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 2352. Grothar:
I've got to run. I hope it's good news. If not, you won't have old Grothar to kick around anymore. :)


You are strong and it will be good news. Check back in when you get home.
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2385. StormWx
Quoting wunderkidcayman:

Very weak storm


Chantal is headed for you it looks like.
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Quoting 2381. stormpetrol:
Time: 13:35:00Z
Coordinates: 16.1333N 71.6667W
Acft. Static Air Press: 968.8 mb (~ 28.61 inHg)
Acft. Geopotential Hgt: 393 meters (~ 1,289 feet)
Extrap. Sfc. Press: 1013.7 mb (~ 29.93 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 305° at 4 knots (From the NW at ~ 4.6 mph)
Air Temp: 22.0°C (~ 71.6°F)
Dew Pt: 22.0°C (~ 71.6°F)
Peak (10s) Flt. Lvl. Wind: 5 knots (~ 5.8 mph)
SFMR Peak (10s) Sfc. Wind: 43 knots (~ 49.4 mph)
SFMR Rain Rate: 16 mm/hr (~ 0.63 in/hr)
(*) Denotes suspect data


I'd say they have enough to maintain advisories for now.
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Time: 13:34:30Z
Coordinates: 16.15N 71.7W
Acft. Static Air Press: 969.5 mb (~ 28.63 inHg)
Acft. Geopotential Hgt: 388 meters (~ 1,273 feet)
Extrap. Sfc. Press: 1013.4 mb (~ 29.93 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 303° at 5 knots (From the WNW at ~ 5.8 mph)
Air Temp: 22.8°C (~ 73.0°F)
Dew Pt: 22.7°C (~ 72.9°F)
Peak (10s) Flt. Lvl. Wind: 7 knots (~ 8.0 mph)
SFMR Peak (10s) Sfc. Wind: 26 knots (~ 29.9 mph)
SFMR Rain Rate: 7 mm/hr (~ 0.28 in/hr)
(*) Denotes suspect data
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2382. Drakoen
Looks like there still may be some circulation still spinning south of the southern tip of the DR.
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Time: 13:35:00Z
Coordinates: 16.1333N 71.6667W
Acft. Static Air Press: 968.8 mb (~ 28.61 inHg)
Acft. Geopotential Hgt: 393 meters (~ 1,289 feet)
Extrap. Sfc. Press: 1013.7 mb (~ 29.93 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 305° at 4 knots (From the NW at ~ 4.6 mph)
Air Temp: 22.0°C (~ 71.6°F)
Dew Pt: 22.0°C (~ 71.6°F)
Peak (10s) Flt. Lvl. Wind: 5 knots (~ 5.8 mph)
SFMR Peak (10s) Sfc. Wind: 43 knots (~ 49.4 mph)
SFMR Rain Rate: 16 mm/hr (~ 0.63 in/hr)
(*) Denotes suspect data
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Quoting 2370. Levi32:
Recon found the most pronounced wind shift yet, but pressures are 1013mb.



Looking back to this mornings satellite loops it's no doubt pressures have come up substantially.
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Quoting 2375. stormpetrol:


That is correct, just not posted on google graphics, yet theyt are posted on tropicalatlantic.com

They need to get it up
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2378. A4Guy
Quoting 2351. tj175:




Fay was a Joke, lol. We have rainstorms that are way worse here in South Florida than she was and Hurricane Georges was nothing but a rain and wind event for mainland South Florida with the Florida Keys getting the bulk of the action. The last big event that we had was Katrina and Wilma back in 2005.


Fay was no joke. Much of the State received flooding rains - she was very slow moving, and crossed the state a few times.

Isaac (last yr) was also a vigorous trop storm. Reat the NHC reports...parts of SoFla had 50+ winds, and quite a bit of rain. Neither was a Wilma, for sure, but they were meaningful events for a lot of poeple.
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Tropical Storm Chantal may still have a low level circulation, albeit not totally well-defined and quite small.

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Quoting 2370. Levi32:
Recon found the most pronounced wind shift yet, but pressures are 1013mb.


Very weak storm
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Quoting 2364. stormwatcherCI:
I don't know if it has been posted but apparently they have found NW/WNW winds too.


That is correct, just not posted on google graphics, yet theyt are posted on tropicalatlantic.com
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Quoting 2351. tj175:




Fay was a Joke, lol. We have rainstorms that are way worse here in South Florida than she was and Hurricane Georges was nothing but a rain and wind event for mainland South Florida with the Florida Keys getting the bulk of the action. The last big event that we had was Katrina and Wilma back in 2005.
Fay caused a lot of destruction here in Brevard County. I haven't seen winds or flooding here worse than that since.
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2373. StormWx
Chantal headed to Mexico.
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Quoting 2361. MadinBoy:
I'm thinking we'll get a ellow circle very soon....

Even though the GFS has dropped this I still believe it'll develop.
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Quoting 2364. stormwatcherCI:
I don't know if it has been posted but apparently they have found NW/WNW winds too.

Well she lives

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2370. Levi32
Recon found the most pronounced wind shift yet, but pressures are 1013mb.

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Quoting 2358. cchsweatherman:
Getting some WNW winds being reported by Hurricane Hunters at around 16.2 N and 71.5 W. They did get notable wind shifts from almost every direction except did not find a true westerly wind. Will be interesting to see another pass through the center to see if they could find any west winds.


That's consistent with where it should be if the circulation maintained it's previous heading. So maybe there's still some llc after all.

