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: 955 - 905

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 916. ncstorm:
Good Lord..where is Bobby McFerrin when you need him..
Now when u hear NCSTORM calling for Bobby McFerrin, u know it's bad...
Member Since: October 25, 2005 Posts: 19 Comments: 21537
Quoting 902. Abacosurf:
that radar imaging is from last month. It's broken now. If that makes you feel better. :)
I always find it hard to believe that the Bahamas has no working radar.
It's not that it's not working, it's just that it's not online... I hear through the grapevine that there were software issues...
Member Since: October 25, 2005 Posts: 19 Comments: 21537
Quoting 947. MiamiHurricanes09:
97L won't be classified until there's solid evidence that a closed surface circulation exists. Gonna have to wait for a good ASCAT pass of recon on Tuesday.


Actually I think it is more the iffy look to the convection which lacks the symmetry and sustainability one normally expects of a TD. There are lots of West winds to support a closed low.

The NHC would probably not wish to classify it and then have to deactivate within 12 to 18 hours if it fades away again like yesterday. Late tonight or tomorrow morning is the soonest I think we could expect an upgrade unless the satellite presentation improves.
Member Since: Posts: Comments:
Quoting 941. kmanislander:


No reason it should with steering like this. I think the center keeps reforming to the East as the convection is tail end loaded.



Very slow mover, just like I love them !!!!
Member Since: Posts: Comments:
Quoting 947. MiamiHurricanes09:
97L won't be classified until there's solid evidence that a closed surface circulation exists. Gonna have to wait for a good ASCAT pass of recon on Tuesday.

There's already more than solid evidence of a closed surface circulation, as shown by surface observations and an OSCAT pass from 1536z. The circulation is too broad to classified in my opinion. Convection needs some work as well.

Member Since: Posts: Comments:
Quoting 938. FOREX:


fish?





97L is not a fish storm all ready
Member Since: May 21, 2006 Posts: 5091 Comments: 114758
Quoting 897. Kowaliga:


I want to do all of the islands (big/small) if I ever get the $$$.
I agree... wish I had that kind of $$...
Member Since: October 25, 2005 Posts: 19 Comments: 21537
948. beell
Quoting 925. kmanislander:


The center still looks like 60W, almost as if every convective blow up keeps relocating it about a half to one degree East.


Agree. Best convergence appears to be along 58W. And every hour it tarries, upper level conditions may begin to improve farther west.
Member Since: Posts: Comments:
Quoting 934. all4hurricanes:
Barry was classified as a TD after having a 40% chance of development 3 hours prior. I think we'll need to wait until 11 at least before the NHC calls it
97L won't be classified until there's solid evidence that a closed surface circulation exists. Gonna have to wait for a good ASCAT pass or recon on Tuesday.
Member Since: Posts: Comments:
18z NAM at 60 hours
Member Since: Posts: Comments:
945. Mikla
Quoting 936. cchsweatherman:


I just said that not even 10 minutes ago. lol

lol... sorry for the repost... just jumped on after fixing the A/C in my kids car.

I was actually on the downcast side of 97L, but it looks like I was wrong... it appears to be coming together pretty quickly.
Member Since: Posts: Comments:
Quoting 938. FOREX:


fish?


Maybe it 'll be ejected northward like models said a few days ago........
Member Since: Posts: Comments:
I want to apologize to all of my friends.....I think the reason I may be single is that I stand my ground...Have always done that....If I am right I will let you know.....If I am wrong I will apologize. Sorry if I offended anyone .If I am right you will definitely know it.
Member Since: Posts: Comments:
Quoting 931. cchsweatherman:


What happened to the islands? lol
I removed them. :P
Member Since: Posts: Comments:
Quoting 933. CaribBoy:
97L HAS STALLED.


No reason it should with steering like this. I think the center keeps reforming to the East as the convection is tail end loaded.

Member Since: Posts: Comments:
You use to stand out and not support this kind of stuff.Now your just like the rest of them.
Member Since: Posts: Comments:
Quoting 927. CybrTeddy:


Almost looks like spiral banding is beginning to take place.
Especially towards the southeast where thunderstorms activity is developing atop the surface inflow.

It's fairing quite well thus far though, compared to what I was expecting anyways.
Member Since: Posts: Comments:
938. FOREX
Quoting 933. CaribBoy:
97L HAS STALLED.


fish?
Member Since: Posts: Comments:
97L looking better. looks less lopsided from east west to more of north south.
Member Since: Posts: Comments:
Quoting 932. Mikla:
Given how 97L is developing and proximity to land, I am surprised that no HH mission is scheduled until Tuesday (including a potential Global Hawk mission).


