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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See the faster winds out ahead of Chantal, in the Central Caribbean, in the image below?




That is the Caribbean Low-Level Jet (CLLJ). This low-level jet exists semi-permanently as a result of the pressure difference between the subtropical Atlantic ridge and the monsoon/heat low over central America and NW South America (sometimes called the Columbian heat low). Accelerating trade winds ahead of the storm are incredibly detrimental to the low-level organization of a storm. Accelerating trade winds rob the storm of convergence and naturally make it harder for the storm to close off it's circulation. This can cause the storm to degenerate into an open wave, like Ernesto did last year. Additionally, the structure of the low-level flow around the COC gets distorted with accelerating trade winds. The amplitude decreases and wavelength increases creating a duller, less pronounced perturbation in the wind field. This means less convergence, less organization and an expansion of the wind field.

Chantal may very well have degenerated into an open wave by now. Will be interesting to see what recon shows...
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Open waves can be very strong. There's no reason Chantal can't be a 60mph open wave. That may very well be what recon finds.
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At 23:07:30Z (last observation), the observation was 176 miles (283 km) to the ESE (121°) from San Juan, Puerto Rico (USA).

Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 9th day of the month at 23:06Z
Date: July 9, 2013
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 306)
Storm Number: 03
Storm Name: Chantal (flight in the North Atlantic basin)
Mission Number: 3
Observation Number: 03

23:07:30Z 17.117N 63.767W 843.2 mb
(~ 24.90 inHg) 1,630 meters
(~ 5,348 feet) 1017.7 mb
(~ 30.05 inHg) - From 133° at 46 knots
(From the SE at ~ 52.9 mph) 15.7°C
(~ 60.3°F) 12.7°C
(~ 54.9°F) 47 knots
(~ 54.0 mph) 29 knots
(~ 33.3 mph) 0 mm/hr
(~ 0 in/hr) 28.4 knots (~ 32.6 mph)
61.7%
Time Coordinates Aircraft
Static Air Pressure Aircraft
Geopotential Height Extrapolated
Surface Pressure D-value Flight Level Wind (30 sec. Avg.) Air Temp. Dew Point Peak (10 sec. Avg.)
Flight Level Wind SFMR
Peak (10s Avg.) Sfc. Wind SFMR
Rain Rate Estimated Surface Wind (30 sec. Avg.)
Using Estimated Reduction Factor Peak Wind at Flight Level to
Est. Surface Reduction Factor
HDOB Observations
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Quoting 626. Autistic2:
In that case wont they still use the same name?



not if the old low falls a part and the nhc no longer doing updates on the storm
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Quoting 623. Astrometeor:


If anything we are getting worse at this MLC.


Haha! :) That's what makes it fun. Challenging. And, they're all different.
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Quoting 621. Tazmanian:




what you guys thinking of this happening ?


nope I'm not just saying

Taco :o)
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Quoting 618. Camille33:
Chantal is a very organized system right now with expanding polar outflow to the n/ne,with dvorak intensity estimates nearing right around 70 mph. Chantal will come ashore near sw Haiti as a 80 mph system.



now you are wishcasting this storm is not very organized they be lucky if they can even find a close low too all we no the last few hrs we may have been tracking a open wave
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I am using google chrome....
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Quoting 622. weatherlover94:
what are the chances that the storm keeps moving west...never turns until the west coast of cuba and heads for the west coast of Florida ?


Very low.
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Quoting 621. Tazmanian:




what you guys thinking of this happening ?


slim right now
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Quoting 609. Tazmanian:
you no if are CHANTAL fully falls a part after hiting HISPANIOLA and be come a open wave and re fourms a new low we could get Dorian out of CHANTAL
In that case wont they still use the same name?
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Does anyone have the radar loops of Chantal passing Martinique?
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Quoting 618. Camille33:
Chantal is a very organized system right now with expanding polar outflow to the n/ne,with dvorak intensity estimates nearing right around 70 mph. Chantal will come ashore near sw Haiti as a 80 mph system.


0___o
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting 605. moonlightcowboy:
Good evening, weathergeeks! :)

Y'all got this thing figured out yet?


