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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2899. pottery
Quoting surfmom:
SWFL/Gomex - waves and weather were too rough for me yesterday - got a shot of getting out there this afternoon.
The little yellow circle in the Gomex has most Surfers happy... though it has me a wee bit concerned
Also wondering what this is doing to all the OIL mixed w/dispersants in the Gulf from the BP spill -- it's certainly breaking it up, but that also means it will be washing UP somewhere -- whether or not we can see the oil -- the stuff is still toxic.

Incredible to me, that the Nasty Stuff has remained generally offshore all this time.
The chances were pretty good for a Horrible event.
So far, the weather has been exceedingly kind as far as the Nasty is concerned.
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Quoting tkeith:
you're up early today Taz...




olny druing the summer
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2896. tkeith
Quoting Tazmanian:
meno for the nhc plzs make 96L a TD
you're up early today Taz...
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meno for the nhc plzs make 96L a TD
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2894. surfmom
Quoting pottery:
Heh!!
Looks like August people Rule.......
Naturally, of course.


Well, Pottery -- if you were in charge -- the world would be a much happier place - Lordy, we could do Rum w/our Cafe' first thing! Surfing would be the national sport & perhaps Peace would Prevail
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2893. KEEPEROFTHEGATE (Mod)
Quoting Relix:
Near 100%. Why not just name it? XD

G'morning WU!
it will be named in about hour well renumbered anyway
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2892. surfmom
SWFL/Gomex - waves and weather were too rough for me yesterday - got a shot of getting out there this afternoon.
The little yellow circle in the Gomex has most Surfers happy... though it has me a wee bit concerned
Also wondering what this is doing to all the OIL mixed w/dispersants in the Gulf from the BP spill -- it's certainly breaking it up, but that also means it will be washing UP somewhere -- whether or not we can see the oil -- the stuff is still toxic.
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2891. tkeith
Quoting pottery:

That's just weird....
Coincidence, you think?
Does Jeff have a graph to prove this?
lol...I'm sure of it
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2890. Relix
Near 100%. Why not just name it? XD

G'morning WU!
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great post jeff.While they still have difficulty with intensity and they admit they are usally close as humanly possible on track and forward speed.And for people to come on here and say its thier right to come on here and critisize them that this is a hobby blog.Well thats the same people that get upset when somebody critisizes obama lol. But seriously there are people that do read this blog regurally or see the nhc constantly ridiculed where they may believe these hobbyist.Also this is for ike and Destin Jeff.The same gfs everybody gets hyped up on when it shows development(as far as the 00z run shows.) Nothing significant hitting the conus or more in tune in our area the ncnegc regoin.As far as us in our area looking at climatologically history since 1964 the only hurricanes to hit the northern gulfcoast were hilda, juan, Kate, opal,lili.Now sc and se fla is different they do see threats into nov.So when i have been accused of not presenting facts,well these are facts.So ike if we get through the next 4 weeks on the northern g/c without a hurricane strike odds greatly favor a quiet season for our aea.Also another fact.The troughs are comming quite far south already .Been much less humid and drier air here on the ms coast last few days look at the wator vapor image.So that tells me in sept with even deeper troughs and dry air in the northern gulf if this continues that bodes well for us.Now this is present casting lol. Also look at the east coast of florida climatological history.How many westward moving storms from the atlantic have hit florida?East coast of florida oct and later get hurricane conditions that come form the gulf side moving east.Examples wilma, irene. So if the gfs 384 continues to show fish we are getting closer and closer to a lot of the conus being climatologically closer to the threat of a hurricane strike lessening.I think with the interneta nd all these models and mojo charts we ignore history and climatology.these are facts and present setup not down or wishcasting have a blessed day.
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2888. pottery
Heh!!
Looks like August people Rule.......
Naturally, of course.
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Astronaut takes a dive in Cayman.


(CNS): While he may have missed out on the giant leap for mankind Buzz Aldrin enjoyed a giant splash in Cayman last week when he visited the islands for and enjoyed a spot of diving. The famous former astronaut, who was the second man on the moon after Neil Armstrong during the Apollo 11 voyage in 1969, was here on behalf of the Astronaut Scholarship Foundation which provides college scholarships to top science and engineering students across the USA.
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2886. pottery
Quoting stormwatcherCI:
Hmm, that's funny. My mother had 3 in August.

LOL....triplets!
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2885. surfmom
Quoting stormwatcherCI:
Hmm, that's funny. My mother had 3 in August.


TIMING IS EVERYTHING - lol - weather & kids
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AM surfmom:
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2883. KEEPEROFTHEGATE (Mod)
morning wunder ground
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2882. pottery
Quoting Thundercloud01221991:


so are 1 in 12 people born in January too.... :)

That's just weird....
Coincidence, you think?
Does Jeff have a graph to prove this?
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2881. scott39
Quoting pottery:

Early Greetings from me then!!
August People are The Best!!
And here is an interesting Statistic...

Only one in twelve people are born in August!

Pretty Unique, huh??
My Mom aways said I was "unique". She had few other names for me too! LOL 8/26/69
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2880. IKE
Quoting surfmom:

Bawhahaaahaaaaa - you crack me up Pottery
Morning Cot! IKE, TAZ


Morning surfmom.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
This is amazing. Danielle still hasnt gained above 20 N

Location: 18.8°N 51.0°W
Max sustained: 85 mph
Moving: WNW at 17 mph
Min pressure: 982 mb


Some models are forecasting a track west of Bermuda now while most have readjusted their trac more west again.

