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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1849. Skyepony (Mod)
I think the NASA DC-8 data today is part of the Pre-Depression Investigation of Cloud-Systems in the Tropics, atleast that's what the data page says.. Link
Member Since: Posts: Comments:
Quoting mcampb2811:
Has there ever been a year that 2 hurricanes or TSs have hit the US at the same time?


TS Bonnie and Hurricane charley in 04 made landfall in the same state in fact within a 24 hour window
Member Since: Posts: Comments:
SAB at T3.5:

SAB, JK, IM, 3, 3540 /////, , , , LLCC, T, DT=3.5 BO CBND MET=3.5 PT=3.5 FTBO DT PA=30 NMI

TAFB at T5.0, very generous IMO:

TAFB, JS, I, 3, 4550 /////, , , GOES13, CSC, T, DT = 5.0 BASED ON CENTER EMBEDDED IN B. NLINE NLIN

Based on this and the ATCF best track intensity,
it is likely that Danielle be upped to a category 1 hurricane at 11p.m EDT, which I agree with right now.
Member Since: Posts: Comments:
Quoting miamiheat:
,,,august 24th
,,,4 named Storms
,,,2 Hurricanes
,,,0 major
,,,0 landfall in USA

,,,"THE VERY ACTIVE HURRICANE SEASON 2010"

,,,yeahh right!!

someone once told me that forecasters tend to exaggerate and create panic, and now I can see why








Did you forget about Bonnie?
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Thanks
Member Since: Posts: Comments:
Quoting galvestonhurricane:


I'm sorry... what system are we talking about? I just got on.


2. 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.
Member Since: Posts: Comments:
Quoting miamiheat:
,,,august 24th
,,,4 named Storms
,,,2 Hurricanes
,,,0 major
,,,0 landfall in USA

,,,"THE VERY ACTIVE HURRICANE SEASON 2010"

,,,yeahh right!!

someone once told me that forecasters tend to exaggerate and create panic, and now I can see why









Bonnie made landfall on the US even though it was a total joke.
Member Since: Posts: Comments:
Quoting TampaSpin:
HOnestly the GFS and NGP have come together is very troubling. The NGP has been showing this move to the WEst nearly the entire time. Now to have the GFS start doing the same is something to watch for sure.


Yeah but the gfdl and the hwrf 18 z's are trending opposite and thats good. The GFS seems odd in that at 150 hours the ridge to the storms west completely and rapidly weakens and allows the storm to move almost just north of west. It just doesnt seem quite right but time will tell....
Member Since: August 22, 2010 Posts: 0 Comments: 652
Has there ever been a year that 2 hurricanes or TSs have hit the US at the same time?
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1837. will45
Quoting Capeskies:
Has the 0z run of the GFS come out yet?


starts at 11:30 PM
Member Since: July 18, 2009 Posts: 1 Comments: 994
ok
Member Since: Posts: Comments:
Quoting Tazmanian:
96L not fish


What is with everybody. It hasn't even developed yet and yet people are still saying its fish, what has this blog come to? And as far as i know the models are taking this pretty much west with a touch of a northerly movement to it. Patience is an absolute virtue.
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Quoting angiest:
Wooo GFS is going a little loco.


Looks like it's bowling LOL
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AL, 96, 2010082500, , BEST, 0, 136N, 267W, 30, 1008, LO,
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1832. bwt1982
Quoting Tazmanian:
96L not fish


Oh no, not you again on fish patrol! IMO 96L is a fish! Its my opinion and I am sticking with it. Just like Colin, Danille and 96L they are all fish to me and so far, I am right! So Taz you can keep wishcasting and I will keep being correct at "fishcasting"!!!! LOL
Member Since: Posts: Comments:
,,,august 24th
,,,4 named Storms
,,,2 Hurricanes
,,,0 major
,,,0 landfall in USA

,,,"THE VERY ACTIVE HURRICANE SEASON 2010"

,,,yeahh right!!

someone once told me that forecasters tend to exaggerate and create panic, and now I can see why







Member Since: Posts: Comments:
Looks like Danielle is taking a wobble north right now.
Member Since: Posts: Comments:
Quoting FLPandhandleJG:


Plus its going to be a slow mover as well.. right now its hard to say exactly where this potential system will go.. But most models have been point from south texas up too southwestern LA.. But we def need to watch it.. But im going out for now.. But bbl hopefully.. Gotta meet my girl for some drinks.. Everyone be safe and play nice.. ttyl


I'm sorry... what system are we talking about? I just got on.
Member Since: Posts: Comments:
Quoting Capeskies:
Has the 0z run of the GFS come out yet?