I just said that not even 10 minutes ago. lol
Member Since: Posts: Comments:
935. JRRP
i don't see 97L so well
Member Since: August 16, 2007 Posts: 0 Comments: 5478
Barry was classified as a TD after having a 40% chance of development 3 hours prior. I think we'll need to wait until 11 at least before the NHC calls it
Member Since: Posts: Comments:
97L HAS STALLED.
Member Since: Posts: Comments:
932. Mikla
Given how 97L is developing and proximity to land, I am surprised that no HH mission is scheduled until Tuesday (including a potential Global Hawk mission).
Member Since: Posts: Comments:
Quoting 924. MiamiHurricanes09:


What happened to the islands? lol
Member Since: Posts: Comments:
Quoting 919. HuracanTaino:
24 hours, straight to TS, only if "reckon" pay a visit to the system , that is...
I reckon recon will be there tomorrow...
Member Since: Posts: Comments:
TROPICAL STORM KIKO DISCUSSION NUMBER 8
NWS NATIONAL HURRICANE CENTER MIAMI FL EP112013
200 PM PDT SUN SEP 01 2013

SINCE THE PREVIOUS ADVISORY...THE SATELLITE APPEARANCE OF KIKO HAS
DEGRADED SIGNIFICANTLY. DEEP CONVECTION...WHAT LITTLE THERE IS THAT
REMAINS...IS LIMITED TO THE NORTHEASTERN QUADRANT. NEVERTHELESS...
KIKO REMAINS A SIGNIFICANT TROPICAL STORM BASED ON A 47-KT
SCATTEROMETER WIND REPORT FROM A 1653 UTC ASCAT OVERPASS. AS A
RESULT OF THE SCATTEROMETER DATA...THE INITIAL INTENSITY IS ONLY
BEING DECREASED TO 50 KT ON THIS ADVISORY.

THE INITIAL MOTION ESTIMATE IS 350/05 KT. THERE IS NO SIGNIFICANT
CHANGE TO THE PREVIOUS FORECAST TRACK OR REASONING. KIKO IS
EXPECTED TO CONTINUE MOVING NORTHWARD TODAY AND TONIGHT...AND
GRADUALLY SLOW AND TURN TOWARD THE NORTH-NORTHWEST ON MONDAY. AS
KIKO WEAKENS AND BECOMES A SHALLOW CIRCULATION...THE CYCLONE COULD
BECOME STATIONARY AS A REMNANT LOW ON TUESDAY AND WEDNESDAY. THE
NHC FORECAST TRACK IS JUST AN UPDATE OF THE PREVIOUS ADVISORY
TRACK...AND REMAINS CLOSE TO THE CONSENSUS MODEL TVCE.

KIKO IS BEGINNING TO MOVE ACROSS A TIGHT SST GRADIENT AND WILL BE
MOVING OVER SUB-26C OCEAN TEMPERATURES SHORTLY. IN ADDITION...
SATELLITE IMAGERY INDICATES THAT THE CYCLONE HAS STARTED TO INGEST
COOLER AND MORE STABLE AIR LOCATED TO ITS NORTH AND NORTHWEST. THE
COMBINATION OF THESE TWO UNFAVORABLE PARAMETERS IS EXPECTED TO
HASTEN THE WEAKENING OF KIKO OVER THE NEXT 48 HOURS...AND RESULT IN
A NON-CONVECTIVE REMNANT LOW BY 48 HOURS...IF NOT SOONER. THE
OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY...
AND FOLLOWS THE TREND OF THE SHIPS AND LGEM INTENSITY MODELS...
WHICH ARE FORECASTING DISSIPATION OF THE SYSTEM IN 48 AND 96
HOURS...RESPECTIVELY.

FORECAST POSITIONS AND MAX WINDS

INIT 01/2100Z 21.8N 115.7W 50 KT 60 MPH
12H 02/0600Z 22.5N 115.9W 40 KT 45 MPH
24H 02/1800Z 23.1N 116.0W 35 KT 40 MPH
36H 03/0600Z 23.5N 116.2W 25 KT 30 MPH
48H 03/1800Z 23.7N 116.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 04/1800Z 24.0N 116.4W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 05/1800Z...DISSIPATED

$$
FORECASTER STEWART
Member Since: July 21, 2011 Posts: 83 Comments: 7167
BULLETIN
TROPICAL STORM KIKO ADVISORY NUMBER 8
NWS NATIONAL HURRICANE CENTER MIAMI FL EP112013
200 PM PDT SUN SEP 01 2013

...KIKO WEAKENS AS IT MOVES SLOWLY NORTHWARD...


