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: 2155 - 2105

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 2148. 954FtLCane:

any back door cold fronts possibly moving n towards the middle of the week moving in? I remember someone posting a graphic earlier today that showed high pressure moving in from the NE down towards the Ohio Valley and continue the same trek. I'm checking to see if thats the case.


Even if there were, that doesn't explain the immediate west-northwest to northwest motion being forecast by the 6z dynamical consensus. Satellite images clearly depict the wave axis to be centered around 14N 57W, moving due west. It's easy to spot on shortwave infrared images, even if it's not the most well-defined axis in the world.

What they're projecting literally makes no sense. And if their forecast for the initial motion is off (which it is -- badly), the entire forecast will be off in the extended range.
Member Since: Posts: Comments:
Quoting 2153. KoritheMan:


Fizzle?

no not fizzle
Member Since: Posts: Comments:
Quoting 2151. Stormchaser121:

I have a pretty good idea of what this will do...but im not saying just yet.


Fizzle?
Member Since: Posts: Comments:
Quoting 2150. daddyjames:


Ask beeli - I'm trying to get into costume here :)

Have a good night all. We'll see - but don't you think that it is odd that it has averaged a westward motion of 5 mph for the past 12 hours? What's stopping it from going into the Caribbean? Just asking.


Nothing. It's also not unusual for a model consensus to undergo consistent and erratic shifts for a system lacking no well-defined center. And that's not even factoring in the tug o war Hispaniola likes to cause.
Member Since: Posts: Comments:
Quoting 2140. KoritheMan:


I don't understand the reason for this, and I... don't think it's going to happen. And it's not because I want 97L to reach me either, before anybody says anything, XD.

But I mean, what's causing this? Increasing influence from the upper low over eastern Haiti? The 850 mb does not support such a poleward bend.



I mean seriously, Puerto Rico? 97L is way too far south to feel that weakness south of Bermuda. In addition, the trough over the western Atlantic, if there is one, is very weak. There is an upper low trailing a cold front near Toronto, but the upper support appears locked in too far north to allow for a significant southward propagation of the associated shortwave.

I would really expect some westward shifts in the guidance today, especially since 97L is not likely to develop anytime soon.

I have a pretty good idea of what this will do...but im not saying just yet.
Member Since: Posts: Comments:
Quoting 2146. KoritheMan:


What weakness? This is at the 500 mb level:



Again, there is clearly a weakness, but it's situated all the way at 26N 60W. How in the world is 97L going to feel that even remotely?


Ask beeli - I'm trying to get into costume here :)

Have a good night all. We'll see - but don't you think that it is odd that it has averaged a westward motion of 5 mph for the past 12 hours? What's stopping it from going into the Caribbean? Just asking.
Member Since: Posts: Comments:
Quoting 2146. KoritheMan:


What weakness? This is at the 500 mb level:



Again, there is clearly a weakness, but it's situated all the way at 26N 60W. How in the world is 97L going to feel that even remotely?

Even with the way it is right now. That is not happening at all.
Member Since: Posts: Comments:
Quoting 2140. KoritheMan:


I don't understand the reason for this, and I... don't think it's going to happen. And it's not because I want 97L to reach me either, before anybody says anything, XD.

But I mean, what's causing this? Increasing influence from the upper low over eastern Haiti? The 850 mb does not support such a poleward bend.



I mean seriously, Puerto Rico? 97L is way too far south to feel that weakness south of Bermuda. In addition, the trough over the western Atlantic, if there is one, is very weak. There is an upper low trailing a cold front near Toronto, but the upper support appears locked in too far north to allow for a significant southward propagation of the associated shortwave.

I would really expect some westward shifts in the guidance today, especially since 97L is not likely to develop anytime soon.

any back door cold fronts possibly moving n towards the middle of the week moving in? I remember someone posting a graphic earlier today that showed high pressure moving in from the NE down towards the Ohio Valley and continue the same trek. I'm checking to see if thats the case.
Member Since: September 30, 2008 Posts: 0 Comments: 108
2147. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #11
Gale Warning
TROPICAL STORM YUTU (T1316)
15:00 PM JST September 2 2013
==============================

Midway Island Waters

At 6:00 AM UTC, Tropical Storm Yutu (1004 hPa) located at 33.6N 177.3E has 10 minute sustained winds of 35 knots with gusts of 50 knots. The cyclone is reported as almost stationary.

