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: 684 - 634

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 Weather456:


I've been seeing alot of those questions and comments and it points to someone who wants something to hit Florida. Persistent questions about landfall when the asnwer is always "we dont know". Honestly its tiresome, and sad.


Yeah there are thousands of school kids with there eyes closed hoping it comes before back to school happens down in South Florida
Member Since: Posts: Comments:
Quoting IKE:
12Z NOGAPS through 192 hours....



Geez Ike,..you gotta tilt dat Machine Like a Bad O
pinball ,and keep dat Bugger away from the GOM
Member Since: Posts: Comments:
last year Dr. Masters posted a site on which one can bet on weather futures....I'd love to see some of these people who're so certain about where things are gonna be in 7-10 days put their money where their keyboard is...
Member Since: Posts: Comments:
my ws just said td2 is coming back
Member Since: Posts: Comments:
I'm very interested to see what this mornings GFDL and HWRF do with both storms...

the 06UTC HWRF run moved TD2 on a path curving to the northwest quite quickly. I wonder if this is in response to a weakness caused by the ULL..

the 06UTC GFDL kept TD2 weak

I guess we'll see here quite soon!

Also, I think we may have RED again on the NHC map for 2 pm for old TD2
Member Since: Posts: Comments:
Quoting jasoniscoolman10:
anyone watch the football game last night..i watch the patriots game..tom brady played bad football last night..he suck..

Football on a hurricane blog. It is an interesting connection.
Member Since: Posts: Comments:
Quoting WeatherStudent:
Afternoon Drak. Do you forsee this critter hitting us? Afternoon Pressy.
ws i gonna say this once and only once

models are meant to be used as guidance purposes only and do not depict final outcome to any one event things can and will change

so if a model don't know where an when what makes you think anyone else knows

i will tell ya where its going its going forward 1 degree from its present location and it will continue moving 1 degree from its previous point till it hits something that is in front of it thats about as much as we really know at the moment anything else is just a rough idea

the best advice for anyone have a plan listen to local AUTH. evac if ordered to do so the life you could be saving may be your own
Member Since: Posts: Comments:
Quoting Patrap:
Big difference between intuition and gut feelings.

US Marines are trained,as Modern Day "Jedi's" to Ignore ones gut feeling and forge forward into Battle.

We also Know that Intuition,along with Best available Data imputed along side,usually will results in a Solution that benefits a successful Outcome of the Prime Mission,..


And with that,can someone get me another roll of TP ?


(Passes the Charmin)
Member Since: Posts: Comments:
my "gut feeling" is usually the result of too much coffee which is then promptly taken care of by a trip to see the porcelain goddess..

~jk'in of course no hard feelings
Member Since: Posts: Comments:
Big difference between intuition and gut feelings.

US Marines are trained,as Modern Day "Jedi's" to Ignore ones gut feeling and forge forward into Battle.

We also Know that Intuition,along with Best available Data inputed along side,usually will result in a Solution that benefits a successful Outcome of the Prime Mission,..


And with that,can someone get me another roll of TP ?
Member Since: Posts: Comments:
670. IKE
12Z NOGAPS through 192 hours....
Member Since: Posts: Comments:
Quoting Weather456:
Dean



90L



Both 90L, both mid august, both off Africa.. wow. Extremely similar.
Member Since: Posts: Comments:
Quoting Patrap:


Well,press.to Quote a Movie scene,and I'll catch some flak about this one,Go figure,

..."Moods and feelings are for Women and Cattle,..up on yer feet and watch the storm,sport"..

Taking me a while to read all this crap and catch up!! lol..
Member Since: Posts: Comments:
TD 2 and 90L close enough to be on the same floater

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Nolehead:
afternoon everyone..so looks like a s fl hit???


Get your board ready. Haha.
Member Since: Posts: Comments:
SFL hit?! damn girl- ana!
Member Since: Posts: Comments:
afternoon everyone..so looks like a s fl hit???
Member Since: June 3, 2008 Posts: 0 Comments: 1924
Link

Check out the NAEFS (North American Ensemble Forecast System) forecast for MIA.

Control runs from GFS and GEM and GFS deterministic all indicate quiet weather> CMC deterministic shows CAT-1 conditions.

Point forecasts from ensembles can be interesting. Small differences in modeled feature locations can create completely different forecasts. In this case, the ensemble mean is likely to be right for the wrong reasons. There will probably be some kind of tropical system in the area..just not right over MIA.

Member Since: Posts: Comments:
Quoting louisianaboy444:
So you think the high will be strong enough to keep 90L from curving out to sea?

Well i'm leaning more towards Florida and the GUlf but anything is possible right now we will know more in a few days


I hate waiting. lol.
Member Since: Posts: Comments:
Quoting jasoniscoolman10:
anyone watch the football game last night..i watch the patriots game..tom brady played bad football last night..he suck..


poof
Member Since: Posts: Comments:
Quoting hurricane23:
Hello,

Just took a quick look at the 12z GFS and it was nice knowing you miami lol.This system is still quite a distance away BUT one thing is for sure the models are pretty tightly clustered just north of the islands. Track on the 12z is somewhat similar to the 1926 miami cane.


I hope not!!!
Member Since: Posts: Comments:
I hate to say it... But I'm actually starting to wonder if TD2 may be a much bigger problem then we've been thinking over the past few days...

The Upper Level Low to TD2's north is increasing ventilation (divergence) and supporting an increase in convection.

The newest GFS shows the ULL moving west and not increasing shear, but providing good outflow to the north of TD2.

Admittedly, the GFS doesn't make much of TD2, but we HAVE to remember that TD2's interal structure is tiny and not well resolved with the resolution of the GFS.

