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

By: Dr. Jeff Masters , 2:02 PM GMT on August 14, 2009

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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

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Quoting mobilegirl81:
A southerly trajectory will delay an east coast landfall and be more of a florida and gulf coast storm.
Hey there Mobile, I believe the term "love thy neighbor" but all this talk of gulf coast storm and I may have to deport you to FL....LOL
4883. jpsb
That blob about to enter the GoM was/is a tropical wave correct? It appears to have spin (link a hour or so ago) and it appears to be gaining a lot of energy (link a few minutes ago) I for one think that blob deserves a little attention from the experts here. It is after all entering the very warm, stable GoM. And there are lots of folks going to be very upset if a hurricane pops up unexpectedly in the Gulf.
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Quoting canesrule1:
almost 5000 post, time for a new blog, jeff, lol.




no no keep it going
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MobileGirl Did you see that CMC model that Aussie posted where it maybe looks like Ana gets in the GOM and makes a beeline for central to N gulfcoast?
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Quoting leftovers:
we need a bookie to place bets


lol thats meteorology im afraid
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Quoting WeatherStudent:


KMan said it, so it'll happen, OK?


Kman said nothing would happen. Your taking his words out of context.
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Quoting cardinal56:
there is no tropical depression 3 yet, the navy page still says 90L, and the nhc hasnt issued any advisories or special tropical disturbance statements



yes there is a TD 3 the navy site shows it


Atlantic
green ball03L.THREE
green ball02L.ANA
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Quoting Hurricane4Lex:4772. Hurricane4Lex 1:34 PM GMT on August 15, 2009
Quoting AussieStorm:


What's that developing in the GOM?


Look at key west radar you'll see what I think may be humberto's cousin as someone put it



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Quoting Weather456:
Dr lyons said 03L has 40 mph winds at the center.


Well then.. Lets say Hi to Bill.
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almost 5000 post, time for a new blog, jeff, lol.
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cyclone...i agree...somone might be asleep at the wheel....it's going to blow up i'm affraid this afrernoon...but that's just me
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4870. Seastep
Quoting cardinal56:
there is no tropical depression 3 yet, the navy page still says 90L, and the nhc hasnt issued any advisories or special tropical disturbance statements


Yes, there is. WU updates automatically from official data feeds.

They just haven't pulled 90L yet... in the data and literally said TD, but there is no such thing as invest03
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well look what happen with Ana, when it was 99L, all models cry fish, now forecast to reach Florida by mid-next week.
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A southerly trajectory will delay an east coast landfall and be more of a florida and gulf coast storm.
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Quoting polarcane:

Sheer does not appear to be an issue for some time now!


That's what I see...I mentioned shear to be sarcastic. I also mentioned SSTs sarcastically. The GoM is hotter-n-hell right now.

So what is it that makes this wave, that's starting to fire, that's starting to spin, that's moving into a red hot GoM...make it not develop? What?

NO MODEL SUPPORT? You've got to be kidding me!
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Quoting Funkadelic:
Hey weather456,

Do you think TD3 will be fish storm? In my opinion it is to far south, and currently it is moving W/WSW. The models are a little to north in my opinion.
Might go over the islands and then after that its very uncertain.
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4865. jipmg
Quoting Weather456:


far from fish, the models are not verifiying since 03L remains at 12N and jogging a little south of due west.

Dejavu with 02L


that was the forecast before these model runs taking it to sea!
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I seem to recall years ago when there was a line of storms like this, the media was all over the place and had re-scheduled there evening news. By the time they came back on the air two hours later, all the storms were gone. If I remember, they explained that there was just to much energy and they all disapaited
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The models will put both of them back west again.
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Quoting Funkadelic:
Hey weather456,

Do you think TD3 will be fish storm? In my opinion it is to far south, and currently it is moving W/WSW. The models are a little to north in my opinion.


far from fish, the models are not verifiying since 03L remains at 12N and jogging a little south of due west.

Dejavu with 02L
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Quoting floridafisherman:
4815. canesrule1 1:43 PM GMT on August 15, 2009
Quoting WeatherStudent:


Geeze, why did they upgarde it then. RIP. Ana, your giving the NHC a bad name here.
Rip Ana, are u insane???? This has a rather high possibility of affecting us here in SFLA as a possible Cat 1 and u r saying Rip ana, WTF?
---
canesrule, i would just ignore WS. as far as im concerned, hes the same as stormno, kerryinnola, and all these other downcasting absolutists. i personally have had WS on my ignore list for a longgg time. in fact hes up near the top at #3.
lol, i haven't put him on my ignore since occasionally he has good stuff to share, and he is also young, but i might be rethinking now, lol.
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4860. kachina
Quoting Hurricane4Lex:


Tech is updating as this unfolds


Gonna have to get Tech another pot of coffee... *grin*
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there is no tropical depression 3 yet, the navy page still says 90L, and the nhc hasnt issued any advisories or special tropical disturbance statements
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Quoting ackee:
90L does look that organize maybe NHC will wait a while before may it TD#3



its now TD 3 lol
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Dr lyons said 03L has 40 mph winds at the center.
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4856. jipmg
so guys any new model tracks, and quick skats? When can we expect them
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The 06 GFS ten Image Loop changes so fast...yesterday, we were going to suffer a direct hit here in SLA, today, it has everything going fishing?????
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Quoting CycloneOz:
You know, I understand that Ana and TD3 are interesting CV storms...

