TD 2 nearly dead; African disturbance 90L gathering strength

By: Dr. Jeff Masters , 2:38 PM GMT on August 13, 2009

Share this Blog
4
+

Tropical Depression Two is near death, but is still worth watching. The dry, Saharan air to the north and west of the depression, combined with moderately high levels of wind shear of 15 - 20 knots, have almost completely destroyed all of TD 2's heavy thunderstorms. Satellite loops of the storm show a well-formed circulation, but almost no heavy thunderstorm activity.

Wind shear over TD 2 is expected to remain in the modereate range, 10 - 20 knots, over the next five days. Sea Surface Temperatures (SSTs) are 27°C, but will warm to 28°C three days from now. There is plenty of dry, stable air from the Saharan Air Layer (SAL) to to TD 2's north and west that will continue to cause the storm problems. The relatively cool SSTs and dry air mean that TD 2 will not be able to intensify quickly, and some of the models indicate the TD 2 may get destroyed in the next day or two. However, several models still predict TD 2 will become a tropical storm. The HWRF model predicts TD 2 will become a hurricane five days from now, but this seems unlikely given the dry air and relatively high wind shear affecting the storm.


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

African tropical wave 90L
A strong tropical wave with a large circulation and plenty of heavy thunderstorm activity is a few hundred miles south of the Cape Verdes Islands, off the coast of Africa. NHC dubbed this disturbance 90L this morning. This morning's QuikSCAT pass shows that 90L has a very large circulation, and top winds of about 30 mph. Satellite imagery from the European METEOSAT satellite show that the heavy thunderstorms associated with 90L are in two major bands, to the north and to the south of the center. There is no heavy thunderstorm activity near the center yet, and this would have to happen before 90L can be named Tropical Depression Three. 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 has been. Wind shear is about 20 knots over 90L, and is forecast to remain in the moderate range, 10 - 20 knots, over the next five days. Sea Surface Temperatures are about 28°C, and will remain in the 27 - 28°C range the next five days, which are high enough above the 26°C threshold for tropical cyclone formation to allow some slow development to occur. The GFS and ECMWF models continue to predict the development of this wave, though they are now less aggressive about intensifying it than they were in earlier runs. The consensus among the reliable HWRF, GFDL, GFS, and ECMWF models is to bring 90L to point near or just north of the northernmost Lesser Antilles Islands 6 - 8 days from now. The storm could be at hurricane strength by then, as forecast by the SHIPS intensity model.

I'll have an update Friday morning.

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: 1487 - 1437

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 | 72Blog Index

I still say we need to keep a close eye on the Caribbean wave as it approaches the GOM - lots of moisture, low sheer and hot water to work with....
Member Since: Posts: Comments:
Quoting Ameister12:
Poll Time!!!

Do you think exTD2 is going become a depression again?

A) Yes
B) No
C) Maybe



C
Member Since: Posts: Comments:
Quoting canesrule1:
It' closed its just very elongated.


I don't think there are enough northerly winds on the western side of the circulation to justify calling it closed. The circulation is quite broad at this point.
Member Since: Posts: Comments:
1483. slavp
Quoting java162:


dude!!!! all thats missing is the convection which will muild during dmax. stop being so pecimestic and pretending that you don't want it to develop. it is huge and needs some time to get going. after that i think there will be some rapid intensification.
exactly, It will take time to develop..It won't develop overnight
Member Since: Posts: Comments:
1482. IKE
Quoting java162:


dude!!!! all thats missing is the convection which will muild during dmax. stop being so pecimestic and pretending that you don't want it to develop. it is huge and needs some time to get going. after that i think there will be some rapid intensification.


?

Pessimistic.

Pretending? I could care less if it develops.
Member Since: Posts: Comments:
Quoting P451:


When it adds deep convection it will be. For now for as impressive as that image looks there's nothing there.

