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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1649. XStormX
Member Since: August 19, 2010 Posts: 0 Comments: 171
Quoting centex:
Your easily amazed by the obvious. If only they could really tell us what it was going to do.


The models have been fantastic on this storm......what r u talking about....this is a mid ocean storm..
Member Since: August 22, 2010 Posts: 0 Comments: 652


hmm.. no visible eye but one could pop later or soon..
Member Since: August 15, 2008 Posts: 0 Comments: 2133
1646. centex
Quoting jason2010xxxx:
wow 10% in the GOM NOT GOOD AT ALL the water is over 90F
I've been waiting for that.
Member Since: August 10, 2007 Posts: 0 Comments: 3278
NVM that sat refreshed and it is gone....
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1644. xcool
boy oh boy about ramp-up oh my
Member Since: September 26, 2009 Posts: 2 Comments: 15684
984 at the benchmark!!!

Looks like a typical NOREASTER!!!

(But its early September)


Gotta love the GFS


One thing IS for sure there is going to be a VEEEEEEEEEEEEEEEEEEEEEERRRRRRRRRRRRRRYYYYYYYYYYY

Long period of huge surf on the EC!!!!
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XstormX..

at first it didnt seem as a joke.. If u were going to use it as a joke.. put something like LOL or something at the end.. But all i said was that I disagree with that statement.. I dont hate ya and now i get what ur getting at.. so its all good mane..
Member Since: August 15, 2008 Posts: 0 Comments: 2133
1641. xcool
W'E NEED 20% TO GETTING Invest
Member Since: September 26, 2009 Posts: 2 Comments: 15684
1640. centex
Quoting barotropic:


Yes we could all do that but the models dont do it cause they know the odds - like we could. They do it because of Scientific data and when they do it so far in advance as with this storm, its amazing
Your easily amazed by the obvious. If only they could really tell us what it was going to do.
Member Since: August 10, 2007 Posts: 0 Comments: 3278
Guys no joke look at rainbow IR and I see a possible eye!
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Wow I guess the NE= Mid Atlantic casters can be as bad as the FLa, LA and Texas wishcasters.... who knew!
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1636. Walnut
Is the yellow hashed area in the GOMEX an Invest? Not high probability, but this may be an indication of the MJO working to that area?
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1635. xcool
Invest 97L MAYBE
Member Since: September 26, 2009 Posts: 2 Comments: 15684




Member Since: August 15, 2008 Posts: 0 Comments: 2133
1633. xcool
HERE WE GOM 10%
Member Since: September 26, 2009 Posts: 2 Comments: 15684
1632. JLPR2
Hm... the blog ate one of my posts.

As I was saying in the one that got eaten.
I'm amazed at how much the models have changed since yesterday for 96L.

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1631. XStormX
Quoting FLPandhandleJG:
XstormX..

I disagree with ur statement on post 1614..

It was joke, i love this blog and the people on it ;-)
Member Since: August 19, 2010 Posts: 0 Comments: 171
1630. will45
Quoting LongBeachNY:
Can someone post the new gfs?



Link

18Z gfs
Member Since: July 18, 2009 Posts: 1 Comments: 994
Quoting KanKunKid:


Umm, White Castles?


Sliders (White Castle Hamburgers) are wonderful. I used to be able to buy the hamburgers for 8 cents apiece and the cheeseburgers for 12 cents apiece back in the mid-60's at the White Castle Outlet where Madison Avenue and US31 split apart as you head south out of Indianapolis towards my old birthplace in Southport. Had some when I was back up near Indy on vacation this summer.

They are no different now then they were 45 years ago.

Anyway, looks like Danielle did not move fast enough to avoid the trough and she is starting to move north at a 1:2 ratio (north vs west) but the speed and trough weakness may have been enough so that she can put some pressure on Bermuda or even Boston/Cape Cod area.

But with TD7 and a bunch of other disturbances coming off of Africa the fun (odd term) has just started for the next 8-10 weeks.....
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danielle on the rebound shes baaaaaaaaaaaack
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I think I see the eye..... I am probably wrong but look at center carfully.
http://www.ssd.noaa.gov/goes/flt/t1/rb-l.jpg
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1626. HarryMc
18Z NAM also has a nice little jog left at about 80 hours out compared to 12Z. Gonna give it a rest and check back in the morning. Night all.
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Quoting centex:
I would not give models too much credit for Danielle. I predict cape verde system in two week in the middle of August. While not a sure bet, not bad odds.


Yes we could all do that but the models dont do it cause they know the odds - like we could. They do it because of Scientific data and when they do it so far in advance as with this storm, its amazing
Member Since: August 22, 2010 Posts: 0 Comments: 652
1624. JLPR2
Quoting XStormX:
I'm not liking your new picture or avatar, que paso con la palma?


Learn to like it, that's actually me, I'm not a palm tree. XD LOL
Member Since: Posts: Comments:
000
ABNT20 KNHC 242335
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT TUE AUG 24 2010

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

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM DANIELLE...LOCATED ABOUT 895 MILES EAST OF THE LESSER
ANTILLES.

A BROAD AREA OF LOW PRESSURE LOCATED ABOUT 125 MILES SOUTHWEST OF
THE CAPE VERDE ISLANDS IS ACCOMPANIED BY A LARGE AREA OF CLOUDINESS
AND SHOWERS. ALTHOUGH SHOWER ACTIVITY HAS RECENTLY BECOME A LITTLE
LESS ORGANIZED...ENVIRONMENTAL CONDITIONS AND COMPUTER MODELS FAVOR
THE FORMATION OF A TROPICAL DEPRESSION DURING THE NEXT COUPLE OF
DAYS. THERE IS A HIGH CHANCE...90 PERCENT...OF THIS SYSTEM BECOMING
A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES
WEST-NORTHWESTWARD NEAR 15 MPH.

