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: 3087 - 3037

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

Quoting Cotillion:


All the way with it?


Yessir.
Member Since: Posts: Comments:
3085. HadesGodWyvern (Mod)
METEO France
High Sea Forecast for the eastern Atlantic
---------------------------------------

Strong tropical wave along 24W south of 20N moving west near 10 kts.

Associated low 1010 near 12N, expected becoming tropical depression in the next 24H or 48H.
Member Since: Posts: Comments:
Quoting CybrTeddy:


The SAL and dry air is almost gone, I listened to the Bob barometer last night and he agreed with that. An anticyclone is moving in tandem with 90L too, protecting it from shear.


All the way with it?
Member Since: Posts: Comments:
morning 456 you should be praying all the time. not only last night LOL
Member Since: Posts: Comments:
Quoting Cotillion:
It will have to overcome ex-TD2's problems first. If it can't contend with dry air and shear, the invest will have problems.



The SAL and dry air is almost gone, I listened to the Bob barometer last night and he agreed with that. An anticyclone is moving in tandem with 90L too, protecting it from shear.
Member Since: Posts: Comments:
3080. HadesGodWyvern (Mod)
referring to Dolly, are we?
Member Since: Posts: Comments:
Quoting CybrTeddy:


It appears the ECMWF is the outlier here 456. Look how tight the models are, the ECMWF is the only one sending it out to sea.


However, ECMWF is the one that has done the best this year IMHO. Keep on praying 456.
Member Since: Posts: Comments:
GFS turned it back into a MISS/ALA storm. WE are probably going to see it jump east,west,east,west again.
Member Since: Posts: Comments:
Quoting CybrTeddy:


It appears the ECMWF is the outlier here 456. Look how tight the models are, the ECMWF is the only one sending it out to sea. :(


yea i notice, it is becuz it has 90L slower feeling more of a weakness.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
3076. jipmg
Quoting zoomiami:
Good morning
456 - do you know why the models are in such agreement? I don't ever remember seeing them do this before.


Ridge of high pressure to the north might end up being stronger than originally forecasted by these models.. then again its a weeks forecast, I honestly would take it only with a grain of salt "for now".
Member Since: Posts: Comments:
it is clear that the flow is really east to west. ex TD 4 continues to move west despite at 41W where the models expected it to start making the turn. this could be a problem for the islands in regard to soon to be TD3 which looks likely to continue west for a few days
Member Since: Posts: Comments:
Good morning
456 - do you know why the models are in such agreement? I don't ever remember seeing them do this before.
Member Since: Posts: Comments:
It will have to overcome ex-TD2's problems first. If it can't contend with dry air and shear, the invest will have problems.

Member Since: Posts: Comments:
Quoting Weather456:
Morning, I prayed alot last night so I hope the ecmwf is right



It appears the ECMWF is the outlier here 456. Look how tight the models are, the ECMWF is the only one sending it out to sea.
Member Since: Posts: Comments:
3071. HadesGodWyvern (Mod)
Japan Meteorological Agency

Tropical Disturbance Summary (0600z 14AUG)
=========================================
SUBJECT: Tropical Depression In Sea East of Marshalls Island

At 15:00 PM JST, Tropical Depression, Former Maka (1008 hPa) located at 13.4N 177.1E has 10 minute sustained winds of 30 knots with gusts of 50 knots. The depression is reported as moving west-southwest at 7 knots.
Member Since: Posts: Comments:
Good morning. 90L looks to be consolidating
Member Since: Posts: Comments:
Morning, I prayed alot last night so I hope the ecmwf is right

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Guillermo takes the biscuit though.

Looks like it's slowly trying to make itself an eyewall.
Member Since: Posts: Comments:
90L's looking good this morning.
Member Since: Posts: Comments:
3065. HadesGodWyvern (Mod)
National Hurricane Center
Tropical Cyclone Advisory #8
SEVERE TROPICAL CYCLONE GUILLERMO (EP102009)
9:00 AM UTC August 14 2009
====================================

At 6:00 AM UTC, Hurricane Guillermo (987 hPa) located at 17.6N 125.9W or 955 NM west-southwest of the southern tip of Baja California Peninsula has sustained winds of 65 knots with gusts of 80 knots. The cyclone is reported as moving west at 13 knots.