SUMMARY OF 200 PM PDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...21.8N 115.7W
ABOUT 380 MI...610 KM W OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H
PRESENT MOVEMENT...N OR 350 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...996 MB...29.41 INCHES
Member Since: July 21, 2011 Posts: 83 Comments: 7167
Quoting 924. MiamiHurricanes09:


Almost looks like spiral banding is beginning to take place.
Member Since: Posts: Comments:
Quoting 922. PalmBeachWeather:
Loved that song nc......1988 or so.....


As someone who is in and out of jail on here..let it go, dont do it on the main..take it to sensitivethug..you wont get banned there and can say what you really want..:)

admin will address you there..I know..
Member Since: August 19, 2006 Posts: 13 Comments: 14590
Quoting 915. beell:


The center still looks like 60W, almost as if every convective blow up keeps relocating it about a half to one degree East.
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Quoting 915. beell:
What d-min....
Member Since: Posts: Comments:
Quoting 916. ncstorm:
Good Lord..where is Bobby McFerrin when you need him..
Loved that song nc......1988 or so.....
Member Since: Posts: Comments:
Quoting 913. BahaHurican:
You are VERY late... where were you this AM????

lol

We're just glad it looks like it may get to be a TD.... lol
Off tending to the garden.It'll be getting cool soon and the sun has already started going down early.This can't be compared to Irene because she was already a 50mph disturbance by then.
Member Since: Posts: Comments:
I find it interesting, given the gradual development from Invest 97L, that the National Hurricane Center continues to maintain no flights scheduled until possibly Tuesday afternoon. Color me surprised on no changes to the flight plan as of yet.
Member Since: Posts: Comments:
Quoting K8eCane:




By Christmas, at which time I become known as CandyCane
24 hours, straight to TS, only if "reckon" pay a visit to the system , that is...
Member Since: Posts: Comments:
Quoting 776. Gearsts:
So is this thing moving?


I would say NO xd xd xd xd
Member Since: Posts: Comments:
Quoting 887. BrandenCordeiro:
Does anyone have an reccomendations on good accurate personal weather stations I could buy? I would prefer somethinh below $230...

Any suggestions thanks!
I have a Davis VantagePro2 as well.
In any price range though, I'd check with Rainmanweather.com
Not an endorsment but the owners are long-time members here and they take care of all concerns for other members.
Member Since: Posts: Comments:
Good Lord..where is Bobby McFerrin when you need him..
Member Since: August 19, 2006 Posts: 13 Comments: 14590
915. beell
Member Since: Posts: Comments:
18z at 45 hours - NAM
Member Since: Posts: Comments:
Quoting 878. washingtonian115:
So have the doom predictions of "this is going to be the next _____(Insert name here) major hurricane begun?.Have the doom predictions of a cat 5 running into the gulf started yet or am I ahead of the game?.
You are VERY late... where were you this AM????

lol

We're just glad it looks like it may get to be a TD.... lol
Member Since: October 25, 2005 Posts: 19 Comments: 21537
Quoting 860. Gearsts:
Is just going to keep developing convection the other way lol Is like wave is moving East.


Forecasters have no handle on the system... just saying. We saw crazy things in the past right at that location.
Member Since: Posts: Comments:
Quoting 888. ackee:
if 97L was to be upgrade to a TD/ TS when do u guys think this would happen ?

A 24 HOURS
B 48 HOURS
C 72 HOURS
D 96 HOURS
E 120 Hours

C
Member Since: Posts: Comments:
Quoting 906. PalmBeachWeather:
KEEPER>
I know just do me a favor keep it out of the main don't attack wab you have concearns address them too sens or her blog
Member Since: Posts: Comments:
909. L1990
i think this one is gonna cause a problem for someone
Member Since: Posts: Comments:
Quoting Relix:
97L is actually pulling it out. WOw. I am surprised. Should bring lots of rain to PR on Tuesday. Don't expect much from it but then again Irene made me swallow my words in 2011
If it continues moving at 8MPH, and strengthen, it might feel a weakness due to the TUTT NE of Hispaniola, moving more WNW, it might have time to pull an Irene in PR. doubted, but will see...
Member Since: Posts: Comments:
18z NAM at 42 hours
Member Since: Posts: Comments:
Quoting 884. KEEPEROFTHEGATE:
pbw if ya upset take it to this blog pls

iam being more than reasonable

Link
KEEPER.......I respect you , I really do... BUT, I do, and have always stood my ground when I thought I was wrongfully accused .... AND when I screw up with my stupid remarks or actions I have always apologized... In this case I will not....KEEPER, This is not about you and I have always respected you.
Member Since: Posts: Comments:
Quoting 901. K8eCane:




By Christmas, at which time I become known as CandyCane
Good one! Good sense of humor. :D
Member Since: June 30, 2013 Posts: 11 Comments: 7557

Viewing: 955 - 905

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.