Danielle a hurricane; TD 7 forming off coast of Africa

By: Dr. Jeff Masters , 2:18 PM GMT on August 24, 2010

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Hurricane Danielle has stopped intensifying and is now looking a bit ragged this morning, but remains a respectable Category 1 hurricane with 80 mph winds. The intensity of Danielle's heavy thunderstorms has waned in the past few hours, and the organization of the storm is less impressive. This is probably due do strong upper-level winds out of the west that are creating a moderate 10 - 20 knots of wind shear, and injecting some of the dry air from the Saharan Air Layer (SAL) that surrounds Danielle. Danielle is over warm 28°C water, but is far from any land areas.


Figure 1. Morning satellite image of Tropical Storm Danielle (left side of image) and the forming Tropical Depression Seven (right side of image.)

Forecast for Danielle
A powerful trough of low pressure over the mid-Atlantic Ocean will begin to pull Danielle more to the northwest by Wednesday, keeping Danielle well to the east of Bermuda. Most of the models predict that this trough will be strong enough to fully recurve Danielle out to sea. It is possible that Danielle could eventually threaten Newfoundland, Canada, but it currently does not appear that any other land areas will be at risk from this storm. History suggests that a storm in Danielle's current location has only a 20% chance of making landfall on the U.S. East Coast. If Danielle passes east of Bermuda, as forecast, these percentages drop to less than 5%. As far as intensity goes, it is looking unlikely that Danielle will attain major hurricane status (115+ mph winds.) There is enough dry air and wind shear affecting the storm today that it will take several days for the storm to recover its strength, making it less likely the storm can hit Category 3.

The formation of Danielle is remarkable in this it was successfully forecast by the GFS model nearly two weeks in advance. The ECMWF and NOGAPS models also did a good job of predicting Danielle's formation a week in advance. The models are getting better and better each year at forecasting genesis of tropical cyclones, though a successful 1-week forecast of genesis is still a rarity. For example, none of the models foresaw the development of 96L until just 3 - 4 days ago.


Figure 2. Plot showing historically the percent chance of a tropical cyclone in a given location impacting the U.S. East Coast. For storms in Danielle's current position (orange hurricane symbol), about 20% of them go on to hit the U.S. East Coast. For storms in 96L's current location (red circle with a "?" in it), the odds are also 20%. Image credit: Bob Hart, Florida State University.

96L (soon to be Tropical Depression Seven)
Satellite images suggests that a tropical wave (96L) that emerged off the coast of Africa yesterday morning has developed a closed circulation, low-level spiral bands, and an increasing amount of heavy thunderstorms. While this morning's ASCAT pass does not show a clear closed circulation, satellite estimates of 96L's strength support calling this a 30 mph tropical depression. It is likely that this storm will be designated Tropical Depression Seven later today. 96L is already bringing heavy rain and strong, gusty winds to the southern Cape Verde Islands. Winds were sustained at 26 mph at Mindelo in the northwest Cape Verde Islands this morning, and 24 mph at Praia, the station closest to the center of 96L. Both stations were reporting widespread dust, due to strong winds blowing Saharan dust from the coast of Africa. However, water vapor satellite images show that only a modest amount of dry air is accompanying this dust, and dry air is currently not a major detriment to 96L. Wind shear is about 10 - 20 knots, and sea surface temperatures are warm, 28°C.

Forecast for 96L/Tropical Depression Seven
Wind shear is predicted to remain low, 5 - 10 knots, for the next four days. SSTs will cool a bit to 27°C by Thursday, but this is still above the 26.5°C threshold for hurricane development. Dry air will probably be the main inhibiting factor for 96L. Most of the intensity forecast models bring 96L to hurricane strength by four days from now, and this is a reasonable forecast. 96L should become Tropical Storm Earl later today or on Wednesday, and will probably bring sustained winds of 40 mph to the southernmost Cape Verdes Islands tonight and Wednesday.

The long range fate of 96L remains unclear. The storm is being steering by the same ridge of high pressure steering Danielle, and will initially follow a track similar to Danielle. 96L may encounter the cold waters stirred up by Danielle at times this week, inhibiting development. As 96L approaches the central Atlantic five days from now, the storm will encounter the same mid-Atlantic trough that will be steering Danielle, and 96L should turn more to the northwest. It is unclear at this point whether this trough will be strong enough to fully recurve 96L out to sea, east of Bermuda. This will, in part, depend upon how strong Danielle gets. A stronger Danielle is likely to create more of a break in the ridge of high pressure steering 96L, encouraging the storm to turn north and recurve out to sea. A weaker Danielle will make 96L more likely to miss recurvature, and follow a track to the west or west-northwest towards the U.S. East Coast early next week. History suggests that a storm in 96L's current location has only a 20% chance of making landfall on the U.S. East Coast.

