Disturbance 90L close to tropical depression strength; TD 2 may rise again

By: Dr. Jeff Masters , 2:02 PM GMT en Agosto 14, 2009

Share this Blog
5
+

A strong tropical wave (90L), with a large circulation and a moderate amount of heavy thunderstorm activity, is a few hundred miles southwest of the Cape Verdes Islands, off the coast of Africa. This morning's QuikSCAT pass shows that 90L has a large circulation, but this circulation is not yet well-formed, as it is elongated along an east-west axis. Satellite imagery from the European METEOSAT satellite show that the heavy thunderstorms associated with 90L are gradually becoming better organized, with some spiral banding evident on the south side of the storm. Satellite intensity estimates from NOAA already put 90L at tropical depression strength with 30 mph winds, but the storm does not yet have a well enough formed circulation to be classified as a depression. Water vapor imagery shows that since 90L is forming several hundred miles south of the dry air of the Saharan Air Layer (SAL), the storm should not be affected by dry air and dust as much as Tropical Depression Two was. However, there is some dry air from the SAL being sucked into the circulation of 90L, and this is retarding its development.

Wind shear is moderate, about 10 - 15 knots, but is forecast to fall to the low range, 5 - 10 knots, later today. Shear is then forecast to remain low for the next five days. Sea Surface Temperatures are about 28°C, and will remain in the 27 - 28°C range the next five days. The combination of low wind shear and sufficiently warm SSTs should allow 90L to develop into a tropical depression by Saturday, and potentially reach hurricane strength by Wednesday. Most of our reliable models strengthen 90L into a hurricane by Wednesday, when the storm is expected to be near the northern Lesser Antilles Islands. One important outlier is the ECMWF model, which has 90L passing to the north of the islands, and eventually recurving out to sea east of Bermuda. The ECMWF was by far the most reliable model for forecasting hurricane tracks last year. However, all of our models are pretty unreliable going out 5 days in advance for systems that have yet to reach tropical depression strength. Once 90L becomes a tropical depression and develops a well-formed circulation, the models will have a better handle on forecasting where it will go.


Figure 1. The remnants of Tropical Depression Two (left side of image) and tropical wave 90L (right side of image).

Tropical Depression Two may come back
Tropical Depression Two died yesterday, but may rise again. Satellite loops of the remnants of the storm show that heavy thunderstorms are again attempting a comeback near the axis of what is now a tropical wave. However, dry air continues to interfere with the development of the thunderstorm activity, and moderately high wind shear of 15 - 20 knots is also inhibiting the process. Wind shear over the remnants of TD 2 is expected to remain in the moderate range, 10 - 20 knots, over the next four days. Sea Surface Temperatures (SSTs) are 27°C, but will warm to 28°C two days from now. There is plenty of dry, stable air from the Saharan Air Layer (SAL) to the north and west that will continue to cause the storm problems. The relatively cool SSTs and dry air mean that any re-development of the storm will be slow to occur. NHC has given the system a medium (30 - 50% chance) of becoming a tropical depression again by Sunday morning. Only one reliable model, the NOGAPS, is predicting regeneration of TD 2. The NOAA Hurricane Hunters are flying research missions into the remnants of TD 2 today and Saturday.

I'll have an update Saturday morning, or earlier, if significant developments occur.

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: 184 - 134

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 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 | 80 | 81 | 82 | 83 | 84 | 85 | 86 | 87 | 88 | 89 | 90 | 91 | 92 | 93 | 94 | 95 | 96 | 97 | 98 | 99 | 100 | 101 | 102 | 103 | 104 | 105 | 106 | 107 | 108 | 109 | 110 | 111 | 112 | 113 | 114Blog Index

Looking at the floater of X-TD2 ...
To these untrained eyes, it looks like as dry air from the south of the storm wraps to the east, then 90L passes off some moisture, helping with the deficit of moisture.
It is a passing game! LOL
Member Since: Posts: Comments:
Quoting Drakoen:
Accuweather thinking an east coast threat


he is always thinking east coast threat when its not straight for nola
Member Since: Posts: Comments:
Quoting leftovers:
ex td 2 or 90l?


90L
Member Since: Posts: Comments:
181. jipmg
Quoting extreme236:


Well when it was close to TS status it looked better than this.


It did "look" better, but as they say looks can be deceiving, TD 2 never had convection concentrated over the center based on what ive seen of it until now
Gotta run.....BBL tonite.....NO FIGHTING KIDS! watch TD2 to come back!
Member Since: Posts: Comments:
Quoting Drakoen:


It's amazing how things can change in 24hours lol. Yesterday we were talking about a monster trough taking this thing out to sea and now we have to be concerned with a building ridge and an advancing trough.


