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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1500 UTC maps are in. Low level vorticity has strengthened and remained almost stationary over the last 3 hours, allowing the main convection to get closer to being stacked on top of it. Upper divergence is extremely high, but lower convergence is only okay. An anticyclone is beginning to develop over the deepest convection, and shear is in the 10-20kt range over most of the invest. Lower level winds still support a closed but elongated circulation.
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Quoting 102. Hurricanes305:
Our system has now close off the gap where dry air was intruding cold cloud tops now south of the LLC. It has quickly improved structurally in the last 3 hours becoming more consolidated. While trying to get going a lot faster than the NHC is saying. I would raise the chances of development to at least 30% in the next 48 hours and 50% in the next 5 days.



In the meanwhile, tropical storm like conditions likely for the lesser Antilles tonight spreading into Monday.



hmm if 97L all ready has winds of a tropical storm that means if they upgrade it. it may go right two a TS
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Our system has now close off the gap where dry air was intruding cold cloud tops now south of the LLC. It has quickly improved structurally in the last 3 hours becoming more consolidated. While trying to get going a lot faster than the NHC is saying. I would raise the chances of development to at least 30% in the next 48 hours and 50% in the next 5 days.



In the meanwhile, tropical storm like conditions likely for the lesser Antilles tonight spreading into Monday.
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101. JRRP
Quoting hurricanes2018:
invest 97L WILL NOT be a fish storm!! its will hit land somewhere!

who say that
LoL
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Watch my thinking of the tropics:

Link
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GO TO A ZOOMED IN RGB OR VIS LOOP AND WATCH THE LOW LEVEL CLOUD DIRECTION AROUND BARBADOS....GOES FROM MOVING ALMOST DUE NORTH TO ALMOST DUE WESTERLY IN A MATTER OF FRAMES....COC IS DEFINITELY CONSOLIDATING TO THE EAST AROUND 15N,59W...
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Quoting 50. CaribBoy:


I'm gonna swim instead :)
Snap! was just thinking the same thing.. lol
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My tropical update video for today:

Link
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Quoting 78. Dakster:
I wonder what would happen if a Hurricane (Typhoon) hit the Fukushima site with all that radiation?

Especially since for some unknown reason the readings spiked to 2300 mSV/Hr... Considerng that at 70-100 mSV/HR is unhealthy for human contact, that seems quite high.

Link: http://www.cnn.com/2013/09/01/world/asia/japan-fuk ushima-radiation-spike/index.html?hpt=hp_t2

Link

P.S. No I do not want find out in real life either.
sat imagery would be interesting never seen a glow in the dark hurricane typhoon before

and i really don't want to see one in the future to be honest they have made a nice mess on there own mom don't need to help them out at all
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Quoting 90. hurricanes2018:
invest 97L WILL NOT be a fish storm!! its will hit land somewhere!


If it develops.
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Click for full size. ir 4 over visible.
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Any system that stays in the Caribbean for 7 days is a scary thing. I know most models don't forecast development and i'm not sure Shear will relax enough either....but its never good to see a system in the Caribbean that long as most will develop when moving that slow. This could very well be a GOM storm eventually.
Member Since: September 2, 2007 Posts: 178 Comments: 20439
Damage surveys (link) from August 29th's EF1 tornado show it was a weak and short-lived tornado that first touched down at 18:28. NWS Duluth released some good maps of the path and extent of damage, pasted below. Luckily the area is in the Chippewa National Forest (correction: and State Forests) and except for the side-swipe of Remer, MN, affected mostly rural and forested areas. It was on the ground about 13 miles over a half-hour.

A spotter was able to grab some great photos of the tornado, (link).









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invest 97L WILL NOT be a fish storm!! its will hit land somewhere!
Member Since: March 12, 2013 Posts: 15 Comments: 30229
Quoting 78. Dakster:
I wonder what would happen if a Hurricane (Typhoon) hit the Fukushima site with all that radiation?

