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 2530. RTSplayer:


Is that surface? Or flight?

If that's surface that would be incredible given the poor presentation.


Estimated Surface Wind (30 sec. Avg.)
Using Estimated Reduction Factor

SFMR
Peak (10s Avg.) Sfc. Wind
64 knots
(~ 73.6 mph)
Member Since: August 19, 2005 Posts: 5 Comments: 5452

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.4
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 10 JUL 2013 Time : 134500 UTC
Lat : 17:12:35 N Lon : 71:00:30 W


CI# /Pressure/ Vmax
3.4 / 999.0mb/ 53.0kt


Final T# Adj T# Raw T#
3.4 3.6 3.6

Center Temp : -67.5C Cloud Region Temp : -63.4C

Scene Type : UNIFORM CDO CLOUD REGION

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : 0.7T/6hr
Weakening Flag : OFF
Rapid Dissipation Flag : OFF
Member Since: Posts: Comments:
Time: 14:32:30Z
Coordinates: 16.1667N 71.7333W
Acft. Static Air Press: 924.9 mb (~ 27.31 inHg)
Acft. Geopotential Hgt: 805 meters (~ 2,641 feet)
Extrap. Sfc. Press: 1014.7 mb (~ 29.96 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 206° at 8 knots (From the SSW at ~ 9.2 mph)
Air Temp: 19.8°C (~ 67.6°F)
Dew Pt: 19.8°C (~ 67.6°F)
Peak (10s) Flt. Lvl. Wind: 12 knots (~ 13.8 mph)
SFMR Peak (10s) Sfc. Wind: 34 knots (~ 39.1 mph)
SFMR Rain Rate: 17 mm/hr (~ 0.67 in/hr)
(*) Denotes suspect data
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If she still has a llc I am very impress not even her foward movement nor trade winds have kill her.Impressive
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Quoting 2524. RTSplayer:
Well, what I found isn't as good as whatever you're using, but it looks like Chantal is either a depression or a 40mph minimum TS.

Recon was finding winds of 45-50 mph still, shes not a depression.
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Quoting 2510. fabian171017:
I expect Chantal to move into the Gulf strenghtening into an upper end Cat. 2 Hurricane. Then it should move over Florida and up the East Coast steadily strenghtening into Cat. 4 Hurricane striking NYC with 150 mph.
that will nevere happern in july maybe in late august..
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Quoting 2520. ProgressivePulse:
14:36:00Z 16.167N 71.933W
59.1 knots (~ 67.9 mph)
Tropical Storm


WOaa


Is that surface? Or flight?

If that's surface that would be incredible given the poor presentation.
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Quoting 2521. southernema:
Update should be out in about 15 minutes right?
What is everyone's opinion on what it will show?


A shift to the west. A rain event to the FL Keys up the peninsula.
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Recon found a closed Circulation. Very, very ill defined. But it's still there, amazingly.
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2526. LargoFl
for MY area i sure hope this does NOT come true track wise, we do NOT need any more rain here....................
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The circulation is closed it was apperant last night on RGB loops.
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Well, what I found isn't as good as whatever you're using, but it looks like Chantal is either a depression or a 40mph minimum TS.
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Quoting 2517. Levi32:
Chantal will still have a chance to restrengthen later. If one looks at the visible loop below, the trade winds slow in speed greatly north of 17N west of Chantal. Once in this region of the NW Caribbean, the low-level flow into the system will then be convergent, meaning air would be piling up and potentially rising. This would be favorable for restrengthening, but then modest upper-level wind shear and interaction with mountainous Cuba would be the negative factors that could potentially kill her off for good. Even beyond that, she may have another chance in the eastern gulf in the face of a retrograding upper low. It's not over, but for now Chantal has ceased to be an immediately significant threat.


