Unusual Chantal Disorganized, but has 65 mph Winds

By: Dr. Jeff Masters , 8:06 PM GMT on July 09, 2013

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Unusual Tropical Storm Chantal has strengthened a bit more as it speeds west-northwestwards at 26 mph away from the the Lesser Antilles Islands. Sustained winds of 38 mph, gusting to 52 mph, were observed at Martinique at 10 am AST as the storm passed. However, an automated weather station at the airport measured sustained winds of 60 mph, gusting to 78 mph, according to an official with Meteo-France. The Associated Press reported that Chantal ripped the roofs off of several homes on neighboring Dominica. An Air Force hurricane hunter aircraft measured top winds at their 1,000' flight level of 89 mph at 12:55 pm AST. Top winds seen by the aircraft's SFMR instrument were about 65 mph, in a small area east of Chantal's center. The Hurricane Hunters have departed Chantal, and the next plane is due in the storm at 8 pm EDT. Chantal's winds are unusually high considering the storm's high central pressure of 1006 mb and disorganized appearance on satellite imagery. Chantal is fighting dry air associated with the Saharan Air Layer (SAL), as seen on water vapor satellite loops. This dry air is creating strong thunderstorm downdrafts that are robbing Chantal of moisture and energy. Visible satellite loops show the outflow boundaries of these thunderstorm downdrafts at the surface, spreading to the northwest of Chantal. Martinique Radar shows a large area of heavy rain that is not well-organized, lying mostly to the west of the Lesser Antilles Islands.


Figure 1. MODIS image of Chantal taken at approximately 1 pm EDT Tuesday, July 9, 2013. At the time, Chantal had top winds of 65 mph, but looked very disorganized, due to high wind shear and dry air. Dry air is creating strong thunderstorm downdrafts that are robbing Chantal of moisture and energy. Outflow boundaries from these downdrafts are spreading out to the northwest of Chantal, as seen on this satellite image. Image credit: NASA.

An small-scale easterly jet creating high shear in Chantal
Chantal is not very impressive on satellite images, with a modest amount of heavy thunderstorms that are not well-organized. Only a small amount of upper-level outflow is visible. The reason for Chantal's rather disorganized appearance can be found by looking at this morning's balloon sounding from Guadaloupe. This island was just northwest of the center of Chantal when the balloon was launched at 8 am EDT. The sounding showed typical easterly trade winds at the surface of 12 knots (14 mph.) However, the winds rose quickly aloft, with a jet of easterly winds of 35 - 53 knots between 800 - 600 mb (about 7,000 - 15,000'.) But, by the time the ballon hit 500 mb (18,000'), the winds had died down to 15 knots. A change of wind speed from 12 knots to 53 knots and back down to 15 knots from the surface to 500 mb is a tremendous amount of wind shear, which will make it very difficult for a tropical storm to keep the surface center aligned with the upper level center. The traditional measure of wind shear, the difference in wind between 200 mb and 850 mb, was 44 knots in this morning's Guadaloupe sounding, but was a much higher 56 knots from 200 mb to 700 mb. The powerful easterly wind jet was not apparent at any of the other balloon soundings this morning at adjacent islands (Barbados, Puerto Rico, Saint Martin), and demonstrates that there is a lot going on the atmosphere at small scales we cannot see which makes intensity forecasting of tropical cyclones very challenging. Thanks go to Jason Dunion of NOAA's Hurricane Research Division for pointing out this morning's interesting Guadaloupe sounding.

Forecast for Chantal
Chantal will have difficulty intensifying much more before hitting Hispaniola on Wednesday afternoon. In their 11 am EDT wind probability forecast, NHC gave Chantal a 29% chance of becoming a hurricane before hitting Hispaniola. Working against intensification will be the high wind shear from the strong mid-level easterly jet discussed above, plus the fast forward speed of the storm--tropical storms moving faster than 20 mph in the deep tropics usually have trouble intensifying. In addition, the Eastern Caribbean is an area where the trade winds accelerate, helping drive sinking air that discourages tropical storm intensification. Dry air will also slow down the intensification process. Interaction with the high mountains of Hispaniola and high wind shear may be able to destroy Chantal by Thursday. The 2 pm EDT Tuesday wind shear forecast from the SHIPS model calls for shear to rise to the high range, 20 - 35 knots, Tuesday night through Friday. On Saturday, when Chantal is expected to be in the Bahamas, moderate wind shear of 10 - 20 knots is predicted. If Chantal survives until Saturday, it will then have the opportunity to re-strengthen. The latest 12Z run of the European model (ECMWF) dissipates Chantal as it crosses Hispaniola. The 12Z run of the American GFS model has Chantal barely surviving.

