Lesser Antilles Disturbance 97L a Threat to Develop

By: Dr. Jeff Masters , 2:46 PM GMT on September 01, 2013

Share this Blog
70
+

A tropical wave over the Lesser Antilles Islands (Invest 97L) is moving westward at 15 mph, and is bringing heavy rains and gusty winds to the islands. Top sustained winds in the islands as of 10 am AST Sunday were 26 mph at Monserrat. Heavy thunderstorm activity has sharply increased since Saturday, as seen on satellite loops. A large circulation is evident, with some westerly winds blowing to the south of the disturbance. However, the thunderstorms are poorly organized, and there is no sign of a well-organized surface circulation. Martinique radar shows some rotation to the echoes, though well-organized spiral bands are not evident, and do not appear to be forming. Wind shear has dropped to a moderate 10 - 20 knots over the system. An area of dry air from the Saharan Air Layer (SAL) surrounds 97L and is interfering with development.


Figure 1. Latest satellite image of Invest 97L.

Forecast for 97L
Wind shear is expected to be in the low to moderate range for the next five days, and ocean temperatures will be warm, 28 - 29°C. The disturbance is steadily moistening the atmosphere and is moving into a moister environment, so dry air will be less of an impediment to development as the week progresses. The main factor keeping the disturbance from developing over the next two days would appear to be the fact that 97L is quite large, and is stretched out from east to west over a wide expanse. Large, elongated systems like 97L usually take several days to consolidate and spin up. Another factor that will likely retard development is the presence of strong surface trade winds over the Eastern Caribbean ahead of 97L, south of the Dominican Republic. These strong trade winds are a common feature of the Eastern Caribbean, and make the region something of a hurricane graveyard. As the surface wind flow to the west of 97L accelerates into this wind max, air will be sucked from aloft downward towards the surface, creating sinking air, interfering with the formation of thunderstorm updrafts. The best chance for development of 97L would appear to be on Wednesday or Thursday, when the disturbance reaches the Central Caribbean. The wave will likely spread heavy rains to Puerto Rico, the Virgin Islands, and the Dominican Republic by Tuesday, and to Haiti by Wednesday. These rains will be capable of causing life-threatening flash flooding and mudslides in mountainous regions in Puerto Rico and Hispaniola. Of our three reliable models for predicting genesis, the UKMET, GFS, and European models, only the UKMET model develops the disturbance, predicting it will become a tropical depression south of Haiti on Wednesday, and near Jamaica on Thursday. In their 8 am EDT Sunday Tropical Weather Outlook, NHC boosted the 5-day odds of formation of 97L to 30%, and the 2-day odds to 20%.


Video 1. You can see why landslides triggered by heavy rains from a tropical cyclone are among the most dangerous hazards of these storms, thanks to a dashboard cam that caught this extraordinary rock slide in Northeast Taiwan on August 31, 2013, after heavy rains from a cold front drenched the island with up to 200 mm (7.87") of rain in 24 hours. The rains fell upon soils already saturated by Thursday's torrential rains from Tropical Storm Kong-Rey, which dumped up to 482 mm (19") of rain on Taiwan, killing three people. The driver of the car caught in the rock slide survived with minor injuries. Thanks go to wunderground member Robert Speta for bringing this video to my attention. A separate video showing the damage to the car and the course of the rock slide is here.

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: 805 - 755

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 | 50Blog Index

Member Since: Posts: Comments:
Quoting 786. whitewabit:


PBW would you pleaase remove your quote .. thank you
I don't see a reason why?
Member Since: August 1, 2011 Posts: 28 Comments: 8046
Sloppy weather in southeast for NASCAR race south of Atlanta (track is located in the pink icon between Atlanta and Griffin).

Member Since: August 1, 2011 Posts: 28 Comments: 8046
this is the ukmet one. i think is will change

Member Since: Posts: Comments:
ok storms have passed for now and time for some "Sea Food" :o)

Be back later on this evening :o)

Taco :o)
Member Since: Posts: Comments:
slowing down so it can reorganize
Member Since: Posts: Comments:
Levi Cowan ‏@TropicalTidbits 2 min
The wind shear cited as a problem for 97L by many is not an issue. Why? Zonal TUTTs split in the face of heat. Convection was all it needed.

