Lesser Antilles Disturbance 97L a Threat to Develop

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

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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

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Sure starting to look like the real player is the wave behind 97L and that a Bahama run, bypassing the Caribbean for the most part,may be what we get. (If we even get that).
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2404. ackee
I think my numbers for the season will hold through or come close 13 name storm with 3 hurricane my numbers was base on observation I am no expert but this seasons have prove the expert wrong in almost all the predation Dangerous pattern that will cause CV storm track west have not materialize we have yet to see a hurricane none in AUG I think its important to use human observation and trends for each seasons and not only models the only model I think have done well with showing little activity is the EURO just my view on the seasons
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Quoting 2389. GTstormChaserCaleb:
That's cool, but you're not the one pursuing a spot as a hurricane specialist, forecaster, or storm chaser.


Just curious, but how would a hurricane help you? Yes, I know you are pursuing a spot, but is there a specific opening coming up somehow? Personally, I'd be a very happy person if all hurricanes went out to sea, not affecting anyone anywhere other than shipping lanes.
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2402. WoodyFL
Quoting 2397. c150flyer:


Actually if the storm were anywhere near 130 kts, 950 mb would be higher than the surface pressure. It'd probably be closer to 930 or even 920.


I'm not being funny i just don't understand what that means.
Member Since: April 24, 2011 Posts: 1 Comments: 601
First off Invest 97L is entering an area that never develops. The John Hope theory of if its not developed before reaching the islands then Central Caribbean it will wait.
Member Since: September 2, 2007 Posts: 178 Comments: 20439
DMAX is just before sunup? Correct? Or do I have it backwards?
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2399. WoodyFL
I posted this earlier and it seems all the models are still moving more towards the nw. I think with this one its not the strength. Many times weak systems are steered by low level winds and strong systems are steered by upper level winds. I know a lot of people think just because a system is weak it will move west.

Member Since: April 24, 2011 Posts: 1 Comments: 601
Quoting hurricanes2018:
watch this tropical wave
Interesting, nice rotation, low latitude,lack of dry air, climatology, everything is there for this one, to be a player, we'll see....
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Quoting 2352. WoodyFL:



I believe on that model, 134 knots is not the surface winds. It would be winds at 950mb. To convert to estimated surface winds I usually reduce that amount by 20% and it will give approximate surface level winds. In this case roughly 100 knots. (still laughable at the moment)



Actually if the storm were anywhere near 130 kts, 950 mb would be higher than the surface pressure. It'd probably be closer to 930 or even 920.
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Once again the morning bustcasters are out in full force, claiming the season is over. Why not wait until November 30th gang?
Member Since: June 30, 2013 Posts: 11 Comments: 7700
2393. TampaSpin Manatee Hurricanes Football
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Quoting 2350. Neapolitan:
I'd personally like us to go the rest of the year without any further named storms whatsoever. Now that would be something to see...

Assuming no storm will be named by midnight, 2013 will be six storms behind 2012 and 1995, and seven storms behind 2011 and 2005, by the end of the day. ACE-wise, the current tally of eight is fewer than half that of the 1983 season, which featured the lowest ACE (17) in the years from 1950 through 2012. However, while that season saw only four storms form, three of those were hurricanes, and one (August's Alicia) went on to become a major. IOW, the odds are increasingly favoring a historically low accumulation of ACE this year (though it should of course be noted that a single large and/or longlasting storm could quickly banish that possibility). (To put things in perspective, 2013's current ACE is just 3.23% of 2005's final tally.)

2013

2013


nice graphs
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Morning...Invest 97L looks like it wants to kick a winning field goal, but if it kicks its getting blocked from the front and tripped by the referee from the back. Might wanna take a long pass thru the Caribbean as the better call!
Member Since: September 2, 2007 Posts: 178 Comments: 20439
2392. Skyepony (Mod)
Quoting 2352. WoodyFL:



I believe on that model, 134 knots is not the surface winds. It would be winds at 950mb. To convert to estimated surface winds I usually reduce that amount by 20% and it will give approximate surface level winds. In this case roughly 100 knots. (still laughable at the moment)


134kts is roughly a 930mb storm at the surface.
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Quoting 2388. Autistic2:


6-0-0 on sept 2 with no development in sight = BUST

Time to start the smoker...got some beef brisket :)

???
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Unless 97L gets stronger in a hurry, I don't see how it could go that for north as to what the models are showing, can't be right? imo
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Quoting 2384. fldude99:
Who wouldn't be rooting for a record? When it comes down to it, does ANYBODY really want to see a hurricane? If they didn't exist it would be fine for me and millions of others.
That's cool, but you're not the one pursuing a spot as a hurricane specialist, forecaster, or storm chaser.
Member Since: June 30, 2013 Posts: 11 Comments: 7700
Quoting 2254. IKE:
LOL....they lowered the odds. Watched pot never boils. The incredible season rocks on.....

6-0-0.

NOTE: I thought they might raise the odds to 50% and 60%.


