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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thank you thecanewhisperer
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Still looking @ Wednesday AM for 90L on 12GFS

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Quoting StormW:
See everyone later.

Have a great day, stay safe.
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Quoting Elena85Vet:


Elena went straight up the spine of Cuba and reached Cat 3.

I have the entire satellite loop of elaina on video tape.I remember this storm too,I was living on fort myers bch then, but I was working on Lake Superior at the time.
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06 GFS Run
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Quoting jeffs713:

Its on the tropical page here on WU.

the models don't show 90L going into the gulf. they don't go out that far.

the only one that does is the long range GFS.
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Quoting AussieStorm:

Hey StormW, your talking about Hurricane Gordon atm.... just looked it up in the archive.

Damn that's 1 wild storm track.


Holy Hell! Was he drunk?? Did he get a HUI?
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Cat 3 before the northern Antilles:





looks like EX TD2 will be making a comeback advisories will likely be reissued later today if this trend continues but 90L is fighting easterly shear but will probably be a TD by tonight or tomorrow watch out northern leeward islands 2 systems headed in yor general direction
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Quoting leelee75k:
Hey all, just dropping in out of the shadows with a dumb question, but if both storms stay at current speed and size, what dates would south florida be affected IF let's say they both travel the same direct path here? I suck at Math and this is a purely hypothetical question I have no opinion or wishes for either of these storms except that they both dissapate into nothingness over the ocean. Thanks in advance.


Mid Next Week #1 (Aug 18/19) Next weekend #2 (Aug 22-23)
Were in the clear on this one, just hope I didn't jinx us
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373. MahFL
"But honestly that was a freak scenerio that we may never see again the path it took."

Do not bet your life on that.....:)
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Quoting P451:
90L - Certainly fighting some easterly shear. Center seems on the eastern edge of the

convection.


VIS





WV




AVN





FUNKTOP





RGB



Definitely fighting off some shear. Look how all the cirrus clouds on the convection are streaming off to the WNW.
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Hey all, just dropping in out of the shadows with a dumb question, but if both storms stay at current speed and size, what dates would south florida be affected IF let's say they both travel the same direct path here? I suck at Math and this is a purely hypothetical question I have no opinion or wishes for either of these storms except that they both dissapate into nothingness over the ocean. Thanks in advance.
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Quoting AussieStorm:

Hey StormW, your talking about Hurricane Gordon atm.... just looked it up in the archive.

Damn that's 1 wild storm track.


Someone gave Gordon WAY too many Pina Coladas.
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Quoting jeffs713:

Rita went north of the islands too, IIRC.


Yes, it did.....
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Quoting RitaEvac:
I always knew there was just no way a hurricane going north of the Islands could come to SE TX. Ike changed all that, so now when I see something thats supposed to go north of the Islands I have to be somewhat hesitant to say I'm in the clear. But honestly that was a freak scenerio that we may never see again the path it took.


I think IKE caught everyone with their pants down, lol. Just goes to show you that mother nature ALWAYS rules.
365. ackee
what the chance we see TD#2 again by 5pm
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364. jpsb
Quoting weatherfan92:


I think it's too far south for the steering currents to steer it away from the Gulf in time.
Well I certainly hope it does not come to Galveston Bay area, no way we can handle another hit after Ike. Half of my little town (San Leon) is already gone and the other half still in recovery. Lots of dead trees, fema trailers, half built houses and abandoned houses. A big hurricane now would be horrible beyond belief.
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Quoting RitaEvac:
I always knew there was just no way a hurricane going north of the Islands could come to SE TX. Ike changed all that, so now when I see something thats supposed to go north of the Islands I have to be somewhat hesitant to say I'm in the clear. But honestly that was a freak scenerio that we may never see again the path it took.

Rita went north of the islands too, IIRC.
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Quoting StormW:


Cool...enjoy!

Hey StormW, your talking about Hurricane Gordon atm.... just looked it up in the archive.

Damn that's 1 wild storm track.
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Quoting BatTracker:
Guys,

Anyone have a link to the models for the Artist Formerly Known as TD2?

Thanks in advance!
Just look under the list of models and click "add all"and you should be good to go:Link
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Frederic rolled over islands, came off as a depression, and turned into a cat4 then hit the Miss/Al border as a 3
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Quoting jeffs713:

For the next 5 days, steering currents for weak to moderate storms are generally westward. A stronger storm *may* feel a slight pull to the NW, but nothing beyond a course of 290 or so. After 5 days (when it is near the islands), there are just too many factors involved. Between the system's strength, its latitude, how deep the trough off the east coast is, and how far south the trough goes all factor in. It is similar to trying to predict how traffic will be next Wednesday when driving across Houston or Atlanta.


hahaha, that's a good analogy Jeff!
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Met's worse nightmare is when a hurricane gets so powerful it starts to control the weather around it, and then it basically does what it wants regardless of models, when its supposed to be turning it keeps barreling one way
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Quoting TexasHurricane:
Quoting RitaEvac:
Somewhat shocked to see models in the Gulf like this...


Have a link for this?

