Danielle steams towards Bermuda; Earl organizing over eastern Atlantic

By: Dr. Jeff Masters , 3:20 PM GMT on August 26, 2010

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Hurricane Danielle continues on its steady northwesterly path towards Bermuda, as a respectable Category 2 hurricane with 105 mph winds. However, the hurricane has had its troubles this morning--Danielle wrapped a significant amount of dry air into its core between 4am - 8am EDT this morning, and Infrared satellite loops show that Danielle's cloud tops warmed late this morning, indicating that this dry air reduced the vigor of Danielle's thunderstorms. Danielle has managed to quickly mix out most of this dry air and reform its broken eyewall early this afternoon, as seen on recent visible satellite imagery (Figure 1.) We'll get a better idea of Danielle's intensity on Friday afternoon, when the first Hurricane Hunter mission is scheduled. The storm is still too far from land to reach with their airplanes today.


Figure 1. Morning satellite image of Danielle. A huge thunderstorm has blown up on the west side of the eyewall, giving the hurricane a rather lopsided appearance.

Intensity forecast for Danielle
Once Danielle recovers from its current troubles with dry air, warm 29°C SSTs combined with low wind shear of 5 - 10 knots should allow the storm to intensify. There is substantial dry air to the west and south of Danielle, though, and it is quite possible that some unexpected increase in shear could inject dry air into the hurricane at any time over the next few days. The latest SHIPS model forecast predicts that this shear will remain low, 5 - 10 knots, over the next three days, but then rapidly rise to a high 20 - 40 knots on Sunday. Danielle will probably reach peak intensity Saturday night or Sunday morning, near the time of its closest approach to Bermuda. NHC is giving Danielle a 41% chance of becoming a major Category 3 hurricane.

Track forecast for Danielle
On Saturday, a trough of low pressure that is expected to move off the East Coast of the U.S. and Canada should begin pulling Danielle due north, with the hurricane passing east of Bermuda Saturday night through Sunday. NHC is giving Bermuda a 25% chance of receiving tropical storm force winds of 39 mph or greater from Danielle, and a 1% chance of getting hurricane force winds. This is a substantial reduction from the odds given in the 5am forecast, which were 37% and 6%, respectively. The Bermuda Weather Service is predicting 15 - 20 foot waves this weekend for Bermuda's offshore waters. The most likely scenario once Danielle passes north of Bermuda is for the storm to recurve out to sea, missing the U.S. and Canadian coasts. All of the computer models currently call for this scenario. The possibility of Danielle stalling north of Bermuda and potentially tracking northwest towards the U.S. and Canadian coasts, as called for by the NOGAPS model in some of its runs yesterday, is looking less likely.

History suggests that a storm in Danielle's current location has only a 5 - 10% 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%. However, Danielle will bring high surf conditions to the U.S. East Coast beginning this weekend. The latest wave forecast from NOAA's Wavewatch III model (which uses the GFS model as its prediction for the position and intensity of hurricanes), calls for waves from Danielle to begin hitting the coast of North Carolina on Saturday. These waves will build to 7 - 10 feet in the offshore waters from Northern Florida to North Carolina by Sunday. The latest near shore water forecast for Cape Hatteras calls for 5 - 8 foot waves Saturday, and 7 - 10 feet on Sunday.


Figure 1. Morning satellite image of Danielle, Earl, and a new tropical wave emerging from the coast of Africa (possibly to be designated 97L?)

Tropical Storm Earl
Tropical Storm Earl developed late yesterday afternoon, one week ahead of when climatology suggests the fifth named storm of the year should occur in the Atlantic. Earl is currently very weak and ragged looking, thanks to dry air and wind shear. The wind shear analysis from the University of Wisconsin CIMSS group shows an upper level trough of low pressure to the north of Earl is bringing a high 20 - 30 knots of wind shear to the northern portion of the storm, though the center of Earl is under low wind shear of 5 - 10 knots. The shear has injected dry air into the storm, disrupting the circulation. As a result, Earl has a rather disorganized clumpy appearance on satellite imagery, and the center jumped 30 miles to the south this morning to reposition itself farther from the shear, and closer to the main region of heavy thunderstorms. Water vapor satellite images show a large region of dry air from the Sahara lies to the west of Earl, and this dry air will likely be the primary inhibiting factor for development over the next three days. Sea surface temperatures are warm, around 28°C. Earl is too far from land for the Hurricane Hunters to reach, and the first flight into the storm is not scheduled until Sunday afternoon.

Forecast for Earl
Wind shear is predicted to remain low to moderate, 5 - 15 knots, for the next five days. SSTs will steadily warm--to 28°C on Friday, and 29°C by Sunday. Earl may cross Danielle's cold water wake at some point, which could interrupt development. Dry air will probably be the main inhibiting factor for Earl over the next three days. In combination, these factors should allow for a slow intensification of Earl into a hurricane 4 - 5 days from now.

