Disturbance 90L close to tropical depression strength; TD 2 may rise again

By: Dr. Jeff Masters , 2:02 PM GMT on August 14, 2009

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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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Quoting Tazmanian:



your going to in up get ban if you keep this up


Taz take a chill......go to bed!
Member Since: September 2, 2007 Posts: 178 Comments: 20443
Quoting PensacolaBuoy:


...northwest Florida was too dangerous to settle, a belief that endured for 135 years. (Wikipedia)


...and a believe that came again in 2004 when Hurricane Ivan struck.
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Quoting reedzone:
Don't forget, IF they release it, maybe the wait is caused by issuing Tropical Storm watches for the northern Islands.. Then I can see how it takes a while.


The NHC dont issue our advisories, we do. They advise us and we can decide to follow.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Evening all.
Quoting Stormchaser2007:

It could.

Its going to be interesting if 02L can take advantage of the OHC and low shear over the Bahamas. Its a particularly small system so it could ramp up quickly.
It would have to be relatively fast-moving also since the water in that area is mostly very shallow (hence the name (baja mar).
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we have to have a TD at 11, its on the tropical atlantic and navy page.
Large blowup with 90L.

Member Since: June 9, 2007 Posts: 4 Comments: 15920
Quoting reedzone:
Don't forget, IF they release it, maybe the wait is caused by issuing Tropical Storm watches for the northern Islands.. Then I can see how it takes a while.


Yea, they have been known to delay advisory because of issuing warnings and watches.
Member Since: August 10, 2009 Posts: 3 Comments: 672
My computer might explode if I press F5 one more time!!!
Member Since: August 9, 2009 Posts: 10 Comments: 5026
F5 doesnt make the NHC go faster.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
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Quoting CaicosRetiredSailor:
JeffMasters's WunderBlog
No entries have been made.

JeffMasters does not have any blog entries.


sometimes the blog kicks in and out due to high traffic.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting sammywammybamy:
Commmeeeeee Onnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn


F5..F5...F5..F5...F5...F8.. OPPS...F5..F5...



your going to in up get ban if you keep this up
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Quoting CaicosRetiredSailor:
JeffMasters's WunderBlog
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JeffMasters does not have any blog entries.


Where are we?
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Quoting ALCoastGambler:
It's Ingalls now known as Northrop Grumman. I used to work there till I broke my neck out there. They aren't doing well anyway.

Did Frederic reck them in '79?
Member Since: August 31, 2008 Posts: 0 Comments: 833
3020. Patrap
..Come In CycloneOz,..you got a copy on me,..JFV,..you there ?..

Test,Test...

Member Since: July 3, 2005 Posts: 426 Comments: 128631
Don't forget, IF they release it, maybe the wait is caused by issuing Tropical Storm watches for the northern Islands.. Then I can see how it takes a while.
Member Since: July 1, 2008 Posts: 13 Comments: 7396
3018. GatorWX
Who cares what the nhc says at 11??? If they don't declare it until tomorrow, does it matter? It's obviously going to develop. We all know where to find the advisories, so if you want to see them, take a gander at 11. I can't stand when people post huge advisories and usually more than one person posts them. Post links PLEASE!!
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Dam it Sammy i won't that dam report now or your fired.......LOL
Member Since: September 2, 2007 Posts: 178 Comments: 20443
Quoting Tazmanian:
are you guys wanting a 24hr ban???


this is not a fun blog this is a Tropic blog


the ones are being off key can you get back on key Please


God forbid we have fun.

Who knows what could happen.

We might get off topic.
Member Since: June 9, 2007 Posts: 4 Comments: 15920
Quoting mobilegirl81:
If a major hurricane strike pascagoula, MS, then the biggest ship builder in the nation will be crippled. Ingles Shipyard.

Is Ingalls. And they saw a lot more than one might think during Katrina. Had a functioning anemometer through it.
Member Since: August 16, 2007 Posts: 6 Comments: 12461
Quoting extreme236:


Then stop hitting refresh so much?


Don't tell him to stop!!! He could get cold. Let him pitch!
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Quoting pcolasky:


Yeap! Pcola is celebrating its 450 year aniversary. It should be a wash in the afternoon! Any one need a shower?


Due to prior exploration, the first settlement of Pensacola was large, with over 1,400 people on 11 ships from Vera Cruz, Mexico landing on August 15, 1559, led by Don Tristán de Luna y Arellano. However, weeks later on September 19, 1559, the colony was decimated by a hurricane which killed hundreds, sank five ships, grounded a caravel, and ruined supplies. The 1,000 survivors decided to relocate and resupply the settlement but, due to famine and attacks, the effort was abandoned in 1561. About 240 people sailed to Santa Elena (today's Parris Island, South Carolina), but another storm hit there, so they sailed to Cuba and scattered. The remaining 50 at Pensacola were taken back to Mexico, and the Viceroy's advisers concluded that northwest Florida was too dangerous to settle, a belief that endured for 135 years. (Wikipedia)
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Quoting mobilegirl81:
If a major hurricane strike pascagoula, MS, then the biggest ship builder in the nation will be crippled. Ingles Shipyard.
It's Ingalls now known as Northrop Grumman. I used to work there till I broke my neck out there. They aren't doing well anyway.
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Quoting extreme236:
I think the NHC has spoiled us with releasing early advisories. They dont have to release anything till around 11.
noooooooooooooo, lol
Sammy's F5 key will have no F5 on it before the TWO comes out :))
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Quoting DaytonaBeachWatcher:
This is the most i have laughed reading this blog when it didnt have anything to do with WS... lol


same here.....lol lol


Member Since: July 24, 2005 Posts: 407 Comments: 19076
are you guys wanting a 24hr ban???


this is not a fun blog this is a Tropic blog


the ones are being off key can you get back on key Please
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ROFL!

