Danielle a hurricane; TD 7 forming off coast of Africa
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
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NHC has done a great job on track.
Props to you folks in Coral Gables.
it also takes 96L right over Bermuda later in the run
But what are the negatives? The world is not black and white, it is in grey. I know we had a lot of ULL's this year. But why? That is the important question to me. I can see with my own eyes they were there. But the question to me once again is why? And what can we learn from that unexpected development, insofar as future forecasting goes?
This blog has lost its value to me.
Have a good day and remember, threat your neighbor the way you would want them to treat you! (some people may due well to remember this rule - remember the golden rule)
it does however guarantee that you will make more money at forecasting JMO
A nice loop of eyewall to its current... plight.
It doesn't get much better than that
Thanks.
If she does that- could she pull a "Betsy" and cross FLA?
Good afternoon Ike...I would say 40 miles is great considering all the variables.
Looks like we are in for more boomer's this afternoon...
Take Care.
v/r
Jon
46.5W...OR ABOUT 985 MI...1585 KM E OF THE LESSER ANTILLES
...MOVING WEST 17 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS
985 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 70 KT WITH GUSTS
TO 85 KT. DANIELLE HAS WEAKENED DURING THE PAST SIX HOURS BUT
RE-STRENGTHENING IS POSSIBLE DURING THE NEXT 48 HOURS. PLEASE
READ THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT1/WTNT21 KNHC AND THE LATEST PUBLIC ADVISORY UNDER
MIATCPAT1/WTNT31 KNHC FOR MORE DETAILS. SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION IS FROM 14N-18N BETWEEN 44W-48W.
But they're not in Coral Gables anymore; they moved out to FIU after Andrew. But I know what you mean... ;-)
Looks that way doesn't it.Lol
It's hard to argue with model consensus like Danielle has had since it was 95L
Noticed that. Now, when are we going to see yours? ;-)
Right but it is fair to call it a loss in the 3rd inning like many try to do?
I think not, calling the season a bust now is just like saying your team is going to lose because they are losing in the 3rd inning.
Ike....Frances....Katrina....Lili....Chris....list goes on. They are wrong just as many times as a lot of other people, but they do a great job most of the time.
If you can't think of a time they were wrong then you haven't been around long lol.
Thanks :)
Link
Danielle seems to be falling apart, or just not as well defined as it was yesterday. wonder why?
And look at the hollow "TS" symbol on Danielle. It hasn't been a hurricane all morning....should be downgraded next advisory.
That is scary
Big shift from the NOGAPS at 12z...hints that the ridge could still do tricky things, but recurvature east of the US is still most likely.
Problem is most people are saying both, so it really does not matter much
Take two (blog ate take 1)
We do not fully understand tropical cyclogenesis yet, though we are getting better at it.
Forecasting mesoscale and smaller features, such as ULLs more than a few days out is still rather difficult (look at the praise given to GFS for forecasting Danielle 2 weeks out).
Now, we know some of the large scale features necessary for tropical cyclogenesis, and those are met this year. But perhaps we do not yet understand the large scale features that have lead to the persistent ULLs across the basin this season. So in the coming years people are likely to study this, and perhaps they will discover what has caused these negative features to be so prevalent in the early part of the season this year. This will, in turn, give us better seasonal forecasts.
I have been saying for awhile now, the early part of this year is likely to teach us a lot.
haha i think "threat your neighbor" is almost as funny as "we are doom" !
When dealing with a TC, never let your guard down, no matter how set in stone the forecast appears.
I like Storm W comments too. Everything else you said in your message, I totaly agree. I come here to get informative info about any tropical system out in the Atlantic or what could develop. I'm not professional weather met. But I like reading and getting good info from others. This is the only forum that I found thats happening right now.jmo
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