Chantal's fast west-northwest forward speed of 26 mph will slow to 20 mph by Wednesday morning and then 10 mph by Thursday night, as the storm "feels" the presence of a trough of low pressure over the U.S. East Coast. This trough will steer Chantal to the northwest and then north-northwest across Hispaniola and into the Bahamas. The trough of low pressure pulling Chantal northwards is expected to lift out the the northeast over the weekend, leaving Chantal behind off the coast of Florida. High pressure will likely build in, potentially forcing Chantal westwards into the Florida or Southeast U.S. coast, with a possible Sunday landfall.

Jeff Masters

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Quoting 533. Stormchaser121:
Are the models getting confused?? Whats going on?


They haven't known what to do with it since it formed both intensity and track wise
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Quoting 524. ncstorm:


but ends up killing it..

I mean the 00z run for the GFS was showing annilation and now nothing??..LOL..
Honestly the CMC model is the only model yet to really drop Chantal after its passage over Hispaniola. I guess we will see what tonight brings.
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System is looking worst in every new loop, Levi nailed this system very well.

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Are the models getting confused?? Whats going on?
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Quoting 491. Levi32:
A col is a region simultaneously in between two regions of high pressure and two regions of low pressure. The "C" in the upper portion of this image is an example of a col. The one I'm talking about occurs at the 200mb level in 4-5 days.

Euro has a similar upper-level set up. Really hard to say how she will look after Hispanola though. Not looking pretty right now, that's for sure.
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Quoting 523. barbamz:


Our former dear blogger weather456 had an entry about Caribean jet streams in 2009. As far as I've seen there is a site providing details but you have to sign in to see it.


What happened to 456?
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DOOM!

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Funnel cloud in West Bradenton. Reports of several homes damaged 2800 block of 10th Street West in Palmetto.

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Hi my friends,

I am watching with you all... all this flipping and flopping of the track and when that left turn will happen..

and the intensity unknown...

keep the info coming.. I am popping in and out as I can.


Thanks, Gamma/Gams

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527. FOREX
I see it missing
Hispaniola and DR as of right now. Any opinions?
Member Since: August 17, 2011 Posts: 0 Comments: 1436
San Juan Long Range Radar



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Quoting 508. wunderkidcayman:

Yes



What would it take for a charley track and would conditions be more or less favorable if it where to pull a charley track ?
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Quoting 516. washingtonian115:
Shows a strong vorticity with the African wave.


but ends up killing it..

I mean the 00z run for the GFS was showing annilation and now nothing??..LOL..
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Quoting 497. canehater1:
Alot was explained in Dr.asters Intro to this blog regarding the ragged appearance of Chantal..very
unusual shear pattern.....


Our former dear blogger weather456 had an entry about Caribean jet streams in 2009. As far as I've seen there is a site providing details but you have to sign in to see it.
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Quoting 506. washingtonian115:
The GFS isn't excited by either storm.Now watch the blog start downcasting.I wonder why the GFS are dropping the storm.


LOL you predicted i didnt even take a few minutes to see it lol

511. floridaboy14 10:39 PM GMT on July 09, 2013 +0
looks like we will be waiting for august to get dorian
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Quoting 514. Gearsts:
What's wrong with the 18z?




the 18z is a outliner


i would wait in tell the 00z wish is the better run
Member Since: May 21, 2006 Posts: 5091 Comments: 114750
Quoting 497. canehater1:
Alot was explained in Dr.asters Intro to this blog regarding the ragged appearance of Chantal..very
unusual shear pattern.....


Yes I read that. Not certain exactly what it implies, but... This is a very unusual storm. Formed with 20 to 30 kts fwd motion (and hasn't slowed down yet), Sucking SAL dust, formed TS strength winds with a central pressure of 1010mb (HH last night), All of that in Early July ?!?!

If I told you back in June that a storm would do all of that early next month, you would have thought I was crazy; yet here we are with Chantal. This storm is already one for the books, and may have more surprises yet to go.

She may not be unprecedented, but she certainly is highly unusual. I'm impressed.
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downcasters will be out in full force tonight let me leave before I get swallowed
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Quoting 513. ncstorm:


we dont need anymore rain..especially a tropical entity whether it develops or not..


I agree some rivers are running over as it is
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Quoting 507. ncstorm:

The latest 12Z run of the European model (ECMWF) dissipates Chantal as it crosses Hispaniola


Dr. Masters, the 12z Euro never develops Chantal nor does it dissipates it..just shows nothing but vorticity throughout the run for Chantal however it actually strengthens the vorticity before heading into NC
Shows a strong vorticity with the African wave.
Member Since: August 14, 2010 Posts: 10 Comments: 16421
Quoting 511. floridaboy14:
looks like we will be waiting for august to get dorian




nop not at all



the 18z are all ways the bad runs


the 00z 06z and 12z are normly the better runs
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Quoting 509. Tazmanian:
guys i nevere go with the 18z



wait the the 00z
What's wrong with the 18z?
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Quoting 505. will40:
that precip map didnt look good at all tho NC


we dont need anymore rain..especially a tropical entity whether it develops or not..
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Looks like she's just another Karen dying on the run.
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looks like we will be waiting for august to get dorian
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<

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guys i nevere go with the 18z



wait the the 00z
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Quoting 477. weatherlover94:
Is it possible this could pull a Charley track ?

