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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1786. 7544
what time will the plane go in
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HH's if they don't find a well defined center. This will be downgraded to a tropical wave or inverted trough of low pressure. This doesn't mean it will not get better organized once it nears cuba by Thurs night but right now.. Chantal is almost another that came and went.
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Quoting 1753. KoritheMan:


I really don't see why the GFS dropped it. Upper-level winds look at least light, if not anticyclonic. As long as it stays south of 20N, it should be fine.


Hey, Kori seems to be the trade winds also!!!
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Quoting 1778. alexhurricane1991:
Oh I know just don't want to see it


If the pattern remains this way all summer, and we still avoid a major hurricane, I will seriously consider the credibility of governmental weather modification.

It's one thing to have an out to sea year when there's an east coast trough, but in years with an east coast ridge like this one...

Only so many times before it can no longer be called a coincidence.

But I don't want to open a can of worms here, or veer off topic. That's for another time, but this year should be very telling.
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1782. 7544
ull saves the day
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Quoting 1769. nigel20:

Agreed. I would not want to be anywhere close to a Dean type storm anytime soon.

Hurricane Dean.


Try this bad boy, Ivan.



He was a hurricane before the lesser antillies too.
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Although there still appears that there maybe some spin (not even sure that is closed circulation on the San Juan radar... The beam is shooting pretty high up at that point. Perhaps mid level circulation still exists, but I don't think there is a surface reflection any longer. If there is mid level circulation, then deep convection could bring it back down to the surface. But it is moving waaaaaay to fast for that. I say Chantal is no more. It is so hard to maintain integrity moving that fast. Who knows what may happen if/when it gets north of Hispanola.
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Quoting 1776. KoritheMan:


Or in Chantal's case, migraine-inducing. v_v


lol. yep.
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Quoting 1773. KoritheMan:


Like it not, another big US year will eventually be in store.

I don't know if it'll be this year, or 2014, or 2015, or 2016, but...

You get the idea.

I just hope people remember how relentless things can get. I do.
Oh I know just don't want to see it
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Quoting 1773. KoritheMan:


Like it not, another big US year will eventually be in store.

I don't know if it'll be this year, or 2014, or 2015, or 2016, but...

You get the idea.

I just hope people remember how relentless things can get. I do.
Sometimes people forget how rare seasons in 2000s were, especially 2005. People are always expecting more. Also, this is July. It's not normal for a wave to turn into a tropical storm entering Caribbeans. This is good hint of active season, but we already lost the pace with 2005 season.
Member Since: August 1, 2011 Posts: 28 Comments: 8075
Quoting 1774. AtHomeInTX:


Yeah. That's one thing you can usually count on in weather things usually change. Which keeps it interesting. :)


Or in Chantal's case, migraine-inducing. v_v
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1775. nigel20
Quoting 1772. stormchaser19:


Yeah, Hurricane Dean was already hurricane when he passed windward islands.

It's outer eyewall went just to the south of us.
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Quoting 1770. KoritheMan:


It's still possible the pattern will change, but it hasn't so far.


Yeah. That's one thing you can usually count on in weather things usually change. Which keeps it interesting. :)
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Quoting 1771. alexhurricane1991:
better change quick though or else well I don't need to go any further.


Like it not, another big US year will eventually be in store.

I don't know if it'll be this year, or 2014, or 2015, or 2016, but...

You get the idea.

I just hope people remember how relentless things can get. I do.
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Quoting 1769. nigel20:

Agreed. I would not want to be anywhere close to this:

Hurricane Dean.


Yeah, notice that Hurricane Dean was already hurricane when he passed windward islands.
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Quoting 1770. KoritheMan:


It's still possible the pattern will change, but it hasn't so far.
better change quick though or else well I don't need to go any further.
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Quoting 1761. AtHomeInTX:


Yep, I hope it will be another long while before we see another. If we have one of those this year I hope it finds a break in the ridge and heads to the north Atlantic. Steering looks scary though so far.


