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: 1655 - 1605

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

Quoting 1622. wunderkidcayman:

Well it's been a while that Florida had anything catastrophic so it could be a good thing not that anything catastrophic is good but it's a good way to see if the state of Florida is prepared for a strong hurricane it's been a wile and I bet some people have become laid back
the issue is we have had a very very wet season here and we are having major issues with lake Okeechobee's levee which can breech with any tropical system at this point , they have been lowering the lake thus far and that has been causing catastrophic algae blooms on both coasts.
Member Since: Posts: Comments:
1654. JLPR2
Quoting 1645. ncstorm:
CMC, HWRF and GFDL are all calling for hurricane..CMC and HWRF calling for a major..



I guess these models made a club and didn't invite the GFS and the EURO. LOL!
Member Since: Posts: Comments:
Quoting 1651. RGVtropicalWx13:
Btw did we not forget about the nw Caribbean wave that's expected to move across the Yucatan and into the Boc? It does have a 20% chance after 48 hrs. If you don't keep an eye on it then I'll surprise a lot of all.



its heading for mx
Member Since: May 21, 2006 Posts: 5091 Comments: 115456
My take on this is: it's going to be a problem almost no matter what.

The worst (in the sense for the storm itself) it could do is just completely disintegrate into nothing. And that almost certainly is not going to happen.

It already seems to have a chance of getting into the Gulf, and if it takes longer to develop and stays weaker there may be more of a chance of that.

And then something tells me that once it becomes a tropical depression or above, it will start to increase in forward speed, because it ain't movin much now!!

2013 may just be one of those years like 1965 or 1975 where we just have one or two major hurricanes that significantly impact land somewhere.
Member Since: Posts: Comments:
Btw did we not forget about the nw Caribbean wave that's expected to move across the Yucatan and into the Boc? It does have a 20% chance after 48 hrs. If you don't keep an eye on it then I'll surprise a lot of all.
Member Since: Posts: Comments:
1650. Skyepony (Mod)
Average model error for 97L recap.. ave error (nm or kts) 0hr & 24hr..

Forecast track top performers..
GFDL 22.2 13.1
AEMN 28.1 21.2
CMC 24.7 34.8

Intensity Top Performers..
DSHP 0 1.7
SHIP 0 1.7
IVCN 0 2.0
LGEM 0 1.7
Member Since: Posts: Comments:
Quoting 1645. ncstorm:
CMC, HWRF and GFDL are all calling for hurricanes..CMC and HWRF calling for a major..


Unreliable models when a system does not have a definitive COC. None of that is going to happen!!
Member Since: Posts: Comments:
LOL.I see if your not predicting doom and gloom from this storm your opinion is looked down on.lol.Well I'm out.
Member Since: Posts: Comments:
1647. xcool
good job cmc imo lol
Member Since: Posts: Comments:
Quoting 1623. Relix:
Shear is hitting 97L hard (from the north) but the system seems stalled and the Low center could be father east than the best track.

Oh yeah 97L is getting pounded by very light shear oh I wonder how its to survive the very light shear lol good joke Relix
Member Since: Posts: Comments:
1645. ncstorm
CMC, HWRF and GFDL are all calling for hurricane..CMC and HWRF calling for a major..

Member Since: August 19, 2006 Posts: 13 Comments: 16225
Quoting 1608. wunderkidcayman:
Looking at the steering flow
I expect 97L to continue on a W-WSW course until 65W then W until 75W then a WNW and then NW when it nears 80W

What a mess.This blog is really crazy.
Member Since: Posts: Comments:
1643. beell
Quoting 1629. wunderkidcayman:


Or maybe it's just dying convection due to D-Min


Could very well be. 8PM TWO made a mention of dry mid-level air. Maybe I'm looking too hard for it, lol.
Member Since: Posts: Comments:
1642. JRRP
?
Member Since: August 16, 2007 Posts: 0 Comments: 6213
1641. JLPR2
Moisture from the TW to the east is getting awfully close to 97L. It might try to steal some energy from it or if it stays east of 60W a while longer (like it did all day today) we could see a merger.

I remember Hurricane Alex in 2010 ate another wave. That was interesting to watch.

Member Since: Posts: Comments:
Quoting 1626. xcool:



00z consensus
If this system was a Hurricane or Tropical Storm,I would be worried about this consensus of models.However being a relative weak low pressure area.These models are a joke at this time.
Member Since: Posts: Comments:
Quoting 1626. xcool:



00z consensus

Lets see what the next couple of runs show

Quoting 1628. Bluestorm5:
Guys, storm do not have to develops in Central or East Caribbean to be bad... Wilma didn't develops until West Caribbean...