Gale Force Winds
=================
180 NM from the center in southeast quadrant
120 NM from the center in northwest quadrant

Dvorak Intensity: T2.5

Forecast and Intensity
========================
24 HRS: 34.1N 178.5E - 35 knots (CAT 1/Tropical Storm) Midway Island Waters
48 HRS: 34.0N 179.8W - 35 knots (CAT 1/Tropical Storm) Midway Island Waters
72 HRS: 33.8N 178.4W - Tropical Depression In Midway Island Waters

Japan Meteorological Agency
Tropical Cyclone Advisory #13
Gale Warning
TROPICAL STORM TORAJI (T1317)
15:00 PM JST September 2 2013
==============================

Near Okinawa Island

At 6:00 AM UTC, Tropical Storm Toraji (996 hPa) located at 27.2N 126.1E has 10 minute sustained winds of 40 knots with gusts of 60 knots. The cyclone is reported as moving northeast at 8 knots.

Gale Force Winds
===============
100 NM from the center

Dvorak Intensity: T2.5

Forecast and Intensity
========================
24 HRS: 28.4N 126.9E - 40 knots (CAT 1/Tropical Storm) Amami Islands
48 HRS: 29.2N 127.3E - 45 knots (CAT 1/Tropical Storm) East China Sea
72 HRS: 29.8N 127.4E - 45 knots (CAT 1/Tropical Storm) East China Sea
Member Since: Posts: Comments:
Quoting 2143. daddyjames:
beeli pointed out a weakness in the ridge to the north at the 500 mb level earlier. Maybe that is what is tugging it to the north?

Anyways, I was unsuccessful on the first tooth fairy attempt - attempt number two will be underway soon. otherwise, the tooth fairy ain't coming tonight!



What weakness? This is at the 500 mb level:



Again, there is clearly a weakness, but it's situated all the way at 26N 60W. How in the world is 97L going to feel that even remotely?
Member Since: Posts: Comments:
EP, 11, 2013090206, , BEST, 0, 226N, 1162W, 35, 1005, TS, 34, NEQ, 50, 40, 0, 40, 1010, 125, 20, 0, 0, E, 0, , 0, 0, KIKO, S,
Member Since: Posts: Comments:
This is one instance where I feel it's better to use your eyes rather than the models. Besides, we don't even have a well-defined center yet.
Member Since: Posts: Comments:
beeli pointed out a weakness in the ridge to the north at the 500 mb level earlier. Maybe that is what is tugging it to the north?

Anyways, I was unsuccessful on the first tooth fairy attempt - attempt number two will be underway soon. otherwise, the tooth fairy ain't coming tonight!

Member Since: Posts: Comments:
Quoting 2139. IKE:

True. Back to sleep for me.

did you see that what new MODELS say!
Member Since: Posts: Comments:
Quoting 2140. KoritheMan:


I don't understand the reason for this, and I... don't think it's going to happen. And it's not because I want 97L to reach me either, before anybody says anything, XD.

But I mean, what's causing this? Increasing influence from the upper low over eastern Haiti? The 850 mb does not support such a poleward bend.



I mean seriously, Puerto Rico? 97L is way too far south to feel that weakness south of Bermuda. In addition, the trough over the western Atlantic, if there is one, is very weak. There is an upper low trailing a cold front near Toronto, but this the upper support appears locked in too far north to allow for a significant southward propagation of the associated shortwave.

I would really expect some westward shifts today, especially since 97L is not likely to develop anytime soon.

Thank you
Member Since: Posts: Comments:


I don't understand the reason for this, and I... don't think it's going to happen. And it's not because I want 97L to reach me either, before anybody says anything, XD.

But I mean, what's causing this? Increasing influence from the upper low over eastern Haiti? The 850 mb does not support such a poleward bend.



I mean seriously, Puerto Rico? 97L is way too far south to feel that weakness south of Bermuda. In addition, the trough over the western Atlantic, if there is one, is very weak. There is an upper low trailing a cold front near Toronto, but the upper support appears locked in too far north to allow for a significant southward propagation of the associated shortwave.

I would really expect some westward shifts in the guidance today, especially since 97L is not likely to develop anytime soon.
Member Since: Posts: Comments:
2139. IKE

Quoting 954FtLCane:

LOL.... not the type of record many that visit this website are clamoring for.
True. Back to sleep for me.
Member Since: Posts: Comments:
Quoting 2135. IKE:

Yeah it does....lol. 00Z ECMWF.....no canes through Sept. 12th.....breaking the record.

LOL.... not the type of record many that visit this website are clamoring for.
Member Since: September 30, 2008 Posts: 0 Comments: 108
Quoting 2131. IKE:
i just died in your arms tonight.....




The "center" is that light grey patch o' low level clouds just north of where the convection is flaring up - just north of Barbados. Looks like its doing the right thing. Putting up cloud tops around the llc.

