Danielle steams towards Bermuda; Earl organizing over eastern Atlantic
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
Reader Comments
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Tropical Disturbance Summary
TROPICAL DEPRESSION 08
9:00 AM JST August 27 2010
================================
At 0:00 AM UTC, Tropical Depression (1004 hPa) located at 25.8N 127.8E has 10 minute sustained winds of 30 knots with gusts of 45 knots. The depression is reported as moving north northwest at 12 knots.
Forecast and Intensity
========================
24 HRS: 31.2N 124.6E - 35 knots (CAT 1/Tropical Storm)
*Storm number may change when TCNA designates..
ok, thanks
Tropical Disturbance Summary
TROPICAL DEPRESSION 09
9:00 AM JST August 27 2010
================================
At 0:00 AM UTC, Tropical Depression (1004 hPa) located at 15.1N 116.8E has 10 minute sustained winds of 30 knots with gusts of 45 knots. The depression is reported as moving west northwest at 8 knots.
Forecast and Intensity
========================
24 HRS: 15.9N 113.9E - 35 knots (CAT 1/Tropical Storm)
*Storm number may change when TCNA designates
It shows it being a little weaker, about 1021mb.
And lol I did not see this until today....hadn't checked the CFS in a while. Look at these sea-level pressure anomalies for September!
You honestly can't ask for worse than that, if you don't like big hurricane seasons that threaten the US.
15.9N, 39.4W is approximately where the center looks to be, to me.
Wonder if she making her north turn now, and if the ridge will fill in behind her quicker, allowing Earl to be pushed further west and kept further south. Anyone?
That's only cause Taz has 50,000 of those in his blog and they all go something like this "qwerwew" or "dasdasdfasdf" ect :P Oh silly taz.
On the tropics.. It sure looks like Danielle is getting the breath squeezed out of her. What would cause that?
I hate bad news!
Am I seeing this correctly?
And...you can't ask for much worse with the 500mb pattern for september either:
20100827.0115.goes13.x.ir1km_bw.07LEARL.40kts-1003mb-156N-396W.
Yes.
I just use paint, no photoshop, I just try to make it look good :). Right now I'm looking at Earl reaching near the Bahamas in a few days, south of Bermuda.
Bro you can see that big high in the loop i just posted....i just noted how strong it was....when that rolls off the East coast look out....the blocker is on.
Yay I was right =)
Next question... what does this mean.. a shift to the right in the 11 pm update or what?
One stop shopping?
Good Idea!
99W Invest near Okinawa, Japan
91W Invest west of the Philippines
The models will likely respond a little bit yes, and thus the NHC forecast will get adjusted northward, but this is probably more just Earl forming his center in a different spot than an actual track change. The track will probably remain roughly the same, just shifted north a tad.
Meant to say a couple of days, few is like 3 days lol, my bad.
Thanks guys, my internet whent down for a little bit
testing...
again.
I will have a new blog out on your site Tampa after the 11 PM advisories comes out on Danielle and Earl.
Forecast models are characterized as either early or late, depending on whether they are available to the forecaster during the forecast cycle. For example, consider the 1200 UTC forecast cycle, which begins with the 1200 UTC synoptic time and ends with the release of an official forecast at 1500 UTC. The 1200 UTC run of the NWS/Global Forecast System (GFS) model is not complete and available to the forecaster until about 1600 UTC, an hour after the forecast is released. Thus, the 1200 UTC GFS would be considered a "late" model since it could not be used to prepare the 1200 UTC official forecast. Conversely, the BAM models are generally available within a few minutes of the time they are initialized. Therefore, they are termed "early" models. Model timeliness is listed in Table 1.
Due to their complexity, dynamical models are generally, if not always, late models. Fortunately, a technique exists to take the latest available run of a late model and adjust its forecast so that it applies to the current synoptic time and initial conditions. In the example above, forecast data for hours 6-126 from the previous (0600 UTC) run of the GFS would be smoothed and then adjusted, or shifted, so that the 6-h forecast (valid at 1200 UTC) would match the observed 1200 UTC position and intensity of the TC. The adjustment process creates an "early" version of the GFS model that becomes part of the most current available guidance for the 1200 UTC forecast cycle. The adjusted versions of the late models are known, largely for historical reasons, as "interpolated" models.
Statistical Models
Statistical models are based on established relationships between storm-specific information, such as location and time of year, and the behavior of historical storms. While these models provided key forecast guidance in past decades, today these models are most often used as benchmarks of skill against which more sophisticated and accurate models and the NHC official forecast are compared. Models that are less accurate than a simple statistical model are considered "unskillful" and models that are more accurate than statistical models are considered "skillful". Due to their simplicity, statistical models are among the quickest to run and are typically available to forecasters within minutes of initialization.
Dynamical Models
Dynamical models are the most complex and most computationally expensive numerical models used by NHC. These models make forecasts by solving the physical equations that govern the atmosphere, using a variety of numerical methods and initial conditions based on available observations. Since observations are not taken at every location in the model domain, the model initial state can vary tremendously from the real atmosphere, and this is one of the primary sources of uncertainty and forecast errors in dynamical models. Errors in the initial state of a model tend to grow with time during the forecast, so small initial errors can become very large several days into the forecast period. It is largely for this reason that forecasts become increasingly inaccurate in time.
Well you did say the high will be a little weaker and as of now these storms are pulling away. So if it is going to be weaker then it will even curve more storms out to sea so there won't be much threat from the Cape Verde hurricanes I suspect. But closer to home is a different story with the MJO coming soon.
I respectfully disagree... Look at the loop that I linked to. You'll see how in the first couple of frames that center is rather easy o see as it's pretty void of convection, then in the next 4 frames or so, you see in tuck itself under that ball of convection.
I'm not meteorologist or anything, but I would expect a shift to the right in the next update if this continues.
I'm just giving my opinion. You're entitled to yours. Tell me what you see happening, and we'll see what happens!
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