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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As I live in East Central Florida I intend to put up hurricane shutters at least on my gable vents this weekend to save me time when I really need to board up the rest of the house this summer.

It's going to be that type of season.
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what happern if Chantal go in the GOM!! watch out
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Quoting 2280. HurricaneAndre:
they know how to track multiple systems.




this ones closer too land the that one is
Member Since: May 21, 2006 Posts: 5091 Comments: 115247
2283. palmpt
Quoting 2275. RitaEvac:
This is what happens when a system moves over 20mph and doesn't develop....all models just play catch up of where ever it is



Like I said yesterday, it will not go over the mountains and will possibly get in the Gulf... Now that seems more likely. Not saying its going to be a big event, just that the weak system races off to the West. We are far from done talking about Chantal.
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It has been a good experience for all of us (the good and the bad) to experience how crazy it can get on the blog when a storm is threatening and it gave me the added bonus of being able to update my ignore list before the peak of the season.

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Quoting 2255. Grothar

Hope all goes well with your doctors appointment, will keep you in my prayers.
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Quoting 2276. Tazmanian:



chill out they have there hands full right now with Chantal


they know how to track multiple systems.
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Look at the voticity south of the Cape Verde island around 26 west..maybe invest 96L in a few days from now
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Good news for Chantal the dry air SW of Chantal is retreating.
Member Since: May 23, 2012 Posts: 0 Comments: 4664
Quoting 2273. HurricaneAndre:
What is it with the NHC Giving that wave a chance ,someone email them.I give it a 30-60% crayons right now.



chill out they have there hands full right now with Chantal


Member Since: May 21, 2006 Posts: 5091 Comments: 115247
This is what happens when a system moves over 20mph and doesn't develop....all models just play catch up of where ever it is

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Quoting 2261. pcola57:




Look at the voticity south of the Cape Verde island..i am going to say wow!
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What is it with the NHC not Giving that wave a chance ,someone email them.I give it a 30-60% crayons right now.
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2272. Nimitz
Quoting 2259. indianrivguy:


play Misty for me....


You dated her too? OMG....
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Quoting 2255. Grothar:



I'm looking out over the ocean and it is getting dark. And I have a doctors appointment in an hour. Obviously they didn't like my last EKG

Don't unplug the machine so you can plug in your laptop this time, Gro...
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2270. Dakster
Quoting 2262. BahaHurican:
Not really downplaying so much as realism... Call an open wave an open wave.


Just wanted to make sure I wasn't giving my opinion of a n all clear. Not that anyone should take life or death advice from a blog.
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Since the initial position has been
shifted substantially westward in comparison to the previous
advisory... this necessitates a large westward shift to the NHC
forecast track. Nonetheless...the new official forecast is still
on the eastern side of the track model guidance suite
.

Ok, why?
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Quoting 2264. HurricaneAndre:
DO WE HAVE A NEW AOI.?!?!?!?!




NO NOT YET!
Member Since: May 21, 2006 Posts: 5091 Comments: 115247
2265. Dakster
Quoting 2255. Grothar:



I'm looking out over the ocean and it is getting dark. And I have a doctors appointment in an hour. Obviously they didn't like my last EKG



One day all our EKGs will look like that. Too bad the Atlantic Basin's EKG doesn't look like that right now.
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DO WE HAVE A NEW AOI.?!?!?!?!
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Member Since: May 21, 2006 Posts: 5091 Comments: 115247
Quoting 2243. Dakster:
Having downplayed Chantal -- I wouldn't rule out strengthening once whatever is left gets into a more favorable environment.

Not really downplaying so much as realism... Call an open wave an open wave.
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2261. pcola57
Quoting 2251. washingtonian115:
Look at the voticity south of the Cape Verde island.Thats what I'm more interested in.


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Well that's pitiful
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Quoting 2248. ExumaMET:
Look, I woke up this morning fully expecting this storm to be killed off.

...alas...

She reminds me of that crazy, stalkerish girlfriend that you don't realize is crazy until its too late to get rid of her and the more you push her away, the more she latches on and loves you.


play Misty for me....
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Recon is still in there currently, they could still find a weak west wind.
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She still poses a heavy rain threat to Haiti.

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Interesting

Models have shifted quite a bit S and W south of Haiti or SW Haiti S of Cuba or southern coast of Cuba and N of Jamaica




Member Since: June 13, 2009 Posts: 2 Comments: 12138
2255. Grothar
Quoting 2236. mikatnight:


It's Grothar's other blob.




I'm looking out over the ocean and it is getting dark. And I have a doctors appointment in an hour. Obviously they didn't like my last EKG

Member Since: July 17, 2009 Posts: 71 Comments: 26402
Anybody saying Chantal is dead is rather off. A Twave is not a dead thing. Rather it is the root of the TC in our basin... so it's a wait and see, not a write off, that should be ongoing. I'll not be surprised to see "possibility of regeneration" type language if Chantal is downgraded at 11...
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Quoting 2243. Dakster:
Having downplayed Chantal -- I wouldn't rule out strengthening once whatever is left gets into a more favorable environment.


That's what I'm thinking
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Quoting 2236. mikatnight:


It's Grothar's other blob.



That thing seems to be losing intensity... you can see some rotation in Geoffs post 2230, but overall, it appears to be drying out.. and I am glad.
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Quoting 2235. hurricanes2018:
26 west!!
Look at the voticity south of the Cape Verde island.Thats what I'm more interested in.
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Hurricanes Frederic and Eloise are examples of westward-moving tropical systems that struggled through the Caribbean, getting tangled up with the Greater Antilles, and facing hostile conditions, but once they got to the NW Caribbean and SE Gulf of Mexico, they managed to re-organize, so we must continue to watch Chantal to see what she decides to do once she gets there. In my opinion, she may go more west than north.
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Look, I woke up this morning fully expecting this storm to be killed off.

...alas...

She reminds me of that crazy, stalkerish girlfriend that you don't realize is crazy until its too late to get rid of her and the more you push her away, the more she latches on and loves you.
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Quoting 2230. GeoffreyWPB:


I think some of that new convection is land enhanced. Getting some orographic lift now from the mountainous terrain of Hispanola. Don't know about the circulation, guess we'll find out shortly from reconnaissance.
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Quoting 2241. unknowncomic:
She does have warm SSTs in front of her.


She is really taking one of the worst tracks any system can take, she is skirting all of Florida's East Coast while over the Gulf Stream and then up into South Carolina, where major flooding has already been occurring...

I think we could see some regeneration in the Gulf Stream a little.
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2244. Grothar
I'm giving her a few more hours before I write her off completely.

Member Since: July 17, 2009 Posts: 71 Comments: 26402
2243. Dakster
Having downplayed Chantal -- I wouldn't rule out strengthening once whatever is left gets into a more favorable environment.

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Member Since: May 23, 2012 Posts: 0 Comments: 4664
She does have warm SSTs in front of her.
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It appears she still has some life left in her.
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2239. MahFL
The dry air SW of Chantal is retreating.
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location... 16.5n 70.8w
about 155 mi...245 km SSW of Santo Domingo Dominican Republic
maximum sustained winds...45 mph...75 km/h
present movement...W or 275 degrees at 29 mph...46 km/h
minimum central pressure... 1011 mb...29.85 inches
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2237. Dakster
Quoting 2224. hurricanes2018:
I am calling it Tropical wave CHANTAL now..


The NHC is ready to call it that too.
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Quoting 2216. SFLWeatherman:
Look at SE FL!!


It's Grothar's other blob.

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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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