Hurricane-force Winds
=====================
15 NM from the center

Gale/Storm-force Winds
================
90 NM from the center

Forecast and Intensity
======================
12 HRS: 17.9N 127.9W - 70 knots (SSHS-1 Cyclone)
24 HRS: 18.4N 130.5W - 70 knots (SSHS-1 Cyclone)
48 HRS: 19.6N 135.7W - 55 knots (Tropical Storm)
72 HRS: 21.0N 141.0W - 45 knots (Tropical Storm)
Member Since: Posts: Comments:
So, it appears this may be a good time for every one to brush up on their Eye Wall Replacement Cycle knowledge.
Member Since: Posts: Comments:
morning
90L looks rather impressive this morning. also ex TD4 is trying a comeback. for the ist time it is surrounded by a moisture field
Member Since: Posts: Comments:
Quoting HurricaneFCast:

I'm showing a 1.1 now for 02L.. It's like the little engine that could :)


For the ADT, yup. Guess that's basically just admitted 'it's there'. But yeah, it's like li'l 96L of '07 all over again.

Chugging away despite dry air and shear. May have the same result, though.
Member Since: Posts: Comments:
Okay, well night all, need to get some sleep as it's now 4:55 a.m. :)
Member Since: Posts: Comments:
Quoting Cotillion:
They won't classify it as a TD yet.

It has gone up to 1.5 on the Dvorak and strangely, 02L has just reappeared on the Dvorak from SAB for 1.0 too.

90L has dropped a millibar to 1008, but that's all. Still at 25kts.

I'm showing a 1.1 now for 02L.. It's like the little engine that could :)
Member Since: Posts: Comments:
They won't classify it as a TD yet.

It has gone up to 1.5 on the Dvorak and strangely, 02L has just reappeared on the Dvorak from SAB for 1.0 too.

90L has dropped a millibar to 1008, but that's all. Still at 25kts.

Plus there's no ATCF renumbering which is generally a good indication.
Member Since: Posts: Comments:
Quoting GetReal:


If you do not like the results of that GFS run just stick around a little longer... The next could be to your, or someone else's liking... LOL


True! It could be a record though - two runs in a row with basically the same destination. :)
Member Since: Posts: Comments:
Quoting tornadofan:
Morning all.

See the overnight 0z GFS does not think much of the potential east coast trough. Has 90L in the Gulf still after slamming the Islands.

I just can't believe the consistent NOLA landfalls projected by the models.. That is, however, usually a good sign because, as we all know, these models adjust over time and are almost never correct with their initial assessments.
Member Since: Posts: Comments:
3056. GetReal
Quoting tornadofan:
Morning all.

See the overnight 0z GFS does not think much of the potential east coast trough. Has 90L in the Gulf still after slamming the Islands.


If you do not like the results of that GFS run just stick around a little longer... The next could be to your, or someone else's liking... LOL
Member Since: Posts: Comments:
I'm waiting to see if they classify it as a TD @ 5am.. I wouldn't be surprised, especially with how well-defined the circulation has become over the past 6 hours. QuikSCAT missed most of the circulation although you can see the eastern edge of 90L with at least 25Knots, and a couple of 30Kt barbs.. and that's just the eastern edge. I'd say it's TD3 as we speak.
Member Since: Posts: Comments:
Morning all.

See the overnight 0z GFS does not think much of the potential east coast trough. Has 90L in the Gulf still after slamming the Islands.
Member Since: Posts: Comments:
3053. 7544
Quoting Cotillion:
90L really does look like it's in the wrong basin.


yeap and ikes post looks spooky too
Member Since: May 6, 2007 Posts: 0 Comments: 6874
90L really does look like it's in the wrong basin.
Member Since: Posts: Comments:
3051. IKE
Member Since: June 9, 2005 Posts: 23 Comments: 37860
3050. IKE
Member Since: June 9, 2005 Posts: 23 Comments: 37860
3049. 7544
evrything is lighting up

new blob est of fla

ext td

and 90l looks best of all stay tuned this one could a td already
Member Since: May 6, 2007 Posts: 0 Comments: 6874
3048. jipmg
Quoting GetReal:
As someome else observed earlier, it does appear that 90L has picked up the pace towards the west...


yep, not good news for the Antilles
Member Since: Posts: Comments:
3047. GetReal
As someome else observed earlier, it does appear that 90L has picked up the pace towards the west, under the south side of the azore high.
Member Since: Posts: Comments:
Wow 90L looks great.
Member Since: Posts: Comments:
Quoting IKE:


Yup...I just woke up....had my computer on looking at TD2 and 90L.

