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 770. BaltimoreBrian:
Chantal's 8 p.m. advisory by the NHC is out.

wow, this is surprising:
MAXIMUM SUSTAINED WINDS ARE NEAR 65 MPH...100 KM/H...WITH HIGHER GUSTS. THESE WINDS ARE CONFINED TO A SMALL AREA TO THE EAST THE CENTER. CHANTAL IS FORECAST TO BE NEAR HURRICANE STRENGTH BEFORE REACHING HISPANIOLA.

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Looks more like WWNW on the last couple frames! :P
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for the first time since I been on here I reported and ignored somebody
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783. Kumo
Quoting 760. stormhawg:
Damn....just when I thought Jeffy the troll was dead....


I just put him on ignore. I tried giving him some advice yesterday on his "people skills", but he wouldn't listen.


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I cannot for the life of me understand how Chantal could have such poor convective structure, and yet contain such a well formed surface circulation accompanied by moderate winds extending outwards a good distance (post 672, yes, I'm aware everyone thinks those are unreliable, but trust me, even if it is partially wrong, the previous HH mission certainly provided evidence of the circulation).

If anyone can explain this phenomenon, it would be greatly appreciated. TIA

-FW6

P.S. Even if the current HH mission finds that the circulation has dissipated, the question still stands about earlier in the day when the 2nd mission was flying.
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Quoting 770. BaltimoreBrian:
Chantal's 8 p.m. advisory by the NHC is out.


Nothing has changed really
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778. SLU
Quoting 768. GTstormChaserCaleb:
How did you all fare in St. Lucia? Yes I agree a remarkable storm considering its origins and how early in the season it developed in the MDR.


We were ok. The worst hit Martinique and just missed us. We had a few fallen trees and power outages but everything's back to normal. Thanks.
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Quoting 772. WDEmobmet:
New convection starting to fire in the center... No open wave here





LOL



recon will tell you if its a open wave not by looking at the IR
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Quoting 764. weatherlover94:
not going to give a name. I am just going to say this is from a Hurricane forecaster and a respected friend of mine

A combination of the wind shear, and Chantal’s fast forward speed will continue to pose a battle for the system as it continues to head toward Hispaniola.

Based on current motion in satellite imagery, and current steering, the forecast track for Chantal has initially shifted very slightly westward, and may put her crossing of Hispaniola, slightly south of the center of the Island.

However, based on the current run of the 12Z forecast steering layers maps (Valid 00Z tonight), even though I pretty much concur with the official forecast track, I prefer the track shape from the Bahamas, to point of landfall, of that between the TVCC / TVCN and AVNI Dynamic Model Guidance. Of course as fluctuations in storm strength, and steering occur, subtle changes to track will most likely occur between now and by the time the system reaches the Bahamas.

Based on this, and if nothing changes much, Tropical Storm Watches could go up for the Florida Peninsula, up to just north of the SC border as early as Fri. morning.

Based on the current wind shear product, and the last update of the Zonal Shear forecast, Chantal may only strengthen slightly more, and become a 70 mph Tropical Storm prior to crossing the Hispaniola coastline. Once she traverses Hispaniola, I do expect some disruption of the system, however with her fast forward speed, and small COC, she may not too much trouble recovering as she enters the Bahamas, especially with a slow down in forward motion. As steering becomes weak and she slows int he Bahamas, timing will depend on how strong she may become. Based on the Zonal Shear, the upper level environment becomes the most conducive prior to a second landfall in the SEUS. Based on the brief time frame, I concur with the NHC intensity forecast, albeit any further slowing just prior to landfall, or improvement of the upper level pattern, I would not rule out a 60 or 70 mph storm.


Deepthroat again?
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Quoting 742. stormpetrol:


I have said that basically all along, my thinking is much in line yours if you've been reading my comments.



HWRF from a few days ago had the storm going to western Cuba, slightly north of the current NGFDL track seen here:




I will admit that my initial intuition even before it was named was that might be the scenario, but it is true that the steering hasn't been that west biased since then. There's a little more northerly play than previously, but I'm still not buying the whole "goes up the east coast" thing at this time.

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Both the GFS and the CMC are now splitting the Cape Verde Wave in half on their runs. I'm not exactly sure if this is valid or not, but We may or may not get Dorian out of this.
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That ULL isn't moving that quickly..What direction is it suppose to move..Lots of shear ahead for Chantal..
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New convection starting to fire in the center... No open wave here

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No Chantal is going to retrograde back to Africa.
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Quoting 759. SLU:
The last few visible frames did show a closed circulation. I expect that the RECON will still find westerlies. Quite remarkable. This really is a storm unlike what we've grown accustomed to in the past.