If anything we are getting worse at this MLC.
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what are the chances that the storm keeps moving west...never turns until the west coast of cuba and heads for the west coast of Florida ?
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Quoting 609. Tazmanian:
you no if are CHANTAL fully falls a part after hiting HISPANIOLA and be come a open wave and re fourms a new low we could get Dorian out of CHANTAL




what you guys thinking of this happening ?
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I think there is a 70% chance that Chantal will not be vouchsafed survival across Hispaniola.

10% chance--survives but barely. A closed low remains but is so disorganized it can't recover. A few thunderstorms pop intermittently near the center to give the blog excitement but it never consolidates. 5% chance it then dies across south FL, 5% chance it goes to the Gulf of Mexico to do what it will.

20% chance---Chantal survives and heads NNW across eastern Bahamas, with the beta effect propelling it northwards. The building ridge then turns it more towards the west where it moves inland between Daytona Beach and Savannah as a strong tropical storm (70% chance) or barely a hurricane (30% chance)

In summary

70% chance Hispaniola kills Chantal.
5% chance of tropical depression landfall in S FL and death.
5% chance of development in the Gulf of Mexico
14% chance of a strong tropical storm in NE FL / SE GA
6% chance of a hurricane in NE FL / SE GA
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Chantal is a very organized system right now with expanding polar outflow to the n/ne,with dvorak intensity estimates nearing right around 70 mph. Chantal will come ashore near sw Haiti as a 80 mph system.
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Quoting 607. 1900hurricane:
Chantal certainly has that classic look of a tropical cyclone right now!



#SaidNobodyEver
Looks like a crackhead tropical cyclone.
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interesting to see the wind as soon as recon took off
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Quoting 607. 1900hurricane:
Chantal certainly has that classic look of a tropical cyclone right now!



#SaidNobodyEver


Yep, look at that beautiful eye!
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Miami
NEXRAD Radar

Base Reflectivity 0.50° Elevation
Range 248 NMI

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Funny GIF regarding today's SPC Tornado Outlook. Definitely an off day for them. Link
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Quoting 599. GoWVU:


Could not agree more I am finally drying out somewhat!


No one in the SE States needs rain. i wish this would roll to TX as a TS to help relieve thedrought out there. unfortunatly we dont get what we want.
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Quoting 605. moonlightcowboy:
Good evening, weathergeeks! :)

Y'all got this thing figured out yet?
Nope!...LOL good evening MLC.
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610. GoWVU
Quoting 601. nash36:


Regardless of what Chantal decides to do, we in SC are unfortunately in for another heavy rain event it appears. Stalled front. Lovely.


I know I cut my lawn and my wife's grandmothers lawn tonight.. ugh this is not Charleston weather...
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you no if are CHANTAL fully falls a part after hiting HISPANIOLA and be come a open wave and re fourms a new low we could get Dorian out of CHANTAL
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Chantal certainly has that classic look of a tropical cyclone right now!



#SaidNobodyEver
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Quoting 596. MiamiHurricanes09:
Recon's flying already?


still quite a ways out tho
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Good evening, weathergeeks! :)

Y'all got this thing figured out yet?
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Excerpt from the Miami NWS Disco

.TROPICAL SYSTEMS...
TROPICAL STORM CHANTAL IS CURRENTLY FORECAST BY THE NATIONAL
HURRICANE CENTER TO MOVE TO THE BAHAMAS THIS WEEKEND. AT THIS
TIME...TROPICAL STORM FORCE WINDS CANT BE RULED OUT FOR SOUTH
FLORIDA...PARTICULARLY OVER THE COASTAL AND METRO AREAS OF PALM BEACH COUNTY
ALONG WITH THE ATLANTIC WATERS OF SOUTH FLORIDA FOR SATURDAY.
RESIDENTS AND VISITORS SHOULD CONTINUE TO MONITOR THE LATEST
FORECAST FROM THE NATIONAL HURRICANE CENTER THROUGHOUT THE WEEK AND
INTO THE WEEKEND...AS THE WEATHER OVER SOUTH FLORIDA WILL DEPEND ON
THE LOCATION AND STRENGTH OF CHANTAL.
Member Since: September 10, 2007 Posts: 0 Comments: 11264
Quoting 595. BaltimoreBrian:


The picture of Dorian. Will it be gray?