Member Since: Posts: Comments:
Quoting 791. SLU:


Highly unlikely given the slow trades (infact they have been non-existent in the last 2 weeks).
Trades south of PR are really fast and can kill the system by pulling the center west leaving behind the convection.
Member Since: Posts: Comments:
Quoting 789. weather12know:


Why? Did I miss something?


nope you have not missed anything :o( I was just making a funny on where this may go that's all :o)

Taco :o)
Member Since: Posts: Comments:
storms still down in south florida.........
Member Since: Posts: Comments:
this is the fim9 plotter. i think only 2 days



Member Since: Posts: Comments:
792. kwad
Quoting 763. SLU:


Yes I've been watching that too. Only when there's a "storm" passing close by does this happen!


Aircraft at Hewanorra Airport St Lucia are flying out in the opposite direction.
Member Since: Posts: Comments:
791. SLU
Quoting 784. Gearsts:
It would be funny if the center runs ahead of the MLC and goes naked. lol


Highly unlikely given the slow trades (infact they have been non-existent in the last 2 weeks).
Member Since: Posts: Comments:
Quoting 753. TropicalAnalystwx13:
I know the main focus is on Invest 97L, and probably rightfully so, but let's not forget to watch the sharp tropical wave axis currently moving into the Yucatan. It's forecast to enter the Bay of Campeche late tomorrow, where atmospheric conditions will be at least marginally conducive for tropical cyclone development. As we saw with Fernand, systems like to go to town down here given the opportunity. While I haven't seen a model that develops it, the NHC is giving this wave a 20% chance of developing within 5 days.

would be good if indeed it did develop there..maybe some rain would go to texas...
Member Since: Posts: Comments:
Quoting 749. taco2me61:


Houston we may have a Problem :o(

Taco :o(


Why? Did I miss something?

Member Since: Posts: Comments:
Quoting 776. Gearsts:
So is this thing moving?
Looks like no question the new center has back pedeled and consolidated to @ 58.5 somewhere near 15N. Giving this more time to qualify before it enters the east carrib. Looks really nice IMO. Very near depression.
Member Since: Posts: Comments:
Quoting 784. Gearsts:
It would be funny if the center runs ahead of the MLC and goes naked. lol
Funny, but typical...
Member Since: Posts: Comments:
786. whitewabit (Mod)
Quoting 785. PalmBeachWeather:
Art...You have mail


PBW would you pleaase remove your quote .. thank you
Member Since: Posts: Comments:
It would be funny if the center runs ahead of the MLC and goes naked. lol
Member Since: Posts: Comments:
782. SLU
Quoting 772. Hurricanes305:


The LLC is NNE of Barbados a dominant center as yet to make it across 60W successful as it waits on the convection to catch it looks to be drifting slowly west at this moment.


Yes at less than 10mph. Big rain maker for the islands.
Member Since: Posts: Comments:
Geeez....... So many predictions, and oh so far away...
Member Since: Posts: Comments:
commet re move

Member Since: May 21, 2006 Posts: 5091 Comments: 115437
Quoting Gearsts:
So is this thing moving?

Not much, eh ?
Member Since: Posts: Comments:
Quoting 776. Gearsts:
So is this thing moving?

If it hit the CONUS, it would probably take 2 weeks at this rate!
Member Since: May 12, 2012 Posts: 11 Comments: 2841


More to come, so much for a boring season!
Member Since: Posts: Comments:
So is this thing moving?
Member Since: Posts: Comments:
Quoting 613. Patrap:


Er, that's the NOAA G 4 "Gonzo" dropping air sampling sondes around the system.

Up round 38,000 ft.





Isn't this just a training mission? If I'm reading it right when it's not in the Gulf...it's been over Florida most of the time. I sure hope they're not dropping dropsondes.
Member Since: Posts: Comments:
Quoting 768. TylerStanfield:

It has the potential, Just not sure if it will be able to take advantage.
They Predicted Ernesto to become a Category 3 in the Western Caribbean last year, and it struggled. Though it does appear that condition are pretty conducive for intensification with 97L this time around. This might be the "G" storm to be reckoned with. Gustav's Sister.
You mean (Gilberts) sister
Member Since: July 20, 2008 Posts: 0 Comments: 347
Quoting 757. GTstormChaserCaleb:
Check this out, mudslide in Taiwan and a boulder nearly crushed the car ahead of this car.



