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
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lmao!!!
Been lurking since before Katrina..
I plan on sailing down to your Gulf area later this fall and am looking forward to that a LOT!
This is a really great informative and important! blog and good fun just following along!
Right, but I'm starting to wonder if it will be the massive Cat 5 that the models were predicting a couple of days ago.
02L was the first to be a tropical cyclone, certainly (with 90L yet to become one). When you say "there first" do you mean as a tropical cyclone or an invest?
Umm the models are still showing that
Yes. They should be put into the 00z runs.
The other day I observed an ant crawling into a crack in the sidewalk in downtown Tampa. Take from that what you will...
THE TROPICS ARE ALSO EXPECTED TO REMAIN QUITE ACTIVE.
EARLIER COORDINATION WITH THE TPC RESULTED IN DEPICTING THE
REMNANTS OF T.D NUMBER TWO REACHING FLORIDA DAYS 6/7...WHICH IS
FAIRLY CLOSE IN POSITION AND INTENSITY TO THE 00Z OPERATIONAL
ECMWF AND ECMWF ENSEMBLE MEAN. HOWEVER THE MODELS REMAIN STRONGER
DEPICTING THE TROPICAL WAVE JUST OFF THE COAST OF AFRICA...WITH A
TRACK FORECAST CLOSEST TO THE 12Z CANADIAN PREFERRED BY DAYS 6/7.
IT SHOULD BE NOTED THAT DETERMINISTIC/ENSEMBLE SPREAD REMAINS VERY
LARGE...WITH EVOLUTION OF THE CENTRAL CONUS TROUGH HAVING A DIRECT
INFLUENCE ON ANY TROPICAL WAVES THAT MOVES INTO THE WESTERN
ATLANTIC TOWARD THE END OF THE MEDIUM RANGE PERIOD. SEE TPC
DISCUSSIONS/ADVISORIES FOR MORE INFORMATION ON THIS TROPICAL
SYSTEMS.
http://www.hpc.ncep.noaa.gov/discussions/pmdepd.html
Not the ones I'm looking at...maybe I've got a bad link.
Here's the site, but it is a blank page at the moment (on my computer at least).
Cuba Radar
TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120
V (KT) NO LAND 25 27 30 33 37 43 51 57 65 68 71 73 76
V (KT) LAND 25 27 30 33 37 43 51 57 65 68 71 73 76
V (KT) LGE mod 25 26 27 29 31 36 41 49 56 66 73 77 80
SHEAR (KT) 8 10 4 2 4 7 1 10 3 13 11 14 5
SHEAR DIR 118 134 168 155 109 242 351 276 81 250 252 269 335
SST (C) 26.7 26.6 26.6 26.7 26.9 27.4 28.0 28.3 28.4 28.5 28.4 28.8 29.5
POT. INT. (KT) 122 120 121 122 125 132 140 145 146 147 145 150 161
ADJ. POT. INT. 118 115 116 119 122 132 142 148 147 146 140 141 149
200 MB T (C) -52.9 -52.9 -53.1 -53.2 -53.0 -53.3 -53.6 -53.6 -53.8 -53.6 -53.8 -54.0 -54.0
TH_E DEV (C) 8 8 8 8 8 9 10 10 11 12 12 12 14
700-500 MB RH 55 59 56 55 56 53 51 49 51 46 48 47 45
GFS VTEX (KT) 9 9 LOST LOST LOST LOST LOST LOST LOST LOST LOST LOST LOST
850 MB ENV VOR 66 69 68 62 57 40 15 -3 -14 -50 -68 -93 -109
200 MB DIV 0 6 7 -10 -25 1 -12 -4 14 8 6 -9 22
LAND (KM) 1481 1428 1374 1331 1304 1238 978 675 257 220 233 264 240
LAT (DEG N) 14.7 14.9 15.1 15.5 15.9 16.6 17.5 18.3 19.5 20.6 21.9 23.1 24.0
LONG(DEG W) 43.2 44.3 45.3 46.7 48.0 51.2 55.1 59.3 63.6 67.6 71.3 74.4 77.0
STM SPEED (KT) 13 10 12 14 14 18 19 21 20 19 17 14 13
HEAT CONTENT 5 6 6 7 13 31 47 60 51 52 22 63 83
It's too early to say that but the models that do regenerate it do take it up to a hurricane in the Bahamas.
You sailing out of Calgary? *wink*
The prefer the Canadian which is no surprise given the ECMWF is still taking this thing out to sea they want to find a balance and the CMC provides that. Depicting a trough as well as a ridge.
Satellite Derived Winds and Analyses
I saw that discussion,sounds like that trough is going to be a player at some point if they get close to the conus
Unlikely if it remains in the open Atlantic. But if it makes it into the Gulf and shear is what it is currently... well, probably.
The only thing really wrong with 90L right now is the easterly shear. If you look at the visible or RGB, its circulation doesn't look half bad. I have a feeling that this one is going to really kick into gear once it gets away from the shearing.
Um, the globals have not changed the intensity of the hit on the Leewards and Puerto Rico. GFDL and HWRF continue to portray a major. And you were saying?
Thank you for indulging me.
Not like it's really important--if one comes my way, I'll have my own names for it, which would get me banned if I posted them here. :)
I agree. Some of the models had it as a Cat 5 east of the islands the other day. Now if it gets into the gulf that's a whole other story.
A major yes. A Cat 5...not that I see.
I think I sall that same ant in st. pete, he was packing his nest full of beer and nuts, for the upcoming storms. lol
Category 3 more likely, but this does appear prime to develop. The conditions are there, an Anti-Cyclone, ex TD-2 taking away the dry air in front of it, ect. It's just got to move away from that shear which it is expected too Tonight and into tomorrow. Because of its size, once it gets away from that shear Dry air wont be much of a problem anyways, because it will be able to moisten its environment.
the ants are in the Hebert Box installing the tunnels.
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