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

By: Dr. Jeff Masters , 2:02 PM GMT on August 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: 2234 - 2184

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

2234. jipmg
interesting developments tonight! How exciting
Member Since: Posts: Comments:
Quoting TampaSpin:
Many i know had old TD2 out to die....NOT!

Your analysis of ex TD2 from this morning so far has been spot on.
Member Since: Posts: Comments:
Quoting cg2916:

I told you earlier in the page description it says do not use it unless you are in NOAA, or else it is illegal.


WHAT....Dam i done for sure.....ROFLMAO......get the blank out of here.
Member Since: September 2, 2007 Posts: 177 Comments: 20430
His Knee was clearly on the ground before the ball popped loose but this ain't the NFL blog lol...I believe 02L will be classified when they are through getting all the data from the aircraft...I believe this is a TD right now...90L will be BILL in my opinon
Member Since: Posts: Comments:
Quoting jipmg:


ingles, and TD 2 has a 1006mb pressure reading?
sorry my bad, lol, and yes 02L has a 1006 pressure reading.
Quoting wunderkidcayman:

WOW where did you get that info from
I get it from a secret software which i can not reveal but u can get a lot of updates from here: Link
Quoting cg2916:

I was using an old computer earlier which had IE6 and it had a page description that said don't use it, and it beats me why it isn't protected.


It even says in the README that you can send questions to them and stuff...doubt they would have to put that there for officials. Looks public to me.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
here are a bunch of people who live in the antilles do not all speak 2 languages ... they also need information ..
Member Since: Posts: Comments:
2227. tbrett
Quoting tikikopamsxm:
Hi Dan!
I live in St Martin too, hope we will all stay safe!

AMEN
Member Since: Posts: Comments:
Quoting louisianaboy444:
Sorry to bring up sports but who are the Saints Fans in here...no way was that a fumble just now


I've been a Saints fan my whole life, not sure why though. Haha...Guess it's just something in the blood.

However, I didn't realize they had already started the game, so I didn't see the play.
Member Since: Posts: Comments:
Quoting extreme236:
Whats NOAA gonna do? Come to my house and arrest me for using their information on a weather blog that has been used for years? If they cared they would lock it with a password like RAMSDIS does.


The weather police are going to show up at your house and rain on you.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting leftovers:
bet you its 81f

Which part, the SST?
Man I wish these guys would put a lat/lon grid on this:
Member Since: August 16, 2007 Posts: 6 Comments: 12461
2223. cg2916
Quoting extreme236:


Where does it say this at? I do not see that. Again, it would not be on a website available to the public if it were illegal.

I was using an old computer earlier which had IE6 and it had a page description that said don't use it, and it beats me why it isn't protected.
Member Since: Posts: Comments:
Many i know had old TD2 out to die....NOT!
Member Since: September 2, 2007 Posts: 177 Comments: 20430
Whats NOAA gonna do? Come to my house and arrest me for using their information on a weather blog that has been used for years? If they cared they would lock it with a password like RAMSDIS does.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Hi Dan!
I live in St Martin too, hope we will all stay safe!
Member Since: Posts: Comments:
Quoting louisianaboy444:
Sorry to bring up sports but who are the Saints Fans in here...no way was that a fumble just now


fumble no doubt
Member Since: Posts: Comments:
Quoting canesrule1:
inside 02L

WOW where did you get that info from
Member Since: Posts: Comments:
2217. jipmg
Quoting canesrule1:
por favor tu puede hablar engles?


ingles, and TD 2 has a 1006mb pressure reading?
Member Since: Posts: Comments:
Only a matter of time(dead red on both systems). Cyclogenesis likely to be slow. I don't like the color graphs and the odds thing for areas of interest!!
Member Since: Posts: Comments:
Looks like we will have ANA and Bill in the next 48hours if not sooner.
Member Since: September 2, 2007 Posts: 177 Comments: 20430
Quoting cg2916:

I told you earlier in the page description it says do not use it unless you are in NOAA, or else it is illegal.