It's still possible the pattern will change, but it hasn't so far.
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1769. nigel20
Quoting 1757. KoritheMan:


Been awhile since we had one of those bad boys in the Caribbean.
Quoting 1761. AtHomeInTX:


Yep, I hope it will be another long while before we see another. If we have one of those this year I hope it finds a break in the ridge and heads to the north Atlantic. Steering looks scary though so far.

Agreed. I would not want to be anywhere close to a Dean type storm anytime soon.

Hurricane Dean.
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Quoting 1763. GTstormChaserCaleb:
It is moving too fast for one and it was supposed to turn more north and take a path towards DR. Also the ULL decided to back southwest instead of heading west into the GOM. Basically the conditions upstream went from favorable to unfavorable just like that.


The upstream conditions were never really favorable. I don't know if I'd use quite such strong wording, lol.
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This might be Chantal's final hours. Possible NHC could declare this an open wave at 2 am or 5 am.
Member Since: August 1, 2011 Posts: 28 Comments: 8075
Ahem...

Station 42059
NDBC
Location: 15.058N 67.528W
Date: Wed, 10 Jul 2013 04:50:00 UTC
Winds: SE (130°) at 15.5 kt gusting to 21.4 kt
Significant Wave Height: 5.2 ft
Dominant Wave Period: 7 sec
Mean Wave Direction: ENE (60°)
Atmospheric Pressure: 29.93 in and falling
Air Temperature: 80.1 F
Dew Point: 75.6 F
Water Temperature: 82.8 F
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Quoting 1753. KoritheMan:


I really don't see why the GFS dropped it. Upper-level winds look at least light, if not anticyclonic. As long as it stays south of 20N, it should be fine.


They toyed with idea of bringing it back a little on this run. Lost it right at the Caribbean though.
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Chantal really looks like its dying out, it might not survive the night.
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Quoting 1758. Astrometeor:


No, it looked good this morning on radar as it passed the Lesser Antilles. This afternoon is when the storm has completely gone wrong.
It is moving too fast for one and it was supposed to turn more north and take a path towards DR. Also the ULL decided to back southwest instead of heading west into the GOM. Basically the conditions upstream went from favorable to unfavorable just like that.
Member Since: June 30, 2013 Posts: 12 Comments: 8774
Quoting 1760. GTstormChaserCaleb:
You can see what the combination of speed shear from the LLJ and Westerly Wind Shear is doing to Chantal.

Dang speed kills
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Quoting 1757. KoritheMan:


Been awhile since we had one of those bad boys in the Caribbean.


Yep, I hope it will be another long while before we see another. If we have one of those this year I hope it finds a break in the ridge and heads to the north Atlantic. Steering looks scary though so far.
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You can see what the combination of speed shear from the LLJ and Westerly Wind Shear is doing to Chantal.

Member Since: June 30, 2013 Posts: 12 Comments: 8774
Quoting 1753. KoritheMan:


I really don't see why the GFS dropped it. Upper-level winds look at least light, if not anticyclonic. As long as it stays south of 20N, it should be fine.
Yeah and looking at it right now I wouldn't be surprised if it gets a mention on the 8 am two
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Quoting 1752. jabjb2:
Like I said earlier today, the reason the HHs were finding such strong winds was because of the pressure gradient. This storm became an open wave yesterday and should have been downgraded.


No, it looked good this morning on radar as it passed the Lesser Antilles. This afternoon is when the storm has completely gone wrong.
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Quoting 1750. AtHomeInTX:


And to be grateful THAT'S not in the Caribbean.


Been awhile since we had one of those bad boys in the Caribbean.
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you may get your wish.
Hunters are inbound.

Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 10th day of the month at 04:48Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 301)

Storm Number: 03

Storm Name: Chantal (flight in the North Atlantic basin)

Mission Number: 4

Observation Number: 01

Mandatory Data...