When will the Caribbean and Gulf of Mexico get active?
The large scale atmospheric circulation over the Caribbean and Gulf of Mexico currently features relatively dry, stable, sinking air. This is due, in part, to the Madden-Julian oscillation (MJO). The Madden-Julian oscillation is a pattern of enhanced rainfall that travels along the Equator from west to east. The pattern has a wet phase with large-scale rising air and enhanced thunderstorm activity, followed by a dry phase with large-scale sinking air and suppressed thunderstorm activity. Each cycle lasts approximately 30 - 60 days. When the Madden-Julian oscillation is in its wet phase over a hurricane-prone region, the chances for tropical storm activity are greatly increased. The latest MJO forecast from the GFS model calls for the wet phase of the MJO to move into the Caribbean during the first week of September. However, keep in mind that forecasts of MJO activity 1 - 2 weeks in advance are not very skillful. The GFS model forecast of MJO activity made two weeks ago did fairly well for the first week, but poorly for the second week of the forecast.

Tropical Storm Frank spares Mexico
Over in the Eastern Pacific, Tropical Storm Frank has moved away the coast far enough from the Mexican coast to no longer pose a heavy rainfall threat, and all tropical storm warnings have been dropped.

"Hurricane Haven" airing again this afternoon
Tune into another airing of my live Internet radio show, "Hurricane Haven", at 4pm EDT today. Listeners will be able to call in and ask questions. The call in number is 415-983-2634, or you can post a question in the comments area on my blog during the show. You can also email the questions to me today before the show: jmasters@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line. I'll focus on Danielle, Earl, and Frank, and discuss the possibilities of a hyperactive Atlantic hurricane period coming during the first week of September.

Today's show will be 30 - 45 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.

Jeff Masters

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Quoting weatherman566:


There might be a low that forms from a stationary front in the Gulf, but nothing significant will develop from it.

Houston looks fine for the next 10 days.

The blobs the forecasters look at are tropical waves. These waves sometimes produce an area of low pressure. If these waves look promising....in other words, they have potential to develop, the National Hurricane Center will designate the wave as an invest. They number it 90-99 for invests, and label it L for Atlantic.

And, really, you shouldn't hope for storms hitting your area. They hurt the economy. Mmmkay?


If you go to StormW blog, he got alot of the terms that would help you follow the terms used here and other weather blogs
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2548. mbjjm
0z Models showing left hook. Things might get interesting, how close to the US Coast will it get before being pushed out to sea?



Computer Models
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Quoting serialteg:


hey, i checked out some of the first names you gave me and i got classical stuff.... is that right?


Well, 'classical' is a period that includes Mozart. Babbit is contemporary American and his music is not anything like Mozart's. Go here and play the sample and you'll see what I mean.

Link
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2546. xcool
AL, 96, 2010082500, , BEST, 0, 136N, 267W, 30, 1008, LO,
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting fatlady99:


Sorry, correction... Apparently they changed the name to Redd Kross on their album. But when I heard them at the Palladium with Black Flag they were still Red Cross... God I'm old!....


listening to that. I definetly come from that grunge-style, simplistic hard rock genre. but i also have that strong Rush, progressive influence on me... plus The Police, Duran Duran, and all that jive lol
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Quoting serialteg:


yup, andrew tore one of my grandma's brother's house down over there in FL. the US got a pretty bad string of canes this decade. andrew was definitely one of those you can't forget


One of the few Cat5's to hit the US.
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Quoting fatlady99:


Sorry, correction... Apparently they changed the name to Redd Kross on their album. But when I heard them at the Palladium with Black Flag they were still Red Cross... God I'm old!....


hey, i checked out some of the first names you gave me and i got classical stuff.... is that right?
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Quoting TXEER:


Went down to Florida in 92 on a church mission after Andrew to help folks...nothing I've ever seen compared to the damage..simply devastating.


yup, andrew tore one of my grandma's brother's house down over there in FL. the US got a pretty bad string of canes this decade. andrew was definitely one of those you can't forget
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2538. xcool


new cmc


Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting fatlady99:


less cohesive than old Red Cross,


Sorry, correction... Apparently they changed the name to Redd Kross on their album. But when I heard them at the Palladium with Black Flag they were still Red Cross... God I'm old!....
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2535. mbjjm
Quoting bigwes6844:
just heard there maybe a disturbance in the gulf probably developing on thursday. VERY INTERESTING!!! the fronts must love the GOM!


Anything which develops in the Gulf along the front, wont have much time to strengthen before moving on the Texas Coast
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just heard there maybe a disturbance in the gulf probably developing on thursday. VERY INTERESTING!!! the fronts must love the GOM!
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2533. xcool
ChrisDcat5Storm nope lol
Member Since: September 26, 2009 Posts: 2 Comments: 15684
2532. TXEER
Quoting serialteg:
For all of those of you remembering and reminising, I remember going back to Hugo in 1988 here in PR... it was our Katrina... nowhere near the death toll but shook us to the bone. Here's an impressive Youtube on that cane's path thru Puerto Rico:

Link

Jesus, I'd love to work in NOAA.

Anywho... I also had my family packed in my parent's modest 3-bedroom home. We were about 15. I remember how my uncle's Volkswagen Beetle was carried up the street by the sheer wind... it's just so impressive, it stays on you. I love hurricane season. I was brought up that way. Plus being a surfer, my dad a surfer and weather freak himself...


