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

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

Share this Blog
5
+

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

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 2884 - 2834

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 | 80 | 81 | 82 | 83 | 84 | 85 | 86 | 87 | 88 | 89 | 90 | 91 | 92 | 93 | 94 | 95 | 96 | 97 | 98 | 99 | 100 | 101 | 102 | 103 | 104 | 105 | 106 | 107 | 108 | 109 | 110 | 111 | 112 | 113 | 114Blog Index

Quoting mobilegirl81:
I talk about the entity that could develop in the gulf, but realistically maybe a weak tropical storm, and thats going a little out of the box.


The upper-level wind forecast looks to be a favorable one for tropical cyclogenesis over the next several days. The tropical wave near Cuba could move into the Gulf in two days or so, and help to enhance thunderstorm activity there by interacting with the current trough in the NE Gulf. Something to watch, to be sure.
Member Since: March 7, 2007 Posts: 575 Comments: 20597
Quoting canesrule1:
the blog is slowing down cuz everyone is on the NHC site reloading every 7 seconds!


Whoever posts the NHC Map first should get a prize...
Member Since: October 18, 2005 Posts: 4 Comments: 3052
This looks like 2004 steering.
Member Since: August 31, 2008 Posts: 0 Comments: 833
Quoting Seflhurricane:
very important looks like we may have a system overload if that happens

i can see 100 repeats of the post. that is aggravating.
Member Since: Posts: Comments:
Ahh!!!
How much longer can I wait for these flipping storms to become TDs!!!
Member Since: Posts: Comments:
NHC should release in 15 minutes and counting
Member Since: July 14, 2009 Posts: 0 Comments: 3022
Quoting canesrule1:
the blog is slowing down cuz everyone is on the NHC site reloading every 7 seconds!


Yeah...ya'll work that refresh button faster!

I'm sitting here waiting to read your hard work! :)
Member Since: Posts: Comments:
NHC putting out the Guillermo advisory now...TD 2 should follow soon.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
somestimes if you refresh the NHC page too long it causes delay in posting the updates. just slow down on the F5 key
Member Since: July 24, 2005 Posts: 407 Comments: 19076
JMO Ex TD 2 is going to continue through the Caribbean.
Member Since: Posts: Comments:
the blog is slowing down cuz everyone is on the NHC site reloading every 7 seconds!
90L is still embedded within the ITZ. That probably is also slowing development of 90L also along with the overall size of Atmosphere it is turning.
Member Since: September 2, 2007 Posts: 178 Comments: 20439
I talk about the entity that could develop in the gulf, but realistically maybe a weak tropical storm, and thats going a little out of the box.
Member Since: August 31, 2008 Posts: 0 Comments: 833
Quoting Patrap:
90L Wind Field,....

1800 UTC




Sitting here waiting for the other shoe to drop...got impatient.
Here is the 0 Z windfield:
Member Since: Posts: Comments:
Quoting jazzygal:
Good Evening. Can someone tell me on the last GFS run. What storm is at the 252 hour hitting NOLA and what storm is hitting the East Coast at the 288 hour? I know this is just a model. Also what is the Saints score? Can't get any info here in Chicago. Thanks


saints 14-7 we're up!
Member Since: Posts: Comments:
Quoting mossyhead:

i was living in ft. walton at the time of opal and i lived in navarre when the hurricane before opal hit navarre.
Member Since: Posts: Comments:
Quoting extreme236:
Please let only one person post the advisory. And if you post it after someone please delete your post.


I will not post, I will read.

You other guys can flash hit the refresh button a hundred times or so! :)
Member Since: Posts: Comments:
Quoting extreme236:


Still a TD on the ATCF site, so they will.