History suggests that a storm in Earl's current location has a 15 - 20% chance of making landfall on the U.S. East Coast, but the long term fate of Earl remains unclear. The storm is being steered by the same ridge of high pressure steering Danielle, and Earl will initially follow a track similar to Danielle's. As Earl enters the central Atlantic 4 - 5 days from now, the storm will encounter the same mid-Atlantic trough that is steering Danielle to the north. This trough should be able to turn Earl far enough to the northwest so that the storm will miss the Lesser Antilles Islands. It is unclear at this point whether this trough will be strong enough to fully recurve Earl out to sea, east of Bermuda. The long range 6 - 10 day forecasts from the GFS and ECMWF models have consistently been calling for Earl to turn north and follow Danielle, bringing Earl very close to Bermuda next week. This is a reasonable forecast, since Danielle is large enough and strong enough to create a low pressure "path of least resistance" for Earl to follow northwestward towards Bermuda.

Elsewhere in the Tropics
A new tropical wave emerged from the coast of Africa yesterday, and has the potential to develop into a tropical depression early next week. Several of the computer models develop this wave 3 - 6 days from now, and I can't see any reason why this would not occur. Conditions for tropical cyclone development will remain favorable in the Eastern Atlantic for at least the next week, and several of these models successfully predicted the development of both Danielle and Earl well in advance. The new wave will follow a track similar to that of Danielle and Earl, with an unknown potential for eventually affecting any land areas.

In the Eastern Pacific, Hurricane Frank has moved away away from the Mexican coast, and does not appear to be a threat to bring heavy rains to Mexico.

Jeff Masters

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1276. nash28
Has anybody noticed the Highs situated off the ECONUS on the run as well?

Does anyone see any amplified troughiness off the ECONUS?

Nope.

Member Since: Posts: Comments:
1275. skep
Earl has a wall of sal to its northwest, might influence it for a while...
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1274. Zeec94
Earl's models have changed from the morning advisory. At this time the GFS model indicates that anywhere from the Outer Banks of Northeast North Carolina, to the Hampton Roads region of Virginia should monitor Earl closely. Looks like if Earl follows GFS, it could be a similar situation to these folks like Isabel back in 2003.

http://ready.arl.noaa.gov/ready2-bin/jmovie.pl?id=GFS&mdl=grads/gfs&file=panel2&nplts=31
Member Since: Posts: Comments:
The ridge in 18Z has an additional isobar for 1020 mb that is not present in the 12Z run.
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1271. will40
Quoting StormJunkie:
OMG...This has to be a joke...Did they really just put the HeRbert box on here???

https://my.sfwmd.gov/sfwmd/common/images/weather/plots/storm_97.gif


So now links nor images are working???


image will SJ i havent tried a link
Member Since: September 19, 2005 Posts: 2 Comments: 4251
HeRbert box
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1269. mbjjm
Joe Bastardi accuweather tropical update

Danielle, Earl, Fiona to Be, and Future Draft Choices
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1268. IKE
Uh-oh...it's slightly further north and east now at 126 hrs....
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1267. KEEPEROFTHEGATE (Mod)
Quoting wxhatt:


I noticed that. Wonder why the NHC hasn't up'd from 20 percent yet.
they will but not until after 730 edt
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1266. xcool


126hrss
Member Since: September 26, 2009 Posts: 2 Comments: 15684
1265. Dakster
Quoting DestinJeff:
Feel like a stoner jonesing for a hit, waiting for GFS to update.


With an avatar like that, I wonder...
Member Since: Posts: Comments:
OMG...This has to be a joke...Did they really just put the HeRbert box on here???

https://my.sfwmd.gov/sfwmd/common/images/weather/plots/storm_97.gif


So now links nor images are working???
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1263. nash28
GFS is sticking to it on the 18z run. BTW, I have a synopsis up for those interested.
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1260. mbjjm
Hurricane City Tropical update
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1259. IKE
18Z GFS is exactly the same location of Earl "the pearl", at 108 hours vs. what it showed at 114 hours on the 12Z GFS.
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1258. wxhatt
Quoting Kristina40:
Fiona is looking better than Earl in that last pic.


I noticed that. Wonder why the NHC hasn't up'd from 20 percent yet.
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1257. KEEPEROFTHEGATE (Mod)
Quoting Hurricanes101:


not Fiona yet
not yet T.C.F.A. will be issued soon and then fiona
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I personally don't put too much stock in the 18Z. Looking forward to the 00Z if the 18Z shifts further W.
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1254. xcool


108hrs
Member Since: September 26, 2009 Posts: 2 Comments: 15684
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1252. hydrus
Quoting xcool:


90hrs
Looks a little unsettling for the Northern Leeward Islands.
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We'll probably end at Fiona by the end of August
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HP seems to be filling in from W to E.
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1249. JLPR2
Quoting xcool:


90hrs


That's a considerable shift to the south, looks like a direct hit to the NE Caribbean there, but the models do change a lot. *crosses fingers*
Member Since: September 4, 2007 Posts: 7 Comments: 8735
1248. xcool
Danielle, Earl, and more in the tropics?