And on that note - I have to go play tooth fairy, then I am off to bed.
Member Since: Posts: Comments:
2136. JRRP
ups

see you tomorrow... or later... what ever
Member Since: August 16, 2007 Posts: 0 Comments: 5482
2135. IKE

Quoting JRRP:

mmmmmm that image looks like a face
Yeah it does....lol. 00Z ECMWF.....no canes through Sept. 12th.....breaking the record.
Member Since: Posts: Comments:
2134. JRRP
Quoting IKE:
i just died in your arms tonight.....



mmmmmm that image looks like a face
Member Since: August 16, 2007 Posts: 0 Comments: 5482
Quoting 2127. Civicane49:
Track guidance has shifted more northward.


Then it will shift southwards then northwards and then southwards again it's been doing the same thing
Member Since: Posts: Comments:
Quoting 2127. Civicane49:
Track guidance has shifted more northward.

Still a messy situation, until we get a discernible center the models will keep flip-flopping back and forth.
Member Since: June 30, 2013 Posts: 11 Comments: 7698
2131. IKE
i just died in your arms tonight.....


Member Since: Posts: Comments:
Quoting 2128. Gearsts:
Wave behind catching up


So, does this mean that another episode of "Would the real invest, please stand up?" is going to play out on the blog for the next 3-5 days?

Much like the great 92L debates that still are unresolved.
Member Since: Posts: Comments:
2129. JLPR2
So far the refire is small and weak, the popcorn convection that is supposed to be happening over 97L is occurring farther east in the intersection between the TW at 50W and 97L.



Well that's it for me, I'm out, goodnight all!
Member Since: Posts: Comments:
2128. Gearsts
Wave behind catching up
Member Since: Posts: Comments:
Track guidance has shifted more northward.

Member Since: Posts: Comments:
Quoting 2124. wunderkidcayman:
NHC has it moving more W bound S of Haiti and ESE of Jamaica in 72hrs





Center is currently placed at 14N - so a W/NW track seems pretty evident. By the time it gets there, should be moving more NW than West.
Member Since: Posts: Comments:
Quoting 2123. daddyjames:


Betcha they draw straws! Then notice that the guy with the most unsteady hands wins the first round, and decide that was the elimination round . . . ;)


Can you imagine the stress these workers will be working under?

Added - I am out for the night. Everyone stay safe and may your weather be whatever you wish it to be.
Member Since: Posts: Comments:
NHC has it moving more W bound S of Haiti and ESE of Jamaica in 72hrs



Member Since: Posts: Comments:
Quoting 2121. Some1Has2BtheRookie:


Yes, they have to move 1,300 fuel rods, just from cooling pond #4, and without a single mishap. One rod at a time. #4 cooling pond contains some MOX rods as well. This has always been performed with the aid of computers and a special crane. The computer held the data concerning all of the information on rods. What type of rod it is, its exact location and proximity to any other rods and how long the rod has been in the cooling pond. The computer, crane and complete data for each rod no longer exists. This all has to be done manually and without knowing the condition and position of each rod. ... Fun stuff.


Betcha they draw straws! Then notice that the guy with the most unsteady hands wins the first round, and decide that was the elimination round . . . ;)
Member Since: Posts: Comments:
Quoting 2117. wunderkidcayman:

I ain't buyin it nor is the NHC

???

What do you mean? NHC has it moving now to the W/NW at 10 kts, and bringing it over the greater Antilles by Tues-Thurs (it certainly is not going anywhere fast). The NHC has said this in the past two TWDATs.
Member Since: Posts: Comments:
Quoting 2111. daddyjames:


Yes, I know. Was reading (perhaps your posts) about the fact that they have to move the rods manually - and if they happen to drop one . . . "ooops!" would be the understatement of the new millennium.

Like I said, you gotta feel for those guys working on site.


Yes, they have to move 1,300 fuel rods, just from cooling pond #4, and without a single mishap. One rod at a time. #4 cooling pond contains some MOX rods as well. This has always been performed with the aid of computers and a special crane. The computer held the data concerning all of the information on rods. What type of rod it is, its exact location and proximity to any other rods and how long the rod has been in the cooling pond. The computer, crane and complete data for each rod no longer exists. This all has to be done manually and without knowing the condition and position of each rod. ... Fun stuff.
Member Since: Posts: Comments:
2120. JRRP
Member Since: August 16, 2007 Posts: 0 Comments: 5482
Member Since: June 30, 2013 Posts: 11 Comments: 7698
LGEM and SHIPS a little lighter on the intensity this time around.

