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

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

Share this Blog
1
+

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

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: 2365 - 2315

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 | 48Blog Index

2365. msphar
2:10 PM GMT on July 20, 2009
Burned - you still believe in your Westward thesis or was it SW? Looks to me like it gained a degree Northwards overnight while it moved West 7.5 degrees.
Member Since: August 20, 2006 Posts: 0 Comments: 289
2364. Mikla
2:04 PM GMT on July 20, 2009
97L with some models and mid & upper shear...
Member Since: October 13, 2006 Posts: 0 Comments: 305
2363. Grothar
1:53 PM GMT on July 20, 2009
I agree with the comments on The Weather Channel. One must infer from their format that they believe they are the focus of the show, when in fact the weather is secondary. Weather, in itself is dynamic. They interject themselves in front of the maps so you cannot see the "massive storms and fronts, etc". It should be more informative and precise.
Member Since: July 17, 2009 Posts: 71 Comments: 27208
2362. moonlightcowboy
1:52 PM GMT on July 20, 2009
Good morning. I see 97L survived the night with the "dreaded" shear.

GFDL does not do cyclcogenesis, folks. 97L maintained despite the shear, still moving with steering mostly westerly, big convection there with dmax from all the lift. LLC? Can't see it. MLC, difficult too; but, I imagine it's still there - it's just grappling with how to manage all that convection now. ;)

Member Since: July 9, 2006 Posts: 184 Comments: 29610
2361. jurakantaino
1:52 PM GMT on July 20, 2009
Ghotar- From now on anything that come out of Africa should be interesting, since we are approaching rapidly Cape VERDE season.
Member Since: July 31, 2008 Posts: 0 Comments: 730
2360. canesrule1
1:51 PM GMT on July 20, 2009
Quoting StormW:


Good...you?
im doing good, following those models, just wondering do you believe we might have our first named system of the season with 97L or is this just going to die?
2359. BurnedAfterPosting
1:51 PM GMT on July 20, 2009
NEW BLOG!!
2358. canesrule1
1:50 PM GMT on July 20, 2009
Quoting stormsurge39:
1010 pressure was the last one that was posted and its the lowest yet.
i posted a 29.83
2356. canesrule1
1:49 PM GMT on July 20, 2009
i will
2355. Drakoen
1:48 PM GMT on July 20, 2009
Quoting BurnedAfterPosting:


morning Drak, yea I agree, seems to me that it is fighting fairly well though, not just dying out


I don't think it's done yet.
Member Since: October 28, 2006 Posts: 57 Comments: 30825
2353. StormFreakyisher
1:47 PM GMT on July 20, 2009
Okay I have two questions.Is all that rain and cloudiness east of the Bahamas the remnants of the tropical wave that was sheared apart and is interacting now with a frontal boundary that will make it form into somethin?And what will happen with the tropical wave in the mid atlantic that is still holding a pouch of thunderstorms?
Member Since: May 16, 2009 Posts: 0 Comments: 684
2352. stormsurge39
1:46 PM GMT on July 20, 2009
1010 pressure was the last one that was posted and its the lowest yet.
2351. weathermanwannabe
1:45 PM GMT on July 20, 2009
Quoting canesrule1:
those models keep on getting closer to S-FL, scaring me a bit now.


No need to worry; this is not going to make it to South Florida.......Don't take my word for it...You only have to worry down the road when NHC officially declares a tropical storm or hurricane watch for your area.......On a related note, if you have a hurricane plan in place and have bought supplies in case, there is no need to worry....Take care of these items during this "lull" if you have not already done so...........Dont' Worry...Be Happy...... :)
Member Since: August 8, 2006 Posts: 0 Comments: 9402
2350. homelesswanderer
1:45 PM GMT on July 20, 2009
Quoting StormW:


TAFB= Tropical Analysis Forecast Branch


Thanks Storm. :)

