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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Wow

Major Hurricane for the NE?

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Thanks storm...
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168 hours, Danielle, Earl, and Fiona. Danielle approaching the U.S with a banana ridge to the north this is heading W/WNW.

Member Since: September 2, 2009 Posts: 130 Comments: 21193
Quoting ROBTX09:
prweathercenter idk think so all it needs is pretty much convection


No, it needs a well-defined circulation.
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Quoting eliteforecaster:


Well its removed now...no idea why, but whatever.


For those who missed it, here is the latest SRSO (Super Rapid Scan Operation) on Danielle from Goes-15. The animation ends at 4:34 est.

http://cimss.ssec.wisc.edu/goes/blog/wp-content/uploads/2010/08/100824_g15_vis_srso_2_anim.gif


Taken from Here.
Neat page!
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1392. NJ2S
Quoting xcool:


18z


at the end of this run is that a jog to the nw toward the N E U.S??
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1378. PRweathercenter 10:28 PM GMT on August 24, 2010

That is last nights 00Z run you are showing
Member Since: March 10, 2010 Posts: 1 Comments: 7715
Quoting MiamiHurricanes09:
Two hurricanes with a third one trying to become a tropical cyclone. 108 hours:




is there even a 4th one lol
Member Since: May 21, 2006 Posts: 5091 Comments: 115107
what does Danielle's eyewall looks like now
Member Since: August 1, 2006 Posts: 28 Comments: 3716
1388. xcool
so take gfs126hrs before going out to sea quite interesting
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1387. KEEPEROFTHEGATE (Mod)
Quoting KanKunKid:
Does anybody know where I can find the actual track lat lon points of Danielle?

HERE YA GO

0610081912 110N 236W 25
0610081918 110N 241W 25
0610082000 110N 247W 25
0610082006 110N 253W 25
0610082012 110N 260W 25
0610082018 104N 290W 25
0610082100 104N 296W 25
0610082106 105N 303W 25
0610082112 106N 310W 25
0610082118 108N 318W 25
0610082200 112N 323W 25
0610082206 117N 330W 30
0610082212 122N 339W 30
0610082218 132N 346W 30
0610082300 139N 359W 40
0610082306 143N 373W 50
0610082306 143N 373W 50
0610082312 148N 387W 50
0610082312 148N 387W 50
0610082318 152N 407W 65
0610082318 152N 407W 65
0610082400 155N 425W 75
0610082400 155N 425W 75
0610082400 155N 425W 75
0610082406 157N 440W 85
0610082406 157N 440W 85
0610082406 157N 440W 85
0610082412 161N 458W 75
0610082412 161N 458W 75
0610082412 161N 458W 75
0610082418 171N 475W 60
0610082418 171N 475W 60
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Skepony: Looks like a big anticyclone formed over MS this morning causing very low shear in the area..Since it's been drifting south toward the wanna be blob in the Gulf of Mexico.
-------
I see three wannabees. Looks like two get developed.
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Wow

At 168 hours Danielle is approaching the CONUS

This is quite a run.

174

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Quoting philliesrock:
18z GFS says get ready Bermuda...a hurricane is coming for you. At least it appears that way through 72.


The 18z vs 12z run are nearly the same in relation to Bermuda.
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LOOKS LIKE A PARADE OF STORMS IN THE 18Z GFS!
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Hey I noticed on the 18 Z GFS model it has a huge ridge of high pressure over the Northeast..wouldnt that force Danielle towards the Northeast/New England?
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invest 96 doesn't look that great, i think the chances of 90 percent are way too high, maybe a medium chance is more reasonable 40-50 percent.

The GFS does turn invest 96 into a formidable hurricane about a week from now.

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1377. HarryMc
What is it with 18Z GFS, D chugs along and looks like it parks for a day or so. Huh.
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Holy crap lol, this run is about to hit/brush the Northeast.
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Very close proximity.

Member Since: September 2, 2009 Posts: 130 Comments: 21193
Quoting philliesrock:
The GFS has Danielle moving WNW at 150, lol. At such a high latitude, I doubt it.


why?

if the ridge is to its north, it is a possibility

there is no written rule that says there is a certain latitude that storms cant go west
Member Since: March 10, 2010 Posts: 1 Comments: 7715
1373. xcool
MiamiHurricane.god olny knows ..
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1372. Engine2
Quoting StormW:


She's definitely not vertically stacked, however, only slightly. Vorticity is just a little WNW of the center.

Hard to tell on the center right now, as the satellite loop imagery is transitioning from RGB/VIS to the point where I have to use IR2.
Ok thank you as always storm
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Quoting xcool:
MiamiHurricane yup about getting wid & crazy
It was going to happen at some point with the pattern we're in so, there you have it. Hopefully they all head out to sea.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
Quoting StormW:


She's definitely not vertically stacked, however, only slightly. Vorticity is just a little WNW of the center.

Hard to tell on the center right now, as the satellite loop imagery is transitioning from RGB/VIS to the point where I have to use IR2.


wumail...
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Quoting ROBTX09:
hr 126 develops a third system



All I can say is, its go time and a lot of people need to be prepared.
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1368. xcool
MiamiHurricanes look at Danielle nott move..
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The GFS has Danielle moving WNW at 150, lol. At such a high latitude, I doubt it.
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Two hurricanes with a third one trying to become a tropical cyclone. 108 hours:

Member Since: September 2, 2009 Posts: 130 Comments: 21193
Danielle is gradually reorganizing. I imagine it will be a hurricane again tomorrow morning then steady intensification afterwards.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
1362. Melagoo


Firing up again!
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1360. KEEPEROFTHEGATE (Mod)
06L/TS/D/CX
MARK
17.43N/48.63W

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Wow.

The GFS develops another storm behind "Earl"

3 storms at once. Impressive.
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1357. xcool
MiamiHurricane yup about getting wid & crazy
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Quoting xcool:
Looks like this image from 2008:

Member Since: September 2, 2009 Posts: 130 Comments: 21193
1354. xcool
some many areas to watch Danielle 96L Gulf of Mexico and gfs shows new storms..
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Looks like 17N 48 W.

But this image is from 4:29 est.
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Something very weird may be about to happen with this run of the GFS, with Danielle's close proximity to Earl.
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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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