NOP
Member Since: May 21, 2006 Posts: 5091 Comments: 115439
1827. xcool
AL, 06, 2010082500, , BEST, 0, 179N, 491W, 65, 990


wnw
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Been gone all day but i've noticed as of the 5pm advisory that the track shifted west quite a bit.
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Quoting bwt1982:


LOL! I doubt that! Its just the year of the fish storms! Everyone should be thankful!
That statement is why we continue to have casualties because people dont believe that it will ever "come here" 25 years of fire/rescue in the State of Florida has taught me different.
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Has the 0z run of the GFS come out yet?
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Quoting centex:
Don't want to slam models too much but what would happen if we just had data feed to humans, wouldn't the tracks adjust similar? I just don't believe the programming is better than experts looking at the same data. I've been watching NWS and NHC forecast for years and they mention the models but also says how they discount them, change forecast inspite of them or pick one they seem to like. Where is the science, not in the models.
If no models, and just humans, then every storm would point to Florida, so most of the time the predictions would be wrong, correct me if I am wrong?
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HOnestly the GFS and NGP have come together is very troubling. The NGP has been showing this move to the WEst nearly the entire time. Now to have the GFS start doing the same is something to watch for sure.
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1821. bwt1982
Quoting Dakster:


Thank you for cursing us...


LOL! I doubt that! Its just the year of the fish storms! Everyone should be thankful!
Member Since: Posts: Comments:
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Quoting AtHomeInTX:


That doesn't sound very south Texas. Unless it goes that far west first.


Plus its going to be a slow mover as well.. right now its hard to say exactly where this potential system will go.. But most models have been point from south texas up too southwestern LA.. But we def need to watch it.. But im going out for now.. But bbl hopefully.. Gotta meet my girl for some drinks.. Everyone be safe and play nice.. ttyl
Member Since: August 15, 2008 Posts: 0 Comments: 2133
1817. XStormX
Quoting StormW:


Here is what he had as far as a post for 8:00 p.m.

TUESDAY 8 PM

GFS TRENDING WEST WITH TROPICAL CYCLONES.

The wild 18z run which tries to "short cut" danielle into the mid and upper atlantic coast is a long shot, but shows the problem we have with this pattern, and will

probably have to deal with once or twice on the east coast this hurricane season. Whether its Daniel or a future storm, the kind of pattern that occurred in years like 1933, 1995,2003, when storms threatened further north than normal while moving west of north is a function of the tendency for ridges to build further north than normal so they are able to block storms. Given these storms are like corks in the water, they are looking for ways to join the main stream but when that stream becomes confused because of abnormal positive heights to the north, it can lead to what you see in the model on some of its runs. The 18z run is simply following some of the ensemble runs, which you do not see, and by the way can be seen if you look at not only individual GFS runs, but also the Canadians and the NAEFS.

I cant answer the question now if it will do this except to say that until a storm is absorbed in the westerlies this year, it is best not to simply write it off.

The overall pattern is such that there is reason to now watch everything. The Hatch it people have not upped the system in the eastern atlantic, I would have, but then again I dont have a hatch it job. It is interesting to note they are now seeing my worries in the gulf. In close western gulf development is possible Thursday into Friday and then off the south atlantic coast on the weekend.

In the week heading to Labor Day, the focus of deep tropical wave development or movement should shift into the Caribbean and gulf. The fact the pattern turns hot this weekend into next week and the tropics are coming to life should give lovers of the summer somthing to crow about. Its a heck of a an end game... major chill coming in and reversing to what may be record heat centered in the lakes early next week.. a pattern favoring the development of tropical cyclones even more than normal right at the height of the season.... ( forgive me, I have been setting this MJO cycle up for almost 6 months now ( first forecast came out in Feb ) so it will be be tough for me to quit on it given what I am seeing now.

Hopefully you will see enough of it to convince you of the merit of some of the theories I have on all this. If not, well the sun rises each morning for all of us that are fortunate enough to make it through the night.

ciao for now


that was deep
Member Since: Posts: Comments:
Quoting KerryInNOLA:
Elway is not my brother, he's my bro. He just left for happy hour and thanks you all for your support.