A LARGE AREA OF SHOWERS AND THUNDERSTORMS OVER THE CENTRAL GULF OF
MEXICO EXTENDING EASTWARD FOR SEVERAL HUNDRED MILES IS ASSOCIATED
WITH A SURFACE TROUGH. DEVELOPMENT...IF ANY...OF THIS SYSTEM IS
EXPECTED TO BE SLOW TO OCCUR AS IT DRIFTS WESTWARD. THERE IS A LOW
CHANCE...10 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 BLAKE
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Member Since: August 15, 2008 Posts: 0 Comments: 2133
XstormX..

I disagree with ur statement on post 1614..

Member Since: August 15, 2008 Posts: 0 Comments: 2133
1620. XStormX
Quoting JLPR2:
96L weakened slightly, pressure went up, yet the winds rose a little.
And look at this, it's heading west, yesterday it was moving towards the WNW.
Also, its identified as a Low(LO) instead of a disturbance(DB).

AL, 96, 2010082400, , BEST, 0, 121N, 191W, 25, 1006, DB
AL, 96, 2010082406, , BEST, 0, 130N, 210W, 25, 1008, DB
AL, 96, 2010082412, , BEST, 0, 131N, 235W, 25, 1008, LO
AL, 96, 2010082418, , BEST, 0, 130N, 253W, 30, 1008, LO
I'm not liking your new picture or avatar, que paso con la palma?
Member Since: August 19, 2010 Posts: 0 Comments: 171
Quoting LongBeachNY:
Can someone post the new gfs?

Good Evening.

LongbeachNY,

The 18Z GFS is particularly disturbing. Look at the animation. The Storm is so powerful, according to the GFS, that it plows right through the ridge building along the Eastern Seaboard.



Triple Tropical Trouble.
Member Since: April 1, 2010 Posts: 9 Comments: 2699
90% still on 96L, AOI in the Gulf now.
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1617. centex
I would not give models too much credit for Danielle. I predict cape verde system in two week in the middle of August. While not a sure bet, not bad odds.
Member Since: August 10, 2007 Posts: 0 Comments: 3278
1616. JLPR2
96L weakened slightly, pressure went up, yet the winds rose a little.
And look at this, it's heading west, yesterday it was moving towards the WNW.
Also, its identified as a Low(LO) instead of a disturbance(DB).

AL, 96, 2010082400, , BEST, 0, 121N, 191W, 25, 1006, DB
AL, 96, 2010082406, , BEST, 0, 130N, 210W, 25, 1008, DB
AL, 96, 2010082412, , BEST, 0, 131N, 235W, 25, 1008, LO
AL, 96, 2010082418, , BEST, 0, 130N, 253W, 30, 1008, LO
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Quoting aislinnpaps:
They really can't evacuate, can they? Could be disastrous. I saw one of those, "what if show" once. The sub city was underwater from a direct hit.

But they don't get water in, food, anything. They have an attitude of 'we don't get hit, nothing to worry about'.
Yep, hate to say it, but my area (TB) has the same attitude, "we never get hit" many say. But never, say never, right?
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Quoting MrstormX:
1596.) Wow really towards VA?


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Quoting Clearwater1:
I think maybe at landfall, the tides could be higher and then it would be a greater effect on the coast it hits, if any. Also, you can see the storm on visible satellite , longer, I've noticed, due to the extra light.


"extra light" - interesting.

But does a Lunar-like Tidal coriolis effect that aids in a hurricanes' intensification ?
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1609. XStormX
hello to all!!!
Member Since: August 19, 2010 Posts: 0 Comments: 171
Howdy all...
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Member Since: August 15, 2008 Posts: 0 Comments: 2133
Can someone post the new gfs?
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NOGAPS is known for being a pretty unreliable tropical model.... Or so I think
Member Since: May 27, 2009 Posts: 0 Comments: 4438
Member Since: August 15, 2008 Posts: 0 Comments: 2133
They really can't evacuate, can they? Could be disastrous. I saw one of those, "what if show" once. The sub city was underwater from a direct hit.

But they don't get water in, food, anything. They have an attitude of 'we don't get hit, nothing to worry about'.
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Quoting KanKunKid:


I think NYC will be safe from my "wishcasting", because:
1. I never get what I wish for, good or bad.
2. Whether it happens or not is something I have no control over, even in an occult sense.

However, my first visit to NYC was one I'll never forget. I also kissed the ground in Indiana when I got back home. Now, Indiana is not a very good kisser, but she sure was pretty to me.


Oh I don't think people can wish hurricanes in any direction either, just saying, I still felt bad about it. Indiana eh? Last year on a road trip (Ontario to Florida and back) we detoured a little ways so we could cross state lines and say we've been to Indiana. The town we passed through was called Rising Sun, we didn't kiss it though. ;oP
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1596.) Wow really towards VA?
Member Since: May 27, 2009 Posts: 0 Comments: 4438
Quoting MrstormX:
Isn't NOGAPS (lol) also trending towards the east coast?


No but whats so funny?
Member Since: August 22, 2010 Posts: 0 Comments: 652

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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.