Oh yeah I remember this one really good cause some really bad weather here in Cayman
Member Since: Posts: Comments:
Quoting 1623. Relix:
Shear is hitting 97L hard (from the north) but the system seems stalled and the Low center could be father east than the best track.

Explain?


I don't see much shear, and if there is, it's definitely not from the North.
Member Since: Posts: Comments:
Quoting 1632. Bluestorm5:
Actually, all computer models keep it weak. Strength and conditions models are the one keeping it strong.
I was referring to the LGEM and the HWRF what ever it's called..
Member Since: Posts: Comments:
Quoting 1623. Relix:
Shear is hitting 97L hard (from the north) but the system seems stalled and the Low center could be father east than the best track.


Correct
Member Since: Posts: Comments:
Shear hitting 97L hard from the north..Like where? Anticyclone on top of it though.
Member Since: Posts: Comments:
1634. ncstorm
18z Ensembles..

Member Since: August 19, 2006 Posts: 13 Comments: 16225
Quoting 1621. beell:
Maybe some evidence of mid-level dry air between 500-600 mb on the RGB. Could just be a coincidence or a short-term oddity. Some dry-ish mid-level westerlies on the evening sounding from Barbados


(click for loop)


(click to open loop in new window

The system is presently being sheared by unfavorable west winds pumping in dry air at the mid levels. Nothing here!
Member Since: Posts: Comments:
Quoting 1624. washingtonian115:
Let's be open minded here..Just because a person doesn't see this turning into the next cat 6 errr Katrina/Great Galveston hurricane doesn't mean their opinions don't manner..I don't trust those models they have been known to hype..
Actually, all computer models keep it weak. Strength and conditions models are the one keeping it strong.
Member Since: August 1, 2011 Posts: 28 Comments: 8075
Could Lake O handle a hurricane if these models were become true?
Member Since: Posts: Comments:
Quoting 1620. Stormchaser121:
I pretty much have a good idea what AL97 is gonna do but im not gonna say what it is yet.


lol why??
Member Since: Posts: Comments:
Quoting 1621. beell:
Maybe some evidence of mid-level dry air between 500-600 mb on the RGB. Could just be a coincidence or a short-term oddity. Some dry-ish mid-level westerlies on the evening sounding from Barbados


(click for loop)


(click to open loop in new window


Or maybe it's just dying convection due to D-Min
Member Since: Posts: Comments:
Guys, storm do not have to develops in Central or East Caribbean to be bad... Wilma didn't develops until West Caribbean...

Member Since: August 1, 2011 Posts: 28 Comments: 8075
Quoting 1617. allancalderini:
It actually its worse for a major to hit Haiti as there core is severly disrupt compare to a ts.Usually when a major hits DR or Haiti it never restablish itself again.
Georges, David, and Cleo, I mean I know they weakened but still stayed intact to cause major damage in the states?
Member Since: June 30, 2013 Posts: 12 Comments: 8774
1626. xcool



00z consensus
Member Since: Posts: Comments:
Quoting 1593. CaribBoy:
97L is and will stay east of the Lesser Antilles for a while
Why? 97L likes the french islands nearby? Maybe is on vacation. What is you reasoning for that?
Member Since: Posts: Comments:
Let's be open minded here..Just because a person doesn't see this turning into the next cat 6 errr Katrina/Great Galveston hurricane doesn't mean their opinions don't manner..I don't trust those models they have been known to hype..
Member Since: Posts: Comments:
1623. Relix
Shear is hitting 97L hard (from the north) but the system seems stalled and the Low center could be father east than the best track.
Member Since: Posts: Comments:
Quoting 1609. Seflhurricane:
If the models were occur this will be a Tropical system that South Florida needs to monitor models bring 97L as a strong hurricane which would be catastrophic for south florida

Well it's been a while that Florida had anything catastrophic so it could be a good thing not that anything catastrophic is good but it's a good way to see if the state of Florida is prepared for a strong hurricane it's been a wile and I bet some people have become laid back
Member Since: Posts: Comments:
1621. beell
Maybe some evidence of mid-level dry air between 500-600 mb on the RGB. Could just be a coincidence or a short-term oddity. Some dry-ish mid-level westerlies on the evening sounding from Barbados