Went down to Florida in 92 on a church mission after Andrew to help folks...nothing I've ever seen compared to the damage..simply devastating.
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Quoting VAbeachhurricanes:


click on the link, and every once and a while hit the refresh button in the top right corner. It is the 500mb mean, I just use it because I find it very easy to see the highs, and lows and see how they interact without the precip forecasts in the way. Dont pay attention to strength either, it is always wrong only good for track.
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its going WNW i dare some1 to say no
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2529. kramus
Sorry it's been so long since my last post.

Stay sane, peeps!
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2528. Seastep
Goodnight all.

No one should have even the slightest concern about Danielle. Nothing to see here. Move on. *sarcasm*

Link

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For all of those of you remembering and reminising, I remember going back to Hugo in 1988 here in PR... it was our Katrina... nowhere near the death toll but shook us to the bone. Here's an impressive Youtube on that cane's path thru Puerto Rico:

Link

Jesus, I'd love to work in NOAA.

Anywho... I also had my family packed in my parent's modest 3-bedroom home. We were about 15. I remember how my uncle's Volkswagen Beetle was carried up the street by the sheer wind... it's just so impressive, it stays on you. I love hurricane season. I was brought up that way. Plus being a surfer, my dad a surfer and weather freak himself...
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Interesting to see the Diurnal Cycles at play with the track of Danielle. Highlights the 2 steering forces directing the cyclone. HP winning the battle so far.
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been away for awhile, what is the latest?
Short version please
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2524. xcool


BACK west
Member Since: September 26, 2009 Posts: 2 Comments: 15684
I looks like this one is slipping her cuffs, with little in the background to stop her westward march.








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Quoting serialteg:


New Periphery album is the best i've heard since the latest Faceless.


Hmmm, I'm more of an Elliot Carter or Milton Babbit fan.

Periphery's harmonic prog is OK, but seems less cohesive than old Red Cross, and a bit more soft. Not much counterpoint. Going for a film contract, maybe?

That said, I like the production values anyway. 'Nite.
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2519. xcool
btwntx08 WHAT TEAM.
Member Since: September 26, 2009 Posts: 2 Comments: 15684
96L is going to take a while to get going. Dry air and too many vortexes in that system. Danielle never had that problem when she came off the coast. The NHC might drop it some on the TWO
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LOL well its safe to say "bye bye bermuda" sounds like a song.


hahaha no but in all realism they're going to begin trending lower and lower its obvious with everything else is going on. the "conus" has been lucky so far . Regardless of strength some storms are going to begin impacting imo.
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Back to TXEER Oh I know we don't sound too bright do we regarding the generator.. believe me when I woke up to the smell of gas fumes in the house, I couldn't believe it! I just consider myself lucky I woke up! If we lose power like that again, I plan to just pack up and head out of town. Won't be staying in the heat again either. That was some kind of misery.

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Quoting smuldy:
ya, that stuff happens here all the time, at least its not middle east terminology 101 tonight


Agreed.....and how is smuldy this morning??

Drinking one for me??
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Quoting btwntx08:
good early morning all


hiya old blogee
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Quoting Amanda44:
Back to TXEER, I am in Sugar Land, although I used to live in Kingwood. I was living in Humble during Alicia. If you were here during Ike.. didn't you find it just a little exciting at the very least?

The sounds the storm makes at night.. sounds like a giant walking around on your roof? (I have no idea what made that sound) and the sound that was coming down the chimney and the weird clanking and the sound of trees cracking? We thought several times the roof was just going to lift right off. It was all just so exciting.. of course we made a party out of it..the whole family all holed up in one house. (27 of us) My brother lives down in Clear Lake and nephew goes to school at UTMB in Galveston. Of course my dad nearly killed all of us running the generator IN THE HOUSE with all the windows and doors closed! (he's getting old.. guess he wasn't thinking..)



all of you had to be anxious seeing what would happen. sounds like a not so bad time except for the generator running inside and also cant be good when too much family hang around enclosed for too long. people could get irritated with one another! hehe
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Quoting F4PHANTOM:
Anyone believing this garbage?





+100

And I'll leave it at that.
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2508. smuldy
Quoting F4PHANTOM:
Amanda 44
ya, that stuff happens here all the time, at least its not middle east terminology 101 tonight
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2507. xcool



96L
Member Since: September 26, 2009 Posts: 2 Comments: 15684
She's a night runner for sure...

All these west jog's stack up to a needle in the haystack (Bermuda) Excuse the pun.
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2505. TXEER
Come on out...I'll be the only house in Oakhurst with lights. ;~)
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How many more changes will we see?
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gn all
Member Since: August 3, 2005 Posts: 10 Comments: 5689
yea its WNW mabey NW
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Quoting TXEER:


I'm sorry Amanda but y'all don't sound too bright!

The only good thing about IKE was my wife and I snuggled up in the laundry room on a mnattress and drank two bottles of very expensive red wine...figured if I was going out it would be in style.

I'm ready this time though...bought an $8,000 22,000 BTU natural gas generator...I will not go without electric and AC for 13 days ever again!
Amen. I sat for three days waiting for Frances to leave. Then another nine waiting for the electricity to turn back on. The wind and rain were fun for awhile but soon turned into pure hell.
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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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