Just amazes me how significantly things can change within 24 hours.
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2522. quante
Tick tock, until 11:00, when NHC will throw some more cold water on old Chantal.
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Update should be out in about 15 minutes right?
What is everyone's opinion on what it will show?
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14:36:00Z 16.167N 71.933W
59.1 knots (~ 67.9 mph)
Tropical Storm


WOaa
Member Since: August 19, 2005 Posts: 5 Comments: 5452
2519. Skyepony (Mod)
Quoting 2467. ProgressivePulse:
Wonder why no VDM was issued. I wonder if they indeed found a closed circulation.


It didn't look good & closed, with no VDM I'd assume it wasn't. They are making another pass at it now.
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If it survives Cuba and makes it to the steaming GOMEX I would not be surprised if it regenerate into at least a strong tropical storm. Rapid intensification doubt it. I guess it will dependo on shear and dry air in the area. I see plenty of misture in the GOMEX anyone here have a clue as to how the shear will be looking this weekend in the GOMEX?
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2517. Levi32
Chantal will still have a chance to restrengthen later. If one looks at the visible loop below, the trade winds slow in speed greatly north of 17N west of Chantal, and have started backing from W to WNW in front of her. Once in this region of the NW Caribbean, the low-level flow into the system will then be convergent, meaning air would be piling up and potentially rising. This would be favorable for restrengthening, but then modest upper-level wind shear and interaction with mountainous Cuba would be the negative factors that could potentially kill her off for good. Even beyond that, she may have another chance in the eastern gulf in the face of a retrograding upper low. It's not over, but for now Chantal has ceased to be an immediately significant threat except for heavy rainfall.

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Quoting 2514. LargoFl:
that HIGH off the east coast wont let that happen.

I hope that doesn't happen.
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2515. GetReal



Interesting???
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2514. LargoFl
Quoting 2510. fabian171017:
I expect Chantal to move into the Gulf strenghtening into an upper end Cat. 2 Hurricane. Then it should move over Florida and up the East Coast steadily strenghtening into Cat. 4 Hurricane striking NYC with 150 mph.
that HIGH off the east coast wont let that happen.
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Recon just flew through the estimated center fix... If she has a circulation, its a wreck and very ill defined..
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From

From 332° at 3 knots
(From the NNW at ~ 3.4 mph)


To


From 147° at 17 knots
(From the SSE at ~ 19.5 mph)


Wind shift but very broad center.
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2511. LargoFl
GFS has it going up the east coast route saturday..way too early yet to believe any one model..by friday we should have a better idea.............................................. ..........
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I expect Chantal to move into the Gulf strenghtening into an upper end Cat. 2 Hurricane. Then it should move over Florida and up the East Coast steadily strenghtening into Cat. 4 Hurricane striking NYC with 150 mph.
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acc/ to my hurricane tracking map the bend to the west last night saved her from going headon into hispanola.
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Quoting 2506. TylerStanfield:

I have it on Google Earth, can't quite remember where I found the download though.


I'll try googling it then. Thanks.
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Quoting 2501. RTSplayer:
Where the heck are you getting live updates on HH mission?

I tried links at NHC.Noaa and it didn't have anything like that.
Link
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Quoting 2501. RTSplayer:
Where the heck are you getting live updates on HH mission?

I tried links at NHC.Noaa and it didn't have anything like that.

I have it on Google Earth, can't quite remember where I found the download though.
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Quoting 2483. RevInFL:
Is Chantal strengthening again? Am I off the hook on the east central FL coast? I am just trying to understand what this little trickster is doing.

Not yet... At this point she could still scrape the East coast, but it's looking more likely that she'll either head right up the peninsula or go west of it.
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Quoting 2501. RTSplayer:
Where the heck are you getting live updates on HH mission?

I tried links at NHC.Noaa and it didn't have anything like that.


http://tropicalatlantic.com/recon/
Member Since: August 19, 2005 Posts: 5 Comments: 5452
2503. GetReal
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2502. LargoFl
Quoting 2499. RitaEvac:


We're becoming a burnt crisp as cracks are widening and opening near foundations of homes, crape-myrtles are drooping and dying, grass is dying.
I hear ya rita..i am hoping it does come your way..only fear is..the gulf waters are real warm..it could get strong again
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Where the heck are you getting live updates on HH mission?