U realize this is the video in the doc's blog, right?
Member Since: Posts: Comments:
Quoting 744. SLU:
The circulation is closed.

Barbados

3:00 PM 82.4 F 94.0 F 80.6 F 94% 29.80 in 6.2 mi NNW 6.9 mph - N/A Mostly Cloudy


The LLC is NNE of Barbados a dominant center as yet to make it across 60W successful as it waits on the convection to its east to catch up looks to be drifting slowly west at this moment.
Member Since: Posts: Comments:
Quoting 766. Gearsts:


The radar will fill in from Monday.
Member Since: April 29, 2009 Posts: 75 Comments: 14770
Quoting SLU:


Yes I've been watching that too. Only when there's a "storm" passing close by does this happen!

True that.
Member Since: Posts: Comments:
The NHC Can upgrade anytime they want all observations from the islands indicate that the LLC is closed and the pressure continues to fall, IMO I think we may see an upgrade tonight or early tomorrow.
Member Since: July 14, 2009 Posts: 0 Comments: 3029
Quoting 743. CybrTeddy:
Not bad:

It has the potential, Just not sure if it will be able to take advantage.
They Predicted Ernesto to become a Category 3 in the Western Caribbean last year, and it struggled. Though it does appear that condition are pretty conducive for intensification with 97L this time around. This might be the "G" storm to be reckoned with. Gustav's Sister.
Member Since: June 2, 2013 Posts: 8 Comments: 1388
Quoting GTstormChaserCaleb:
Check this out, mudslide in Taiwan and a boulder nearly crushed the car ahead of this car.




Errr, I thinkj 'someone' posted that video on their blog.
You should read it......
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Quoting 724. CybrTeddy:
GFDL ensembles.

I love the format of the new GFDL Ensembles, but I feel like they are always too eager to over-strengthen everything.
Member Since: Posts: Comments:
Quoting 748. wunderweatherman123:
HWRF and GFDL take this NW. if the GFS and euro are wrong this could mean trouble. all it takes is one storm.
If this strengthens, it would mean trouble regardless of the direction it takes. Once the COC crosses 60W south of 20N, game is on...
Member Since: Posts: Comments:
763. SLU
Quoting 752. pottery:

Winds have been W-WSW all day here in Trinidad.
Made for a Beautiful day !


Yes I've been watching that too. Only when there's a "storm" passing close by does this happen!
Member Since: Posts: Comments:
Quoting 743. CybrTeddy:
Not bad:

Of note, a meteorologist on AmericanWx noted that only member GT01 comes close to correctly analyzing the broad low-level structure of Invest 97L. You can see what it does with the system in the bottom panel on your image (it dissipates it).

Member Since: Posts: Comments:
Quoting 755. WoodyFL:
Lots of models are moving back some east than before


\

That will change
Member Since: June 13, 2009 Posts: 2 Comments: 12710
Quoting 751. 62901IL:

Nice switching of Emoticons.

I'm usually a happy person but 97L bothers me a bit :o(

Taco :o(
Member Since: Posts: Comments:
Probably back in July, I had posted this picture I had made on paint saying that if my area was going to get hit with a severe hurricane, then this is what I would expect. (track more important than the fictional dates and name I put) Kind of eerie, let's see how 97L pans out.
Member Since: May 12, 2012 Posts: 11 Comments: 2841
Member Since: Posts: Comments:
Check this out, mudslide in Taiwan and a boulder nearly crushed the car ahead of this car.



Member Since: June 30, 2013 Posts: 12 Comments: 8774
Quoting 748. wunderweatherman123:
HWRF and GFDL take this NW. if the GFS and euro are wrong this could mean trouble. all it takes is one storm.

Now do you see why you should not take every model run so seriously?
Member Since: Posts: Comments:
Lots of models are moving back some east than before


\
Member Since: Posts: Comments:

Viewing: 805 - 755

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 | 50Blog 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
28 °F
Overcast