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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349. RMCF
Quoting Levi32:
You guys should feel exceedingly privileged to have someone such as Storm even stick around through all the crap (excuse the word) that goes on in here. A lot of professionals would never stick around on a board like this.

You to are one of the great ones that takes low blows from less educated.
Levi i love your emphasis on the affect on the US. keep up the good work.
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348. 7544
is she still heading west as new conv. fires tia
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Quoting angiest:


There's a chicken and the egg problem there. In may areas, particularly the sciences, entry level jobs are increasingly difficult to find unless you have an advanced degree (minimum of Masters). It shouldn't be that way. Part of that is almost certainly the sorry state of education in the US. Colleges no longer seem to trust that their students received certain basics in high school.


Ha, kinda like how businesses are greedy and what you to have a bachelor's degree so you can do data entry? It's ridiculous.
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Quoting Levi32:
You guys should feel exceedingly privileged to have someone such as Storm even stick around through all the crap (excuse the word) that goes on in here. A lot of professionals would never stick around on a board like this.


Absolutely correct!
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Triplets?

Click for larger image:
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Quoting DestinJeff:
Why is everybody so freakin edgy?

Careful or I'll whop you upside the head with my chart!


Just dont use the pointy end.
You may be up for "greivious bodily harm"!
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Quoting Hurricanes101:
328. divdog 4:35 PM GMT on August 24, 2010

well ok its not that no one listens to him, but there have still been plenty who just continue to say the season is a bust despite all the evidence he keeps showing to the contrary.

This blog can really wear on a person over time
If anybody is saying the seaon is a bust just put them on the ignore list where they belong. Nobody can possibly know what the rest of the season will bring so it becomes obvious they are just trying to elicit a response from us. Just ignore them and the blog becomes a more useful place.
Member Since: August 22, 2008 Posts: 0 Comments: 755
Quoting stormlvr:


That is the preferred path in many different disciplines. I think we can all agree that there are those that are good and those that are not so good in every career area regardless of degree. I can also tell you that 3 forecasters using the same information will come up with varying solutions for a 5 day forecast period with more and more spread through time. There is always room for error.


There's a chicken and the egg problem there. In may areas, particularly the sciences, entry level jobs are increasingly difficult to find unless you have an advanced degree (minimum of Masters). It shouldn't be that way. Part of that is almost certainly the sorry state of education in the US. Colleges no longer seem to trust that their students received certain basics in high school.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
338. TGTTX
Quoting Levi32:
You guys should feel exceedingly privileged to have someone such as Storm even stick around through all the crap (excuse the word) that goes on in here.

I do. I feel silly even writing this in some sort of defense of Storm ... like throwing a water baloon at the ocean and saying "See, it's wet!"

Storm's knowledge, ability, experience and integrity need no defense.
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Quoting DestinJeff:
Why is everybody so freakin edgy?

Careful or I'll whop you upside the head with my chart!




Doh!!!!
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Storm, Levi and others.

Please dont ever let the childishness of a few posters effect your contribution here.
Many folks here truly appreciate what you guys do and it would be a shame for the acts of a few to ruin it for everyone.

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328. divdog 4:35 PM GMT on August 24, 2010

well ok its not that no one listens to him, but there have still been plenty who just continue to say the season is a bust despite all the evidence he keeps showing to the contrary.

This blog can really wear on a person over time
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Storm,

Thanks for posting these maps of 95, 98 and 2004. When you said people are in for a rude awakening, did you mean for Florida?

