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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Is that a crow? Looks like a Grackle
I didn't know Ana was also called "greenball" Lol.
I note how all those 0/0/0 noobs have run away.
We might see a special one.
Talk about around the block and back, sheesh, lol. This is going to be a tough situation with another a day or so behind, most likely Bill will follow Ana. With the size difference I don't see Ana altering Bills path too much. Granted Ana will expand with latitude but not that much.
in two hours it might be a ts instaed
Why does the NHC have to be sooooo conservative? That sucker is spinning up.
Humberto - 8 hours... how long does this one need to cook before NHC upgrades?
The NHC is doing it again!
NOTHING!
From looking at visible sat loops I can see the center of Ana moving out from under weakening convection indicating SW shear. The ULL to the N of Ana has been plaguing the system from yesterday and combined with the very dry environment it looks like Ana may struggle to hold on to TS status.
This one is fighter though as we have seen.
My best guess is TD 3 at 11am and TS Bill by 5pm or 11pm or a special advisory today.
It's going to be a mad house later at the grocery store and HD. My news posted a story on facebook about getting your hurricane plan ready.
I could see Ana making a path for 90L and laying it with moisture
http://www.nps.gov/prsf/naturescience/american-crow.htm
I'm not a noob...but I sure loved the 0,0,0 condition while we had it! :)
Still...1,0,0 ain't that bad considering, huh? :)
Hahah, if TD3 skips TD status then we will need soccer crow.
key west radar,.. you are 100% correct, this will form and hit the upper gulf. hopefully nothing too big
rofl hey man... can someone explain to me the crow deal... lololol i dont get it! haha
Most likely they will issue a special statement for TD3 and Upgrade to Bill @ 11.
How does the NHC come up with the various codes for Invests? Like what does 99L mean? Thanks for answering!
Lurk Mode ON
that's what its doing, its sucking up all the dry air that was there and leaving a path left with moisture for bill
Explain the Fujiwara Effect and what effect it could have on our 2 starting stars? TIA ^_^
I see that 02L regenerated into TS Ana, and 90L might be forming a depression.
Ana should stop flashing herself.
PSS the SFWMD has TD3 on their map
Don't ask - in my 3 or 4 seasons of being here, I never understood it. (under various not used handles)
One of the things I love about this place is your always one step ahead of the masses. I always chuckle as I drive my massive lines at gas stations and brawls in the grocery store over the last can of beanie weanies, lol.
Ana's got problems.
Again.
I cannot get your link to come up.
Somethings blocking it on my in end.
I've tried turing of my popup blocker etc.
Nevermind I had to install java for 32 bit and 64 bit windows....dummyme
i wont answer you.
kidding hehe... they go thru 90-99, 99L just means they've gone thru 90-98 and are up to 99. i guess the L means low but that's just me talking.
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