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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Yeah, I've been "lurking"for a while then posting the past few days when the activity picked up. A lot of the Gulf Coast bloggers have been posting....not liking what the models are showing...yikes!
But 90L is looking amazing this morning
hmmmmmmmmmmmm
Agreed. Time to check the oil in the generator. Hope some of the "sleepers" in here have their supplies ready
We've put Press in charge of giving him Thorazine! lol
So, discarding that, it is the latest start since 1984. (Also, had a STS before its first named storm but that didn't occur until August 18th.)
25 years.
Radar LOOP
Winds & PMSL
:)
But the slight increase seems to be all around 50W anyhow, from different maps and such. So, within the day.
Morning Ike....please, not this early! ;)
"nuttin"
Morning Ike, keep your eyes on the area in the keys, pressure dropping.
I'm watching that too...
Hey Ike,
yeah, there goes quiet season and 2009 will not be 0-0-0 but it tried :)
Good coffee....Maxwell House caffeine light.....
BB -I NEED coffee
you might want to go back to sleep you might not rest for a week.
Well well well, I wake up and hear on the 6am news that we have TS Ana... like I am sure many of you have said already.. don't count a good swirl out..if it is still twirling it can still gather in some weather.
and how is 90L doing?
Just got at my work desk so got to go catch up.
Very wet down here in SE Florida this morning... no measureable rain at my house, just sprinkles but good rain out here in Weston.
bbl!
Happy Saturday everyone.
Gams
LOL.
Dr. Lyons thinks it's going to slowly strengthen and head for the Bahamas and south Florida/WS.
I'm watching closely.
Viewing: 4201 - 4251
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