Pleasure...actually just having severe NOLA withdrawals been back for 8 days and I am detoxing from Rue Bourbon!!
Member Since: August 18, 2008 Posts: 0 Comments: 2265
Quoting nrtiwlnvragn:


1764 28mb gif


ty
Member Since: March 10, 2010 Posts: 1 Comments: 7874
96L not fish
Member Since: May 21, 2006 Posts: 5091 Comments: 115439
1812. xcool
24/2345 UTC 18.0N 48.8W T3.5/4.0
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting Hurricanes101:
something from the cimss site that was posted on here is really causing my computer to slow down


1764 28mb gif
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1810. Dakster
Quoting bwt1982:
96L=Fish!!! Florida is in the clear again!!!! 2010 was a good year for us in the sunshine state for a slow tropical season!


Thank you for cursing us...
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1809. Ossqss
Quoting Snowlover123:


NAM turns it to the west in the later part of the run.



I was referring to the shear that was showing up on both systems in the NW quadrant on the extended run. Kinda like last night :)

http://weather.myfoxtampabay.com/maps/WTVT/custom/models/wrf/wrf_shear.html
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1808. Dakster
Quoting StormW:


Most likely, and, I don't think the U.S. is in any danger as it stands right now.


I hope you are not trying to CON US into thinking we are safe. :-)

Member Since: Posts: Comments:
I am still a novice after several years of sitting in on the blog as a lurker. I have heard of dry air intrusion, and Saharan air coming across the Atlantic. Is there a difference?
Member Since: Posts: Comments:
Quoting StormW:


Here is what he had as far as a post for 8:00 p.m.

TUESDAY 8 PM

GFS TRENDING WEST WITH TROPICAL CYCLONES.

The wild 18z run which tries to "short cut" danielle into the mid and upper atlantic coast is a long shot, but shows the problem we have with this pattern, and will

probably have to deal with once or twice on the east coast this hurricane season. Whether its Daniel or a future storm, the kind of pattern that occurred in years like 1933, 1995,2003, when storms threatened further north than normal while moving west of north is a function of the tendency for ridges to build further north than normal so they are able to block storms. Given these storms are like corks in the water, they are looking for ways to join the main stream but when that stream becomes confused because of abnormal positive heights to the north, it can lead to what you see in the model on some of its runs. The 18z run is simply following some of the ensemble runs, which you do not see, and by the way can be seen if you look at not only individual GFS runs, but also the Canadians and the NAEFS.

I cant answer the question now if it will do this except to say that until a storm is absorbed in the westerlies this year, it is best not to simply write it off.

The overall pattern is such that there is reason to now watch everything. The Hatch it people have not upped the system in the eastern atlantic, I would have, but then again I dont have a hatch it job. It is interesting to note they are now seeing my worries in the gulf. In close western gulf development is possible Thursday into Friday and then off the south atlantic coast on the weekend.

In the week heading to Labor Day, the focus of deep tropical wave development or movement should shift into the Caribbean and gulf. The fact the pattern turns hot this weekend into next week and the tropics are coming to life should give lovers of the summer somthing to crow about. Its a heck of a an end game... major chill coming in and reversing to what may be record heat centered in the lakes early next week.. a pattern favoring the development of tropical cyclones even more than normal right at the height of the season.... ( forgive me, I have been setting this MJO cycle up for almost 6 months now ( first forecast came out in Feb ) so it will be be tough for me to quit on it given what I am seeing now.

Hopefully you will see enough of it to convince you of the merit of some of the theories I have on all this. If not, well the sun rises each morning for all of us that are fortunate enough to make it through the night.

ciao for now



haha This is minor, but I like how Joe writes "Daniel" instead of "Danielle" is this a gender changing storm?
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Quoting StormW:


As far as?
3 storms coming toward the northeast?
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1803. KEEPEROFTHEGATE (Mod)
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1802. bwt1982
96L=Fish!!! Florida is in the clear again!!!! 2010 was a good year for us in the sunshine state for a slow tropical season!
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1801. angiest
Wooo GFS is going a little loco.
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Quoting jason2010xxxx:
she off her path


no she not
Member Since: May 21, 2006 Posts: 5091 Comments: 115439
Quoting alpha992000:


Ah, Churumba Weather... Yes, I remember. Who can forget? LOL

I spent all day away from the PC and now I get back to a significant shift in models. Scary stuff. Not too sure our infrastructure is strong enough to stand a tropical storm/hurricane and I don't particularly fancy another 2 weeks without power nor water. And don't even get me started on surviving this heat without at least a fan! :(


I spend a lot of time in the major hotels after a storm. At least they have cisterns and generators. I am blond and originally from the states so they think I am just one of their guests. Got to keep the tourists happy.

But seriously, I hope that the movement to the west is minimal and that all the storms recurve and do not affect land (including Bermuda)
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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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