Is it fair to say that if the High sets up the way it was predicted back in April or May that this could be a 2004 ending to the season where many storms go into Florida?
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Quoting ShenValleyFlyFish:
Goes to prove my DDD's point. Dr Jeff had experience and an inquisitive mind before he got his Phd. Those guys are a rare treasure. If I were King and Emperor of The World I would require experience in the field before anyone could enter an advanced degree program. JMAO (just my arrogant opinion)


That is the preferred path in many different disciplines. I think we can all agree that there are those that are good and those that are not so good in every career area regardless of degree. I can also tell you that 3 forecasters using the same information will come up with varying solutions for a 5 day forecast period with more and more spread through time. There is always room for error.
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Quoting StormW:


Not right now, until I see EXACTLY how we are setting up with the NAO. However, I had posted these a few days ago, and I'll put them up again so you may get a "general" idea of what could possibly come to fruition. These years match closely to the NAO values and trend(s) of the NAO in which we are experiencing, and may experience







I know 1995 had pretty persistent troughing off the east coast which kept the parade of storms away. I'm not quite sure about the other years, but there does seem to be a trend more towards the Gulf, as far as CONUS impacts.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting Hurricanes101:
292. BobinTampa 4:21 PM GMT on August 24, 2010

Could it be that he is finally tired of how much this blog resembles romper room half the time.

This blog is here so people can discuss the tropics and learn. Lately however, it has been nothing but a big circus. There is too much of the "you were wrong, eat some crow" type posts that have no business in here.

God forbid anyone disagree with the NHC, its like you should be put in front of a firing squad and shot.

Overreactions are a big part too. Just because someone may think the storm is going further west, does not mean they are a wishcaster, want the storm to hit the US or loves destruction. Yet we get numerous comments like that all the time.

StormW has been trying to get a point across about this season and no one listens to him; they ignore what he says and keep spewing off about this season being a bust.

Maybe he just got tired of it, and I cannot blame him one bit.
I would not say no one listens to him. Lots of us respect his opinion and value the hard work he puts into keeping us well informed of what might be happening in the tropics and most importantly why it is happening. Thanks to him i have increased my knowledge of tropical weather many times over. THANKS FOR ALL THAT YOU DO STORMW. Do not get discouraged with all the trash that is getting posted on the blog keep up the good work.
Member Since: August 22, 2008 Posts: 0 Comments: 755
Thank you Storm, much appreciated!
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Greetings!
While all the above has been going on, we have had 2" of Heavy Stuff here..
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324. Relix
Quoting StormW:


Not right now, until I see EXACTLY how we are setting up with the NAO. However, I had posted these a few days ago, and I'll put them up again so you may get a "general" idea of what could possibly come to fruition. These years match closely to the NAO values and trend(s) of the NAO in which we are experiencing, and may experience







Puerto Rico is gonna get hit then probably. Darn. XD!
Member Since: August 3, 2006 Posts: 0 Comments: 2741
Quoting Levi32:
You guys should feel exceedingly privileged to have someone such as Storm even stick around through all the crap (excuse the word) that goes on in here. A lot of professionals would never stick around on a board like this.


Agreed 100%
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You guys should feel exceedingly privileged to have someone such as Storm even stick around through all the crap (excuse the word) that goes on in here. A lot of professionals would never stick around on a board like this.
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Quoting RMCF:
Storm is a profesional forecaster not a wish caster and the NHC will not predict a landfalling hurricane unless it is certain it will affect land as a cat1 or better because they cause such a impact on commerce and scares the public but these guys are telling you what they see and what might happen.


Agreed, I place much faith in StormW as a professional and teacher. It is a good-hearted and kind thing StromW does by providing detailed data about the science behind the tropics on a daily basis.
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292. BobinTampa 4:21 PM GMT on August 24, 2010

Could it be that he is finally tired of how much this blog resembles romper room half the time.

This blog is here so people can discuss the tropics and learn. Lately however, it has been nothing but a big circus. There is too much of the "you were wrong, eat some crow" type posts that have no business in here.

God forbid anyone disagree with the NHC, its like you should be put in front of a firing squad and shot.

Overreactions are a big part too. Just because someone may think the storm is going further west, does not mean they are a wishcaster, want the storm to hit the US or loves destruction. Yet we get numerous comments like that all the time.

StormW has been trying to get a point across about this season and no one listens to him; they ignore what he says and keep spewing off about this season being a bust.

