Caribbean disturbance 99L a dangerous rainfall threat for Haiti, Jamaica, and Cuba

By: Dr. Jeff Masters , 4:12 PM GMT on October 20, 2012

Share this Blog
36
+

A tropical wave embedded in a large trough of low pressure (Invest 99L) covers a large portion of the Central Caribbean between Hispaniola and the northern coast of South America. This storm has the potential to be a dangerous rainfall threat for Haiti, Jamaica, and eastern Cuba. The disturbance is headed west at less than 5 mph, is over very warm waters of 29┬░C, and is in a moist environment. 99L has a large area of heavy thunderstorms that are beginning to show some organization, as seen on visible satellite loops. Wind shear is a low 5 - 10 knots, and is forecast to be in the low to moderate range, 5 - 20 knots, through Tuesday. This should allow for some steady development of 99L, and there has been a good deal of model support for 99L becoming a tropical depression by Wednesday. Steering currents favor a continued slow westward movement for 99L through Tuesday, which will bring a multi-day period of heavy rains to Haiti, Jamaica, and eastern Cuba beginning on Sunday. The Dominican Republic may also see some heavy rains, though not as great. On Wednesday, a strong trough of low pressure will approaching the Eastern U.S., and the GFS and ECMWF models predict that this trough will turn 99L to the north, bringing the storm into the southeast Bahama Islands on Thursday or Friday. In their 8 am EDT tropical weather outlook, NHC gave 99L a 30% chance of developing into a tropical cyclone by Monday morning. I put these odds higher, at 40%. An Air Force hurricane hunter aircraft is scheduled to investigate 99L on Sunday afternoon.


Figure 1. Morning satellite image of Invest 99L.

Invest 90L in the middle Atlantic
A tropical wave (Invest 90L) about 1000 miles east-northeast of the northernmost Lesser Antilles Islands is headed west-northwest at about 10 mph. The disturbance has a modest amount of heavy thunderstorms, as seen on visible satellite images, and has gotten tangled up with an upper-level low pressure system. This upper-level low is pumping cool, dry air into the disturbance, which will keep any development slow over the next few days. Wind shear is a high 20 - 25 knots, but is forecast to drop to the moderate range, 10 - 20 knots, Sunday through Monday. This may allow for some slow development of 90L before it encounters very high wind shear of 20 - 40 knots on Tuesday and Wednesday. None of the reliable computer models develop 90L into a tropical cyclone. It's unlikely that 90L will affect any land areas. In their 8 am EDT tropical weather outlook, NHC gave 90L a 20% chance of developing into a tropical cyclone by Monday morning.

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: 454 - 404

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20Blog Index

Quoting trHUrrIXC5MMX:
For 8 PM TWO
I say

99L 50-60%
90L 30%

I think they may even go up with 99L and 90L, jmo.
Member Since: March 16, 2012 Posts: 127 Comments: 7927
Quoting HuracanTaino:
why in those languages Spanish is more likely since the majority of the population that is affected by"tropical systems speak Spanish in the Caribbean....more than 60 millions,,,by the way..


Because those are the languages I know and the countries my family is in. Never studied Spanish, but I get a lot of it just from how similar to French it is.
Member Since: July 2, 2011 Posts: 0 Comments: 1183
I don't think 99L will be that much strong system.Flooding rain for people though.
Member Since: August 14, 2010 Posts: 10 Comments: 16325
Quoting KoritheMan:


They're not gonna go down on 99L...


I have a feeling they might. And I think they went a little too high from 30 to 60% earlier today.
Member Since: April 23, 2011 Posts: 104 Comments: 14870
Member Since: Posts: Comments:
18Z GFS is out and can i say it going to get cold out!!!!!
Member Since: Posts: Comments:
448. beell
Quoting whitewabit:


Thank you for your answer ...


Sure thing, wab. Not a conventional answer so put a big fwiw after it! So far, no real signs in the sat loops and surface obs for the broader circulation to close off on the west/southwest side and capture the spin along the wave axis. It may not do so until Monday or Tuesday, so westward-ho it is until if/when it does.


