Disturbance 90L close to tropical depression strength; TD 2 may rise again
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
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I think he loves the thrill of a storm, then panics thinking they are all going to hit him....too much time on his hands if you ask me.
Hey StormW, Do you think the next few weeks is going to be overly active?
Has any model really told us what we didn't know from climo - this time of year, anybody down wind could get a storm? If it forms watch it, if you find yourself in the cone (or near it), and you don't have a safe place to hunker down considering the worst case of possible rapid intensification, move out of the way.
Back to work.
Thanks Aussie - it worked!
lol!
I'm listening to the podcast of this morning/last night's show.
Seems like it's moved lot more West than the models had them only few hours ago at 26W!?
What the GFDL and other intensity model is a real possibility. Most of the models have significant strengthening of the system once it gets going.
That image is almost 4 hours old.
That graphics you show re the position of 90L was at 12Z - that was some 4 hours ago now! On latest Sat images loop to me at least it look like 12N - 28W
Gee I hope you don't let a little death and destruction rain on your picnic...
LOL - Thanks for the giggles.
Thanks!
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.
Lol. Sure throw logic and common sense into the mix. ;)
Would that be Mother Eff?
Yeah, but once it hits the GOM with that HOT water - who knows......
the blog is going to go mad lol
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.
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.
Somewhat shocked to see models in the Gulf like this...
Have a link for this?
I have never seen the Atlantic this active all year long!
My dart landed in Wyoming... crap there goes yellowstone.
Some ensemble members go to the gulf, some turn into fish storms. Basically all this tells you is that anything could happen.
LOL
I think it's too far south for the steering currents to steer it away from the Gulf in time.
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