Lesser Antilles Disturbance 97L Still Disorganized

By: Dr. Jeff Masters , 2:34 PM GMT on September 03, 2013

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A tropical wave over the Lesser Antilles Islands (Invest 97L) is moving west-northwest at 10 mph, and is bringing sporadic heavy rain showers to the islands. Top sustained winds observed in the islands as of 10 am AST Tuesday were mostly below 15 mph. Heavy thunderstorm activity has been low since Monday, and is spread out, as seen on satellite loops. The thunderstorms are poorly organized, and there is no sign of a well-organized surface circulation. Martinique radar shows little evidence of rotation to the echoes, and no low-level spiral bands forming. Upper level winds are favorable for development, with wind shear a low 5 - 10 knots, and an upper-level anticyclone overhead. An area of dry air from the Saharan Air Layer (SAL) surrounds 97L and is interfering with development, though the the 12Z Tuesday balloon sounding from Guadeloupe near the center of 97L showed moist air through the entire depth of the atmosphere.


Figure 1. Latest satellite image of Invest 97L.

Forecast for 97L
Wind shear is expected to be low through Friday, and ocean temperatures will be warm, 29°C. The disturbance has not been able to generate enough thunderstorms to moisten the surrounding atmosphere much, and dry air may continue to slow down development over the next few days. The models take 97L to the west-northwest, bringing it near or over Puerto Rico or Hispaniola on Wednesday night. A track over the high mountains of Hispaniola would disrupt the circulation of 97L, forcing the storm to regroup on Thursday over the Southeast Bahamas and Turks and Caicos Islands. The best chance for development of 97L would appear to be on Friday, after the storm has finished its encounter with Hispaniola. This morning's 00Z run of the experimental GFDL ensemble--which produces 10 simulations with slightly varying initial conditions to create a plume of potential storm tracks--foresees that once 97L organizes into a tropical depression, it might take only two days for it to intensify into a hurricane to the north of Hispaniola. The wave will bring heavy rain showers to the Lesser Antilles islands on Tuesday and Wednesday, and this activity will likely spread to Puerto Rico, the Virgin Islands, the Dominican Republic, and Haiti on Wednesday and Thursday. These rains will be capable of causing life-threatening flash flooding and mudslides in mountainous regions of 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 over the Central Bahamas on Saturday. There will be a strong trough of low pressure along the U.S. East Coast this weekend, which will be capable of turning 97L to the north before the storm can hit the U.S. In their 8 am EDT Tuesday Tropical Weather Outlook, NHC left the 5-day odds of formation of 97L at 50%, and 2-day odds at 20%. The Hurricane Hunters are on call to investigate 97L Wednesday afternoon. The flight scheduled for today will likely be cancelled. The Hurricane and Severe Storm Sentinel Mission, a 5-year field project utilizing two remotely crewed Global Hawk aircraft to overfly tropical storms and hurricanes, will have one of their aircraft investigate 97L today, and again on Wednesday. You can follow the progress of the aircraft using NASA's live-plane tracker map (Global Hawk AV6 is tail number NASA872, and Global Hawk AV1 is tail number NASA871.)

98L off the coast of Africa and a Yucatan Peninsula tropical wave
A tropical wave that emerged from the coast of Africa on Monday (Invest 98L) is expected to track northwest over the Cape Verde Islands. This course will take 98L into a region of ocean where historically, very few tropical cyclones have made the long journey across the Atlantic to affect North America. In their 8 am EDT Tuesday Tropical Weather Outlook, NHC put the 5-day odds of development at 20%.

A tropical wave over Mexico's Yucatan Peninsula has a respectable area of heavy thunderstorms associated with it that is bringing heavy rains. This activity will push over the extreme Southern Gulf of Mexico's Bay of Campeche on Wednesday. The wave will have two days over water to develop before moving ashore on the Mexican coast between Veracruz and Tampico on Friday. In their 8 am EDT Tuesday Tropical Weather Outlook, NHC put the 5-day odds of development at 30%, and 2-day odds at 20%.

Jeff Masters

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Quoting 566. HurricaneHunterJoe:


Good afternoon most wisest of wise......I am learning from you. I watched the entire Season 8 of " 24 " yesterday........my eyes hurt so BADDDDDDDD!...LOL


One of the greatest shows.
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Quoting 558. Grothar:


I watched a weeks marathon of Perry Mason and you are all still watching 97L. :)

I have to go. Murder she wrote marathon is starting.