Member Since: Posts: Comments:
850mb Vorticity
9 Hours Previous

Now
Member Since: Posts: Comments:
Quoting trHUrrIXC5MMX:
For 8 PM TWO
I say

99L 40-50% based on disorganization
90L 30% based on better presentation and more definied


They're not gonna go down on 99L...
Member Since: Posts: Comments:
Quoting LargoFl:

YAWNNNNN
Member Since: Posts: Comments:
Quoting Hurricanes305:


Its moving at 7 mph how exactly is it running away from the convection.

it looked like an illusion but then again isn't that how all storms on dmin look
Member Since: Posts: Comments:
Member Since: Posts: Comments:
For 8 PM TWO
I say

99L 50-60%
90L 30%
Member Since: April 23, 2011 Posts: 104 Comments: 14870
Quoting NCHurricane2009:

I would say more from the t-wave than the monsoon. And this t-wave...which came off of Africa on October 12... hasn't really been announcing itself on satellite until now...so I could see how it seems 99-L came from nowhere so to speak...

My studying of t-waves (in conjunction with upper winds) during this year and 2011...thru the birdseye view charts like you see on my blog...leads me to believe tropical waves don't just blow up on their own...but their catalyst is usually associated with some favorable upper wind config such as an upper-level ridge that enhances its upper outflow...


The catalyst for a tropical wave is the temperature difference between Sahel Africa and the Gulf of Guinea.
Member Since: Posts: Comments:
Quoting NCHurricane2009:

Even though the convection has decreased a bit...the structure is better defined than ever. Look carefully at the IR animation...you can see a surface low spinning up around 15N-72.5W with the convection looking less blobby and more streamlined and spiraled about that location....

true
Member Since: Posts: Comments:
Quoting flcanes:

is it just me or am i seeing the coc running out ahead of the convection?


Its moving at 7 mph how exactly is it running away from the convection.
Member Since: Posts: Comments:
Quoting 954FtLCane:
yay, the bicksersons are in the building! Or shall I say.. los bickersons.


models are all over the place
Member Since: Posts: Comments:
Quoting Civicane49:

Even though the convection has decreased a bit...the structure is better defined than ever. Look carefully at the IR animation...you can see a surface low spinning up around 15N-72.5W with the convection looking less blobby and more streamlined and spiraled about that location....
Member Since: September 15, 2009 Posts: 426 Comments: 3580
Member Since: Posts: Comments:
Quoting flcanes:

is it just me or am i seeing the coc running out ahead of the convection?

Trade winds are slow and wind shear is low. It's you.
Member Since: July 6, 2010 Posts: 112 Comments: 31316
Quoting sunlinepr:


WunderBlogs - Dr. Masters' Blog Content Rules

Due to the high amount of traffic that Dr. Masters' blog receives, a special community standard has been established for the blog. The following list comprises the "Rules of the Road" for Dr. Masters' blog.

Keep it civil. Personal attacks, bickering, flaming, and general trollish behavior will not be tolerated. Disagreements are fine, but keep them civil and short.
Stay on topic.
No monomania.
No hot linking external or copyright images without the image owner's permission.
Do not circumvent a ban. Most bans last 24 hours or less, please accept the ban. If you create a new username to circumvent a ban, you will be blocked from the site completely.
No comments that contain only personal notes such as, "Good Morning!", or "You've got mail, X".
Do not "1st!", "1st post!", or any of the numerical/linguistic derivatives. This is a worthless use of blog space.
No spamming.
No spamming.
Seriously, no spamming. Spamming includes but is not limited to, trying to sell products, trying to solicit traffic for your own blog, trying to solicit traffic for other commercial entities, etc. Do not post links to your own site unless they are directly relevant and even then, use sparingly.
Political comments are allowed, as long as they're in reference to science, science policy, or the blog topic.




Maybe you will like to add....

Blog comments should be made ONLY IN ENGLISH... Spanish is prohibited...



Your comment is discriminatory....



that's very inappropriate and off topic.