Way to spoil it Taz.
Member Since: June 9, 2007 Posts: 4 Comments: 15920
Quoting DaytonaBeachWatcher:
This is the most i have laughed reading this blog when it didnt have anything to do with WS... lol


LOL
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I have always found that the NHC advisories are posted earlier on the Weather Underground site than the NHC site. Go figure.
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Quoting sammywammybamy:
NHC LOOKS LIKE ITS ABOUT TO DO SOMETHING IMPORTANT...


TAKING A LONG TIME

BAD FOR MY FINGER


GOOD FOR THEM


Then stop hitting refresh so much?
Member Since: August 2, 2007 Posts: 19 Comments: 19234
3001. RevInFL
We need to start a fund for sammy's finger replacement surgery.
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3000. Patrap
..."Little By little, everything changes"...
Member Since: July 3, 2005 Posts: 426 Comments: 128631
Never remember people acting like this before waiting for an advisory before. People need to calm down before you give yourselves cardiac arrest.
Member Since: Posts: Comments:
ROFL
Quoting DestinJeff:
sammy, if you sit on your hand and make it go to sleep then push F5 it will be like somebody else is doing it
Member Since: Posts: Comments:
I think the NHC has spoiled us with releasing early advisories. They dont have to release anything till around 11.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
this is a first. i have not seen so much funny stuff on here in a short amount of time. i love it.
Member Since: July 7, 2008 Posts: 0 Comments: 473
2995. hahaguy

Taz you ruined it lol j/k
Member Since: Posts: Comments:
CUE Remote Speakers at NHC...

Set to....


THE Chipmunks.
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This is the most i have laughed reading this blog when it didnt have anything to do with WS... lol
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The funny thing is, I dont have the NHC page open. lol lol
Member Since: July 24, 2005 Posts: 407 Comments: 19076
2990. GatorWX
Looks like dmax is being quite kind to 90L, starting to consolidate and convection is at last starting to develop over center. I was hesitant to believe before, but if this persists, and all factors say it should, it most certainly will be a depression tomorrow. In fact once a depression, it could develop rather quickly, not necessarily rapidly, although not out of the question, but could be a ts by Monday morning. Shouldn't take it long to become something to be noticed by the masses!
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2989. jipmg
Looks like TD 3 has gotten a huge amount of convection over the center, oh did I say TD 3 =O
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Quoting tharpgomex:
everyone on here is NUTS...LOL


YOu are so right....
Member Since: September 2, 2007 Posts: 178 Comments: 20443
welcome back TD 2


000
WHXX01 KWBC 150145
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0145 UTC SAT AUG 15 2009

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

TROPICAL CYCLONE TWO (AL022009) 20090815 0000 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090815 0000 090815 1200 090816 0000 090816 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 14.5N 44.8W 14.9N 46.9W 15.9N 49.8W 17.5N 53.9W
BAMD 14.5N 44.8W 15.3N 47.1W 16.4N 49.8W 17.6N 53.0W
BAMM 14.5N 44.8W 15.0N 47.0W 15.9N 49.6W 16.8N 53.1W
LBAR 14.5N 44.8W 15.0N 47.5W 15.8N 50.5W 16.7N 54.0W
SHIP 25KTS 28KTS 32KTS 36KTS
DSHP 25KTS 28KTS 32KTS 36KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090817 0000 090818 0000 090819 0000 090820 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 19.4N 58.2W 23.2N 66.9W 26.7N 73.0W 28.9N 75.6W
BAMD 18.8N 56.5W 21.0N 63.9W 23.5N 70.0W 24.9N 73.6W
BAMM 17.8N 56.9W 19.9N 65.1W 22.2N 72.5W 24.0N 77.7W
LBAR 17.7N 57.7W 20.2N 65.5W .0N .0W .0N .0W
SHIP 41KTS 50KTS 54KTS 59KTS
DSHP 41KTS 50KTS 54KTS 59KTS

...INITIAL CONDITIONS...
LATCUR = 14.5N LONCUR = 44.8W DIRCUR = 270DEG SPDCUR = 14KT
LATM12 = 14.6N LONM12 = 41.7W DIRM12 = 276DEG SPDM12 = 15KT
LATM24 = 14.3N LONM24 = 39.2W
WNDCUR = 25KT RMAXWD = 40NM WNDM12 = 25KT
CENPRS = 1007MB OUTPRS = 1010MB OUTRAD = 150NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM
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Im starting to think no TD at 11...LOL
Member Since: July 31, 2006 Posts: 56 Comments: 8112
Quoting CycloneOz:


That won't stop it. It's coming in here anyway...just like every other one has done.

I know. Just not as excited to see it surrounded by the WU style sheet as everyone else is.
Member Since: August 16, 2007 Posts: 6 Comments: 12461

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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.