Especially since for some unknown reason the readings spiked to 2300 mSV/Hr... Considerng that at 70-100 mSV/HR is unhealthy for human contact, that seems quite high.

Link: http://www.cnn.com/2013/09/01/world/asia/japan-fuk ushima-radiation-spike/index.html?hpt=hp_t2

Link

P.S. No I do not want find out in real life either.


If the storm surge was bad and caused the area to lose power and flood, it could be catastrophic. 1300 fuel rods are being held in one of the buildings, and a loss of power would prevent monitoring and controlling their temperatures. If they get too hot, they can go critical and start a runaway chain reaction that would basically create a completely unshielded reactor that would just spew radiation. OF course, a typhoon is not needed to do this. Another earthquake could easily do so, and even without any natural disasters, TEPCO is going to try and remove these fuel rods later in the year - manually and without proper equipment because those systems were destroyed in the tsunami.
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Quoting 41. hydrus:
NOT... not unless that's a ULL... lol

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C'mon, Gabrielle. Pull it together, hun. You're being counted on to bust a drought in the NW Gulf. Just try and avoid a Galveston landfall. Stay out of Trinity Bay, too. Avoid the refineries altogether, Gabs.
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Quoting 81. bloodyen:
If 97L can clear Cuba and Hispanola, I think we might have a problem with this one. There is no where where the invest can go but eventually hit a landmass.



oh said it was going too Hispanola? I think 97L will move this S of there
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Kiko is starting to quickly weaken.
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Quoting 80. rmbjoe1954:


A long swim will do as well.


Swim from Cuba to Key West... No one seems to be able to do that one. Another person is trying now. I can't wait for someone to actually do it.
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Quoting 79. Dakster:


I wish I could get what I wanted, some of the time...



so ture
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Quoting 27. IKE:

You might need to go take a walk.
Do you realize how HOT it is out there? A walk could be a recipe for sunstroke...

Of course Caribboy could go catch a swim... work off stress and cool off at the same time...

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If 97L can clear Cuba and Hispanola, I think we might have a problem with this one. There is no where where the invest can go but eventually hit a landmass.
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Quoting 27. IKE:

You might need to go take a walk.


A long swim will do as well.
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Quoting 74. Tazmanian:




you cant all ways have what you want


I wish I could get what I wanted, some of the time...
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I wonder what would happen if a Hurricane (Typhoon) hit the Fukushima site with all that radiation?

Especially since for some unknown reason the readings spiked to 2300 mSV/Hr... Considerng that at 70-100 mSV/HR is unhealthy for human contact, that seems quite high.

Link: http://www.cnn.com/2013/09/01/world/asia/japan-fuk ushima-radiation-spike/index.html?hpt=hp_t2

Link

P.S. No I do not want find out in real life either.
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Member Since: June 30, 2013 Posts: 12 Comments: 8226
Quoting 74. Tazmanian:




you cant all ways (get) what you want


Listening to Jagger this morning, Taz? I hear ya! Rock on, brother! ;)
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Quoting 61. CaicosRetiredSailor:
That: ...separate video showing the damage to the car and the course of the rock slide is here.

which Dr. Masters links is pretty amazing! A lot more damage to that white car than I would have guessed seeing the original dashcam view.



Sheeesh! Another tumble and that car would have been a pancake!
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Quoting 71. Dakster:


I asked for a Fish storm. Not GOM disaster... Just for the record.




you cant all ways have what you want
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Tracks of past systems where 97L 12z position was.

Member Since: April 29, 2009 Posts: 75 Comments: 14253
INVEST 96L moving west!
Member Since: March 12, 2013 Posts: 15 Comments: 30229
Quoting 67. Tazmanian:




we got 97L to track and it could be a Threat too mx and the gulf cost most likey areas where they don't need the rain


I asked for a Fish storm. Not GOM disaster... Just for the record.
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You can see that the low level clouds have sped westwards over the last few hours on visible satellite. As of right now, I would say that the vorticity is close to being stacked under the deepest convection, but not quite there.