How did you all fare in St. Lucia? Yes I agree a remarkable storm considering its origins and how early in the season it developed in the MDR.
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I thought tropical storms are suppose to wane like Chantal is doing now...more so than hurricanes?
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765. FOREX
Quoting 757. BaltimoreBrian:
HWRF loses it and treats Chantal as a new storm after Hispaniola.



At its current speed and direction, I think we can stop talking about tall mountains, etc.
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not going to give a name. I am just going to say this is from a Hurricane forecaster and a respected friend of mine

A combination of the wind shear, and Chantal’s fast forward speed will continue to pose a battle for the system as it continues to head toward Hispaniola.

Based on current motion in satellite imagery, and current steering, the forecast track for Chantal has initially shifted very slightly westward, and may put her crossing of Hispaniola, slightly south of the center of the Island.

However, based on the current run of the 12Z forecast steering layers maps (Valid 00Z tonight), even though I pretty much concur with the official forecast track, I prefer the track shape from the Bahamas, to point of landfall, of that between the TVCC / TVCN and AVNI Dynamic Model Guidance. Of course as fluctuations in storm strength, and steering occur, subtle changes to track will most likely occur between now and by the time the system reaches the Bahamas.

Based on this, and if nothing changes much, Tropical Storm Watches could go up for the Florida Peninsula, up to just north of the SC border as early as Fri. morning.

Based on the current wind shear product, and the last update of the Zonal Shear forecast, Chantal may only strengthen slightly more, and become a 70 mph Tropical Storm prior to crossing the Hispaniola coastline. Once she traverses Hispaniola, I do expect some disruption of the system, however with her fast forward speed, and small COC, she may not too much trouble recovering as she enters the Bahamas, especially with a slow down in forward motion. As steering becomes weak and she slows int he Bahamas, timing will depend on how strong she may become. Based on the Zonal Shear, the upper level environment becomes the most conducive prior to a second landfall in the SEUS. Based on the brief time frame, I concur with the NHC intensity forecast, albeit any further slowing just prior to landfall, or improvement of the upper level pattern, I would not rule out a 60 or 70 mph storm.
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Quoting 746. GeoffreyWPB:
We need Grothar's analysis. Let's see if we can get him in...



my girlfriends phone just did the noise when Sammy krinkles her nose.. its her text alert...
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Is it bad to wish that a bloggers house would go out of power or maybe wish that they forgot to pay the power bill... Gesss some people

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everyone from miss to fla be prepared it coming in some shape form or fashion
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Damn....just when I thought Jeffy the troll was dead....
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759. SLU
The last few visible frames did show a closed circulation. I expect that the RECON will still find westerlies. Quite remarkable. This really is a storm unlike what we've grown accustomed to in the past.

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Quoting 745. Chicklit:



I was thinking the image of Chantal looked more like an angry cat, but I always fail the Rorschach Test...
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HWRF loses it and treats Chantal as a new storm after Hispaniola.

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Quoting 742. stormpetrol:


I have said that basically all along, my thinking is much in line yours if you've been reading my comments.


I have been. :) We're in the very small percent that's remotely considered the prospect of a more westerly system. So, that means we're prolly gonna be wrong. Go figure! Won't be the first time here.
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Quoting 751. moonlightcowboy:


Thank you, Taz, for reminding me. No, I don't think there'll be any RI, at least not until if it does indeed trek a bit more westerly. But what the heck do I know, friend? ;) Not much! I just don't follow the models - you know that! :)

What do you think it's gonna do?




am not so sure any more lol i think the HH will find a open wave then oh nos they may find a hurrican
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Quoting 750. eyewallblues:
I submit that these west Pac storms are more impressive in part, because they have great names!!! What sounds more dangerous...Chantal...or Typhoon Soulik.
No Contest.


Chantal sounds more dangerous to take home...


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Quoting 747. EricSFL:


Remember rule #7 ;)




dont be a smarty pants
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Quoting 736. Tazmanian:




i hop you no that you have too have the right wind shear for it too go RI right and right now you we dont have the right wind shear


Thank you, Taz, for reminding me. No, I don't think there'll be any RI, at least not until if it does indeed trek a bit more westerly. But what the heck do I know, friend? ;) Not much! I just don't follow the models - you know that! :)

What do you think it's gonna do?
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Quoting 685. Envoirment:
Typhoon Soulik looks marvelous


I submit that these west Pac storms are more impressive in part, because they have great names!!! What sounds more dangerous...Chantal...or Typhoon Soulik.
No Contest.
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Quoting 712. GTstormChaserCaleb:
Remember if Chantal moves more westbound which model saw it first...you got it the NOGAPS :D


If that is the case then we have bigger problems
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Probably not so far north.

