97L growing more organized, will bring heavy rain to the Lesser Antilles

By: Dr. Jeff Masters , 3:55 PM GMT on July 19, 2009

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The tropical wave near 12N 52W, about 600 miles east of the Lesser Antilles Islands (97 L), has grown more organized this morning as it tracks west at about 20 mph. This wave is surrounded by an area of very dry air from the Sahara Desert, but 97L has been able to steadily moisten a large region of the atmosphere over the past day, insulating itself from the dry air. This moistening process has been aided by sea surface temperatures (SSTs) that have steadily increased from 26.5°C to 27.5°C, plus the presence of only 10 knots of wind shear. The system now has a small area of intense thunderstorms near its center, with some rotation of the cloud pattern evident at mid-levels of the atmosphere. An upper-level outflow channel has opened to the north, and there is evidence that surface spiral bands are beginning to form. This morning's QuikSCAT pass missed 97L, so we don't know what is happening at the surface.

Wind shear is a modest 10 knots over the disturbance, and is forecast to remain in the moderate 10 - 15 knot range through Monday morning. This should allow further development to occur today, and 97L could be approaching tropical depression strength on Monday as it moves through the central Lesser Antilles Islands. Monday night, shear is expected to rise to 20 - 30 knots, thanks to the presence of a trough of low pressure at upper levels of the atmosphere over the eastern Caribbean. Since 97L is a relatively small system, it is very vulnerable to wind shear. This shear may be able to drive some of the dry air west of 97L deep into its interior, significantly disrupting the disturbance. Shear will remain high along 97L's path through Thursday, when the storm should be in the western Caribbean near Cuba. If there is anything left of 97L by then, some development is possible. The National Hurricane Center gave 97L a low (less than 30% chance) of developing into a tropical depression in the next 48 hours in their 8am Tropical Weather Outlook. However, I'd say the odds are now in the medium range (30 - 50%).

None of the computer models are forecasting tropical storm development over the next seven days.


Figure 1. Current satellite image of African wave 97L.

I'll have an update Monday morning. As 97L approaches the islands, you may want to follow local observations there using our wundermap for 97L.

Jeff Masters

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Where is the Oz GFS
Member Since: May 16, 2009 Posts: 1 Comments: 1231
Stormchaser does it look like on satt that the shear is lifting some, and is relaxing a little? Also look at that ball of convection right at the center.This invest is not ready to be riiiiped yet!
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It's starting to rain here and the wind is also picking up....
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New CIMSS update in 40 mins
Member Since: May 16, 2009 Posts: 1 Comments: 1231
1960. KEEPEROFTHEGATE (Mod)
Quoting Orcasystems:


I am almost positive I don't want to read to far back to find out what this is about.
its ok orca don't be scared
Member Since: July 15, 2006 Posts: 174 Comments: 54639
Quoting STORMMASTERG:
last few images show it organizing.


I really am starting to think you are, dare I say it "Wishcasting"

97L is getting blasted by shear, it is clear to see that, yet you seem to keep denying it for some reason
last few images show it organizing.
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Quoting Vortex95:


That was actually his name, well at least his stage name. He was also called Miricle Mike.


I am almost positive I don't want to read to far back to find out what this is about.
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1956. 0741
Quoting cchsweatherman:


Thats why I always place a disclaimer on my graphics. Go back and read my disclaimer.
ok because alot come in here to get information we donot need those think their pro weatherman we all need go by nhc say and national weather service say
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1955. KEEPEROFTHEGATE (Mod)
Quoting TampaMishy:
That is so disgusting.
what vortex or the headless chicken
Member Since: July 15, 2006 Posts: 174 Comments: 54639
Mishy Mike the Headless Chicken is a true story actually

Go check it out lol
Quoting stormsurge39:
Stormchaser a tropical system is not a human thats how i relate to it in trying to understand how it works. Was my analogy right or not?