Everybody have fun.

P.S. The one thing I know is this is not going west!!!!


Good afternoon most wisest of wise......I am learning from you. I watched the entire Season 8 of " 24 " yesterday........my eyes hurt so BADDDDDDDD!...LOL
Member Since: September 18, 2010 Posts: 0 Comments: 5234
Quoting 556. Tropicsweatherpr:
Hi nrt,any data from Global Hawk?


I don't know of any website that has the data. This Global Hawk does not have dropsondes.





HIRAD is a multi-frequency, hurricane imaging, interferometric single-pol passive C-band radiometer, operating from 4 GHz to 7 GHz, with both cross-track and along-track resolution that measures strong ocean surface winds through heavy rain from an aircraft or space-based platform.


HIWRAP (High-Altitude Imaging Wind and Rain Airborne Profiler) is a dual-frequency radar (Ka- and Ku-band), dual-beam (300 and 400 incidence angle), conical scan, solid-state transmitter-based system, designed for operation on the high-altitude (20 km) Global Hawk UAV.


The Airborne Detector for Energetic Lightning Emissions (ADELE) detects gamma-rays and relativistic electrons associated with lightning and thunderstorm charging. The primary scientific target is terrestrial gamma-ray flashes (TGFs), brief (< 1 millisecond), extremely bright bursts of high energy radiation that have mostly been detected from satellites in low Earth orbit.


The High Altitude Monolithic Microwave integrated Circuit (MMIC) Sounding Radiometer (HAMSR) is a microwave atmospheric sounder developed by JPL under the NASA Instrument Incubator Program. Operating with 25 spectral channels in 3 bands (50-60 Ghz, 118 Ghz, 183 Ghz), it provides measurements that can be used to infer the 3-D distribution of temperature, water vapor, and cloud liquid water in the atmosphere, even in the presence of clouds.


Or, it has a singer and a hamster on board :)
Member Since: September 23, 2005 Posts: 14 Comments: 11215
Quoting 554. wunderkidcayman:


No bottom line it's not at 15N 63W maybe further S where NHC BEST track Data put it which is what the models are based on


Your meal is waiting Wunderkid :-) Cold meals are not as good.
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Quoting 557. ncstorm:
setting up to be a dangerous situation..if the Euro is not seeing a strong enough trough to take 97L out to sea, there is a potential big'um right behind it..
Maybe a real Cape Verde TC to track!?!?
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Could be another wet evening and week with this front hanging out!

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National Hurricane Center's (NHC) Aircraft Reconnaissance

Plan of the Day ( Today / Tomorrow ) - How to Read


Dropsonde data from NASA's Hurricane and Severe Storm Sentinel (HS3) mission does not currently appear in our recon system. However, our experimental manual decoder in our recon system in development, which appears here, can manually decode some of these sondes which are archived here with all other sondes from 2013. (Some data may be added manually here after a mission ends.)

To track GlobalHawk unmanned aircraft in real time, please use NASA's viewer here.
Member Since: July 3, 2005 Posts: 426 Comments: 128665
559. IKE

Quoting ncstorm:
looks like the Euro is trying to take 97L into Florida..no NE out to sea-last frame

Looks like a trough of low pressure stretching SW toward the Yucatan.
Member Since: June 9, 2005 Posts: 23 Comments: 37858


I watched a weeks marathon of Perry Mason and you are all still watching 97L. :)

I have to go. Murder she wrote marathon is starting.

Everybody have fun.

P.S. The one thing I know is this is not going west!!!!
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setting up to be a dangerous situation..if the Euro is not seeing a strong enough trough to take 97L out to sea, there is a potential big'um right behind it..
Member Since: August 19, 2006 Posts: 13 Comments: 15675
Hi nrt,any data from Global Hawk?
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Member Since: July 3, 2005 Posts: 426 Comments: 128665
Quoting 543. sar2401:

I'm sure the NHC will be sad to hear about that. :-)Seriously, as the low has become a bit better consolidated, almost every numerical and dynamical model wants to take 97L north. go over the PR and Virgins, brush the lower Bahamas, and then go out to sea. As you know, I'm not a great believer in models but, when more and more start to pile up on a path, that pile is likely to be close to be right. You can be our Don Quixote, tilting as western wind mills, but you're, going to be wrong.