Its on the tropical page here on WU.
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Guys,

Anyone have a link to the models for the Artist Formerly Known as TD2?

Thanks in advance!
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Quoting extreme236:
Interesting blobs north of the Bahamas and off the southeast coast.

href="http://radar.weather.gov/ridge/radar.php?rid=TBW&product=N0V&overlay=11101111&loop=yes"

Tampa radar base velocity

Little spin in the doppler velocity...not a "ying yang" yet though.
Member Since: September 4, 2007 Posts: 0 Comments: 491
Quoting sarahjola:
that gfdl model run is scary. i have a bad feeling it might pull a Katrina and go across Florida and into the gulf and hit Louisiana and Mississippi. according to the models it is going to be a hell of a storm. gfdl says it'll be a cat. 3 before it hits the islands. i think its going to go right along the northern edge of the islands and not meet much to bring the strength down. gut feeling its a gulf storm, or bad nerves. lol! Texas may be in its path too. well its far away, but what do you all think about it being a gulf storm. does it look or feel that way to you? what about the steering currents? what and where are they and how can i read them to see where the steering currents might take it?

For the next 5 days, steering currents for weak to moderate storms are generally westward. A stronger storm *may* feel a slight pull to the NW, but nothing beyond a course of 290 or so. After 5 days (when it is near the islands), there are just too many factors involved. Between the system's strength, its latitude, how deep the trough off the east coast is, and how far south the trough goes all factor in. It is similar to trying to predict how traffic will be next Wednesday when driving across Houston or Atlanta.
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Quoting CaneWarning:


The good thing, or bad thing depending on your perspective, is if this gets in the gulf these models have it going through PR, DR, and Cuba before getting there. Going up the spine of Cuba and the other islands would greatly diminish it.


Elena went straight up the spine of Cuba and reached Cat 3.

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Quoting sarahjola:
that gfdl model run is scary. i have a bad feeling it might pull a Katrina and go across Florida and into the gulf and hit Louisiana and Mississippi. according to the models it is going to be a hell of a storm. gfdl says it'll be a cat. 3 before it hits the islands. i think its going to go right along the northern edge of the islands and not meet much to bring the strength down. gut feeling its a gulf storm, or bad nerves. lol! Texas may be in its path too. well its far away, but what do you all think about it being a gulf storm. does it look or feel that way to you? what about the steering currents? what and where are they and how can i read them to see where the steering currents might take it?


I think it's too far south for the steering currents to steer it away from the Gulf in time.
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Quoting weathersp:


My dart landed in Wyoming... crap there goes yellowstone.


LOL
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Quoting RitaEvac:
Somewhat shocked to see models in the Gulf like this... this far out?<


Some ensemble members go to the gulf, some turn into fish storms. Basically all this tells you is that anything could happen.
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Quoting jeffs713:

Some of those ensemble tracks that go right over Hispanola and Cuba are very similar to the 1900 Galveston storm. Right now, it is just too far out to make any kind of guess, beyond throwing darts at a map.


My dart landed in Wyoming... crap there goes yellowstone.
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I always knew there was just no way a hurricane going north of the Islands could come to SE TX. Ike changed all that, so now when I see something thats supposed to go north of the Islands I have to be somewhat hesitant to say I'm in the clear. But honestly that was a freak scenerio that we may never see again the path it took.
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Press...I think I hear the call for Thorazine! I have officially put you in charge ;)
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I have never seen the Atlantic this active all year long!
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Interesting blobs north of the Bahamas and off the southeast coast.
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Quoting weathersp:
Born of the same mother...

you can make out the umbilical cord, lol.
Quoting RitaEvac:
Somewhat shocked to see models in the Gulf like this...


Have a link for this?
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Thank you Drak.

As I may have mentioned before, I have a very good friend who is a meterologist. She informed me this morning that former TD 2 has a very good chance of strengthening again, although a much smaller system. Their test models would have TD2 coming very close to the islands and staying at a much lower latitude and maintaining a westerly movement before a turn to the WNW. Anyone have any opinions in reference to this scenario? I do not mean to be condescending to myself, but you all seem to have a much better understanding of these dynamics than do I.
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Quoting RitaEvac:
Somewhat shocked to see models in the Gulf like this...


Some of those ensemble tracks that go right over Hispanola and Cuba are very similar to the 1900 Galveston storm. Right now, it is just too far out to make any kind of guess, beyond throwing darts at a map.
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Quoting mikatnight:


Gee I hope you don't let a little death and destruction rain on your picnic...
well never have one of my family members died from a cane, but no it doesn't rain on my picnic, lol!
Quoting TheCaneWhisperer:
Very possible to have 2 tropical depressions @ 5pm


Quoting extreme236:


the blog is going to go mad lol
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Quoting CaneWarning:


The good thing, or bad thing depending on your perspective, is if this gets in the gulf these models have it going through PR, DR, and Cuba before getting there. Going up the spine of Cuba and the other islands would greatly diminish it.


Yeah, but once it hits the GOM with that HOT water - who knows......
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Quoting weathersp:
Born of the same mother...



Would that be Mother Eff?
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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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