Where does it say this at? I do not see that. Again, it would not be on a website available to the public if it were illegal.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Sorry to bring up sports but who are the Saints Fans in here...no way was that a fumble just now
Member Since: Posts: Comments:
Quoting CaneWarning:


Nobody cares...
i know someone that works at noaa, there u go, now stop telling us its illegal no one cares, lol.
2211. tbrett
Quoting Tropicaldan:


Montserrat? Do you know Angelos ?
Do business with them regularly

Keep safe !

Yes I know Angelo's, in fact my daughter works there until schools starts again
Member Since: Posts: Comments:
Quoting java162:



yes it certainly looks so... (from the island of dominica to your south)


Greetings Dominica

90L is one to monitor for sure

Dan
Member Since: Posts: Comments:
Quoting CaneWarning:


My concern is that 90L makes it into the gulf, then the trough drops down and swings it into the west coast of FL.

Yea I can see that happening. i think the norhtern West coast of FL to about the LA MS border are the threat areas. If I had to draw a cone that is my area of concern.
Member Since: Posts: Comments:
Quoting wunderkidcayman:

where
inside 02L
Quoting farhaonhebrew:
A punto de volver a ser Depresión Tropical.

Las baja presión asociada a los remanentes de la Depresión Tropical DOS luego de ayer haber sido desclasificada, hoy han encontrdo condiciones favorables para un fortlaleciento lento y se espera que para esta noche o mañana vuelva a ser clasificada como un depresíón tropical. El rumbo que lleva hasta ahora el sistema pone en riesgo a la Isla de Puerto Rico de recibir lluvivias torrenciales entre este lunes y martes. Favor de permanecer atentos a los boletines este fin de semana por aquí en wunderground.com/tropical o su canal de preferencia.

Revise su plan de contingencia contra inundaciones.
por favor tu puede hablar engles?
Quoting canesrule1:
yup, 1006MB

where
Member Since: Posts: Comments:
Quoting cg2916:

I told you earlier in the page description it says do not use it unless you are in NOAA, or else it is illegal.


Nobody cares...
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting HaboobsRsweet:

I am with you except for the Gulf Coast storm there now. I think it will be a whole lot of rain and that is about it. Still of course has a shot to form but I just dont think it will. I just have a strange feeling that the trough moving across CONUS next week will slow down opening the door for 90L to work its way into the Gulf before taking a turn north. Still aways out but that is what I see and feel. Time will tell.


My concern is that 90L makes it into the gulf, then the trough drops down and swings it into the west coast of FL.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
2202. cg2916
Quoting extreme236:


Here is the file for it Link

I told you earlier in the page description it says do not use it unless you are in NOAA, or else it is illegal.
Member Since: Posts: Comments:
2201. java162
Quoting farhaonhebrew:
A punto de volver a ser Depresión Tropical.

Las baja presión asociada a los remanentes de la Depresión Tropical DOS luego de ayer haber sido desclasificada, hoy han encontrdo condiciones favorables para un fortlaleciento lento y se espera que para esta noche o mañana vuelva a ser clasificada como un depresíón tropical. El rumbo que lleva hasta ahora el sistema pone en riesgo a la Isla de Puerto Rico de recibir lluvivias torrenciales entre este lunes y martes. Favor de permanecer atentos a los boletines este fin de semana por aquí en wunderground.com/tropical o su canal de preferencia.

Revise su plan de contingencia contra inundaciones.




english please
Member Since: Posts: Comments:
Quoting tbrett:

Hey Dan..This is Tina in Montserrat, Hope you and yours will be safe too.


Montserrat? Do you know Angelos ?
Do business with them regularly

Keep safe !
Member Since: Posts: Comments:
Quoting leftovers:
90l wont be classified until at least tomorrow when nhc gets their first visiable. but i have my own hurricane center i classified it a couple days ago why not everyone knows it eventually will be a storm eventually



lol
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting mobilegirl81:

TD2 might be a diversion for florida, and 90L could be a gulf storm . Right now we need to keep an eye on this system that could develop in the gulf because it is supposed to slow down , and anybody on the gulf coast knows, that, is not good.