(click for loop)


(click to open loop in new window
Member Since: Posts: Comments:
I pretty much have a good idea what AL97 is gonna do but im not gonna say what it is yet.
Member Since: Posts: Comments:
Quoting 1614. TropicalAnalystwx13:
As a person, I hope the GFS comes true and this moves into Hispaniola as a weak tropical wave. As a weather enthusiast, I hope this gets into the NW Caribbean and becomes a Category 5 hurricane. I'm going to be pretty upset if the former happens given how persistent the statistical models have been with a great environment farther west.
Be careful, the blog is bound to get their panties in a bunch over that lil' sentence. ;P
Member Since: Posts: Comments:
Quoting 1594. GTstormChaserCaleb:
And to add if this were to be a major hurricane going over the mountainous terrain of Hispaniola it would almost have little to no effect disrupting it completely, maybe knocking it down to a minimal hurricane or tropical storm, definitely one to watch as we head into this week as the models seem to want to move it fast.

You're getting ahead of yourself. 97L is NOT going to develop due to dry air in the vicinity, unfavorable winds it will be heading into and and whatever weak system it becomes it will likely get destroyed by the mountains of Hispanola. No worries here!
Member Since: Posts: Comments:
Quoting 1594. GTstormChaserCaleb:
And to add if this were to be a major hurricane going over the mountainous terrain of Hispaniola it would almost have little to no effect disrupting it completely, maybe knocking it down to a minimal hurricane or tropical storm, definitely one to watch as we head into this week as the models seem to want to move it fast.
It actually its worse for a major to hit Haiti as there core is severly disrupt compare to a ts.Usually when a major hits DR or Haiti it never restablish itself again.
Member Since: Posts: Comments:
Quoting 1609. Seflhurricane:
If the models were occur this will be a Tropical system that South Florida needs to monitor models bring 97L as a strong hurricane which would be catastrophic for south florida



don't for get any one living around lake O
Member Since: May 21, 2006 Posts: 5091 Comments: 115456
here we go again
Member Since: Posts: Comments:
As a person, I hope the GFS comes true and this moves into Hispaniola as a weak tropical wave. As a weather enthusiast, I hope this gets into the NW Caribbean and becomes a Category 5 hurricane. I'm going to be pretty upset if the former happens given how persistent the statistical models have been with a great environment farther west.
Member Since: Posts: Comments:
Quoting 1598. flsky:

Spin over Haiti??

Yeah ULL
Member Since: Posts: Comments:
Quoting 1598. flsky:

Spin over Haiti??

Upper Level Low.
Member Since: Posts: Comments:
Quoting 1606. sebastianflorida:
The wolf says to the 3 little piggies, "I'm going to huff and puff and blow your house down!"
Member Since: June 30, 2013 Posts: 12 Comments: 8774
Quoting 1603. GTstormChaserCaleb:
CCKW or TW moving towards 97L, the spark for this thing to take off that the models are seeing?


Maybe XD

And if this happens... guidance will change XD
Member Since: Posts: Comments:
If the models are true this will be a Tropical system that South Florida needs to monitor models bring 97L as a strong hurricane which would be catastrophic for south florida
Member Since: Posts: Comments:
Looking at the steering flow
I expect 97L to continue on a W-WSW course until 65W then W until 75W then a WNW and then NW when it nears 80W

Member Since: Posts: Comments:
My intuition has just spoken...
Member Since: Posts: Comments:
Quoting 1585. hurricanes2018:
Intensity models showing no signs of backing down.

LGEM forecasting a category 4, SHIPS forecasting a category 3.

V (KT) LAND 30 33 37 41 46 57 67 78 86 89 96 99 101
V (KT) LGE mod 30 31 33 36 40 49 63 78 94 106 114 115 113.. NO WAY!! I DO NOT SEE IT HAPPERN
Member Since: Posts: Comments:
Quoting 1559. farhaonhebrew:
no importa ' the name Hurricanes come from the spanish word Hurac�n...named by the western indians... so cual es el problema con hablar espa�ol..la mayoria de las islas y tierras afectadas son hispano parlantes..inclusive en la costa este de Estados Unidos..
Lee mis labios(Read my lips) Yo no dije eso (I don't said that) NO cambies lo que dije (Dont change what I said and stop thinking the wrong way,Entendiste? Did you understand my friend?
Member Since: Posts: Comments:

Viewing: 1655 - 1605

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.

JeffMasters's Recent Photos

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