V (KT) LAND 30 32 35 39 44 54 64 74 82 88 74 83 82
V (KT) LGE mod 30 31 33 36 39 47 59 72 87 101 87 102 104
Member Since: Posts: Comments:
Quoting 2113. MiamiHurricanes09:
Can't say I'm buying the new more northerly track forecasts...unless the circulation is able to consolidate a lot further north than anticipated.

I ain't buyin it nor is the NHC
Member Since: Posts: Comments:
Quoting 2112. Civicane49:
AL, 97, 2013090206, , BEST, 0, 140N, 597W, 30, 1008, DB, 34, NEQ, 0, 0, 0, 0, 1011, 200, 70, 0, 0, L, 0, , 0, 0, INVEST, M,
Interesting they relocated the "center" to about 50-75 miles north of Barbados.
Member Since: June 30, 2013 Posts: 11 Comments: 7698
2115. JRRP
Member Since: August 16, 2007 Posts: 0 Comments: 5482
2114. JRRP
06 GMT 09/2/13 14.0N 59.7W 30 1008 Invest
Member Since: August 16, 2007 Posts: 0 Comments: 5482
Can't say I'm buying the new more northerly track forecasts...unless the circulation is able to consolidate a lot further north than anticipated.
Member Since: Posts: Comments:
AL, 97, 2013090206, , BEST, 0, 140N, 597W, 30, 1008, DB, 34, NEQ, 0, 0, 0, 0, 1011, 200, 70, 0, 0, L, 0, , 0, 0, INVEST, M,
Member Since: Posts: Comments:
Quoting 2109. Some1Has2BtheRookie:


I had heard the same that the current level of radiation being leaked would prove lethal to anyone directly exposed for 4 hours.

The plume crossing the Pacific will be highly diluted, I would guess, by the time it gets to the west coast here. The accumulative effect from continued leaks would be my concern.

Should there be an open air nuclear reaction of the fuel rods from one of the cooling ponds happened, then all bets are off. There is no way to stop an open air nuclear reaction from the fuel rods. It would continue no matter what efforts we tried to stop it. ... and the MOX is some bad stuff when not controlled.


Yes, I know. Was reading (perhaps your posts) about the fact that they have to move the rods manually - and if they happen to drop one . . . "ooops!" would be the understatement of the new millennium.

Like I said, you gotta feel for those guys working on site.
Member Since: Posts: Comments:
00z UKMET: over Puerto Rico in 3 days.

Member Since: Posts: Comments:
Quoting 2100. daddyjames:


I thought that the levels at Fukishima were lethal if exposed for 4 hours. That coming to the US is not lethal thugh, correct?


I had heard the same that the current level of radiation being leaked would prove lethal to anyone directly exposed for 4 hours.

The plume crossing the Pacific will be highly diluted, I would guess, by the time it gets to the west coast here. The accumulative effect from continued leaks would be my concern.

Should there be an open air nuclear reaction of the fuel rods from one of the cooling ponds happened, then all bets are off. There is no way to stop an open air nuclear reaction from the fuel rods. It would continue no matter what efforts we tried to stop it. ... and the MOX is some bad stuff when not controlled.
Member Since: Posts: Comments:
Quoting 2106. Tribucanes:
Fukishima news was very disturbing. Makes you wonder how they missed levels of radiation were 18 times higher than they thought. Hard to believe it was an oversight. Experts say Pacific will dilute the water coming to non-toxic levels. That's what their saying at least. The fact that you hear so little on what is happening there is not a good sign.


Readings were from one of the holding tanks they had to construct to hold the contaminated water. I don't think those are readings they have gotten from water leaking into the ground/ocean. But who knows. Gotta feel for those guys working on the site.
Member Since: Posts: Comments:
Quoting 2105. scottsvb:

Nope...need persistant convection for 18-24hrs


OK - then in the afternoon :)
Member Since: Posts: Comments:
Fukishima news was very disturbing. Makes you wonder how they missed levels of radiation were 18 times higher than they thought. Hard to believe it was an oversight. Experts say Pacific will dilute the water coming to non-toxic levels. That's what their saying at least. The fact that you hear so little on what is happening there is not a good sign.
Member Since: Posts: Comments:
Quoting 2095. daddyjames:
Interestingly enough, if I am reading this correctly, the NHC has 34 kt winds in the Northeast Quadrant. If I am not reading it correctly, let me know.

We could have a TD in the morning - if the convection picks up.

Center fix is still south at 14N

AL, 97, 2013090200, , BEST, 0, 140N, 607W, 30, 1008, LO, 34, NEQ, 0, 0, 0, 0, 1011, 200, 70, 0, 0, L, 0, , 0, 0, INVEST, M,

Nope...need persistant convection for 18-24hrs
Member Since: Posts: Comments:

Viewing: 2155 - 2105

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.