I am with you except for the Gulf Coast storm there now. I think it will be a whole lot of rain and that is about it. Still of course has a shot to form but I just dont think it will. I just have a strange feeling that the trough moving across CONUS next week will slow down opening the door for 90L to work its way into the Gulf before taking a turn north. Still aways out but that is what I see and feel. Time will tell.
Member Since: Posts: Comments:
Quoting farhaonhebrew:
A punto de volver a ser Depresión Tropical.

Las baja presión asociada a los remanentes de la Depresión Tropical DOS luego de ayer haber sido desclasificada, hoy han encontrdo condiciones favorables para un fortlaleciento lento y se espera que para esta noche o mañana vuelva a ser clasificada como un depresíón tropical. El rumbo que lleva hasta ahora el sistema pone en riesgo a la Isla de Puerto Rico de recibir lluvivias torrenciales entre este lunes y martes. Favor de permanecer atentos a los boletines este fin de semana por aquí en wunderground.com/tropical o su canal de preferencia.

Revise su plan de contingencia contra inundaciones.


I agree, everyone have a plan and review it!
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting Weather456:


where can I get the TAFB numbers?


Here is the file for it Link
Member Since: August 2, 2007 Posts: 19 Comments: 19234
A punto de volver a ser Depresión Tropical.

Las baja presión asociada a los remanentes de la Depresión Tropical DOS luego de ayer haber sido desclasificada, hoy han encontrdo condiciones favorables para un fortlaleciento lento y se espera que para esta noche o mañana vuelva a ser clasificada como un depresíón tropical. El rumbo que lleva hasta ahora el sistema pone en riesgo a la Isla de Puerto Rico de recibir lluvivias torrenciales entre este lunes y martes. Favor de permanecer atentos a los boletines este fin de semana por aquí en wunderground.com/tropical o su canal de preferencia.

Revise su plan de contingencia contra inundaciones.
Member Since: Posts: Comments:
I really hope and pray that if either of these systems become anything significant that they recurve and go out to sea into no mans land, but I doubt that either will do that.
Member Since: Posts: Comments:
Quoting leftovers:
have they dropped a drop that measured the water temperture under our system?

I imagine they are dropping a couple of XBTs
Member Since: August 16, 2007 Posts: 6 Comments: 12461
LOL talk about weather drama and competition at the same time =D who will be first and when LOL
Member Since: Posts: Comments:
Quoting CaneWarning:
Pressure falling...
yup, 1006MB
2189. alcomat
with the way td2 has picked up speed and with the large high building back into the southeast states,and with its position and movement,I see this as a GOM storm.the calculations I came up with,show it moving w-wnw and slipping under the high pressure ridge,almost on a track similar to Ike last year.I recall too well how it was in Ike since I was in the direct path of his eye.it all depends on how strong,and how far west the high builds.we shall see!
Member Since: Posts: Comments:
Quoting extreme236:
SAB kept 90L at T1.5 again, so unless TAFB goes up to T2.0 it may not be classified tonight.


where can I get the TAFB numbers?
Member Since: July 24, 2005 Posts: 407 Comments: 19076
The satellite analysis takes the existing obs and moves them along in time in an analysis fashion to match up expectations for 0, 6, 12, 18 utc.

This is what is looks like for the 18 utc surface-based scatterometer obs:



We will see soon how that latest QuikScat gets embedded.
Member Since: August 16, 2007 Posts: 6 Comments: 12461
SAB kept 90L at T1.5 again, so unless TAFB goes up to T2.0 it may not be classified tonight.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Quoting louisianaboy444:
I think 02L will become TD2 again shortly

TD2 might be a diversion for florida, and 90L could be a gulf storm . Right now we need to keep an eye on this system that could develop in the gulf because it is supposed to slow down , and anybody on the gulf coast knows, that, is not good.
Member Since: Posts: Comments:
2184. jdjnola
Quoting louisianaboy444:
I think 02L will become TD2 again shortly


Agreed.
Member Since: Posts: Comments:

Viewing: 2234 - 2184

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 JeffMasters

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
48 °F
Overcast