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 someone might be focusing on the pretty colors in the precip forecast, rather than the isobars.
Adrian, what do u think of our two systems? If they both blow up tonight or tomorrow I think we may start to see some interaction.
I see. I thought someone said central FL, which I took to mean Atlantic coast central FL.
TD2
90L
AOI
AOI
He mustn't be basing that on the 00 GFS.
The next wave after 90L goes right to the Caribbean and get destroyed by...are you ready for this...Montserrat. Little island shreds hurricane. After visit hurricane just gives up completely. Right.
G'Nite.
I don't think there is anything you can do about it. That's just an old-fashioned global model flaw when you start looking past five days.
In general, I guess we have to remember that these are imperfect models and deal with it. *sigh* Thanks for the input though.
Night folks! Have fun watching!
modeling : Use of mathematical equations to simulate and predict real events and processes.
Don't forget the GIGO principle.
I wonder how is the circulation looking right now =P
watch wait see
It's more or less, I think, because this is the first potential United States landfall we've had all year, and not necessarily because it's south Florida.
That's right, and those mathematical equations are based upon inaccurate assumptions of our atmosphere. We need to stop this conversation though, or I'll be dragging textbooks out before sunrise! I'm out for the night... I have a feeling everything will just be miles west of where it is now when the baby wakes me up in a few hours.
Never.
Lets hope 90L does not pull a Felicia and TD2 can stay a TS like that other storm in the EPAC.
You probably will not read this, but do you remember that most all of our physics proofs start out with "assume the sin of theta equals theta"? Only actually happens when theta is zero...almost never for most of those physics principles.
Thats one of your better forecast jobs.......LMAO
I'll be doing the same thing this weekend as well as topping of my Hairy Cane supplies. Watched Max Mayfield on 10 tonight and he highly recommends South Floridians to get out this weekend and get their plans in order.....
Link
Yeah, I'm still reading... and I do remember all that.
Do you realize what you're doing to me? Bringing back flashbacks of Dynamics classes, where I walked out naseous every Monday, Wednesday, and Friday. I thought I had drank most of those memories away.
You're right though... too many assumptions that cause a ripple effect of imperfections. Like we said... "Garbage In, Garbage Out".
Geez, I'm glad someone can relate to this. Thanks for re-instilling my faith in this comment section.
Have a great night.
No, that is quite correct. Convective activity increases at nighttime over the ocean.
lol
and i call it as i see it 02l died and was reborned just as was stated just the facts friend
Whoa, you were in my dynamics classes? Sounds like em!
Good god.. don't use facts, that just confuses him.
Link
Goodnight.
If j is an imaginary number?
How come j * (-j) = -1
Thanks, no matter how much I read about the MJO, it still perplexes me :-)
Anyway... i am now in Key west.. I have always loved hurricanes... now that i am on an island that is just about at sea level... i have much more concern than before. i have been commenting to people that it only takes one or two hurricanes to put a season in the record books... it has been quiet up till now.... and now we have potential development in several places. while i watch in anticipation, i have a new found respect for mother nature..... i cant help but think back to those poor folks in texas that got hit with a storm surge much larger than expected.. I appreciate all the informational post, even the wish/down caster ones..
Ron
AB'S OR WANABEES
Yeah, I was probably the guy in the back with every equation typed in code into my TI-83 calculator!
University of LA-Monroe grad, 2006.
I think I got lost after the Geopotential Height equation... stayed confused for 2 years. Then, everything clicked, and the Vorticity Equation actually made sense. That was the happiest and scariest day of my life.
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