Member Since: August 15, 2008 Posts: 10 Comments: 3665
2349. BurnedAfterPosting
1:45 PM GMT on July 20, 2009
Quoting Drakoen:
Not much change with 97L. The reason for the convection you are seeing is is because of the systems location at the base of the trough producing upper level diffluence as well being near the northeastern coast of South America. Some of the models indicate that shear may become more favorable for development in 2 days.


morning Drak, yea I agree, seems to me that it is fighting fairly well though, not just dying out
2348. canesrule1
1:44 PM GMT on July 20, 2009
Quoting StormW:


TAFB= Tropical Analysis Forecast Branch
Hey there Storm, how you doing?
2347. BurnedAfterPosting
1:45 PM GMT on July 20, 2009
Quoting StormW:


TAFB= Tropical Analysis Forecast Branch


morning StormW, can you please shed some light on 97L

It is being called dead as a doornail by so many people lol, thought maybe you could help us out and give us a more enlightened opinion


I feel the convection that is being induced by the shear will help 97L to survive somehow
2346. Drakoen
1:43 PM GMT on July 20, 2009
Not much change with 97L. The reason for the convection you are seeing is is because of the systems location at the base of the trough producing upper level diffluence as well being near the northeastern coast of South America. Some of the models indicate that shear may become more favorable for development in 2 days.
Member Since: October 28, 2006 Posts: 57 Comments: 30825
2344. StonedCrab
1:41 PM GMT on July 20, 2009
Quoting StormFreakyisher:

The Weather Channel is becoming more stupid each day.It is becoming of a more reality/entertainment show then a weather news channel.


And now they add Al Roker, the Ed McMahon of weather...jeez.

Does anybody know why all of the HiDef radar sites are down?
Member Since: October 30, 2007 Posts: 0 Comments: 270
2343. stormsurge39
1:40 PM GMT on July 20, 2009
97 is not going to die, once it gets thru today lookout!!!! The last wave that was in that area looked like it was taking on more shear than 97 is. Also no other wave coming off africa this year has done this good.Dont let your guard down.
2342. surfmom
1:40 PM GMT on July 20, 2009
Quoting StormFreakyisher:

The Weather Channel is becoming more stupid each day.It is becoming of a more reality/entertainment show then a weather news channel.


the continued dumbing down of America -- distraction & diversion..............people don't wanna think anymore.... 'cept those of us here -- we may fight, but at least we're thinking LOL
Member Since: July 18, 2007 Posts: 30 Comments: 26536
2341. canesrule1
1:39 PM GMT on July 20, 2009
I found a SHIP around Barbados showing only 2 knot winds but pressure was at 29.83, something is going on there.
2340. surfmom
1:39 PM GMT on July 20, 2009
97L ain't over till the fat lady sings..... though she seems to be choking a bit now...

memories of Dolly --some of the most beautiful groundswell I have ever surfed on the Gulf

Good rainstorm this AM in SRQ/FL -- hiding out at the house b/4 I head out East and work the horses. going to a MUD FEST, MOSQUITO BANQUET day for sure....but it beats sitting in an office, under fluorescent light --least for me.

All water holes/ponds are FULL to the top -- haven't seen that in several years......well... the year of Charlie,Frances & Jeanne --so I wonder if that's a ....clue

CHICKLIT -- GOOD to see you.....
Member Since: July 18, 2007 Posts: 30 Comments: 26536
2339. StormFreakyisher
1:35 PM GMT on July 20, 2009
Quoting InTheConeOIO:
Did anyone happen to look at TWC tropical updates last night? Anyway, they spent 3 min having people write in to decide when is it too cold for the pool and when is it too cold for ice cream. Maybe it's me, but what the hell dose that have to do with the tropics? I mean it's stupid, and then she rushed through the tropical update.