Admit it looks pathetic right now, but RGB suggests teh center should be in that vicinity.
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2368. GetReal
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Chantal Lives On For Now

13:37:00Z 16.067N 71.583W
From 193° at 5 knots
(From the SSW at ~ 5.8 mph)
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Quoting 2347. ProgressivePulse:



NNE winds coming in from recon now
I don't know if it has been posted but apparently they have found NW/WNW winds too.
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We bloggers have the luxury of making snap judgements and quick changes to our idea of what we see on radar loops..the nhc handled their business properly...without proper recon last night they left intensity in advisories higher than it actually was..
Kudos to the guys at the Forecast Center...
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Quoting 2347. ProgressivePulse:



NNE winds coming in from recon now


I'm a first year Meterology student, so I'm still learning, could you explain to me what does it mean?

Isn't it necessary to find west winds?
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I'm thinking we'll get a ellow circle very soon....

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2360. eddye
cchs i agree with u dude this thing not dieing i think it could become stronger near the bahamas.
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Quoting 2337. tj175:


LOL I hope your not looking into a crystal ball, lol.
yeah no data, to support, just gut feeling, like I said it is entertaining. I feel like right now my prediction is as good as anyone else's, again adding to the entertainment factor.
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Getting some WNW winds being reported by Hurricane Hunters at around 16.2 N and 71.5 W. They did get notable wind shifts from almost every direction except did not find a true westerly wind. Will be interesting to see another pass through the center to see if they could find any west winds.
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2357. hydrus
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2356. Grothar
Quoting 2351. tj175:




Fay was a Joke, lol. We have rainstorms that are way worse here in South Florida than she was and Hurricane Georges was nothing but a rain and wind event for mainland South Florida with the Florida Keys getting the bulk of the action. The last big event that we had was Katrina and Wilma back in 2005.


The point was not whether or not they hit the US, but that storms survived crossing both Hispaniola and Cuba. Which part didn't you understand.?
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From San Juan NWS

AFTER
SATURDAY BANDS OF MOISTURE COME THROUGH BEARING SHOWERS WITH THE
BEST MOVING THROUGH ON TUESDAY IN THE FORM OF A TROPICAL WAVE AND
WIND SURGE. ANOTHER BETTER DEFINED TROPICAL WAVE IS SHOWN
APPROACHING THE AREA ON THURSDAY OF NEXT WEEK AND MAY HAVE
POTENTIAL FOR DEVELOPMENT.


This is what the GFS had as Dorian.
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2354. Dakster
Quoting 2351. tj175:




Fay was a Joke, lol. We have rainstorms that are way worse here in South Florida than she was and Hurricane Georges was nothing but a rain and wind event for mainland South Florida with the Florida Keys getting the bulk of the action. The last big event that we had was Katrina and Wilma back in 2005.


Tell the Folks that got flooded out of house and home that Fay was a joke.
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Quoting 2347. ProgressivePulse:



NNE winds coming in from recon now



HOw are people getting recon data so fast?

How do you view it on google Earth, or at least some other site as it becomes available?
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2352. Grothar
I've got to run. I hope it's good news. If not, you won't have old Grothar to kick around anymore. :)
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2351. tj175
Quoting 2339. Grothar:
Fay survived and so did Georges










Fay was a Joke, lol. We have rainstorms that are way worse here in South Florida than she was and Hurricane Georges was nothing but a rain and wind event for mainland South Florida with the Florida Keys getting the bulk of the action. The last big event that we had was Katrina and Wilma back in 2005.
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2350. hydrus
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Quoting 2344. GetReal:


I am going to go out on a short limb and say that if there is anything left of a LLC with Chantal it is currently near 16N and 72.3W

On motion there is still some evidence of low level clouds spinning in on the south side.

Agreed
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Quoting 2315. Grothar:


I think you are right. That is why I am not writing her off.



NNE winds coming in from recon now
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Hilariously, half the models now want to take the storm south of Jamaica, and the others want to do what Stormpetrol and I said from the start: middle to west end of Cuba...

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2344. GetReal
I am going to go out on a short limb and say that if there is anything left of a LLC with Chantal it is currently near 16N and 72.3W

On motion there is still some evidence of low level clouds spinning in on the south side.






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Quoting 2338. Tropicsweatherpr:


Or this.





Yes...

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2342. StormWx
RIP Chantel
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2341. hydrus
Quoting 2315. Grothar:


I think you are right. That is why I am not writing her off.
If she heading west, The folks at the hurricane center will have a lot to say about Chantal.
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Looking at the incoming Hurricane Hunter data so far as well as the first visible satellite images this morning, it would appear that Tropical Storm Chantal (surprised it's still a tropical storm after the data that came in last night from the Hurricane Hunters) may be attempting a comeback and possibly reorganizing as the wind pattern reported so far looks better and suggests better low level organization than last night. In addition, the latest RGB satellite loops show what could be some semblance of inflow trying to get going in the southwest quadrant.
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2339. Grothar
Fay survived and so did Georges






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Quoting 2330. CaribBoy:
GFS definitely dropped Dorian... maybe because of the unfavorable MJO through the end of July :(


Or this. For the first time this year,the MDR sst anomalies fall to negative. Let's see when they rebound again but between the persistent sal and strong high pressure kicking up the trade winds have cause the waters to cool.



Member Since: April 29, 2009 Posts: 75 Comments: 14210
2337. tj175
Quoting 2300. kingcane:
I don't post often, but I must say Chantal and this blog is as entertaining as the heat spurs series. Chantal like both teams seems to bounce back from the brink of defeat. I woke up at four curious how she was doing and saw no convection, now she is back in the game. Personally I think she will make it over the mountains of both Haiti and Cuba. Going with a Miami (go heat) land fall as a hurricane, probably minimal but she has been so resilient I can't not help but root for her to make(not wish casting, really don't want to see life and property loss) it.


LOL I hope your not looking into a crystal ball, lol.
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Another look
Member Since: August 14, 2010 Posts: 10 Comments: 16756

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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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