Yeah I agree, it looks great on Visible but on AVN it has no deep convection.
Member Since: Posts: Comments:
1480. KEEPEROFTHEGATE (Mod)
Quoting Tazmanian:



way too soon too tell best thing too do is wait see and watch
at the moment all we can say is its moving forward at a westly direction from its current location
Member Since: July 15, 2006 Posts: 178 Comments: 55972
Quoting cg2916:

It looks much better than it did a little while ago. AND it's DMIN. It's LLC is almost closed, just a little exposed to the west.
It' closed its just very elongated.
Member Since: Posts: Comments:
Quoting Ameister12:
Poll Time!!!

Do you think exTD2 is going become a depression again?

A) Yes
B) No
C) Maybe



Going with B. 200 mb flow doesn't look promising.
Member Since: Posts: Comments:
1475. Drakoen
Quoting DM21Altestic:
Drak, will 90L recurve out to sea?


I don't know. It will come down to timing. The models handle the trough differently. ECMWF most aggressive. CMC least aggressive. GFS in between.
Member Since: Posts: Comments:
Quoting cg2916:

It looks much better than it did a little while ago. AND it's DMIN. It's LLC is almost closed, just a little exposed to the west.

that quikscat was from early this morning.
Member Since: Posts: Comments:
Quoting Chicklit:

You'll drive yourself crazy with that.
Just pretend it isn't happening.
I'm a certified English teacher and blog.
You cannot have it 'your way' here.
Or should I say, "ur?"


Hey.. I've been here for a few years lurking.. and reading WS comments I've been wondering could he be dyslexic?

This season is off to a slow start, but by next week this blog will be going nuts with all the storms forming. 90L scares me but I'm still weary of TD2 as well as the wave near Cuba. I reckon it's a race to see which of these storms/waves will be "Ana"

-goes back to lurking-
Member Since: Posts: Comments:
1472. cg2916
Quoting Ameister12:
Poll Time!!!

Do you think exTD2 is going become a depression again?

A) Yes
B) No
C) Maybe


Probably not.
Member Since: Posts: Comments:
Quoting TampaSpin:
I swear I did not have sex with that woman "Miss ANA"



LMFAO!!!!
Member Since: Posts: Comments:
Quoting TampaSpin:
I saved this pic from early this morning......check out the smiley face....LOL


wow, we had a''Grumpy old man'' & "Smiley face" generated by the same system already! What's next? I hate to make predictions!
Member Since: Posts: Comments:
Quoting Ameister12:
Poll Time!!!

Do you think exTD2 is going become a depression again?

A) Yes
B) No
C) Maybe



Uh I'll go with c just to be on the safe side =D
Member Since: Posts: Comments:
Quoting IKE:
as you can see there is a very thin layer of SAL because 02L cleaned up, and 90L has an anticyclone in front of it, so shear and SAL will not be a factor, so I expect very rapid intensification, i think it will be a CAT 3 by the time it reaches the northern Antilles, imo.
Member Since: Posts: Comments:
I saved this pic from early this morning......check out the smiley face....LOL

oh no'sss we have a joker system on our hands...
Member Since: Posts: Comments:
1464. java162
Quoting IKE:


I never answered the poll question.

I would have said this weekend.

Just doesn't look that good right now...


dude!!!! all thats missing is the convection which will muild during dmax. stop being so pecimestic and pretending that you don't want it to develop. it is huge and needs some time to get going. after that i think there will be some rapid intensification.
Member Since: Posts: Comments:
1462. IKE
Quoting Stormchaser2007:


Wasnt referring to you IKE. Dont worry.


I know you weren't. I was just throwing in my opinion on it.

Amazing that it's almost August 14th and>>>0-0-0....still.

Member Since: Posts: Comments:
Quoting philliesrock:
Wow, this thing is a beast:



It's a mess right now - gots a long way to go - convection needs to contract towards the center, it won't be this wide in a few days
Member Since: Posts: Comments:
Poll Time!!!

Do you think ex-TD2 is going become a depression again?

