TD 2 nearly dead; African disturbance 90L gathering strength

By: Dr. Jeff Masters , 2:38 PM GMT on August 13, 2009

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Tropical Depression Two is near death, but is still worth watching. The dry, Saharan air to the north and west of the depression, combined with moderately high levels of wind shear of 15 - 20 knots, have almost completely destroyed all of TD 2's heavy thunderstorms. Satellite loops of the storm show a well-formed circulation, but almost no heavy thunderstorm activity.

Wind shear over TD 2 is expected to remain in the modereate range, 10 - 20 knots, over the next five days. Sea Surface Temperatures (SSTs) are 27°C, but will warm to 28°C three days from now. There is plenty of dry, stable air from the Saharan Air Layer (SAL) to to TD 2's north and west that will continue to cause the storm problems. The relatively cool SSTs and dry air mean that TD 2 will not be able to intensify quickly, and some of the models indicate the TD 2 may get destroyed in the next day or two. However, several models still predict TD 2 will become a tropical storm. The HWRF model predicts TD 2 will become a hurricane five days from now, but this seems unlikely given the dry air and relatively high wind shear affecting the storm.


Figure 1. Tropical Depression Two (left side of image) and tropical wave 90L (right side of image).

African tropical wave 90L
A strong tropical wave with a large circulation and plenty of heavy thunderstorm activity is a few hundred miles south of the Cape Verdes Islands, off the coast of Africa. NHC dubbed this disturbance 90L this morning. This morning's QuikSCAT pass shows that 90L has a very large circulation, and top winds of about 30 mph. Satellite imagery from the European METEOSAT satellite show that the heavy thunderstorms associated with 90L are in two major bands, to the north and to the south of the center. There is no heavy thunderstorm activity near the center yet, and this would have to happen before 90L can be named Tropical Depression Three. 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 has been. Wind shear is about 20 knots over 90L, and is forecast to remain in the moderate range, 10 - 20 knots, over the next five days. Sea Surface Temperatures are about 28°C, and will remain in the 27 - 28°C range the next five days, which are high enough above the 26°C threshold for tropical cyclone formation to allow some slow development to occur. The GFS and ECMWF models continue to predict the development of this wave, though they are now less aggressive about intensifying it than they were in earlier runs. The consensus among the reliable HWRF, GFDL, GFS, and ECMWF models is to bring 90L to point near or just north of the northernmost Lesser Antilles Islands 6 - 8 days from now. The storm could be at hurricane strength by then, as forecast by the SHIPS intensity model.

I'll have an update Friday morning.

Jeff Masters

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90L most likely be TD3 at 5am and TD2 rises from it deathbed at 5am at D-MAX
Member Since: Posts: Comments:
1436. slavp
Quoting TexasHurricane:
Can I ask why some people seem to have this obsession with the GOM since 2005? That's a serious question, not tryin to be rude...

No, not an obsession. Personally I think tropical stroms and Cat 1 hurricanes (Humberto) are pretty cool. Don't mind those kind of storms at all. Don't get me wrong though. I am in NO WAY wanting anything catostrophic (to anybody)

I used to think Like that until Allison (TS) dumped 20 inches of rain on me
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X TD 9E is makeing a come back looks we TD 9E will be back with us with in the next 24hr

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1434. IKE
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Quoting CaneWarning:


Well that isn't nice.


Not really.
Member Since: August 13, 2007 Posts: 10 Comments: 4141
1431. cg2916
Remember, it's at a point called DMIN, where convection wanes. It just finished a few minutes ago.
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I saved this pic from early this morning......check out the smiley face....LOL

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convection starting to refire, may be strengthing
models agree...

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Last Advisory for TD 2 issued by NHC...

498
WTNT32 KNHC 132041
TCPAT2
BULLETIN
TROPICAL DEPRESSION TWO ADVISORY NUMBER 11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022009
500 PM AST THU AUG 13 2009

...DEPRESSION HAS DECAYED INTO A REMNANT LOW PRESSURE AREA...
AT 500 PM AST...2100 UTC...THE CENTER OF THE REMNANTS OF TROPICAL
DEPRESSION TWO WAS LOCATED NEAR LATITUDE 14.2 NORTH...LONGITUDE
38.3 WEST OR ABOUT 930 MILES...1500 KM...WEST OF THE SOUTHERNMOST
CAPE VERDE ISLANDS.

THE LOW IS MOVING TOWARD THE WEST NEAR 8 MPH...13 KM/HR. THE
REMNANTS OF THE DEPRESSION ARE EXPECTED TO CONTINUE A GENERAL
WESTWARD MOTION FOR THE NEXT COUPLE OF DAYS.