Maybe he just got tired of it, and I cannot blame him one bit.
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315. Relix
BobinTampa just sounds like an envious guy. That's all. Don't get mad at it Storm, it's not worth it!
Member Since: August 3, 2006 Posts: 0 Comments: 2741
I do read your blog. And I always look forward to your posts. Lately though, your reponses to people have come off rather defensive and pissy.

You bash the NHC, you bash PH.D's. You talk down to people who disagree with you. You can let your work speak for itself.

I do think it's in poor taste to come into Dr. Masters blog and make comments like (paraphrasing) "Dr. Masters obviously read my blog..." and ridiculing the Ph.D designation he worked hard to achieve. You may not mean to come off that way, but you do (lately anyway)


I have noticed that too. Maybe you need a break Storm.
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312. RMCF
Storm is a profesional forecaster not a wish caster and the NHC will not predict a landfalling hurricane unless it is certain it will affect land as a cat1 or better because they cause such a impact on commerce and scares the public but these guys are telling you what they see and what might happen.
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Quoting StormW:


In theory, yes. However, the trof that is supposed to strengthen, is forecast to basically split the subtropical ridge in between the two centers, allowing for her escape...however the satellite loop imagery shows the ridge "building" somewhat at the moment, and I believe this is going to delay her turn.

As far as pre "Earl", he should follow a WNW course for about 72 hours, then could or should most likely bend back to the west, based on the ridge building back in in the steering layers forecast maps.


StormW~~ Thanks for taking time and answering my question. I understand better know. Have a great day gone back to reading.
sheri
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Quoting Michaelkaii10:


Why are you Talking to Yourself??


He talks to himself because his other names are the only ones who don't have him on ignore.

Too bad the admins can't de-activate all but his current name.
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Quoting StormW:


If you click on my handle, it will take you to my forecast.

As far as the coming months, folks are in for a rude awakening I feel.


I really believe in what the experts have been saying all along that this will be a really challenging year for us all. I believe that CONUS will came under threat especially late in the tropical period (Oct-Nov). My daughter is getting married in San Ramon, California on Sept 4th so I am glad things are not appearing dreadful through Sept 5th for SEUSA, when I return. Then all heck will bust loose.
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Good morning all.

Blog Update:

Tropical Tidbit for Tuesday, August 24th, with Video
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Quoting StormW:


Well, not in the monetary sense. They did fly me to the Norfolk Command a couple years ago...and paid for a Hotel room on the water, breakfast and meals...and that's where I received my second Coast Guard Public Commendation. But for the most part, I volunteer for the CG, seeings how I put in 20 years.
Are we talking European breakfast...or full American breakfast?
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Now in days it is getting harder to get information that makes sense in this blog. I ran out of ignore space in my ignore list. As always, thank you for your synopsis Storm. Back to lurking.
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Quoting StormW:


If you click on my handle, it will take you to my forecast.

As far as the coming months, folks are in for a rude awakening I feel.


As early as the first week of September, I believe.

Danielle looks really beaten down right now. The next 12 hours look to be pretty crucial if re-strengthening is in her future.
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Quoting DestinJeff:


Want to start an office pool on who will be the first to invoke "Fujiwhara" into the discussion?


Do I get the over?
Member Since: September 23, 2005 Posts: 15 Comments: 11343
Quoting StormW:


If you click on my handle, it will take you to my forecast.

As far as the coming months, folks are in for a rude awakening I feel.


Do you have any specific area in mind?
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I don't get why we can't have proper building codes in the US to withstand hurricanes. Hurricanes happen all the time in Japan but don't entail the kind of destruction that happens here.

What prevents proper building of houses so that hurricanes aren't nearly such a threat? Corruption? Cheapness? I don't get it. There's no reason a Cat 2 should be blowing off roofs if a house is built to code. And there's no reason someone shouldn't expect their house to be totaled if they live near enough the sea to get a storm surge.
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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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