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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Gretter Antilles 2009 Major Huricane. Times running out for us here in the NE Caribbean.
It is not current
Today is not the 13th.
A
I do hope your right =] maybe the fact of being affected by the shear will keep it a little bit more to our south
I guess its too early to tell, at Wednesday we should have a clearer picture
Yup... Prairie schooner of course lol
Who is sick of polls on how many bloggers are sick of polls? :)
Actually, check out www.intrade.com to see the prediction markets for the hurricane season (you can participate if you are outside the U.S.).
Would you mind telling me what do you think will be the strength of 90 L and ex td 2 while passing the northern island
Thanks a lot
Would you mind telling me what do you think will be the strength of 90 L and ex td 2 while passing the northern island
Thanks a lot
Right you are ... my bad, sorry. Removed link.
Would you mind telling me what do you think will be the strength of 90 L and ex td 2 while passing the northern island
Thanks a lot
I cannot say what the strength of either system will be exactly. Model point towards a strong hurricane bearing down on the Lesser Antilles with 90L. With TD2 models that show development forecast a moderate hurricane in the Bahamas.
What evidence do you have to prove that?
At. Loop
and that would put the gulf more at risk
He lives in south Florida and that's where the GFS takes it...wishcaster...
He is telekinetic with Mother Nature. Only person that would give him a baby...
there all primers pat for the path of whats yet to come follow that and its where it goes
The..."It takes it over my house, therefore its right."
YouGov
All the polls you'd ever need.
Knock yourself out...
LOL for what I highlighted in bold. I should be careful though... my g/f might hurt me for that comment (she is from NOLA).
Of course, I am a Houston Texans fan, so...
Anyway, on the topic of the tropics, in one way, I am glad to see the blob moving away from FL, but at the same time, I don't want it sitting over the 30C water in the GOM.
Easy does it, none of us have proof, just opinions.
a beauty and a beast all in one
.SYNOPSIS...TROPICAL WAVE ALONG 79W MOVING W ABOUT 20 KT WILL
MOVE W OF THE AREA SUN. A REMNANT LOW...FORMERLY TROPICAL
DEPRESSION TWO...IS FORECAST TO TRACK IN A W TO NW DIRECTION
ACROSS THE TROPICAL N ATLC LATE SUN AND MON AS A POSSIBLE
TROPICAL CYCLONE...THEN APPROACH THE FAR SE PORTION OF THE
SW N ATLC LATE MON AND TRACK THROUGH THE SOUTHERN BAHAMAS
TUE AND WED.
Link
90L is back stealing moisture and disrupting the inflow/convergence on the southeast side of former TD2. It also appears to be stretching TD2's circulation a bit longitudinally.
There is also some dry air being pulled in towards the east just south of TD2.
I know that, I was just curious if he could back it up with anything.
Explains why the NHC didn't reinstate it at 5pm.
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