I speak 5 languages but I never play around like that.
If it's English is English ok guys..?!
The blog is done in English, however.
Member Since: April 23, 2011 Posts: 104 Comments: 14870
Member Since: Posts: Comments:
Member Since: Posts: Comments:
It is 76!:) in WPB
Member Since: Posts: Comments:
Member Since: August 2, 2010 Posts: 21 Comments: 9690
Quoting flcanes:

t-wave/monsoon troughing

I would say more from the t-wave than the monsoon. And this t-wave...which came off of Africa on October 12... hasn't really been announcing itself on satellite until now...so I could see how it seems 99-L came from nowhere so to speak...

My studying of t-waves (in conjunction with upper winds) during this year and 2011...thru the birdseye view charts like you see on my blog...leads me to believe tropical waves don't just blow up on their own...but their catalyst is usually associated with some favorable upper wind config such as an upper-level ridge that enhances its upper outflow...
Member Since: September 15, 2009 Posts: 426 Comments: 3580
Quoting MAweatherboy1:
I would say DMIN is definitely the main reason for the decrease in convection... no obvious dry air that would kill convection:



is it just me or am i seeing the coc running out ahead of the convection?
Member Since: Posts: Comments:
yay, the bicksersons are in the building! Or shall I say.. los bickersons.

Member Since: Posts: Comments:
Member Since: Posts: Comments:
Quoting sunlinepr:


WunderBlogs - Dr. Masters' Blog Content Rules

Due to the high amount of traffic that Dr. Masters' blog receives, a special community standard has been established for the blog. The following list comprises the "Rules of the Road" for Dr. Masters' blog.

Keep it civil. Personal attacks, bickering, flaming, and general trollish behavior will not be tolerated. Disagreements are fine, but keep them civil and short.
Stay on topic.
No monomania.
No hot linking external or copyright images without the image owner's permission.
Do not circumvent a ban. Most bans last 24 hours or less, please accept the ban. If you create a new username to circumvent a ban, you will be blocked from the site completely.
No comments that contain only personal notes such as, "Good Morning!", or "You've got mail, X".
Do not "1st!", "1st post!", or any of the numerical/linguistic derivatives. This is a worthless use of blog space.
No spamming.
No spamming.
Seriously, no spamming. Spamming includes but is not limited to, trying to sell products, trying to solicit traffic for your own blog, trying to solicit traffic for other commercial entities, etc. Do not post links to your own site unless they are directly relevant and even then, use sparingly.
Political comments are allowed, as long as they're in reference to science, science policy, or the blog topic.




Maybe you will like to add....

Blog comments should be made ONLY IN ENGLISH... Spanish is prohibited...

would that be wrong
Member Since: Posts: Comments:
I would say DMIN is definitely the main reason for the decrease in convection... no obvious dry air that would kill convection:


Member Since: February 11, 2012 Posts: 82 Comments: 7565
Quoting Tazmanian:




take this too your own blog plzs this is not a Spanish blog


WunderBlogs - Dr. Masters' Blog Content Rules

Due to the high amount of traffic that Dr. Masters' blog receives, a special community standard has been established for the blog. The following list comprises the "Rules of the Road" for Dr. Masters' blog.

Keep it civil. Personal attacks, bickering, flaming, and general trollish behavior will not be tolerated. Disagreements are fine, but keep them civil and short.
Stay on topic.
No monomania.
No hot linking external or copyright images without the image owner's permission.
Do not circumvent a ban. Most bans last 24 hours or less, please accept the ban. If you create a new username to circumvent a ban, you will be blocked from the site completely.
No comments that contain only personal notes such as, "Good Morning!", or "You've got mail, X".
Do not "1st!", "1st post!", or any of the numerical/linguistic derivatives. This is a worthless use of blog space.
No spamming.
No spamming.
Seriously, no spamming. Spamming includes but is not limited to, trying to sell products, trying to solicit traffic for your own blog, trying to solicit traffic for other commercial entities, etc. Do not post links to your own site unless they are directly relevant and even then, use sparingly.
Political comments are allowed, as long as they're in reference to science, science policy, or the blog topic.