Looks like 90L is viewable now on SSD.

It's lookin' mighty purdy too. :)
Member Since: Posts: Comments:
3044. IKE
Quoting GetReal:
Ike are you ready for the upcoming all night long sessions that are about to start here. You know the ones where everyone is watching each incoming satellite pic, trying to determine the exact position of the center, and was that a jog, or a new motion, did it pass to the north, or the south of the last forecast point???????


Yup...I just woke up....had my computer on looking at TD2 and 90L.

Looks like 90L is viewable now on SSD.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
3043. GetReal
Ike are you ready for the upcoming all night long sessions that are about to start here. You know the ones where everyone is watching each incoming satellite pic, trying to determine the exact position of the center, and was that a jog, or a new motion, did it pass to the north, or the south of the last forecast point???????
Member Since: Posts: Comments:
3042. IKE
Quoting jipmg:
eh is it just me or is 90L moving a bit faster than it was before based on satellite imagery?


It does look like it's moving a little faster.

Surprised with the 00Z ECMWF showing 90L curving north near 60W. After looking at the South America loop on the ECMWF, it shows 90L near 13N and 37W on Monday. It's approaching 30W now. You can see it on the SSD satellite loops now.

ECMWF is too slow with 90L's movement. It may be near 50W by Monday.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
SST's for TD2:
SST's
http://cimss.ssec.wisc.edu/tropic2/real-time/storm.php?&basin=atlantic&sname=02L&zoom=4&img=1&vars= 1111100000000000000000&loop=0

WV Imagery for TD2:
WV Imagery
http://cimss.ssec.wisc.edu/tropic2/real-time/storm.php?&basin=atlantic&sname=02L&zoom=4&img=1&vars= 1111100000000000000000&loop=0

Shear for TD2:
Shear
http://cimss.ssec.wisc.edu/tropic2/real-time/storm.php?&basin=atlantic&sname=02L&zoom=4&img=1&vars= 1111100000000000000000&loop=0

Actually, the links aren't working properly, you'll have to click on the selections on the top of the screen to view each aspect of the image.
Beside "Ocean:" click SST (Reynolds)
Beside "Satellite Imagery" click WV
Beside "Sat Derived Products" check the Shear box

(I know it's pretty self-explanatory, but just for those who lurk and may not use CIMSS, I'm sure that will help)


Member Since: Posts: Comments:
Quoting jipmg:
Very impressive convective activity around 90L.. we might end up with ana sooner than expected..

As for TD 12 it seems its moved into a more conductive environment for some slow tropical development, based on the latest satellite loops TD 2 isn't in such a hostile environment when compared to yesterday

The environment is marginally conducive at best due to the fact that SST's are barely 26C until it reaches 50W, a large layer of dry air lies between it and 50W, and shear is forecast to remain moderate for at least 24 or 48 hours.
Member Since: Posts: Comments:
3039. jipmg
eh is it just me or is 90L moving a bit faster than it was before based on satellite imagery?
Member Since: Posts: Comments:
3038. GetReal
Quoting gaweatherboi:
Ive asked before but does anyone see Ex TD2 or 90L heading towards GA or the carolinas?


ATT anything, and I mean anything and anywhere along the east coast, or GOM is possible... Like others have mentioned these are just models, that should be used as tools, not solid forecast.
Member Since: Posts: Comments:
Quoting gaweatherboi:
Ive asked before but does anyone see Ex TD2 or 90L heading towards GA or the carolinas?


Probably not.
Member Since: Posts: Comments:

Viewing: 3087 - 3037

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.

JeffMasters's Recent Photos

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