Yea it was right but this may be more than a harmless haircut. Ever hear of King Louis lol?
Member Since: June 9, 2007 Posts: 4 Comments: 15923

AOI

AOI

AOI
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Quoting Vortex95:



MIKE THE HEADLESS CHICKEN LOL!!!
That is so disgusting.
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Stormchaser a tropical system is not a human thats how i relate to it in trying to understand how it works. Was my analogy right or not?
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The environment could be more favorable for the next one and then you'll be sorry!
It's good to go pfffttt! if you're an Invest.
Unless you're needed to put out a fire.
Goodnight Wunderbloggers.
Sleep well and dream of nice places.
Walter Cronkite died this week, rest his soul.
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Quoting StormJunkie:
15-20 knots over the COC

reed, also have to consider the system is moving in the opposite direction at 20-25knts...Not a good environment for development.


I didn't say it was a good environment, I don't expect development at all.. I Just said that wins shear wasn't that hostile yet. I have a gut feeling the Anticyclone in the WC will be a player for this in a few days.
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Quoting Stormchaser2007:


Name how many things can live without a head lol.


Remember watching Ripley's Believe it or Not where a chicken had its head cut off, but with the brain stem still there, it lived out the rest of its life.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
Currently 97l looks like a drunk man that can't walk straight.Hopefully extra warmth and tstms can supply him his well needed help.
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Quoting stormsurge39:
stormchaser i said a haircut. headlesshorseman real scary guy lol.


Alright, off topic but the headless horse man is a ghost.
Member Since: June 9, 2007 Posts: 4 Comments: 15923
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Here's another wave that recently came off of Africa: Link

IMO 97L is about to get smashed to smithereens.
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stormchaser i said a haircut. headlesshorseman real scary guy lol.
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15-20 knots over the COC

reed, also have to consider the system is moving in the opposite direction at 20-25knts...Not a good environment for development.
Member Since: August 17, 2005 Posts: 26 Comments: 16874
1937. Patrap
Anytime..security is my forte..
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Quoting Patrap:
er,cchs..ya may wanna edit that Post 1882,cuz yer whole album is available to the Public as Posted.



Thanks for the warning. I didn't even realize that.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
Quoting stormsurge39:
The way it looks to me is that 97L is getting a buzzed haircut on top right now from the shear. 97Ls heart is lower than its head. A haircut wont kill it,and i dont see the shear wiping out its heart. Thats my own analogy,i dont know meterologist termonology.


Name how many things can live without a head lol.
Member Since: June 9, 2007 Posts: 4 Comments: 15923
1934. JRRP
BurnedAfterPosting
Exactly
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Shear isn't going to make any difference anyways if it can't get an llc together. There's no shear at the mid-levels where the coc is located. It's doing a fair job so far through night time lift, but not good enough.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
The way it looks to me is that 97L is getting a buzzed haircut on top right now from the shear. 97Ls heart is lower than its head. A haircut wont kill it,and i dont see the shear wiping out its heart. Thats my own analogy,i dont know meterologist termonology.
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Quoting 0741:
their only nhc we need listern to why you call your self weather center remember tell people listern to nhc people think you national hurricane center noaa by putting out statement like this


Thats why I always place a disclaimer on my graphics. Go back and read my disclaimer.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
Quoting KEEPEROFTHEGATE:


AOI



An Anticyclone, not the one i'm talking about, but another one. It's on the shear map, that's how I found out about this one.
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Quoting CaneAddict:
It would obviously have to expand it's moisture field as much as possible before getting slammed by the shear.

Sometimes you just have to let go . . .
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TampaMishy...