But wow, they're still days away from affecting anything...

I would like to see a focus on what the GoM blob is doing. P451 posted a floater-type image of it some posts back and it is firing up.

Models are not developing it, so that's why it is not going to develop? Are you kidding me?

Since when did a developing TC need model support in order to come around?

What's stopping this thing right now? Shear? SSTs? Some other unfavorable condition? What?

If there are no unfavorable conditions, why doesn't it develop into something very very bad?

Sheer does not appear to be an issue for some time now!
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Quoting kachina:
What's up with the Wunderground's tropical/hurricane page? It's showing Invest 03 and 90L as separate entities - both with the same coordinates and wind speeds?


Tech is updating as this unfolds
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Quoting Tazmanian:
4800 commets


olny 100 more too go
Quoting extreme236:


Ana needs to go back to the dmax store and get some more clothes...


lol
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Since the latest Nogaps gas a hit very close to Miami, where do u think the center of the cone of uncertainty will be? lol.
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4847. RM706
For Goggle Earth and Google Map users: http://tropicalatlantic.com/plots/02.shtml
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4846. kachina
What's up with the Wunderground's tropical/hurricane page? It's showing Invest 03 and 90L as separate entities - both with the same coordinates and wind speeds?
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Quoting HurricaneKyle:
Anyone that calls 90L a fish or a US landfall this far out doesn't have a clue what they are talking about.
You know common sense in not so common anymore! Good to see some level headed folks on here.
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Quoting CycloneOz:
You know, I understand that Ana and TD3 are interesting CV storms...

But wow, they're still days away from affecting anything...

I would like to see a focus on what the GoM blob is doing. P451 posted a floater-type image of it some posts back and it is firing up.

Models are not developing it, so that's why it is not going to develop? Are you kidding me?

Since when did a developing TC need model support in order to come around?

What's stopping this thing right now? Shear? SSTs? Some other unfavorable condition? What?

If there are no unfavorable conditions, why doesn't it develop into something very very bad?


I asked about it too but noone seems to be paying attention the African blob seems to be more of a concern
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4815. canesrule1 1:43 PM GMT on August 15, 2009
Quoting WeatherStudent:


Geeze, why did they upgarde it then. RIP. Ana, your giving the NHC a bad name here.
Rip Ana, are u insane???? This has a rather high possibility of affecting us here in SFLA as a possible Cat 1 and u r saying Rip ana, WTF?
---
canesrule, i would just ignore WS. as far as im concerned, hes the same as stormno, kerryinnola, and all these other downcasting absolutists. i personally have had WS on my ignore list for a longgg time. in fact hes up near the top at #3.
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4842. KBH
right now that new wave is almost as big as the gulf!.. it's probably fizzle out when the SAL catches up with it
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Quoting mossyhead:
Ok, thanks for the info.
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4840. jipmg
by the way ANA's center is a bit further south than the NHC had estimated it to be
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From what i understand if Ana stays weak it will keep going W then WNW? I Really dont think Ana is going to die according to all the info. I am starting to get concerned about it getting in the GOM! Dont most systems that form before 40W go out to sea like TD3?
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4838. jipmg
Quoting CycloneOz:
You know, I understand that Ana and TD3 are interesting CV storms...

But wow, they're still days away from affecting anything...

I would like to see a focus on what the GoM blob is doing. P451 posted a floater-type image of it some posts back and it is firing up.

Models are not developing it, so that's why it is not going to develop? Are you kidding me?

Since when did a developing TC need model support in order to come around?

What's stopping this thing right now? Shear? SSTs? Some other unfavorable condition? What?

If there are no unfavorable conditions, why doesn't it develop into something very very bad?


I agree.. people rely on models too much, up until now I didn't give a rats about the forecast models, I would predict my own track.
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Quoting extreme236:


Ana needs to go back to the dmax store and get some more clothes...


Uh-oh, Bill might be disgusted and go another way towards land. lol
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Member Since: August 19, 2006 Posts: 0 Comments: 15826
The ships intensity model had ana with 66mph wind @ 120hrs at 8:45am and at 9:30am they moved it up to 75mph at 120hrs.If it gets in the bahamian waters who knows what can happen.
Member Since: October 9, 2008 Posts: 0 Comments: 204
Quoting jasoniscoolman10:
WHAT HAPPERN TO 90LNOW ITS 03L WHY??
Don't worry, it's a TD now.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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