Nobody said it was a "Monster trough"
Member Since: Posts: Comments:
Quoting Drakoen:
Accuweather thinking an east coast threat
ex td 2 or 90l?
Member Since: Posts: Comments:
That sounds like Bastardi.
Member Since: Posts: Comments:
Quoting MrSea:
in terms of convection over the center, and a well-established circulation on the SW quadrant of the storm, ex TD2 looks better now than it ever did


Well when it was close to TS status it looked better than this.
Member Since: Agosto 2, 2007 Posts: 19 Comments: 19234
Accuweather thinking an east coast threat
Member Since: Posts: Comments:
174. IKE
Quoting Drakoen:


It's amazing how things can change in 24hours lol. Yesterday we were talking about a monster trough taking this thing out to sea and now we have to be concerned with a building ridge and an advancing trough.


I checked the discussions in Amarillo,TX...St.Louis...Chicago...saw very little mention of any significant trough heading east over the next 7 days.
Member Since: Posts: Comments:
Quoting Drakoen:


It's amazing how things can change in 24hours lol. Yesterday we were talking about a monster trough taking this thing out to sea and now we have to be concerned with a building ridge and an advancing trough.


Hehe... yeap.
Member Since: Posts: Comments:
172. srada
Good Morning Everyone!

Until both of these storms become a depression, the models runs wont be accurate per Dr. Masters..(Once 90L becomes a tropical depression and develops a well-formed circulation, the models will have a better handle on forecasting where it will go.)

so I will wait until that happens before thinking the worst if the storm is coming my way of not
Member Since: Posts: Comments:
Quoting KYhomeboy:


Not necessarily. I always wanted to see what one was like just out of curiosity. But after going through Ivan as a Cat. 4 I realized that sometimes it's just better to imagine what something would be like rather than going through it to find out. lol. I'm no longer curious...thats for sure.


I have to admit when I moved to West Palm in 04 the thought of going through a hurricane intrigued me. Slow moving Frances took care of that in a quick hurry. Now, it's just about protecting my wife and daughter.
Member Since: Posts: Comments:
Quoting Drakoen:
Slow starting seasons are always bad for South Florida and I don't like what I see regarding these models track and how they are backing up the trough.
yup, ex-02L's models are forecasting a SFLA hit ans so are 90L's models, damn!
Not a fan of Bastardi.
Member Since: Posts: Comments:
168. jipmg
Can we get some TD 2 track/strength models? I really cant seem to find any
Quoting WxLogic:


To be expected in a way since for this time of the year... it shouldn't have been that strong.


It's amazing how things can change in 24hours lol. Yesterday we were talking about a monster trough taking this thing out to sea and now we have to be concerned with a building ridge and an advancing trough.
Member Since: Posts: Comments:
I corrected my earlier post - meant TD#2...
not enough coffee yet. :)
Member Since: Posts: Comments:
165. IKE
Accuweather's take..
Member Since: Posts: Comments:
Quoting Melagoo:
TD 2 shows exactly how unpredictable storm formation can be ... maybe its the spin it started with ... they justa keepa spinnin!


As of late (last 10 days or so), at this stage of storms a good day for one is a good day for others.
Member Since: Posts: Comments:
163. jpsb
Quoting hurricanehanna:
guess those that want to "experience" a hurricane have never had their homes damaged or lost precious photos...etc.... Let them buy property and see how it feels...
Yes, my little town is still recovering from Ike. Only one dead but the lives and property ruined is amazing. It will be years before we fully recover. Hope 90L stays out of the GOM! Galveston Bay area is in no shape to take another hit.
Member Since: Posts: Comments:
162. MrSea
Quoting centex:
Is old TD2 not even an invest?


It still has a floater satellite and it still is being plugged into the models, so its still an invest
Member Since: Posts: Comments:
Quoting Drakoen:
Slow starting seasons are always bad for South Florida and I don't like what I see regarding these models track and how they are backing up the trough.


