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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2949. surfmom
Quoting NovaScotia33:


Excuse my ignorance, but looking at this chart, I only see one path that veers away from Nova Scotia.Does anyone think there is still a chance that Nova Scotia will get affected at all? Thanks


HOPE NOT - got friends up there and your ocean is mean even w/out a storm
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models show another system behind td7. but all pay follow the leader out to sea.were lucky to have a weak a/b high during this time otherwise a pattern like 2004 we would be looking down the gun
[s}.
Member Since: October 19, 2005 Posts: 0 Comments: 234
Quoting tkeith:
Let me guess...fish?



not fish
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lol - Jeff.

Orca - I will send you some rain. We have been "rain free" since Sunday - thank goodness!
But I know that the chances are creeping back into the forecast. I will make arrangements with Mother Nature Express Service and ship you some ASAP!..lol
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Tropical storm Frank:



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Quoting vince1966:
Is there any models predicting a large storm for the Gulf, namely Mobile? I need a big one to wipe out my house so I can get out of here. Tired of the Insurance hassle. Lat 30.68 Long 88.25.


30.17N 90.50W here. It can have my house as well, I hate it. I still want my lot though it's deep draft waterfront.
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invest_RENUMBER_al962010_al072010.ren
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2942. tkeith
Quoting jason2010xxxx:
WE HAVE 07L.SEVEN NOW
Let me guess...fish?
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2941. surfmom
Quoting Orcasystems:


You have to keep bragging don't you.
Hopefully we are suppose to get some rain in a few days.

are you still in tinder conditions????
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mode runs where right about forcasting two name storms and look what we got
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000
WHXX01 KWBC 251234
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1234 UTC WED AUG 25 2010

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

TROPICAL CYCLONE SEVEN (AL072010) 20100825 1200 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
100825 1200 100826 0000 100826 1200 100827 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 14.2N 30.3W 14.8N 33.8W 15.2N 37.0W 15.7N 40.1W
BAMD 14.2N 30.3W 15.0N 32.7W 16.0N 35.3W 17.1N 37.8W
BAMM 14.2N 30.3W 15.0N 33.3W 15.8N 36.5W 16.6N 39.5W
LBAR 14.2N 30.3W 14.7N 33.6W 15.4N 37.2W 16.3N 40.8W
SHIP 30KTS 35KTS 42KTS 49KTS
DSHP 30KTS 35KTS 42KTS 49KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
100827 1200 100828 1200 100829 1200 100830 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 16.1N 43.1W 17.1N 48.7W 19.1N 54.8W 21.9N 59.5W
BAMD 18.1N 40.6W 19.4N 45.9W 20.5N 51.0W 22.5N 56.4W
BAMM 17.2N 42.6W 18.0N 48.9W 19.2N 54.6W 20.7N 58.3W
LBAR 17.0N 44.2W 17.8N 50.2W 17.7N 54.0W 19.7N 57.4W
SHIP 59KTS 73KTS 79KTS 85KTS
DSHP 59KTS 73KTS 79KTS 85KTS

...INITIAL CONDITIONS...
LATCUR = 14.2N LONCUR = 30.3W DIRCUR = 270DEG SPDCUR = 20KT
LATM12 = 14.0N LONM12 = 25.8W DIRM12 = 278DEG SPDM12 = 19KT
LATM24 = 13.1N LONM24 = 23.5W
WNDCUR = 30KT RMAXWD = 40NM WNDM12 = 30KT
CENPRS = 1007MB OUTPRS = 1010MB OUTRAD = 200NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

$$
NNNN
Member Since: August 23, 2008 Posts: 7 Comments: 5300
2936. tkeith
Quoting DestinJeff:


LocalMet (awesome handle, by the way) is just a westcaster.
LOL...I thought the same thing :)

umm, can I still quote you?
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Quoting AllStar17:


Excuse my ignorance, but looking at this chart, I only see one path that veers away from Nova Scotia.Does anyone think there is still a chance that Nova Scotia will get affected at all? Thanks
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and 07L is on the navy site
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2933. surfmom
Quoting pottery:
P.S...
it is coming down in Torrents right now.
Roof-Gutters are overflowing............

ahhh good to fill the rain barrels, wells & cisterns
my rain barrels runneth over today
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Quoting Cotillion:
BEGIN
NHC_ATCF
invest_RENUMBER_al962010_al072010.ren
FSTDA
R
U
040
010
0000
201008251224
NONE
NOTIFY=ATRP
END



oh my god my be loveing nhc did the right thing


we now have TD 7
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2930. 900MB
Morning All!