6-0-0 on sept 2 with no development in sight = BUST

Time to start the smoker...got some beef brisket :)
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This is from Jason CWG

Jason-CapitalWeatherGang
9:39 AM EDT
it's been an extremely quiet weather pattern this August and now Sept...no hurricanes to track and minimal t'storm activity. Today we've got the storm chance though...
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2386. WoodyFL
97L

Member Since: April 24, 2011 Posts: 1 Comments: 601
Quoting 2351. IKE:
Strip-tease taking place east of the islands.....


If that can become one, this will be one big storm.
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Who wouldn't be rooting for a record? When it comes down to it, does ANYBODY really want to see a hurricane? If they didn't exist it would be fine for me and millions of others.
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Is that a good thing or a bad thing for the storm not moving at all?
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It looks like models are continuing to shift 97L's path north (TVCA now takes it over western PR rather than Hispaniola)...



...Even though they have backed way off on intensity, which usually implies a more westward moving storm:

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So it has moved a degree south?
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Quoting hurricanewatcher61:
Why is this storm, if you want to call it that, not moving at all?
More tan 24 hore without any movement what so ever...
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By the way look at the last 2 positions, according to DVORAK estimates.

20130902 1145 14.3 59.4

20130902 0545 14.2 59.5

Link
Member Since: June 30, 2013 Posts: 11 Comments: 7700
Couple of things not there yesterday with 97l.

Convergence


upper vorticity


Still has lower vorticity elongated, with another elongated meeting up with it.



Summary: better today, has work to do yet.
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2376. WoodyFL
Quoting 2360. hurricanes2018:
maybe invest 98L SOON




Isn't this the wave the NHC was talking about 5 days ago and mentioned in Docs blog?

Member Since: April 24, 2011 Posts: 1 Comments: 601
97L goes from looking like a chicken breat to a chicken nugget!.What?
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It's like baseball, 97L waiting for that relief pitcher/storm to the east, to make it a better game!
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I couldn't get a decent pic of Dex this morning, so here's one from about a month after we got him. It's one of my favorites.


Dexter's favorite things: Mom, Ball, Nap!

Have a great Labor Day everyone, and don't work too hard - you know Dex won't!
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2372. yoboi
Quoting 2357. washingtonian115:
I actually saw a season like this coming..I posted this last year..

"2012 is now tied with 011,and 010 xD how ironic.We've been spoiled and when a season like 2009 comes back around I wonder how this blog will react! But I never thought It'll be this year..


2 more weeks and things will get going....:)
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Quoting 2358. SLU:
DMIN killed 97L. It now has to start all over again ....

Good morning everyone I see the tropical wave is continuing to catch up to 97L and that 97L hasn't moved much from earlier this morning, interesting things at play here, still a large system that may take some time to get its act together.

Member Since: June 30, 2013 Posts: 11 Comments: 7700
Can the models really do much till we actually have a storm? Not really, but which one will be right?
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Quoting 2367. IKE:
I'm rooting for the record too. Also...prove the experts wrong on their pre-season bust cast.
watch this tropical wave
Member Since: March 12, 2013 Posts: 8 Comments: 13908
HERE IS very nice spin to this tropical wave and still got t.storms and rain with it and its south to
Member Since: March 12, 2013 Posts: 8 Comments: 13908
2367. IKE
I'm rooting for the record too. Also...prove the experts wrong on their pre-season bust cast.
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2366. ncstorm
6z GFS Ensembles

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Good morning, afternoon and evening, everyone. 73 degrees and the garden is watered. Possible rain on Tuesday, but not a very good chance so odds are I'll be out there watering.

Breakfast's on the sideboard: Corn Waffles With Cajun Vegetables and Shrimp, whole wheat English muffins with poached egg whites, low fat cheese, ham, tomato and sauce, whole wheat pancakes with fruit sauce, egg burritos with cheese and chorizo, eggs and hash brown, Scrambled Eggs With Ricotta and Broccolini, cheese Danishes, yogurt, fresh fruit and orange, apple or pineapple juice. Enjoy!
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Quoting 2291. CybrTeddy:
LMAO HWRF. 134kts.
must be a typo.
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Quoting 2354. hurricanes2018:
I'd say that you maybe right, that is fi a disturbance forms right in front of 97L, if not, it ill be anYucatan or Louisiana storm.
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Quoting 2358. SLU:
DMIN killed 97L. It now has to start all over again ....



Wave behind is larger and can steel the energy from 97L. Any observations from the islands about wind direction?
Member Since: April 29, 2009 Posts: 75 Comments: 14076
Quoting 2358. SLU:
DMIN killed 97L. It now has to start all over again ....



DMin is a pest, I hate it. But our system STILL looks very interesting.
Member Since: October 6, 2007 Posts: 0 Comments: 6028
maybe invest 98L SOON
Member Since: March 12, 2013 Posts: 8 Comments: 13908
HMMMM strange the models want to make this storm go more east does this look at likely to happpen cuz i dont see that happening.
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2358. SLU
DMIN killed 97L. It now has to start all over again ....

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I actually saw a season like this coming..I posted this last year..

"2012 is now tied with 011,and 010 xD how ironic.We've been spoiled and when a season like 2009 comes back around I wonder how this blog will react! But I never thought It'll be this year..
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2356. ncstorm
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Oye...

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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.

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