I can almost for sure tell you this won't be a hurricane..most I see it becoming is a moderate TS at best. Hope that helps.
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Bud light presents real man of genious tonight we solute you mr.97l we pray that u are killed by shear! Not gona happen but who knows.
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If it cant survive 15 knots then I cant wait to see how it does against 25knots.
Member Since: June 9, 2007 Posts: 4 Comments: 15923
Shear is not THAT hostile over the COC just yet. It'll be interesting when the new map comes in later on tonight to see how much shear has really increased. I'd say shear is 15-20 knots over the COC, 25-30 knots on the northern half, and 5-10 knots over the second half, expect any blow up tonight to be on the southeastern side of the invest.
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1923. Patrap
er,cchs..ya may wanna edit that Post 1882,cuz yer whole album is available to the Public as Posted.

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1920. Thanks

And well done with the word...lol
Member Since: August 17, 2005 Posts: 26 Comments: 16874
1921. KEEPEROFTHEGATE (Mod)


AOI

Member Since: July 15, 2006 Posts: 174 Comments: 54639
1920. amd
Quoting StormJunkie:
...but instead deformed the TUTT...

Any chance that the deformation of the tutt is part of it breaking as well?

I was looking at imagery and the CIMMS maps and it seems there is a small area on the tendency map that is decreasing just to the E of the northern islands...So could it be breaking?

I am way out of my league with this question, but noticed I at least managed not to use The Word....lol


That could happen if one of the upper level highs, either the one in the eastern atlantic moves west, or the upper level high on the coast of south america moves to the north east, which would effectively pinch off the TUTT's southeast movement. This would decrease the upper level westerlies to the east of the lesser Antilles to more manageable levels. (Notice I also did not use the word)

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1919. 0741
Quoting cchsweatherman:
Photobucket

Been doing some in-depth analysis tonight in regards to Invest 97L and decided to share my findings and try to establish the current situation through graphic display.

Throughout the day, Invest 97L has been getting better organized with an increasingly better defined low-level structure noted with some banding becoming established. During the afternoon and evening, it seemed that the system mixed out some mid-to-upper level dry air that remained and in combination with diurnal minimum, caused the convection to significantly wane. In the past couple hours, it seems that the system is trying to build some convection over the assumed center which would give it more promise.

In the meantime, a rather strong upper level low over the open Atlantic south of Bermuda induced a TUTT (tropical upper tropospheric trough) over the Eastern and Central Caribbean creating very hostile wind shear over the region. This can clearly be seen with the streaming pattern in the thunderstorm clouds over the region. Throughout the day, this hostile wind shear has continued and really hasn't eased much at all. In fact, it almost seems as the TUTT had expanded further south deeper into the Eastern Caribbean.

Based upon the latest computer models, the TUTT should gradually lift out of the region and into the SW Atlantic in the coming days. At the same time, an upper level anticyclone (or upper level high) should become established over the Western and Central Caribbean creating a more favorable upper level environment. This should happen in about two to three days as this will be rather slow to occur.

Continuing with the computer models, Invest 97L (should it survive the rather unfavorable wind shear that it will encounter starting sometime tomorrow afternoon) should begin to take on a more WNW to NW heading in about 24 hours as it rides the southeastern periphery of a deep layered ridge in the open Atlantic. If this does indeed verify and if the system survives to this point, it would then become under the influence of the upper level anticyclone which would give it a better chance for development.

After that point, things become too cloudy for any reasonable forecast, so that will have to wait for now.

For now, I'm not going to discount Invest 97L's chances for possible further development since the current computer model trends offer it better hope than this morning, but I'm not totally sold either. Just going to have to wait and see what becomes of Invest 97L.
their only nhc we need listern to why you call your self weather center remember tell people listern to nhc people think you national hurricane center noaa by putting out statement like this
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Does anyone think 97L will turn into a hurricane? Or is it just done?
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Already getting slammed CA, and evening to you.

I think it's a good thing the shear is there...If it hadn't been 97 might be well on it's way to getting it's act together.
Member Since: August 17, 2005 Posts: 26 Comments: 16874
It would obviously have to expand it's moisture field as much as possible before getting slammed by the shear.
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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.