Storm, local Met here (WABC NYC) pointed out last night that he noticed a handful of models throwing a left hook. I see that a couple of the 2am models have Danielle aimed at or West of Bermuda. What are they picking up on? What are the odds that this thing hits Bermuda, or gulp, goes west of Bermuda and pulls a left turn?
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Quoting pottery:
P.S...
it is coming down in Torrents right now.
Roof-Gutters are overflowing............


You have to keep bragging don't you.
Hopefully we are suppose to get some rain in a few days.
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BEGIN
NHC_ATCF
invest_RENUMBER_al962010_al072010.ren
FSTDA
R
U
040
010
0000
201008251224
NONE
NOTIFY=ATRP
END
Member Since: August 23, 2008 Posts: 7 Comments: 5300
2925. KEEPEROFTHEGATE (Mod)
07L FLYING ON NAVY SITE
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2924. surfmom
2907 Wayfaring - no worries, I've read it -- the "gunk" has sunk... and is "lining" those canyons becuase of the dispersants... we just don't know (since the gulf was BP's dispersant experiment) what the effect of turbulent waters due to storms will be.

I purchased a UV flashlight used in mechanics to spot oil leaks - this was used to find oil deep in the sand up in the panhandle, after all this SLOOSH, I'll be checking my beach here in SWFL...prob. tonight as the OIL glows in the dark. I doubt I'll find anything.... but I want to check for myself.
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2923. pottery
P.S...
it is coming down in Torrents right now.
Roof-Gutters are overflowing............
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2922. KEEPEROFTHEGATE (Mod)
NMFC Norfolk Tropical Feed
As of WED 25 Aug 2010 12:31:02Z
Active Tropical Warnings in the Atlantic, Caribbean, or Gulf of Mexico
HURRICANE 06L (DANIELLE) Warning C1
07L SEVEN
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
07L.SEVEN
06L.DANIELLE
East Pacific
09E.FRANK
Central Pacific

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

Southern Hemisphere
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2921. tkeith
Quoting surfmom:
hey Tkeith! - you watching that yellow circle?
I'm watching...Local Met says it's gonna go west even if it forms. But that's not gonna make me stop watching.
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Good morning all!

well, I see that we have a yellow thing in the gulf, oil smell at surfmom's and DestinJeff on the ignore list - well, I must be in DrM's blog for sure!..lol
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waves and weather were too rough for me yesterday

rains moved through late yesterday, and winds ended up dying leaving us with some fun waist to occasional chest high surf until dark.
gone this morning.

Looks like the winds will finally drop off and move more offshore by mon/tues, which now looks like the peak of Danielle's swell.

6.9 ft. @ 13 sec.
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nishi thats interesting you smelled oil i was thinking the same thing wehave not smelled oil for weeks in south ms.
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The nhc and whatever models and human intel they are using did a good job so far with Danielle and I bet they will with 96L as well. . . but with that said, what fun would this blog be without different views, opinion and even wild guesses?
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HWFI has 96L becoming a CAT 4



AOI

AOI

AOI

AOI

AOI

TS BUSTED FORECAST ALIBI
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Morning, Surf - is today the day?
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has you can see in this loop of 96L its a TD





Link
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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.



I am not sure what it is doing to it, but here in SE LA the smell of oil was horrible yesterday. It has not smelled like that in weeks.
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2908. surfmom
hey Tkeith! - you watching that yellow circle?
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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.


I think I was reading an article -have to dig it up - but scientist have found a trof of oil in deeper currents.

If you have ever worked on an engine block, then you can understand this because there is nothing worse than blowing an engine. When you pull drop the oil pan and see nothing but water and antifreeze on top (oil is heavier and sinks) then you just want to cry.

I blew a nice 350 cu inch Chevy one time. Oh well...
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2906. pottery
Quoting surfmom:


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

Sounds Fantastic!!

But now, I have to go and Follow Instructions...
See you all later!
Peace.
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2905. tkeith
Quoting surfmom:


He's making sure the NHC are doing their jobs correctly
lol...

Mornin Surfmom :)
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i was post 2900 what do i win
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Quoting KEEPEROFTHEGATE:
it will be named in about hour well renumbered anyway


It will be name at 5 AM EDT. vorticity is more than Frank. and near to Danielle.



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2902. surfmom
Quoting tkeith:
you're up early today Taz...


He's making sure the NHC are doing their jobs correctly
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2900
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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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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.