Strengthening should occur but vertical sheering becomes less conducive the closer Danielle gets to Bermuda.

96L should be reaching a TD classification any moment now and should reach TS as early as this evening or tomorrow morning.

Whatever chance the L in the GOM had of materializing into anything has pretty much dimished and hasnt organized into much of anything.

Elsewhere, good morning my friends its hump day!
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Quoting pottery:

Early Greetings from me then!!
August People are The Best!!
And here is an interesting Statistic...

Only one in twelve people are born in August!

Pretty Unique, huh??
Hmm, that's funny. My mother had 3 in August.
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Quoting scott39:
Goodmorning, Do we analyze the NHC when a TC goes N of a tropical point too? Nah, just S! LOL


Actually we were talking about Longitude.
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2876. surfmom
Quoting canefreak:
Hey Storm - when is your next update? I am curious about the GOMEX feature.....

me TOO!
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Quoting pottery:

Early Greetings from me then!!
August People are The Best!!
And here is an interesting Statistic...

Only one in twelve people are born in August!

Pretty Unique, huh??
You can add me in there too. Was 54 on the 3rd and I agree, August people ARE the best.
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Quoting pottery:

Early Greetings from me then!!
August People are The Best!!
And here is an interesting Statistic...

Only one in twelve people are born in August!

Pretty Unique, huh??


so are 1 in 12 people born in January too.... :)
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2873. KEEPEROFTHEGATE (Mod)
NMFC Norfolk Tropical Feed
As of WED 25 Aug 2010 12:01:02Z
Active Tropical Warnings in the Atlantic, Caribbean, or Gulf of Mexico
HURRICANE 06L (DANIELLE) Warning C1
Atlantic Tropical Cyclone Formation Alert (TCFA) 96L
Active Tropical Warnings in the Northwest Pacific, North Indian Ocean, Central Pacific, Eastern Pacific, or Southern Hemisphere
Tropical Storm 09E (Frank) Warning
2010 Storms
All Active Year
Atlantic
96L.INVEST T.C.F.A.
06L.DANIELLE
East Pacific
09E.FRANK
Central Pacific

West Pacific
98W.INVEST
97W.INVEST
Indian Ocean

Southern Hemisphere
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Quoting pottery:

That is plenty rainfall!
Where is it?


Good Morning...Callaway Florida, but most identify with Panama City.

v/r

Jon
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2871. pottery
Quoting StormW:


Pottery,
I saw you were speaking of accumulated years...don't put mine in there, we'll be over the top...53 in two days.

Early Greetings from me then!!
August People are The Best!!
And here is an interesting Statistic...

Only one in twelve people are born in August!

Pretty Unique, huh??
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Quoting CoopsWife:


Ok - no more talk about blind fish, LOL. ODU - you from Norfolk?


No, chucktown SC, but I spend a lotta time in norfolk :-D
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2869. surfmom
Quoting pottery:

I can Respect that.
Good post.
But the Game is, to try to come up with a scenario that is different to the NHC, so we can say "I told you so! I am Fabulous!"
And since it is Weather, sometimes we get it right.........

Bawhahaaahaaaaa - you crack me up Pottery
Morning Cot! IKE, TAZ
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2866. scott39
Goodmorning, Do we analyze the NHC when a TC goes N of a tropical point too? Nah, just S! LOL
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good morning
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The GOM doesn't look as impressive as yesterday...unless I am missing something. hmmmmmm

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Quoting StormW:


Be about a couple of hours...got another to get off to school this morning.
Thanks - I'll be on the lookout.
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Quoting pottery:

LOL Taz!
And he gets the egg free, right?



no the eggs will coast him $1,000
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2859. pottery
Quoting Tazmanian:





the tip is $500 lol

LOL Taz!
And he gets the egg free, right?
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Quoting odubhthaigh:
Seriously, no more talk about food this morning *whine* Normally I don't mind it, but I had to skip brekkie this morning and I'm afraid the rumbling of my stomach's going to set off the seismographs in the surrounding tri-state area.


Ok - no more talk about blind fish, LOL. ODU - you from Norfolk?
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Hey Storm - when is your next update? I am curious about the GOMEX feature.....
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Quoting JupiterFL:


That is as good as it gets. The NHC does an excellent job for the most part. Your really concerned with twists and turns?


I agree most positively that the NHC does a fantastic job. The models while not perfect have improved greatly over time. The amount of uncertainty in that 3 day track however is large enough for a storm that was predicted to hit Jacksonville to hit Miami instead. That is all that I'm saying. Now I'm going to bed.
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2854. pottery
Quoting Eagle101:
Good Morning WU...

Very unusual rain event last night...constant rain from approximatly 12:00am to 03:30 this morning...moderate to heavy thunderstorms. Very small scale system however, none-the-less recorded 5.10 inches of rain.

Very Respectfully,

Jon

That is plenty rainfall!
Where is it?
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Quoting StormW:


How much of a tip Taz?





the tip is $500 lol
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2852. KEEPEROFTHEGATE (Mod)
06L/H/D/C1
MARK
19.87N/51.11W

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2850. KEEPEROFTHEGATE (Mod)
T.C.F.A.
xx/xx/96L
MARK
12.63N/28.98W
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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.