To be expected in a way since for this time of the year... it shouldn't have been that strong.
Member Since: Posts: Comments:
Quoting wunderkidcayman:

caribbean or the northern caribbean islands
Northern antillies, imo
One thing is for sure....if South and Central coast of TX doesn't get a tropical storm those areas are doomed.
Member Since: Posts: Comments:
Slow starting seasons are always bad for South Florida and I don't like what I see regarding these models track and how they are backing up the trough.
Member Since: Posts: Comments:
Quoting JAC737:
Hello all. A request for those of us without your esteemed knowledge: when you post a satellite image could you please explain it in a sentence or two? I live near Galveston. Satellite images make me nervous. :) Thanks!


I agree; they don't make me nervous but I would like to know what it is you are posting a image of. Much appreciated!
Member Since: Agosto 29, 2005 Posts: 299 Comments: 40925
155. MrSea
in terms of convection over the center, and a well-established circulation on the SW quadrant of the storm, ex TD2 looks better now than it ever did
Member Since: Posts: Comments:
td 2 leftovers? finally moving at a reasonable clip
Member Since: Posts: Comments:
I met Max Mayfield several months back at Washington National AP and we were talking about this season and south Fla...I stated looks like a light season based on the early forecasts and possibilities to South Fla...He brought up Andrew and said...."it only takes one" for you to have a bad day...
Member Since: Posts: Comments:
Is old TD2 not even an invest?
Member Since: Agosto 10, 2007 Posts: 0 Comments: 3292
Quoting JAC737:
Hello all. A request for those of us without your esteemed knowledge: when you post a satellite image could you please explain it in a sentence or two? I live near Galveston. Satellite images make me nervous. :) Thanks!


I'd be more nervous without satellite imagry.
Member Since: Posts: Comments:
150. 786
Hello, have been lurking hope everyone is well:

"Discussion
Ex-Tropical Depression #2

After being downgraded yesterday afternoon, shower and thunderstorm activity has increased around Ex-Tropical Depression #2. The system was located about 1350 miles east of the Lesser Antilles this morning. This system does have the potential to regenerate and intensify over the next couple of days as it moves into a more favorable environment. It should be noted that none of the global models really are interested in reintensifying this ex-depression and the GFDL model forecasts dissipation in the next 3 to 4 days due to the large circulation from intensifying 90L/Ana, while the HWRF model forecasts that this system will intensify into a moderate tropical storm in the next 2 to 3 days and remain a moderate tropical storm through day 5. This system will be watched very closely this weekend for reintensification and I will keep you all updated.

Invest 90L Located South-Southwest Of The Cape Verde Islands:

I am closely monitoring Invest 90L, which is located about 175 miles south-southwest of the Cape Verde Islands. Convection has increased overnight and some nice banding has also developed around 90L. All of the latest forecast guidance continues to forecast significant intensification over the next few days. Based on the satellite appearance this morning, I suspect that 90L will be upgraded to a tropical depression either sometime today or at the latest on Saturday.

The overall track model guidance is forecasting a due west course over the next couple of days with a turn more to the west-northwest by early next week. The track model guidance are all in agreement that 90L poses a threat to the northeastern Caribbean, especially the Lesser Antilles from the islands of Guadeloupe and Dominica and points north and west on Wednesday or Thursday. It should be noted that the GFDL model is forecasting a Category 2 hurricane by Wednesday morning and the HWRF model is forecasting that 90L may be a Category 3 hurricane by Wednesday morning.

As for the global models, the GFS model is forecasting an eventual track into the Gulf of Mexico next weekend (Weekend of August 22) after raking the Lesser and Greater Antilles late next week. The European model on the other hand forecasts that 90L will curve into the open Atlantic near 55 West Longitude and miss the Antilles altogether. One thing to note about the European model runs is that it is forecasting that 90L will be near 13 North, 37 West on Sunday night and it is near 28 West right now. So, basically I think the Euro is too slow in its forecast track of 90L and I am discounting the curve out into the open Atlantic near 55 to 60 West Longitude.

So, the idea of a nearly due west track over the next 3 to 4 days seems reasonable given the strength of the high pressure system to the north. After that, a turn a little more to the west-northwest is possible. As for strength, steady strengthening is likely over the next several days and I suspect that this will be classified as a depression within the next 24 to at most 36 hours and then a tropical storm (Ana?) by sometime on Sunday or Monday and a hurricane by Tuesday at the very latest. I expect 90L/Ana to be a major threat to the eastern and especially northeastern Caribbean by Wednesday or Thursday. All interests in the Caribbean Islands, especially from Guadeloupe and Dominica and points north and west should start getting yourselves ready for this potential hurricane around the middle of next week.