I tried links at NHC.Noaa and it didn't have anything like that.
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Quoting 2491. stormwatcherCI:
They found a pressure reading of 1010 mb.

They haven't got a good center fix quite yet, they've been flying around testing all quadrants to make sure she has a closed circulation. Recon is looking to intercept the Center fix right now.
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Quoting 2486. LargoFl:
my best guess is folks in florida had better keep a good eye on this storm, we all know just how much rain we have been getting the last few weeks..every day..now IF this system comes into florida..imagine the added rainfall it will bring...we surely do NOT need this system coming anywhere near us ...now texas does indeed need its rains..and its nice to see ( and its way early yet) but its nice to see several tracks now Going to texas..so texans this IS a slight chance you can get some of this...we'll see what the maps look like say friday..its way too early yet to tell where she is going....good luck over there


We're becoming a burnt crisp as cracks are widening and opening near foundations of homes, crape-myrtles are drooping and dying, grass is dying, detention ponds are down 3 feet
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Quoting 2492. ProgressivePulse:
Also a non-tasked upper level mission started in the SE CONUS

Product: NOAA High Density (HDOB) Message (URNT15 KWBC)
Transmitted: 10th day of the month at 14:25Z
Date: July 10, 2013
Aircraft: Lockheed WP-3D Orion (Reg. Num. N42RF)
Mission: Non-Tasked Mission, possibly not tropical (flight in the North Atlantic basin)
Mission Identifier: Senex18 (Probably storm name and mission number)
Observation Number: 03


Hey PP,

I'm assuming this mission will be used to input correct steering information into the models, and to ascertain some kind of direction this storm will be going.
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2497. hydrus
Quoting 2457. indianrivguy:
Fay, the "joke"















Good thing Fay was not a large cat-4. That storm had a crush on Florida.
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I don't see much happening to Chantal strenght wise unless it makes it to the GOMEX and it slows down.
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2495. LargoFl
Floridians..the NAM for Saturday..................
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Is it still moving at warp speed
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2493. eddye
do u guys see the convenction loping it looks like it geting a little better organized she not dead jim
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Also a non-tasked upper level mission started in the SE CONUS

Product: NOAA High Density (HDOB) Message (URNT15 KWBC)
Transmitted: 10th day of the month at 14:25Z
Date: July 10, 2013
Aircraft: Lockheed WP-3D Orion (Reg. Num. N42RF)
Mission: Non-Tasked Mission, possibly not tropical (flight in the North Atlantic basin)
Mission Identifier: Senex18 (Probably storm name and mission number)
Observation Number: 03
Member Since: August 19, 2005 Posts: 5 Comments: 5452
Quoting 2485. ProgressivePulse:
Did they forget the center fix, lol.
They found a pressure reading of 1010 mb.
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Hurricane Hunters are finding a decent amount of wind shift to say that she still has a circulation, and there are plentiful amounts of 45 mph wind barbs, so she is likely still a 45-50 mph Tropical Storm.
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2489. LargoFl
remember folks this system may look bad right now, but wait till it hits the gulf stream whose waters are very warm its not over til she sings huh
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Quoting 2429. gator23:
She isnt moving due west really. More NW or WNW. Look at the forecast points. Also if you look at the steering layer she will begin to feel the weakness soon.

Steering: Link

Satellite with forecats points:Link



The forecast points are wrong. They are only updated every 6 hours, and the storm moved due west for about 4 hours straight since they were last updated.
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2486. LargoFl
my best guess is folks in florida had better keep a good eye on this storm, we all know just how much rain we have been getting the last few weeks..every day..now IF this system comes into florida..imagine the added rainfall it will bring...we surely do NOT need this system coming anywhere near us ...now texas does indeed need its rains..and its nice to see ( and its way early yet) but its nice to see several tracks now Going to texas..so texans this IS a slight chance you can get some of this...we'll see what the maps look like say friday..its way too early yet to tell where she is going....good luck over there
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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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