A) Yes
B) No
C) Maybe

Member Since: Posts: Comments:
1458. rxse7en
Quoting Stormchaser2007:
Some of you are WAY too bullish with 90L....again. 90L needs to gain a significant amount of convection to be classified a TD. Its not going to do that in 12 hours...simple. Its going to take at least 24-36 hours to develop sustainable sufficient convection. Give it till 11am Saturday.
Concur. It just entered the Atlantic a relatively short time ago and it has a looong way to go.
Member Since: Posts: Comments:
Quoting BenBIogger:


C



Would that be EDT or GMT? if EDT I'll take "What is 90L/TD3 by 5am" for the win, Alex.;)
Member Since: Posts: Comments:
Quoting DM21Altestic:
Drak, will 90L recurve out to sea?



way too soon too tell best thing too do is wait see and watch
Member Since: Posts: Comments:
1454. cg2916
Quoting philliesrock:
Wow, this thing is a beast:


It looks much better than it did a little while ago. AND it's DMIN. It's LLC is almost closed, just a little exposed to the west.
Member Since: Posts: Comments:
Whats happening to 90Ls NE btw?

PS thanks Terra ^_^
Member Since: Posts: Comments:
Just read the 5 o'clock advisory, and i see TD2 is now a remnant low, and they are not going to write anymore advisories, I agree with the NHC 100%, now all eyes on 90L.
Member Since: Posts: Comments:
Quoting IKE:


I never answered the poll question.

I would have said this weekend.

Just doesn't look that good right now...


Wasnt referring to you IKE. Dont worry.
Member Since: Posts: Comments:
Quoting IKE:


Here come the trains down the train track!
Member Since: Posts: Comments:
Quoting Hurricane4Lex:
TerraNova where do you get maps showing day and night like post 1433


Link
Member Since: Posts: Comments:
Wow, this thing is a beast:

Member Since: Posts: Comments:
1445. IKE
Quoting Stormchaser2007:
Some of you are WAY too bullish with 90L....again. 90L needs to gain a significant amount of convection to be classified a TD. Its not going to do that in 12 hours...simple. Its going to take at least 24-36 hours to develop sustainable sufficient convection. Give it till 11am Saturday.


I never answered the poll question.

I would have said this weekend.

Just doesn't look that good right now...
Member Since: Posts: Comments:
Good evening Patrap, Ike, and others
guys we dont need 30 Advisory posted on the blog that says last Advisory on TD 2


one or two is all we need
Member Since: Posts: Comments:
TerraNova where do you get maps showing day and night like post 1433 T.I.A.
Member Since: Posts: Comments:
1441. srada
1393. Patrap 4:56 PM EDT on August 13, 2009
From ones Lips to Gods Ear,.


Remember to always Heed a Evac warning,esp in a Surge Zone.

Mr And Mrs Guerra will be the first to tell ya that.

And everyone from the Brownsville to The Keys Know,..the GOM can bite ya real fast.never discount any threat till its inland.


thats really scary!
Member Since: Posts: Comments:
Some of you are WAY too bullish with 90L....again. 90L needs to gain a significant amount of convection to be classified a TD. Its not going to do that in 12 hours...simple. Its going to take at least 24-36 hours to develop sustainable sufficient convection. Give it till 11am Saturday.
Member Since: Posts: Comments:
1439. KEEPEROFTHEGATE (Mod)
Quoting Drakoen:
90L's structure is very impressive for an invest but it needs convection to congeal around the center of circulation which I suspect will happen within 24 hours according to the latest computer model runs.

Regeneration of TD2 would most likely occur when the system get's past 50W
likly at the triple nickel as i like to call it

15n 55w
Member Since: July 15, 2006 Posts: 178 Comments: 55972
90L most likely be TD3 at 5am and TD2 rises from it deathbed at 5am at D-MAX
Member Since: June 13, 2009 Posts: 2 Comments: 12716

Viewing: 1487 - 1437

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 | 72Blog 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
28 °F
Overcast

JeffMasters's Recent Photos

Lake Effort Snow Shower Over Windsor, Ontario
Sunset on Dunham Lake
Pictured Rocks Sunset
Sunset on Lake Huron