In contrast, the large 90L is relatively well depicted given its larger circulation and development is shown.

Old TD2 also has a nice envelope of moisture surrounding it and warm SSTs in its path.

All in all there is a lot going for it...and now with a more southern track...we NEED to watch this more carefully!
Member Since: Posts: Comments:
Quoting Weather456:


I've been seeing alot of those questions and comments and it points to someone who wants something to hit Florida. Persistent questions about landfall when the asnwer is always "we dont know". Honestly its tiresome, and sad.



...and my "gut feeling" is that you are 100% correct...
Member Since: Posts: Comments:
Interesting link enough the SHIPS intensity takes 90L up to strong tropical storm strength before getting into the Bahamas.
Member Since: October 28, 2006 Posts: 57 Comments: 29886

TD2

90L

AOI


I was right.. I missed about 400 posts.
Member Since: Posts: Comments:
Quoting BrockBerlin:
Just a question at this point what is the probability of 90 becoming at least a hurricane(not neccesarily a major hurricane)


I believe that answer comes when it becomes a TD as NHC then puts % on that.
Member Since: Posts: Comments:
Hopefully the long run GFS loop is off. We do not need 90L to follow that path.

The SST's just South of New Orleans are up to a toasty 92 degF. The majority of the gulf SST's are roughly 90 deg.F.

Just think what an organized system would do if it hits that large area of extra warm water just prior to landfall.
Member Since: Posts: Comments:
So you think the high will be strong enough to keep 90L from curving out to sea?

Well i'm leaning more towards Florida and the GUlf but anything is possible right now we will know more in a few days
Member Since: Posts: Comments:
Quoting Weather456:


I've been seeing alot of those questions and comments and it points to someone who wants something to hit Florida. Persistent questions about landfall when the asnwer is always "we dont know". Honestly its tiresome, and sad.


WeatherStudent is the worst poster I've ever seen on here.. I'm so glad I put him on ignore like 5 days ago
Member Since: Posts: Comments:
Quoting Patrap:


Well,press.to Quote a Movie scene,and I'll catch some flak about this one,Go figure,

..."Moods and feelings are for Women and Cattle,..up on yer feet and watch the storm,sport"..



“Intuition (is) perception via the unconscious”
and
“Intuition will tell the thinking mind where to look next.”
- Jonas Salk

Then there is:
“I feel there are two people inside me - me and my intuition. If I go against her, she'll screw me every time, and if I follow her, we get along quite nicely.”
- Kim Basinger

Member Since: Posts: Comments:
please lets just stop ok no matter what dr masters says no matter what nhc says no matter what the models says people are going to have their own theory especially when they want the storm to hit them it will go their way no matter what some want a east coast storm some want a gulf coast storm thank God storms only last 6 months out of a year i couldnt take a 12 month hurricane season lol
Member Since: Posts: Comments:
Quoting futuremet:
TD2 to hit FL


Everyone keeps forgetting about TD2.

One Two punch possible here.
Member Since: Posts: Comments:
Quoting presslord:



Seriously ?!?!?!?! Are you seriously asking him that?!?!?!?!?!?!


I've been seeing alot of those questions and comments and it points to someone who wants something to hit Florida. Persistent questions about landfall when the asnwer is always "we dont know". Honestly its tiresome, and sad.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Track also similar to donna.
Member Since: Posts: Comments:
I still see a little swirl at 22n 76w looks to be headed towards upper keys s. fl. might be heading to gulf
Member Since: Posts: Comments:
Quoting P451:
12z GFS - thru 138hrs





P451, what software do you use to this?
Member Since: Posts: Comments:
1926 miami hurricane

Member Since: March 19, 2009 Posts: 0 Comments: 1421
Quoting Weather456:
Dean



90L


Wow, they look alike.
Member Since: Posts: Comments:
Quoting futuremet:
TD2 to hit FL


Interesting NOGAPS. Perhaps it could be a player. Models are differing on its track though
Member Since: October 28, 2006 Posts: 57 Comments: 29886
Quoting louisianaboy444:
What support is there for a Gulf strike? There is none at the moment.

I don't like this as much as you don't like it but for now i am leaning towards the last couple runs of the GFS model...it shows the high building in Florida getting hit then a trough picking it up and taking it to the Northern Gulf Coast...I'm hoping that doesn't pan out it just seems reasonable right now based on my past knowledge and events


So you think the high will be strong enough to keep 90L from curving out to sea?
Member Since: Posts: Comments:
Good Afternoon Everyone...from South Fla.
A post in our local paper a short while ago from NHC....

The National Hurricane Center says the strong tropical wave near the African coast still lacks the organization to be deemed a tropical depression this morning.

That’s because both wind shear and dry air are preventing it from developing a closed circulation, said Dave Roberts, a Navy hurricane specialist assigned to the hurricane center.

He said the system’s core has been separated from its thunderstorm activity.

“We’re still looking at the potential for it to develop into a tropical cyclone,” he said. “But it’s going to be a gradual trend.”

It’s far too early to say where it will go, how strong it will get.

The models continue to point the system in the general direction of the Lesser Antilles and the U.S. coastline. They predict it will grow into a hurricane by next Wednesday.

Again, let’s not worry about the models just yet because they won’t have a good handle on the wave until it strengthens into a depression or storm.

Member Since: Posts: Comments:
My below my Gut feeling tells me I hafta go sit in "another Chair for a Spell",

..and that may take a lil while as Im 3 feet short on that end..
Member Since: Posts: Comments:
Quoting Vortex95:


I thought you would be more upset of him calling you pressy.
At least he spelled it correctly....lol
Member Since: Posts: Comments:

Viewing: 684 - 634

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
73 °F
Mostly Cloudy