Beyond that, it is still way too early to tell exactly where or even if this potential major hurricane will be a threat to the United States. The forecast guidance is still forecasting that a trough of low pressure will be in place over the eastern United States in the day 6 to 10 time period, so Invest 90L/Ana may be pulled northwestward towards the United States. Therefore, this system has the potential to threaten the eastern Gulf of Mexico, Florida and the East Coast. So, anyone with a vested interest in these areas should keep very close tabs on the progress of this system as it has the potential to make headlines over the next 10 days or so.

Tropical Wave Near The Southeast Bahamas:

Finally, I continue to monitor a tropical wave that is interacting with an upper-level low pressure system. This weather feature is producing shower and thunderstorm activity over Hispaniola, the Turks
and Caicos Islands and the southeastern Bahamas. This weather system is forecast to track to the west and west-northwest this weekend and is expected to reach the western Gulf of Mexico on Monday. Upper level winds are not favorable for this system to really ramp up. Personally, I still think that it will remain a tropical wave and not develop into a tropical depression or tropical storm. With that said, it will be watched closely this weekend.

The next tropical weather discussion will be issued by 9 am EDT Saturday."

I think that everyone from the Caribbean to New England should monitor this. The Caribbean is by no means out of the woods and the models this far out generally have a North bias.
Member Since: Posts: Comments:
The ridge is set up like 2004, so texas might be in the clear the year unless something forms in the gulf.
Member Since: Posts: Comments:
I could be wrong but I see the distinct possibility of 02L regenerating into a TD later today or tomorrow.
Member Since: Agosto 2, 2007 Posts: 19 Comments: 19234
Quoting Drakoen:
Long range CMC has a South Florida hit the possibly into the GOM or up the state. Definitely an interesting and possible track:

Notice the 999mb low in the TX/MX border region, and the 1008mb low in CATL.
I know a weak TS would be VERY welcome in South Texas (they need the rain in a VERY bad way).

A 981mb in south FL would be pretty nasty, since the actual pressure would probably be in the 940-960 range, due to the lack of resolution.

That said... it is VERY far out, and models are extremely unreliable that far out.
Member Since: Posts: Comments:
Quoting hurricanehanna:
guess those that want to "experience" a hurricane have never had their homes damaged or lost precious photos...etc.... Let them buy property and see how it feels...


Amen Hanna
Member Since: Posts: Comments:
was not that was cooler water north of felicia ? i was taught those are fair weather clouds
Member Since: Posts: Comments:
former TD#2 seems to be firing up a bit this AM...DMIN?
Member Since: Posts: Comments:
Quoting hurricanehanna:
guess those that want to "experience" a hurricane have never had their homes damaged or lost precious photos...etc.... Let them buy property and see how it feels...


Not necessarily. I always wanted to see what one was like just out of curiosity. But after going through Ivan as a Cat. 4 I realized that sometimes it's just better to imagine what something would be like rather than going through it to find out. lol. I'm no longer curious...thats for sure.
Member Since: Posts: Comments:
TD 2 shows exactly how unpredictable storm formation can be ... maybe its the spin it started with ... they justa keepa spinnin!
Member Since: Julio 31, 2006 Posts: 19 Comments: 1604
Worse case scenerio would be a major hitting Florida and the ridges bridge together blocking the northern turn and stalling over Florida.
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Hello all. A request for those of us without your esteemed knowledge: when you post a satellite image could you please explain it in a sentence or two? I live near Galveston. Satellite images make me nervous. :) Thanks!
Member Since: Posts: Comments:
do u think that since TD2 is weak now, that it will enter the caribbean and may regenerate there?
Member Since: Posts: Comments:
guess those that want to "experience" a hurricane have never had their homes damaged or lost precious photos...etc.... Let them buy property and see how it feels...
Member Since: Posts: Comments:
Quoting TampaSpin:


Take a 2000mile boat ride to the East in a 12ft john boat and wait at the 12N 50W line and you can see one....But hurry in don't want you to miss it.....OMG!


LMAO
Member Since: Posts: Comments:
Quoting ackee:
if TD#2does come back where do u think it will track ?

caribbean or the northern caribbean islands
Member Since: Posts: Comments:

Viewing: 184 - 134

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 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 | 80 | 81 | 82 | 83 | 84 | 85 | 86 | 87 | 88 | 89 | 90 | 91 | 92 | 93 | 94 | 95 | 96 | 97 | 98 | 99 | 100 | 101 | 102 | 103 | 104 | 105 | 106 | 107 | 108 | 109 | 110 | 111 | 112 | 113 | 114Blog 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
45 ° F
Nublado