Observation Time: Wednesday, 4:45Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 16.6N 66.5W
Location: 129 miles (207 km) to the SSW (193°) from San Juan, Puerto Rico (USA).
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 920 meters
Flight Level Wind: From 130° at 41 knots (From the SE at ~ 47.1 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: 19°C
Flight Level Dew Point: 19°C
Weather (within 30 nautical miles): Unknown, either due to darkness or some other cause
925 mb Surface Altitude: 842 geopotential meters

Remarks Section - Remarks That Were Decoded...

Surface Wind Speed (likely by SFMR): 32 knots (~ 36.8mph)

Remarks Section - Additional Remarks...

NE INBOUND

Quoting 1736. Bluestorm5:
Just end my suffering, NHC and Hunters... declare this an OPEN wave. Just strip it of name. I don't wanna track this anymore, Mommy.
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Quoting 1742. GTstormChaserCaleb:
No NHC let them suffer some more besides I am not ready to wave the white flag yet.

I'm not ready either. I dont give up that easily...
Member Since: September 2, 2011 Posts: 0 Comments: 1149
1754. nigel20
Quoting 1750. AtHomeInTX:


And to be grateful THAT'S not in the Caribbean.

Yes indeed!
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Quoting 1748. alexhurricane1991:
even though the models don't develop it that African wave could become something


I really don't see why the GFS dropped it. Upper-level winds look at least light, if not anticyclonic. As long as it stays south of 20N, it should be fine.
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1752. jabjb2
Like I said earlier today, the reason the HHs were finding such strong winds was because of the pressure gradient. This storm became an open wave yesterday and should have been downgraded.
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Quoting 1746. KoritheMan:
2300Z partial WindSAT pass. Difficult to gauge the circulation with only a partial pass, but it looks more reminiscent of an open wave to me, albeit a sharp one.

i think that this not Chantal anymore its a open wave but lets see what recon reports.
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Quoting 1745. nigel20:
I guess that we have Soulik to look on. :)


And to be grateful THAT'S not in the Caribbean.
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Quoting 1745. nigel20:
I guess that we have Soulik to look on. :)
You mean Soulik looks at you get it right, Nigel ;)
Member Since: June 30, 2013 Posts: 12 Comments: 8774
even though the models don't develop it that African wave could become something
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Quoting 1742. GTstormChaserCaleb:
No NHC let them suffer some more besides I am not ready to wave the white flag yet.
Yeah, better keep tracking the storm. It could get stronger again and Haiti/DR are still in the path.
Member Since: August 1, 2011 Posts: 28 Comments: 8075
2300Z partial WindSAT pass. Difficult to gauge the circulation with only a partial pass, but it looks more reminiscent of an open wave to me, albeit a sharp one.

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1745. nigel20
I guess that we have Soulik to look on. :)

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The CMC hasn't given up yet.

Member Since: June 30, 2013 Posts: 12 Comments: 8774
I like how the gfs last night showed pretty much doom then tonight nothing
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Quoting 1736. Bluestorm5:
Just end my suffering, NHC and Hunters... declare this an OPEN wave. Just strip it of name. I don't wanna track this anymore, Mommy.
No NHC let them suffer some more besides I am not ready to wave the white flag yet.
Member Since: June 30, 2013 Posts: 12 Comments: 8774
1741. geepy86
nothing to see here, move along folks
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Quoting 1729. TomTaylor:
Chantal looking amazing right now!



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1739. geepy86
rip
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Nothing here, but again look at the position of the Bermuda High:

Member Since: June 30, 2013 Posts: 12 Comments: 8774
Quoting 1729. TomTaylor:
Chantal looking amazing right now!


Not even Ernesto or Isaac could achieve this level of beauty.
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Just end my suffering, NHC and Hunters... declare this an OPEN wave. Just strip it of name. I don't wanna track this anymore, Mommy.
Member Since: August 1, 2011 Posts: 28 Comments: 8075

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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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