Yes

Member Since: June 13, 2009 Posts: 2 Comments: 11111

The latest 12Z run of the European model (ECMWF) dissipates Chantal as it crosses Hispaniola


Dr. Masters, the 12z Euro never develops Chantal nor does it dissipates it..just shows nothing but vorticity throughout the run for Chantal however it actually strengthens the vorticity before heading into NC
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The GFS isn't excited by either storm.Now watch the blog start downcasting.I wonder why the GFS are dropping the storm.
Member Since: August 14, 2010 Posts: 10 Comments: 16421
that precip map didnt look good at all tho NC
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Quoting 470. CaicosRetiredSailor:
Thank you Grothar for your SHIFT



Results for Provo, TCI (21.78N, 72.27W):
The approximate Closest Point of Approach (CPA) is located near 20.4N, 73.9W or about 140.8 miles (226.5 km) from your location. The estimated time of when the center of the storm will be at that location is in about 1 day, 13 hours and 13 minutes from now (Thursday, July 11 at 7:30AM AST).


Oh nice to see you today, was wondering about you as hadn't seen you post today with Chantal, roughly in your neighborhood!

Geesh, went and got some things done I'd been putting off all day following these things, come back and there's another blog already. Great post from the Dr though, bringing up all the issues everyone was discussing in the previous blog.

As Wash and others said though, Soulik was so obviously more! Someone said it should weaken greatly before landfall...and was forecast to, but see that has changed and is forecast to stay strong until then :(
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Soulik is still doing very well:



Been waiting for this image all day, Sun is finally up out there, and beautiful it is!

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Quoting 494. GetReal:
I knew that I had seen similar steering paatern before:


Different time of the year though and we have to remember the pattern hasn't quite established itself. The forecast will be tricky once it passes Hispaniola's longitude. Levi explains this well in his analysis.
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GFS dropped the cape verde TS
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San Juan
NEXRAD Radar

Velocity Azimuth Display Wind Profile ° Elevation
Range 124 NMI

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Quoting 435. GTstormChaserCaleb:
105 hrs.


Its almost completely dropped the Cape Verde storm :/
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498. SLU
The GFS has backed off on the Cape Verde wave but it still maintains another Chantal-like rapid moving system due to the high pressure.

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Alot was explained in Dr.asters Intro to this blog regarding the ragged appearance of Chantal..very
unusual shear pattern.....
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Quoting 435. GTstormChaserCaleb:
105 hrs.


Theres that west turn! If thats what that is...
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Convection has warmed considerably on Chantal. Not sure if it's DMIN, dry air, or both. Either way, I doubt recon finds any strengthening has occurred; weakening if anything.



Of course, that's what we've said on the past two flights...
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I knew that I had seen similar steering paatern before:


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San Juan
NEXRAD Radar

Base Reflectivity 0.50° Elevation
Range 248 NMI

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Quoting 489. ncstorm:


Hey Will,

have the models switched up now..I saw the Euro where it took the Chantal through our neck of the woods..the GFS doing the same?



GFS been back and forth even dropped her on one run
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A col is a region simultaneously in between two regions of high pressure and two regions of low pressure. The "C" in the upper portion of this image is an example of a col. The one I'm talking about occurs at the 200mb level in 4-5 days.

Member Since: November 24, 2005 Posts: 635 Comments: 26548
<
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Quoting 484. will40:


Hi NC not yet


Hey Will,

have the models switched up now..I saw the Euro where it took Chantal through our neck of the woods..the GFS doing the same?
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Quoting 470. CaicosRetiredSailor:
Thank you Grothar for your SHIFT



Results for Provo, TCI (21.78N, 72.27W):
The approximate Closest Point of Approach (CPA) is located near 20.4N, 73.9W or about 140.8 miles (226.5 km) from your location. The estimated time of when the center of the storm will be at that location is in about 1 day, 13 hours and 13 minutes from now (Thursday, July 11 at 7:30AM AST).


I'm gonna just pretend that's Provo, Utah. We could use some rain...
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Quoting 478. ncstorm:
Hey Guys..been busy all day..

so no left turn into Florida now?





No but the overall angle is closer to FL, this may surprise NC watch out
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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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