The Weather Channel is becoming more stupid each day.It is becoming of a more reality/entertainment show then a weather news channel.
Member Since: May 16, 2009 Posts: 0 Comments: 684
2338. HurricaneSwirl
1:35 PM GMT on July 20, 2009
Quoting BurnedAfterPosting:


It didnt meet any fate yet, 97L is still slive and kicking


remember the wave before it tho? it ran into the exact same spot except a bit higher latitude and had the exact same thing happen.. shear. alive and kicking? it lost whatever circulation it had and all of its convection is either from dmax or being shear induced.

im not necessarily saying its over... like I wrote in my edit, shear doesnt harm waves it just prevents a cyclone from forming.. if shear does decide to lessen up it'll still be there, but it might get deactivated and then reactivated again lol.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
2337. BurnedAfterPosting
1:32 PM GMT on July 20, 2009
Quoting leftovers:
remember old rule if tw does not develop before the islands it wont


actually the old rule is if a TW doesnt develop before the islands it wont develop before it gets to the Western Caribbean

doesnt mean it wont develop at all
2336. Grothar
1:32 PM GMT on July 20, 2009
I know that the attention is on 97L, but does anyone have an opinion on the blob which moved off the African Coast yesterday? While it is at a low altitude and not well formed, it appears to have maintained a consistent moisture field. Perhaps my observation is premature; just interested.
Member Since: July 17, 2009 Posts: 71 Comments: 27208
2335. canesrule1
1:30 PM GMT on July 20, 2009
those models keep on getting closer to S-FL, scaring me a bit now.
2334. HurricaneSwirl
1:30 PM GMT on July 20, 2009
Quoting InTheConeOIO:
Did anyone happen to look at TWC tropical updates last night? Anyway, they spent 3 min having people write in to decide when is it too cold for the pool and when is it too cold for ice cream. Maybe it's me, but what the hell dose that have to do with the tropics? I mean it's stupid, and then she rushed through the tropical update.


LOL... i dont watch it. theres really no point in the weather channel, its boring and you can just look at your radar on the internet... and no commercials!
Member Since: July 7, 2008 Posts: 2 Comments: 3237
2333. BurnedAfterPosting
1:29 PM GMT on July 20, 2009
Quoting HurricaneSwirl:
wow looks like 97L had the same fate as the wave before it. whatever circulation it had must be gone now with that shear. shear is just too high for anything to form at all, and it's already late july. typical of an el nino year. many more invests to come will also be ripped apart by shear.

EDIT: however just because it met the same fate doesnt mean shear wont lessen up and it wont get started again in the central caribbean.. shear doesnt harm tropical waves it just prevents them from forming. it'll still be around here for a while and people should keep an eye on it


It didnt meet any fate yet, 97L is still slive and kicking

there is that "assuming" that I was talking about before
2332. nrtiwlnvragn
1:27 PM GMT on July 20, 2009
Member Since: September 23, 2005 Posts: 15 Comments: 11343
2331. InTheConeOIO
1:26 PM GMT on July 20, 2009
Did anyone happen to look at TWC tropical updates last night? Anyway, they spent 3 min having people write in to decide when is it too cold for the pool and when is it too cold for ice cream. Maybe it's me, but what the hell dose that have to do with the tropics? I mean it's stupid, and then she rushed through the tropical update.
2330. HurricaneSwirl
1:25 PM GMT on July 20, 2009
wow looks like 97L had the same fate as the wave before it. whatever circulation it had must be gone now with that shear. shear is just too high for anything to form at all, and it's already late july. typical of an el nino year. many more invests to come will also be ripped apart by shear.

EDIT: however just because it met the same fate doesnt mean shear wont lessen up and it wont get started again in the central caribbean.. shear doesnt harm tropical waves it just prevents them from forming. it'll still be around here for a while and people should keep an eye on it
Member Since: July 7, 2008 Posts: 2 Comments: 3237
2329. KimberlyB
1:25 PM GMT on July 20, 2009
Quoting sporteguy03:
I thought nothing was suppose to remain with 97L after reading the 2000 posts yesterday maybe later in the day??