About 20 minutes or so. So we'll soon find out.
Member Since: June 9, 2007 Posts: 4 Comments: 15891
Quoting Weather456:
Normally a warm glass of milk and counting sheeps gets you to sleep. Nowadays, a good 11PM advisory does the trick.
lol!
Quoting Weather456:
Normally a warm glass of milk and counting sheeps gets you to sleep. Nowadays, a good 11PM advisory does the trick.
LOL But i would be very concerned i finally recoperated from wilma and now this
Member Since: July 14, 2009 Posts: 0 Comments: 3022
Quoting antonio28:


5 Day cone for 90l will end up over PR Florida if get hit by this is in a 8-9 days from now to early to tell but I am stick with the GFS that has been incredible accurate with this one so far. seems that the CONUS thread right now is bettwen NOLA and NC.


He was talking about TD2.
Member Since: March 7, 2007 Posts: 575 Comments: 20597
Quoting TampaSpin:


You just caused 50 post within 30 seconds.....LYNN your right a crash is coming......LOL
lmao
Quoting rareaire:
what kind of cookie? we talking oreo double stuff or fig newton...


Its a surprise.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
Quoting Stormchaser2007:
That would be classic if ExTD2 wasnt classified at 11pm. Actually it wouldnt surprise me at all.


Still a TD on the ATCF site, so they will.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Quoting Weather456:
Normally a warm glass of milk and counting sheeps gets you to sleep. Nowadays, a good 11PM advisory does the trick.


LMAO
Member Since: March 7, 2007 Posts: 575 Comments: 20597
That would be classic if ExTD2 wasnt classified at 11pm. Actually it wouldnt surprise me at all.
Member Since: June 9, 2007 Posts: 4 Comments: 15891
Thanks 456

I have it from the

500 PM AST THU AUG 13 2009

...DEPRESSION HAS DECAYED INTO A REMNANT LOW PRESSURE AREA...

AT 500 PM AST...2100 UTC...


THE LOW IS MOVING TOWARD THE WEST NEAR 8 MPH...

which is last adv


any info about speed since that report 30 hours ago??

perhaps not, but I was hoping.

Thanks
Member Since: July 12, 2007 Posts: 0 Comments: 6036
Normally a warm glass of milk and counting sheeps gets you to sleep. Nowadays, a good 11PM advisory does the trick.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
2851. antonio28
2:31 AM GMT on August 15, 2009
Quoting reedzone:


Or Central Florida.. I live in Northeastern/Central Florida, north of Daytona Beach.. I think I need to watch this one closely as well.


5 Day cone for 90l will end up over PR Florida if get hit by this is in a 8-9 days from now to early to tell but I am stick with the GFS that has been incredible accurate with this one so far. seems that the CONUS thread right now is bettwen NOLA and NC.
Member Since: July 15, 2008 Posts: 0 Comments: 799
2850. LightningCharmer
2:29 AM GMT on August 15, 2009
Quoting WPBHurricane05:
First one to post the 11pm advisory for TD 2 gets a cookie.


Sounds like a lot of page refreshes over and over and quick fingers to post. I ask myself do I really want a cookie that much? hmmm.....

To my untrained eye, these systems appear to be pulling on each other.

GOES Imagery Water Vapor (IR3)
Member Since: September 1, 2007 Posts: 0 Comments: 1316
2849. TampaSpin
2:29 AM GMT on August 15, 2009
Quoting WPBHurricane05:
First one to post the 11pm advisory for TD 2 gets a cookie.


You just caused 50 post within 30 seconds.....LYNN your right a crash is coming......LOL
Member Since: September 2, 2007 Posts: 178 Comments: 20439
2848. BajaALemt
2:29 AM GMT on August 15, 2009
Wow!! (((( Rare )))) !!!! Awesome to see you!!
Member Since: September 25, 2007 Posts: 53 Comments: 8533
2847. Seflhurricane
2:29 AM GMT on August 15, 2009
Quoting cchsweatherman:


Based upon the official forecast in the 00Z model set, thats very possible.
very likely Se florida will be included in the 5 Day track look at the computer models almost all of them bring it between central florida and northern coast of cuba
Member Since: July 14, 2009 Posts: 0 Comments: 3022
2845. canesrule1
2:28 AM GMT on August 15, 2009
Quoting rareaire:
what kind of cookie? we talking oreo double stuff or fig newton...
or fed-ex or UPS?
2844. weathersp
2:29 AM GMT on August 15, 2009
Quoting WPBHurricane05:
First one to post the 11pm advisory for TD 2 gets a cookie.