MAXIMUM SUSTAINED WINDS ARE NEAR 30 MPH...45 KM/HR...WITH HIGHER
GUSTS. THE REMNANTS ARE EXPECTED TO CHANGE LITTLE IN STRENGTH OVER
THE NEXT COUPLE OF DAYS.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB...29.77 INCHES.

...SUMMARY OF 500 PM AST INFORMATION...
LOCATION...14.2N 38.3W
MAXIMUM SUSTAINED WINDS...30 MPH
PRESENT MOVEMENT...WEST OR 275 DEGREES AT 8 MPH
MINIMUM CENTRAL PRESSURE...1008 MB

THIS IS THE LAST PUBLIC ADVISORY ISSUED BY THE NATIONAL HURRICANE
CENTER ON THIS SYSTEM.
THE SYSTEM WILL BE CLOSELY MONITORED FOR
SIGNS OF REGENERATION. ADDITIONAL INFORMATION ON THIS SYSTEM CAN BE
FOUND IN HIGH SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER
SERVICE...UNDER AWIPS HEADER NFDHSFAT1 AND WMO HEADER FZNT01 KWBC.

$$
FORECASTER BEVEN
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Quoting IKE:
A ways to go....



Let it organize Ike, remember how big it is. Dmax might certianly put on a show. :)
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CONUS = Continental United States
Member Since: June 12, 2002 Posts: 0 Comments: 1588
Quoting wunderkidcayman:

regeneration of (ex) TD2 would likely happen when?
When it gets in the Bahamas. :D
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It is pretty amazing looking at both FLOATER Satellite images for TD2 and 90L. TD2 is a tiny swirl to the NW of 90L. The floater for 90L isn't quite yet focused on the COC(soon to be), yet, just the outer fringes showing up look like tenticles of a very, very, large system soon to be shown on that Floater. In comparison to Td2, 90L just seems so much larger in size, yikes
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1422. IKE
A ways to go....

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1421. Drakoen
No deep convection. The center is just south of the Cape Verde islands:
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Quoting Seflhurricane:
lets do a poll on 90L

A) 90L becomes TD3 at 11PM

B)90L becomes TD3 at 5Am

C)90L Becomes TD 3 at 11Am

D) 90L does not become a TD At all

TD 3 at either 5am or 11am tomorrow
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@1395...troughs cause storms to turn north and then northeast...trought over the eastern us increases the chance that a storm will turn north before hitting the gulf...
Member Since: June 12, 2002 Posts: 0 Comments: 1588
Can I ask why some people seem to have this obsession with the GOM since 2005? That's a serious question, not tryin to be rude...

No, not an obsession. Personally I think tropical stroms and Cat 1 hurricanes (Humberto) are pretty cool. Don't mind those kind of storms at all. Don't get me wrong though. I am in NO WAY wanting anything catostrophic (to anybody)

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Quoting TerraNova:


I'm not sure; in the case of Katrina (genesis only of course) TD 10 was renamed TD 11 only because the disturbance that developed resulted from a portion of TD10's remnants merging with a tropical wave. Unless something like that were to happen I think they'd redesignate it as TD 2, sort of like how Ivan developed again in the Gulf and was still called Ivan.


Should be TD 12, TD 11 was Jose, my bad.
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1416. slavp
Quoting Patrap:
From ones Lips to Gods Ear,.


Remember to always Heed a Evac warning,esp in a Surge Zone.

Mr And Mrs Guerra will be the first to tell ya that.

And everyone from the Brownsville to The Keys Know,..the GOM can bite ya real fast.never discount any threat till its inland.





I agree 150%
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Quoting P451:
Anyone else see a really grumpy old man in the final VIS frame of 90L?





Ut oh...

lol!
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1414. IKE
Quoting BradentonBrew:


For Noobs like me, could you explain how that relates to the steering or strengthing of the any potential storm? Where are these Conus' and would would the ridge inhibit or prohibit movement towards GOM/Carib?


C post 1402.
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Detailed 12z Euro change from 0z:

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1412. KEEPEROFTHEGATE (Mod)
Quoting Seflhurricane:
lets do a poll on 90L

A) 90L becomes TD3 at 11PM

B)90L becomes TD3 at 5Am

C)90L Becomes TD 3 at 11Am

D) 90L does not become a TD At all


x when NAVY calls it
x when NHC calls it
Member Since: July 15, 2006 Posts: 169 Comments: 53296
1411. Drakoen
Quoting DM21Altestic:
Drak, do you think they might classify 90L as a depression at 11AM or 5AM?


no.
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Quoting TampaSpin:
Looks like a SEX change will be in order for 90L......Call the nurses and Surgeons in please before he/she changes thems mind again


"The Castration of Bill"
sounds like a good play...
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Quoting IKE:
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS, MD
300 PM EDT THU AUGUST 13 2009



8-14 DAY OUTLOOK FOR AUG 21 - 27 2009

TODAYS GFS-BASED ENSEMBLE MEANS ARE IN GOOD AGREEMENT IN DEPICTING A DEEP
TROUGH NEAR THE EASTERN CONUS AND A RIDGE NEAR THE WESTERN CONUS.


