Danielle a hurricane; TD 7 forming off coast of Africa

By: Dr. Jeff Masters , 2:18 PM GMT on August 24, 2010

Share this Blog
2
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 899 - 849

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68Blog Index

Puerto Rico Tropical Update and Effects from Hurricane Danielle
Link
Member Since: Posts: Comments:
Quoting Hurricanes101:


well even the NHC knows intensity is so hard to predict, I never give them a hard time for that one

Do you think Danielle is trying to pop out an eye? If so, where?
Member Since: Posts: Comments:
Thank you, StormW!
Member Since: Posts: Comments:
Anything past 45W is highly uncertain in terms of track for 96L.
Member Since: Posts: Comments:
lots of weather anomalies worldwide. here in northern ca, we have had fog every morning for 2 months and lucky to reach 80. mid to high 90's is our normal which we have had for 2 days now but it's gonna go back to the "fog n 80's" in a couple of days.

fog n 80's isn't that a song. lol
Member Since: Posts: Comments:
Quoting Hurricanes101:
I love how some are going all the way back to the first advisory and saying "hey the NHC has done a great job"

well they have for the most part, but do not ignore that each advisory the track has been off a bit more

last nights 11pm track was off by quite a bit in the short term, of course it could even out and in the end the NHC could be right, but if we are going to look at one side of this, we should look at both.


Just look at the NHC advisories and notice how they go down the model consensus every time....it's just their way. If the models were off to the north the NHC will be as well. Rarely, if ever, will you ever find their track outside of the model guidance envelope. True, our models have some skill which has been improved over the years and thus the NHC skill has improved as well, but any time the models make a massive mistake in unison, the NHC is right there making it with them, and that is why they aren't as good as they could be if they dared to defy the models. I can see why they don't though.....I mean I would be hesitant to as well if the world's eyes were watching my forecast.
Member Since: Posts: Comments:
892. shauntanner (Admin)
Listen to Dr. Masters here on the Hurricane Haven. Ask questions for the Dr. on this blog.
hmm jurakantaino 96L is moving WSW-SW


Danielle looks to be at now 16.8N 47.8W at 18:45utc 17.1N 47.5W at 17:45utc or between 17:15utc and 17:45 utc
Member Since: Posts: Comments:
Jason, funny vid. And you summed it up pretty good. I'm guessing that you don't have a PH.D. either...lol
Member Since: August 3, 2005 Posts: 10 Comments: 5680
think Danielle is looking better or at minimum organizing i think it's intensity will stay the same though
Member Since: Posts: Comments:
Quoting KanKunKid:


Uh, oh.

Love it! We worry about the same area!
Member Since: Posts: Comments:
Quoting EricSFL:


As well as the intensity forecast.


well even the NHC knows intensity is so hard to predict, I never give them a hard time for that one
Member Since: Posts: Comments:
Quoting Hurricanes101:
I love how some are going all the way back to the first advisory and saying "hey the NHC has done a great job"

well they have for the most part, but do not ignore that each advisory the track has been off a bit more



As well as the intensity forecast.
Member Since: Posts: Comments:
880. P451 7:45 PM GMT on August 24, 2010

No, haven't you heard? any of us that think it will get close to Bermuda is nuts
Member Since: Posts: Comments:
I love how some are going all the way back to the first advisory and saying "hey the NHC has done a great job"

well they have for the most part, but do not ignore that each advisory the track has been off a bit more

last nights 11pm track was off by quite a bit in the short term, of course it could even out and in the end the NHC could be right, but if we are going to look at one side of this, we should look at both.
Member Since: Posts: Comments:
LOL Jason.
Member Since: Posts: Comments:
Quoting wayfaringstranger:


Sorry about that sir. I was thinking about enrolling in the Navy and had some questions. Anyhow I will email you.


A person does not "enroll" in the Navy, or any other military service. If you think it will be like school, you need to rethink that.
Member Since: Posts: Comments:
877. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15684
875. Jaxen
Not a big fan of seeing the 96L models windshield-wipe to the left, although farther out they just about all have a turn to the NW/NNW.
Member Since: Posts: Comments:
thanks elite forecaster and I know I will probably look like a fool for asking this question and Storm has been nice enough to explain this but by looking at this chart, is this an increased chance of landfalling hurricanes? Thanks
Member Since: Posts: Comments:
872. shauntanner (Admin)
Listen to Dr. Masters on the Hurricane Haven at 4 p.m. ET, 1 pm PT. Listen here.
http://www.wunderground.com/wxradio/wubroadcast.html
You can submit questions for Dr. Masters here, on his blog, as well.
yes TAZ that is ex-TD5 hey maybe they might call it TD5 when it get better looking
Member Since: Posts: Comments:
From 11pm last night

24HR VT 25/0000Z 18.3N 47.5W 100 KT


Can this be questioned or is that just blashamy?