That is exactly why anyone worth their salt on here, all the regulars, all the folks with the experience to make an educated guess or opinion, will tell you that it's not over until it's over, that we have to wait and see and that none of them are psychic and nobody is infallible.
Member Since: October 21, 2007 Posts: 27 Comments: 329
2328. StonedCrab
1:22 PM GMT on July 20, 2009
Good Morning folks
Member Since: October 30, 2007 Posts: 0 Comments: 270
2327. BurnedAfterPosting
1:22 PM GMT on July 20, 2009
most of the convection from 97L is shear induced today, it is a way for weak disturbances like this to survive shear like this

it has happened many many times before, if this were a naked system than you could be about to pull the plug, that is clearly not happening
2326. canesrule1
1:19 PM GMT on July 20, 2009
Quoting sporteguy03:
I thought nothing was suppose to remain with 97L after reading the 2000 posts yesterday maybe later in the day??
That's when the convection was down and everyone thought it was all over, the reason the convection wasn't there was the DMIN, now that it has passed the DMAX stage the convection is back, its just one of those ordinary stages a wave goes through.
2325. BurnedAfterPosting
1:18 PM GMT on July 20, 2009
Quoting sporteguy03:
I thought nothing was suppose to remain with 97L after reading the 2000 posts yesterday maybe later in the day??


you know how it works on this site, most dont know how to just go with the flow, instead they jump to conclusions, assume way too much and in the end make themselves look like idiots

2324. sporteguy03
1:16 PM GMT on July 20, 2009
I thought nothing was suppose to remain with 97L after reading the 2000 posts yesterday maybe later in the day??
Member Since: July 7, 2005 Posts: 0 Comments: 5417
2323. homelesswanderer
1:14 PM GMT on July 20, 2009
Quoting extreme236:


TAFB is an organization that is basically the NHC, but it is a Dvorak Satellite Intensity estimate to determine the organization and strength of a disturbance or tropical cyclone.


Oh. Ok. TYVM. :)
Member Since: August 15, 2008 Posts: 10 Comments: 3665
2322. FLWeatherFreak91
1:14 PM GMT on July 20, 2009
example of why the Dominican Weather Service fails:

http://www.onamet.gov.do/pronostico.php?n=1392
Member Since: December 1, 2006 Posts: 2 Comments: 3634
2321. extreme236
1:14 PM GMT on July 20, 2009
Quoting stoormfury:
DT=2.0 and we have TD2


Fay formed last year when her estimates were up to 2.5 and higher, so those dont mean anything without an LLC.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
2320. extreme236
1:13 PM GMT on July 20, 2009
Quoting homelesswanderer:


What does that mean? TAFB is a new one to me. :)


TAFB is an organization that is basically the NHC, but it is a Dvorak Satellite Intensity estimate to determine the organization and strength of a disturbance or tropical cyclone.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
2319. nrtiwlnvragn
1:12 PM GMT on July 20, 2009
Quoting SLU:


yeh it goes back to 456's point yesterday about the lack of consistency


Which I respectfully disagree with.
Member Since: September 23, 2005 Posts: 15 Comments: 11343
2317. SLU
1:09 PM GMT on July 20, 2009
Quoting nrtiwlnvragn:


That data is from the hurricane center.


yeh it goes back to 456's point yesterday about the lack of consistency
Member Since: July 13, 2006 Posts: 13 Comments: 5367
2316. HurricaneKing
1:07 PM GMT on July 20, 2009
Quoting stoormfury:
DT=2.0 and we have TD2


Not without an organized llc. Which is not there. The mid level low doesn't even look like it's there anymore.
Member Since: July 6, 2005 Posts: 71 Comments: 2485
2315. nrtiwlnvragn
1:07 PM GMT on July 20, 2009
Quoting SLU:


more evidence that it's better organised than the hurricane center believes.


That data is from the hurricane center.
Member Since: September 23, 2005 Posts: 15 Comments: 11343

Viewing: 2365 - 2315

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 | 48Blog 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

Overcast
31 °F
Overcast

JeffMasters's Recent Photos

Lake Effort Snow Shower Over Windsor, Ontario
Sunset on Dunham Lake
Pictured Rocks Sunset
Sunset on Lake Huron