For Noobs like me, could you explain how that relates to the steering or strengthing of the any potential storm? Where are these Conus' and would would the ridge inhibit or prohibit movement towards GOM/Carib?
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Quoting Seflhurricane:
lets do a poll on 90L

A) 90L becomes TD3 at 11PM

B)90L becomes TD3 at 5Am

C)90L Becomes TD 3 at 11Am

D) 90L does not become a TD At all


C
Member Since: March 19, 2009 Posts: 0 Comments: 1421
By 11pm tonight -5am tomorrow former TD2 will be in full bloom again, my opinion at least, its actually tapping into moisture from 90L on the East, just a matter of hours before a full regeneration starts, these are the type of systems that bites you in the back when least expected, jmo
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1404. Drakoen
You have a colorful imagination P451
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1403. hahaguy
Quoting P451:
Anyone else see a really grumpy old man in the final VIS frame of 90L?





Ut oh...


I actually see that lol.
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1402. IKE
Quoting caneluver:


90L probably gets kicked east of the USA, like the ECMWF is showing.

Just my unprofessional opinion.
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1401. Drakoen
90L's structure is very impressive for an invest but it needs convection to congeal around the center of circulation which I suspect will happen within 24 hours according to the latest computer model runs.

Regeneration of TD2 would most likely occur when the system get's past 50W
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1400. java162
Quoting TampaSpin:
Looks like a SEX change will be in order for 90L......Call the nurses and Surgeons in please before he/she changes thems mind again


OMG.... bill turns into ANA...lmfao
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Quoting hurricanehanna:
Personally I think the wave near the Bahamas looks better than 90L IMO


It has plenty strong convection but pressures are not low in the area, and there is little in the way of vorticy right now, based on the vorticy map.
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the results are C 90L will be a TD tomorrow at 11Am Possibly
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1396. fire635
Quoting Seflhurricane:
lets do a poll on 90L

A) 90L becomes TD3 at 11PM

B)90L becomes TD3 at 5Am

C)90L Becomes TD 3 at 11Am

D) 90L does not become a TD At all


B
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Quoting TampaSpin:
Looks like a SEX change will be in order for 90L......Call the nurses and Surgeons in please before he/she changes thems mind again


LOL!
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1393. Patrap
From ones Lips to Gods Ear,.


Remember to always Heed a Evac warning,esp in a Surge Zone.

Mr And Mrs Guerra will be the first to tell ya that.

And everyone from the Brownsville to The Keys Know,..the GOM can bite ya real fast.never discount any threat till its inland.





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Quoting Vortex95:
Thats one of the more optimistic Last advisories i've seen. In the chance it does regenerate will it be recalled TD2 or TD 3,4


I'm not sure; in the case of Katrina (genesis only of course) TD 10 was renamed TD 11 only because the disturbance that developed resulted from a portion of TD10's remnants merging with a tropical wave. Unless something like that were to happen I think they'd redesignate it as TD 2, sort of like how Ivan developed again in the Gulf and was still called Ivan.
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Imagine if the Native Americans had the internet, and satellites hundreds of years ago?? They'd say, "I bet all the wampum in my sachtel that the Seminole will not see any big wind and rain this year, but the tee pees of the Lenni Lenape will be offered up to the God of the big storm, as will their crop of maize. The tribe's elders would do a dance to prevent, "hole like tiny pin." Business at the affected tribe's trading post would go into a recession. If they disagreed, friendly tribes would the smoke peace pipe after. Disagreeable tribes would threaten to scalp those that opposed their views.
Or, they might say, "That storm sleeps with the fishes." It would be just like a tropical Luca Brasi!
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1390. IKE
Quoting P451:
5 Looks at 90L - which really needs some deeper convection to be classified IMO - check the color IRs. There's no real cold cloud tops.











System isn't looking that great. Not going to be a TD today....
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any other voters want to vote on the possible future TD see post 1356
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Quoting Patrap:


Speaking of Fire,..I just Lit da pit here Uptown,gonna Burn some Cluckers this evening


Mighty jealous! I'm in the CBD stuck at the office... booooooooo! At least we're slow so this weatherbug can take in some WU today :)
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Personally I think the wave near the Bahamas looks better than 90L IMO
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.