No bottom line it's not at 15N 63W maybe further S where NHC BEST track Data put it which is what the models are based on
Member Since: June 13, 2009 Posts: 2 Comments: 12157
looks like the Euro is trying to take 97L into Florida..no NE out to sea-last frame

Member Since: August 19, 2006 Posts: 13 Comments: 15675
552. Skyepony (Mod)
Quoting 474. wunderkidcayman:
Wow BEST track got it wrong again meaning model runs for 18Z no good



I ran the single track error on today's 18z model runs. Just about all are initialized 50nm in error or more, late track models & all. So good call. One exception was the HWRF which was 6nm off.

Also interesting on that run was the intensity models. Suddenly many look like they didn't call for strong enough.
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Quoting 544. wunderkidcayman:

No not at 50'000 ft


How do you know the radar is not effective at that altitude?
Member Since: September 23, 2005 Posts: 14 Comments: 11215
Still not convinced 97 will be scooped up by the trough. Seems the trough might be to far ahead of it and leave it behind, the high might have a chance to build back in. We shall see.

Closer to home, there seems to be a pretty good hint of a swirl on the visible sat. pic. right over the Yucatan. I see an ULL to the left of it so I doubt it would go into Mexico. Anyway, it has a lot of juice to work with if it got its act together.
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Quoting 523. Tazmanian:



can you plzs kill it with the off topic photos this is not a comedie blog its a weather blog


C'mon Taz......geeeshhhhhhh
Member Since: September 18, 2010 Posts: 0 Comments: 5234


Just MY opinion, this is what I see happening, taking a shot at the east coast of Fl..
EDIT: I was looking at this map and it updated While I was looking at it showing the low heading ne where before it was showing nnw direction.
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Published on May 15, 2013

NASA's Hurricane and Severe Storm Sentinel (HS3) mission uses NASA's Global Hawk Unmanned Aerial Vehicles (UAV) to study tropical storms and hurricanes. This nine-minute video describes the mission, reveals details about the Global Hawk aircraft, and offers a glimpse inside the command centers of both the ground-based pilots and the scientists who analyze satellite images to assist in flight navigation. The video concludes with information about getting students involved directly from the classroom through computer monitoring of the Global Hawk's flight patterns and participating in live chats with the ground-based pilots.

Educational resources about the HS3 mission can be found at the NASA Wavelength Digital Library nasawavelength.org/resource/nw-000-000-0�3-539/

For more information about HS3 and the NASA Airborne Science Program visit airbornescience.nasa.gov, and nasa.gov/hs3


Member Since: July 3, 2005 Posts: 426 Comments: 128665
Quoting 536. HurricaneHunterJoe:



with all these center fixes we are posting....seems most are with in 50 miles of each other....best not to quibble? esp when we STILL do not have an established LLC?


That would be my take, no big difference in the scheme of things at this point, just updated to the latest NHC.
Member Since: September 23, 2005 Posts: 14 Comments: 11215
Good afternoon, Im full after eating so much fish and drinking Mexican beer.
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Quoting 532. weathermanwannabe:
If I am reading the current link Dr. M provided for the Global Hawk (below), the platform has been/is currently flying (green plane image) right over 97L.

Link

Wondering if they are using the plane to adjust the coordinates.....Super Cool if that is indeed the case.

No not at 50'000 ft
Member Since: June 13, 2009 Posts: 2 Comments: 12157
Quoting wunderkidcayman:

Not surprised at all I'm taking this straight to the trash

I'm sure the NHC will be sad to hear about that. :-)Seriously, as the low has become a bit better consolidated, almost every numerical and dynamical model wants to take 97L north. go over the PR and Virgins, brush the lower Bahamas, and then go out to sea. As you know, I'm not a great believer in models but, when more and more start to pile up on a path, that pile is likely to be close to be right. You can be our Don Quixote, tilting as western wind mills, but you're, going to be wrong.
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Quoting 538. BVI:



Which island you on? In the Virgin Islands here


St Barths... not too far :)
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Quoting 523. Tazmanian:



can you plzs kill it with the off topic photos this is not a comedie blog its a weather blog


plttttttttttttttttttttttttttttttttttttttttttttttt ttt,

wah wah wah..................
Member Since: July 3, 2005 Posts: 426 Comments: 128665
Talk about hitting the brakes and a northeast turn......and all pretty tightly clustered....WOW



true...but i trust no model until we actually have a storm....we watch lows form here...and then reform there.....one day it's strong and tracks say one way...the next day they're another....i believe it was 92l that everyone was gambling on texas...and although it disipated......it's influence was actually felt in texas....