I think the season will explode in august like it did last year.
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Quoting 600. Patrap:


Went early seems, as per the Low Sun Angle I figure.
Yeah, it was scheduled for a little later. Thanks.
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Quoting 599. GoWVU:


Regardless of what Chantal decides to do, we in SC are unfortunately in for another heavy rain event it appears. Stalled front. Lovely.
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Quoting 596. MiamiHurricanes09:
Recon's flying already?


Went early seems, as per the Low Sun Angle I figure.
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599. GoWVU
Quoting 571. scwindsaloft:
Sure don't need any more rain here in coastal SC....
Could not agree more I am finally drying out somewhat!
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Quoting 596. MiamiHurricanes09:
Recon's flying already?



yes
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Quoting 586. Patrap:
Recon's flying already?
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Quoting 584. FunnelVortex:
When will we see our first photogenic storm?


The picture of Dorian. Will it be gray?
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Quoting 588. Autistic2:
The difference between models and the ensemble models is what? Which ones are the gooderest or does they all give important feedbacks? At 65 she is knocking on the hurricane 1 door!

If a storm is at 50 and moving at 25 then the front of it would really be at 25 but the back would be at 75? Is I correct on how this works?

How to get to Levis blog again, lost link. He still make great videos this year?

Thank you
Link
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting 553. wunderkidcayman:

Hmm I'm thinking maybe weakening of the ULL building of Bermuda high as well building of NE GOM high this however is highly dependant on what chantal does it's pressure it's organisation it's location it's
I'd say the conditions could be better IMO



Nope their not they are just shift off westward

Still headed west?
Member Since: September 2, 2011 Posts: 0 Comments: 1148
Quoting 581. Joanie38:
Hello everyone from Louisiana!!! Watching Chantal...I have a question...how can you keep this blog from automatically refreshing on ya?!?! It is hard to read anything when your page keeps refreshing.....UGH....


TIA!

\


what browser you using?
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Quoting 583. stormpetrol:
Probably will amaze or shock some what the HHs will find on this mission, just sayin....


already had 50 knot flight level winds
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Yeah. Chantal looks like chewed up bubble gum, but she looked like hell last night and survived. We'll see...
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Quoting 583. stormpetrol:
Probably will amaze or shock some what the HHs will find on this mission, just sayin....


an open wave?
Member Since: Posts: Comments:
The difference between models and the ensemble models is what? Which ones are the gooderest or does they all give important feedbacks? At 65 she is knocking on the hurricane 1 door!

If a storm is at 50 and moving at 25 then the front of it would really be at 25 but the back would be at 75? Is I correct on how this works?

How to get to Levis blog again, lost link. He still make great videos this year?

Thank you
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Quoting 573. weatherlover94:
there is no way Chantal is a 65 mph open wave
Don't bet on that. When Dolly crossed the Cayman Islands we had very strong TS winds but no closed coc.
Member Since: October 9, 2008 Posts: 0 Comments: 8392
At 22:57:30Z (last observation), the observation was 147 miles (236 km) to the ESE (120°) from San Juan, Puerto Rico (USA).


Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 9th day of the month at 22:56Z
Date: July 9, 2013
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 306)
Storm Number: 03
Storm Name: Chantal (flight in the North Atlantic basin)
Mission Number: 3
Observation Number: 02

22:57:30Z 17.350N 64.133W 845.6 mb
(~ 24.97 inHg) 1,603 meters
(~ 5,259 feet) 1017.4 mb
(~ 30.04 inHg) - From 125° at 45 knots
(From the SE at ~ 51.7 mph) 16.2°C
(~ 61.2°F) 12.2°C
(~ 54.0°F) 46 knots
(~ 52.9 mph) - - - -
Time Coordinates Aircraft
Static Air Pressure Aircraft
Geopotential Height Extrapolated
Surface Pressure D-value Flight Level Wind (30 sec. Avg.) Air Temp. Dew Point Peak (10 sec. Avg.)
Flight Level Wind SFMR
Peak (10s Avg.) Sfc. Wind SFMR
Rain Rate Estimated Surface Wind (30 sec. Avg.)
Using Estimated Reduction Factor Peak Wind at Flight Level to
Est. Surface Reduction Factor
HDOB Observations
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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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