doesnt look to bad to me..... considering its forward speed and dry air to the north......
Member Since: September 8, 2005 Posts: 0 Comments: 3805
1422. ricderr
1:22 PM GMT on September 14, 2006
in all seriousness here is what we have. we have the knowns of helene..it's size...posistion and immediate movement...we have the knowns of highs..ridges and jet streams where they are .....we have the knowns of climatology...we have the probabilities of the ridge and high and trough movements...we have the probabilities of interactions between tropical cyclones and the aforementioned.thus..a forecast...can be made made with an expected degree of success...based on knowns and probabilities
Member Since: June 27, 2006 Posts: 673 Comments: 21581
1419. K8eCane
1:19 PM GMT on September 14, 2006
Posted By: GulfScotsman at 1:13 PM GMT on September 14, 2006.

it would appear that the latest model runs do not flatten out to the WNW line today.




BUT
BUT
BUTT......
WHAT IF OB LADEN HAS MANAGED TO GAIN CONTROL OF THE MODELS???
WHAT THEN????
Member Since: April 26, 2006 Posts: 5 Comments: 3098
1418. AllyBama
1:19 PM GMT on September 14, 2006
I see that everyone is in a great mood except for Helene - she looks a little frazzled this morning.
Member Since: August 3, 2006 Posts: 132 Comments: 20635
1416. AllyBama
1:15 PM GMT on September 14, 2006
Good morning everyone!!
going to be a nice hot, humid sunny day in beautiful downtown Mobile!
Member Since: August 3, 2006 Posts: 132 Comments: 20635
1413. WSI
1:12 PM GMT on September 14, 2006
"It's not a fish storm, nor is it a landfalling storm. It's really nothing yet. Long ways to go folks."

Well, when I look and try to forecast, I look at trends. I also look at the models and see if they continue the trends. The "trough train" has been active. Looking at the GFS this morning, that trend looks to continue.

I would say it has a very high probability of staying away from the U.S. Still requires watching, especially for Bermuda. However the chances of this thing NOT curving is pretty low at this point in my opinion.

Yes, we have a lot of time to watch this, and things can change. The current pattern, and the models forecasting that pattern to continue.... both of those have to be considered heavily.
1409. nash28
1:08 PM GMT on September 14, 2006
Dr. Masters needs to hurry up and post the new blog. This one is bloated.
Member Since: July 11, 2005 Posts: 190 Comments: 16972

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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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