reminds me of a song by billy joel....weather adapted of course.....

models may be right...or they may be crazy...but it just might be the lunatic model the blogs are looking for... you may be wrong for all i know you may be right
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Seems like everyone is focusing on 97L and not the other aoi's. It has to be That one. Wow I'm out!!
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538. BVI
Quoting 524. CaribBoy:
I love to be sandwiched between disturbances even though the weather looks great outside. But regarding 97L I can see some interesting things happening in the distance... andgradually approaching.



Which island you on? In the Virgin Islands here
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Global Hawk still orbiting High in the 97L envelope,
Member Since: July 3, 2005 Posts: 426 Comments: 128665
Quoting 508. nrtiwlnvragn:
Moved it

AL, 97, 2013090318, , BEST, 0, 150N, 630W, 30, 1007, LO



with all these center fixes we are posting....seems most are with in 50 miles of each other....best not to quibble? esp when we STILL do not have an established LLC?
Member Since: September 18, 2010 Posts: 0 Comments: 5234
Quoting 531. wunderkidcayman:
Anyway gets I going one break I am badly hungry so I'll be back later


Eat well.
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534. tj175
Quoting 443. hurricanes2018:
good news that invest 97L will go out to sea its not going to hit the east coast at all.




Ok ok we get the point you repost the same garbage on every post no matter what the models say now just please go away. The models have been shifting northward with every update regarding 97l, but any track after 3 days should be taken with caution.
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Quoting 526. JRRP:

now looks better


Yup and it's in the graveyard lol
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If I am reading the current link Dr. M provided for the Global Hawk (below), the platform has been/is currently flying (green plane image) right over 97L.

Link

Wondering if they are using the plane to adjust the coordinates.....Super Cool if that is indeed the case.
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Anyway gets I going one break I am badly hungry so I'll be back later
Member Since: June 13, 2009 Posts: 2 Comments: 12157
530. Relix
Quoting 522. JRRP:



Eastern RD it is.
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529. IKE
Quoting JRRP:

It's already wrong. Throw those tracks out. They can't even track a system correctly for 12-18 hours.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
meanwhile east coast of florida..storms heading your way......
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527. IKE
12Z ECMWF....nothing significant affecting the lower 48. Also, weaker on the eastern ATL storm. Why am I not surprised?
Member Since: June 9, 2005 Posts: 23 Comments: 37858
526. JRRP
Quoting CaribBoy:
15N 63W I'm very OK with that.

now looks better
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Quoting 483. ricderr:
what does Bams see that the other models dont?..someone said to watch Bams when a system is weak and undeveloped..a northward turn would mean its stronger no?...maybe bams knows it will stay weak and move more westward..we'll see in the days to come..
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I love to be sandwiched between disturbances even though the weather looks great outside. But regarding 97L I can see some interesting things happening in the distance... and gradually approaching.
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Quoting 494. Patrap:
Hmmm, the Haus is betting on N by NW then Woosh'


BAM shallow is the outlier....

Hmm, I wunder...?

Dooodle Looo,

wah, wah, wahhhhhhhhh








can you plzs kill it with the off topic photos this is not a comedie blog its a weather blog
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522. JRRP
Quoting nrtiwlnvragn:
Moved it

AL, 97, 2013090318, , BEST, 0, 150N, 630W, 30, 1007, LO

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Quoting 501. Kyon5:
Moving WNW-NW if one looks at this radar: Link




Nah that's just the band on the E side of the COC spreading out a bit giving that appearance
Member Since: June 13, 2009 Posts: 2 Comments: 12157
Quoting 508. nrtiwlnvragn:
Moved it

AL, 97, 2013090318, , BEST, 0, 150N, 630W, 30, 1007, LO


Better position
Member Since: October 28, 2006 Posts: 57 Comments: 30563
15N 63W I'm very OK with that.
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Quoting 483. ricderr:


Talk about hitting the brakes and a northeast turn......and all pretty tightly clustered....WOW
Member Since: September 18, 2010 Posts: 0 Comments: 5234
WOAH..

216 Hours
Member Since: August 19, 2006 Posts: 13 Comments: 15675

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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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