The 1500 UTC vorticity maps will soon provide very crucial data on whether 97L is improving its structure or not.
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Admins must be laughing when reading my comments lol
Member Since: October 6, 2007 Posts: 0 Comments: 6168
Starting to see the new LLC becoming more dominant as the blob of convection moves over it.

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Quoting 63. Dakster:
we need a nice major fish storm to track.




we got 97L to track and it could be a Threat too mx and the gulf cost most likey areas where they don't need the rain
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Owned and maintained by Meteo France
Location 15.850 N 57.467 W (1551'0" N 5728'0" W)
24-hour plot - Wind Direction Wind Direction
(WDIR): ENE ( 70 deg true )
24-hour plot - Wind Speed Wind Speed (WSPD): 18.1 kts
24-hour plot - Wave Height Wave Height (WVHT): 7.5 ft
24-hour plot - Dominant Wave Period Dominant Wave Period (DPD): 7 sec
24-hour plot - Atmospheric Pressure Atmospheric Pressure (PRES): 29.90 in
24-hour plot - Pressure Tendency Pressure Tendency (PTDY): 0.06 in ( Rising )
24-hour plot - Air Temperature Air Temperature (ATMP): 79.2 F
24-hour plot - Water Temperature Water Temperature (WTMP): 83.1 F
24-hour plot - Dew Point Dew Point (DEWP): 75.4 F
24-hour plot - Heat Index Heat Index (HEAT): 83.3 F


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Quoting 58. Hurricanes305:


I also respectfully disagree with Dr. Masters and the Eastern Caribbean graveyard theory. Easterlies ahead of it is slowing down which is why the LLC has been stuck around 60W.


Agreed. I'm thinking the ULL will serve to keep those winds and any sinking air abated.
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we need a nice major fish storm to track.
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Ill be back at 2pm yall till then, 96l doesnt look bad, it has vey good convection -80c which is much more important for development than people think, anyways ILL be back.
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That: ...separate video showing the damage to the car and the course of the rock slide is here.

which Dr. Masters links is pretty amazing! A lot more damage to that white car than I would have guessed seeing the original dashcam view.

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cloud top -80F
Member Since: March 12, 2013 Posts: 15 Comments: 30229
Quoting 53. Tropicsweatherpr:
New wave introduced with low pressure at 45W behind 97L. This one has to be watched.



XD
Member Since: October 6, 2007 Posts: 0 Comments: 6168
Quoting 34. HuracanTaino:
It appears to be forming another COC under the deepest convection, near 15N , 59W...


Yes, you can see what appears to be a donut-like hole which suggest a dominant circulation trying to form. Also the blob moving towards it is where a MLC is trying to get going if the column of cloud stack up with the LLC this can take off. I also respectfully disagree with Dr. Masters and the Eastern Caribbean graveyard theory. Easterlies ahead of it is slowing down which is why the LLC has been stuck around 60W. The sharp SW inflow should continue as it transverse 60-70W and enters 75W where conditions are even more favorable for quick development.

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it is stretched out but to the east it looks good



Member Since: April 24, 2011 Posts: 1 Comments: 601
Quoting 46. chrisdscane:
buoy data would suggest this is already a Tropical storm wind wise, now we need to locate the main LLC is there a recon mission I havent looked just got out of bed.
Nothing for scheduled for today,

000
NOUS42 KNHC 311545
REPRPD
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1130 AM EDT SAT 31 AUGUST 2013
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 01/1100Z TO 02/1100Z SEPTEMBER 2013
TCPOD NUMBER.....13-091

I. ATLANTIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.

II. PACIFIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.

$$
SEF
Member Since: June 30, 2013 Posts: 12 Comments: 8226
that ULL is moving away a decent clip
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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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