Maybe you will like to add....

Blog comments should be made ONLY IN ENGLISH... Spanish is prohibited...



Your comment is discriminatory....
Member Since: August 2, 2010 Posts: 21 Comments: 9690
Quoting TropicalAnalystwx13:

Definitely developing a surface circulation now.

If 90-L keeps taking off...maybe we'll have Subtropical Storm Sandy...then that means 99-L would be Tony? That would mean the more infamous system gets the name Tony...that would be interesting...
Member Since: September 15, 2009 Posts: 426 Comments: 3580
Quoting sunlinepr:


Where is that stated? Show me where and dejo de hablar mi lengua materna...
yes Tazmania, specially coming from you,,we always respect your lack of knowledge of the English language and we never critisize you,,if we hispanic feel to speak Spanish among us,,nobody can't say no,,unless they ban us,,adiministration I mean,,and that will very discriminatory, by the way.
Member Since: Posts: Comments:
Quoting WoodyFL:


Don't ask for that. gro might come on and embarras us all.


I wouldn't do that. :)
Member Since: July 17, 2009 Posts: 68 Comments: 25051
Quoting Slamguitar:
If we're going to do different languages, can we do Scottish Gaelic, French, or German? :P


Don't ask for that. gro might come on and embarras us all.
Member Since: Posts: Comments:
Quoting HuracanTaino:
It seems that is moving due west, too.

is expected for now....:)
Member Since: Posts: Comments:
Quoting washingtonian115:
I'm still confused as to where this came from?

t-wave/monsoon troughing
Member Since: Posts: Comments:
Quoting TropicalAnalystwx13:

Definitely developing a surface circulation now.
It seems that is moving due west, too.
Member Since: Posts: Comments:
Quoting wxchaser97:
While there isn't a lot of convection right now that is expected due to DMIN. However the circulation and structure remains intact and convection will increase again tomorrow. I think we should have a TD in day or two.


Also UoM wins in a nail-bitter over MSU.

i agree
Member Since: Posts: Comments:
I'm still confused as to where this came from?
Member Since: August 14, 2010 Posts: 10 Comments: 16325
While there isn't a lot of convection right now that is expected due to DMIN. However the circulation and structure remains intact and convection will increase again tomorrow. I think we should have a TD in day or two.


Also UoM wins in a nail-bitter over MSU.
Member Since: March 16, 2012 Posts: 127 Comments: 7927
Quoting Tropicsweatherpr:
99L doesn't look too convective at the moment but I guess is the D-MIN period.


Yep. Convection is slightly diminishing likely due to D-MIN period. But, it should increase in the D-MAX period and likely become a tropical cyclone tomorrow or sooner.

Member Since: Posts: Comments:
Quoting Slamguitar:
If we're going to do different languages, can we do Scottish Gaelic, French, or German? :P
why in those languages Spanish is more likely since the majority of the population that is affected by"tropical systems speak Spanish in the Caribbean....more than 60 millions,,,by the way..
Member Since: Posts: Comments:
Quoting NCHurricane2009:
Whoa...look at 90L getting better organized about 48W-20N...I think the 18Z ASCAT pass was on to something...

Definitely developing a surface circulation now.
Member Since: July 6, 2010 Posts: 112 Comments: 31316
The original video was posted in 2009.He took it down and re-uploaded it on Dec/1/2010.Just type in hurricane dolly and cycloneOz's name.
Member Since: August 14, 2010 Posts: 10 Comments: 16325
Quoting Tazmanian:




take this too your own blog plzs this is not a Spanish blog


Where is that stated? Show me where and dejo de hablar mi lengua materna...
Member Since: August 2, 2010 Posts: 21 Comments: 9690
Quoting sunlinepr:


Inclusive la radciacion de microhondas de la estacion situada en el area de Cuba-Florida han afectado tus conclusiones meteorologicas... se nota... Ah perdon le deseo exito Sr...
Wow, "tiraera" meteorol├│gica in Spanish style, cool !!!
Member Since: Posts: Comments:

Viewing: 454 - 404

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20Blog 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.