I am seeing Danielle at 17N 48W and it isn't even 5pm, quite a big difference in a 24-hour forecast wouldn't you say?
Member Since: Posts: Comments:
Quoting wayfaringstranger:


Sorry about that sir. I was thinking about enrolling in the Navy and had some questions. Anyhow I will email you.


LOL..

no Sir required,,I twas a enlisted man,,and a civilian Living in NOLA now.
Member Since: Posts: Comments:
Quoting Patrap:
USMC 80-86.

That's the USMC Emblem. But I served on Many a Naval Vessel.

USS Raleigh for 1.


Pat, how come only 6 years?
Member Since: Posts: Comments:
Quoting duajones78413:
Where is the home brew?

I got some in my kegerator at home...
Member Since: Posts: Comments:
864. xcool


update
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting HCW:
96L 18Z runs from the NHC



thanks
Member Since: Posts: Comments:
Quoting StormW:


...and POOF! Oh, and I'm not here to turn you on anyway...I'm here to provide ACCURATE information...for folks that want it. I tell ya what, you go back and read for the past week, and tell me that there isn't ANYTHING in my forecasts that haven't materialized!
you are right storm, this has shifted more west!
Member Since: Posts: Comments:
Quoting Patrap:
USMC 80-86.

That's the USMC Emblem. But I served on Many a Naval Vessel.

USS Raleigh for 1.


Sorry about that sir. I was thinking about enrolling in the Navy and had some questions. Anyhow I will email you.
Member Since: Posts: Comments:
OK, enough is enough with the StormW bashing! Storm takes time out of his day (almost everyday) to put together a synopsis and then answers questions throughout the day. Sometimes the same question over and over again. I'm sure it gets very frustrating sometimes to have to constantly repeat yourself. He's not getting paid to do this, he does it out of his love for weather and he wants to help those of us who truly want to learn more about storms. Now, I don't know Storm personally, but I say keep up the good work! There are many who appreciate you in this community. Off my soapbox. I'll go back to lurking now...
Member Since: Posts: Comments:
Quoting Relix:


Nice model shift there. Closer to putting the islands at risk now.
To far north already and south of CV, is quite a distance from the northern Antilles, it has to move west without the slightest wobble to the north in order to affect the island directly, but interesting nevertheless,kind of fun to watch how this one plays out.
Member Since: Posts: Comments:
Quoting blueyedhrlyridr:
Just my Opinion, Dont throw hammers at me please. I really think we need to watch the Northwest Gulf for a Thursday or Friday td or ts before moving in around the Galveston area. JUST MY OPINION


I'll be gentle. :) I think you're right after looking at the models and the "inverted trough" supposedly headed our way.

Member Since: Posts: Comments:
Quoting clwstmchasr:


The last thing I want to do is get in the middle of the arguments because I am no forecaster. However, you said that the NHC has been somewhat off with Danielle. I read a post earlier today that had their 72hr forecast points from advisory #1.

72hr forecast from Advisory #1
17.5N
47.5W
Current
16.6
46.5

If we are calling that somewhat off 3 days out then in my opinion we are being too nit picky or our expectations are way too high.

Now, that is where we are right now. IMO, based on StormW and Levi's comments, they will have to shift a bit to the west. How much? Let's wait and see.


how about 11pm last night when they said Danielle would be at 18.5N 47.2W? Can that be questioned?
Member Since: Posts: Comments:
Post 826 - TAZ -- what's going on in my back yard????
Member Since: Posts: Comments:
854. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15684


Member Since: Posts: Comments:
GOM IR Loop

Member Since: Posts: Comments:
so stormW, do you think that danielle has any possibility of hitting the east coast? in my opinion, it is unlikely, but still possible. just wondering what your opinion is! TIA!
Member Since: Posts: Comments:
Quoting Tazmanian:
StormW dont tell me this is X TD 5


The Gulf looks like it is ready to spin up a little something....Very agitated on the satellite pics..
Member Since: Posts: Comments:

Viewing: 899 - 849

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68Blog Index

Top of Page

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.

Local Weather

Overcast
27 °F
Overcast