Hurricane Danielle continues to churn in the Atlantic as a category 2 hurricane with winds of 105mph as of 5am. Danielle continues to move to the northwest and appears destined to re-curve and not threaten the US. The only land as of now that is likely to be threatened is Bermuda. The last few cycles of model data have been shifting Danielle’s path east and posing less of a threat to Bermuda. In fact if you look at the 12z ATCF models in the slideshow below, you can see the NHC official track interpolated, (OFCI the white line) is now well west of most of the model guidance. The ECMWF has been showing this scenario for a few days now and the GFS and other guidance has trended that way. This means a quicker re-curve for Danielle and a passage well east of Bermuda. I agree with this scenario. As far as intensity goes, Danielle has developed a large eye and appears to be gradually getting better organized. Shear is forecast to be light the next 60 hours and Danielle will be moving over warm waters, thus intensification seems likely, and Danielle will probably become a category 3 hurricane. By Saturday night, shear from the approaching trough which will re-curve Danielle will likely begin to take an impact on here and stead weakening is likely as she turns out to sea.

Tropical storm Earl, looks a bit ragged this morning. The center of the storm looks to be between two areas of convection one to the north and one to the south. This is likely a temporary re-organization as intensity guidance shows light shear (less than 15 kt) the next 72-84 hours and warm waters. Intensity guidance shows gradual strengthening into a hurricane by Saturday and it wouldn’t be overly shocking to see Early reach category 3 status at some point in it’s life. Track guidance shows a westward motion the next couple of days but by about the time the storm reaches 50-52W, a turn to the WNW or NW looks to occur. As of now, I have not seen any guidance that takes Earl through the northern Islands. The global model guidance in the 5 to 10 day period, is currently turning Earl north through a weakness left by Danielle on the western flank of the subtropical ridge and looks as of now, to keep Earl away from the US. The ECMWF and Canadian models show a direct hit on Bermuda and the ECMWF Ensemble guidance is even a bit west of Bermuda. It is too early to rule out a US landfall for sure, but as of now it is looking like Earl could take a path similar to Danielle except maybe 5 to 10 degrees further west. The caveat to watch is if Danielle perhaps re-curves quicker than forecast or if Earl slows down or stays further south than forecast. If this happens, then the weakness could fill quicker, and thus allow for a more westward motion to Earl.

There is a strong tropical wave behind Earl just off the coast of Africa, that many models develop and could be our next invest. If it get’s a name it would be Fiona. The models are a bit more divergent with any additional path of Fiona. The operational GFS seems to suggest Earl will absorb possible future Fiona, while the ECMWF does keep them separate but eventually turns here north similar to Danielle and Earl. The Canadian model keeps the system very weak and much further south, with some development as it reaches and passes through the Caribbean. Some members of the ECMWF ensemble show a much further west track and possible threat to the southeast in the week following Labor Day. Right now it is just too early to speculate even, but I did want to tell you what the models are showing.
Allan Huffman
by
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting Kristina40:
Fiona is looking better than Earl in that last pic.


not Fiona yet
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The door is open for Earl. Will he take it???
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1245. JLPR2
Quoting pottery:

Still up against a Wall of dry air there......


yeah, dry air is keeping it on check


Quoting hydrus:
lol. Yes, Earl needs another dose of nourishing hot water with his D-Max...Which he will get...Eventually..


Yeah, we should see it fire up nicely tonight.
Member Since: September 4, 2007 Posts: 7 Comments: 8735
Fiona is looking better than Earl in that last pic.
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1240. wxhatt
Quoting TropicalAnalystwx13:
Tropical Storm Earl, Soon to be Fiona, and maybe Gaston:



Wow, at this rate will we possibly break a record for August?
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Looking at the newest run of the GFS, Earl may not head out to sea, gonna have to see the next few frames.
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1238. pottery

BBL--
visitors...........
Member Since: October 24, 2005 Posts: 0 Comments: 24400
1237. xcool


90hrs
Member Since: September 26, 2009 Posts: 2 Comments: 15684
1236. hydrus
Quoting JLPR2:
Structurally Earl looks great, but convection wise...
eh...
It had a harsh D-min.

lol. Yes, Earl needs another dose of nourishing hot water with his D-Max...Which he will get...Eventually..
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1234. pottery
Quoting JLPR2:
Structurally Earl looks great, but convection wise...
eh...
It had a harsh D-min.


Still up against a Wall of dry air there......
Member Since: October 24, 2005 Posts: 0 Comments: 24400
1231. pottery
Quoting pottery:


And ????
LOL


edited...

aaahhhh!!
Member Since: October 24, 2005 Posts: 0 Comments: 24400
1229. pottery
Quoting DestinJeff:



FOUND IT!




And ????
LOL
Member Since: October 24, 2005 Posts: 0 Comments: 24400
Tropical Storm Earl, Soon to be Fiona, and maybe Gaston:

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1227. JLPR2
Structurally Earl looks great, but convection wise...
eh...
It had a harsh D-min.

Member Since: September 4, 2007 Posts: 7 Comments: 8735

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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.