That would crash the blog..
Member Since: January 14, 2007 Posts: 17 Comments: 4140
2843. hahaguy
2:27 AM GMT on August 15, 2009
Quoting rareaire:
what kind of cookie? we talking oreo double stuff or fig newton...


If it's a fig I want nothing to to with it.
Member Since: August 12, 2007 Posts: 2 Comments: 2838
2842. cchsweatherman
2:27 AM GMT on August 15, 2009
Quoting hurricane23:


The 5 day could be atleast touching if not over southeast florida.


Based upon the official forecast in the 00Z model set, thats very possible.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
2841. Stormchaser2007
2:27 AM GMT on August 15, 2009
Quoting HurricaneKyle:
Some areas of -80C cloud temps over 90L. An indication shear is getting weaker over 90L as it moves away from that area of shear. The Anti-cyclone is not shearing it.


The 15 knots of easterly shear says otherwise. Anticyclone is not in a good position.

Although the fact that the current blowup is able to maintain itself fully vertical is a sign that shear doeant seem to be affecting as much as before.
Member Since: June 9, 2007 Posts: 4 Comments: 15891
2840. Cavin Rawlins
2:27 AM GMT on August 15, 2009
Quoting mobilegirl81:
90L looking like a classic cape verde storm developing. It has characteristics of recent storms since 2004.


thats what some dont get...90L has the trade mark.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
2839. Seflhurricane
2:27 AM GMT on August 15, 2009
Quoting extreme236:
Please let only one person post the advisory. And if you post it after someone please delete your post.
very important looks like we may have a system overload if that happens
Member Since: July 14, 2009 Posts: 0 Comments: 3022
2838. jazzygal
2:27 AM GMT on August 15, 2009
Good Evening. Can someone tell me on the last GFS run. What storm is at the 252 hour hitting NOLA and what storm is hitting the East Coast at the 288 hour? I know this is just a model. Also what is the Saints score? Can't get any info here in Chicago. Thanks
Member Since: June 2, 2008 Posts: 0 Comments: 205
2837. rareaire
2:27 AM GMT on August 15, 2009
what kind of cookie? we talking oreo double stuff or fig newton...
Member Since: August 19, 2007 Posts: 0 Comments: 1601
2836. mikatnight
2:27 AM GMT on August 15, 2009
ABC 20/20 Special on now about EF5 Tornado that struck Parkersburg, Iowa in 2008.
Member Since: October 18, 2005 Posts: 4 Comments: 3052
2835. canesrule1
2:26 AM GMT on August 15, 2009
Quoting extreme236:
Please let only one person post the advisory. And if you post it after someone please delete your post.
ok
2834. GeoffreyWPB
2:26 AM GMT on August 15, 2009
Quoting extreme236:
Please let only one person post the advisory. And if you post it after someone please delete your post.


Thank you extreme...That does get annoying.
Member Since: September 10, 2007 Posts: 0 Comments: 11158

Viewing: 2884 - 2834

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 | 80 | 81 | 82 | 83 | 84 | 85 | 86 | 87 | 88 | 89 | 90 | 91 | 92 | 93 | 94 | 95 | 96 | 97 | 98 | 99 | 100 | 101 | 102 | 103 | 104 | 105 | 106 | 107 | 108 | 109 | 110 | 111 | 112 | 113 | 114Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

Local Weather

Mostly Cloudy
82 °F
Mostly Cloudy