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Quoting 727. Tazmanian:



he saw nothing 1st


i saw it 1st


Remember rule #7 ;)
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We need Grothar's analysis. Let's see if we can get him in...

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Quoting 730. moonlightcowboy:
Meanwhile, I'm thinking she's actually going to miss Hispaniola (maybe graze it), and keep trucking more westerly (still a generally weak system), but getting the heave-to westerwards by that strong low/mid-level easterly flow - just like she has been after butting up against the stiff high pressure. Plus, that ULL is going to help drag her along a bit further west as it retrogrades. There's just enough distance between them not to pull Chantal too far north, but it will eventually help pull her over Cuba and into the GoM.

If she's not careful, she's gonna wind up hitting some high TCHP values. If that happens, all bets have to be pulled back and rethought a bit.


I have said that basically all along, my thinking is much in line yours if you've been reading my comments.
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740. HCW
The only thing Chantal is missing is a silver pole :)
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Quoting 730. moonlightcowboy:
Meanwhile, I'm thinking she's actually going to miss Hispaniola (maybe graze it), and keep trucking more westerly (still a generally weak system), but getting the heave-to westerwards by that strong low/mid-level easterly flow - just like she has been after butting up against the stiff high pressure. Plus, that ULL is going to help drag her along a bit further west as it retrogrades. There's just enough distance between them not to pull Chantal too far north, but it will eventually help pull her over Cuba and into the GoM.

If she's not careful, she's gonna wind up hitting some high TCHP values. If that happens, all bets have to be pulled back and rethought a bit.
Quoting 730. moonlightcowboy:
Meanwhile, I'm thinking she's actually going to miss Hispaniola (maybe graze it), and keep trucking more westerly (still a generally weak system), but getting the heave-to westerwards by that strong low/mid-level easterly flow - just like she has been after butting up against the stiff high pressure. Plus, that ULL is going to help drag her along a bit further west as it retrogrades. There's just enough distance between them not to pull Chantal too far north, but it will eventually help pull her over Cuba and into the GoM.

If she's not careful, she's gonna wind up hitting some high TCHP values. If that happens, all bets have to be pulled back and rethought a bit.
Quoting 730. moonlightcowboy:
Meanwhile, I'm thinking she's actually going to miss Hispaniola (maybe graze it), and keep trucking more westerly (still a generally weak system), but getting the heave-to westerwards by that strong low/mid-level easterly flow - just like she has been after butting up against the stiff high pressure. Plus, that ULL is going to help drag her along a bit further west as it retrogrades. There's just enough distance between them not to pull Chantal too far north, but it will eventually help pull her over Cuba and into the GoM.

If she's not careful, she's gonna wind up hitting some high TCHP values. If that happens, all bets have to be pulled back and rethought a bit.
Quoting 730. moonlightcowboy:
Meanwhile, I'm thinking she's actually going to miss Hispaniola (maybe graze it), and keep trucking more westerly (still a generally weak system), but getting the heave-to westerwards by that strong low/mid-level easterly flow - just like she has been after butting up against the stiff high pressure. Plus, that ULL is going to help drag her along a bit further west as it retrogrades. There's just enough distance between them not to pull Chantal too far north, but it will eventually help pull her over Cuba and into the GoM.

If she's not careful, she's gonna wind up hitting some high TCHP values. If that happens, all bets have to be pulled back and rethought a bit.
thats what i keep saying i totally agree with you
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Quoting 702. tornadodude:



You may want to remove that,off topic posts during storms are not allowed.
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Chantal---Westward...
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Quoting 730. moonlightcowboy:
Meanwhile, I'm thinking she's actually going to miss Hispaniola (maybe graze it), and keep trucking more westerly (still a generally weak system), but getting the heave-to westerwards by that strong low/mid-level easterly flow - just like she has been after butting up against the stiff high pressure. Plus, that ULL is going to help drag her along a bit further west as it retrogrades. There's just enough distance between them not to pull Chantal too far north, but it will eventually help pull her over Cuba and into the GoM.

If she's not careful, she's gonna wind up hitting some high TCHP values. If that happens, all bets have to be pulled back and rethought a bit.




i hop you no that you have too have the right wind shear for it too go RI right and right now you we dont have the right wind shear
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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.