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 932. ProgressivePulse:
Chantal looks like she wants to make another run at a CDO this evening. Convection is expanding and deepening over the center currently. CIMMS still shows good convergence/divergence so she should be able to maintain. Shear is currently 20kts over the center.







She's may be trying to bounce back
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985. HadesGodWyvern (Mod)
Category Four Typhoon Named Cyclone In Sea South Of Japan

At 9:00 AM JST, Typhoon Soulik (925 hPa) located at 21.0N 136.5E has 10 minute sustained winds of 100 knots with gusts of 140 knots. The cyclone is reported as moving west northwest at 12 knots.

Storm Force Winds
==================
100 NM from the center

Gale Force Winds
===============
240 NM from the center

Dvorak Intensity: T6.5

Forecast and Intensity
=======================
24 HRS: 22.0N 130.6E - 105 knots (CAT 5/Intense Typhoon) South Of Japan
48 HRS: 23.1N 125.5E - 105 knots (CAT 5/Intense Typhoon) near Miyako Island
72 HRS: 25.8N 120.7E - 90 knots (CAT 4/Very Strong Typhoon) Overland Taiwan
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I see a d storm in the next five days..
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Quoting HighPressureLarry:
Chantral is dead

LOL. Pretty impressive forecast for your fourth post, especially since you don't seem to know the name of the storm you're killing off. :-)
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Chantel has weakened to a 60 mph tropical storm and the intensity is dropping it still to a 40 mph tropical storm then coming back close to a 70 mph storm at the end of the period.
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Quoting 977. scott39:
That would be babies mamma.


lol dokey okey
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Quoting 969. HighPressureLarry:
Chantral is dead


No, it's not actually. Chantal has not looked too hot since about 11 this morning, however, The storm is now firing some healthy convection near the coc. Dmax should be really interesting.
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At 00:47:30Z (last observation), the observation was 184 miles (296 km) to the S (174°) from San Juan, Puerto Rico (USA).


Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 10th day of the month at 00:47Z
Date: July 10, 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: 13


00:47:30Z 15.767N 65.750W 843.2 mb
(~ 24.90 inHg) 1,591 meters
(~ 5,220 feet) 1011.4 mb
(~ 29.87 inHg) - From 144° at 22 knots
(From the SE at ~ 25.3 mph) 18.4°C
(~ 65.1°F) 15.7°C
(~ 60.3°F) 23 knots
(~ 26.4 mph) 22 knots
(~ 25.3 mph) 0 mm/hr
(~ 0 in/hr) 21.0 knots (~ 24.2 mph)
95.7%
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 972. will40:



who is Chantral?
That would be my babies mamma.
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looking at 18Z models and 00Z models they haved moved West again with the exception of one or two
Member Since: June 13, 2009 Posts: 2 Comments: 11018
Quoting wunderkidcayman:
well guys I said it and almost all of ya said no and call me wishcaster and westcaster so ha

You said what exactly? That Chantal would move more westerly, as she has done for her entire history, regardless of model persistence? Exactly how far west do you think she will go? There was never any doubt in my mnd that she would go further west than the models said but if you're implying that she will get to the Caymans, or even Jamaica, I would still call you a wishcaster.
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Quoting Hurricanes305:
People waiting to poof her should practice practice patient as this is going to be a long flight.


And it's daytime here so I can keep track the whole time. How are you Canes305
Member Since: September 30, 2007 Posts: 9 Comments: 15932
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Quoting 969. HighPressureLarry:
Chantral is dead



who is Chantral?
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The HWRF seems to initialize the pressure and wind speeds almost perfectly:



But look at where it takes it and look at how much more weaker it is, now that doesn't make sense...weaker more west, stronger more poleward:

Member Since: June 30, 2013 Posts: 11 Comments: 7473
970. DVG
My first impression was that the burst of convection did indeed represent the center. It may be that it is or will become the center after all is said and done. However, looking at the water vapor loop in rock mode made me think twice about that. Using that tool, the center seems to be where the NHC thinks it should be.

Time will tell.

If I had a nickel for every time someone said this was a storm unlike any other I'd be rich.
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Chantral is dead
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Quoting wunderkidcayman:
well guys I said it and almost all of ya said no and call me wishcaster and westcaster so ha


If you turn off your atmospheric suction machine off Chantal might start moving NW. LOL
Member Since: September 30, 2007 Posts: 9 Comments: 15932
Quoting 941. GTstormChaserCaleb:
Yep there it is just blew up in the last frame and westbound she goes.



That is worrying to me in South Florida and should be worrying to those in Jamaica too.
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Chantal 15.1 N 65.1 W moving W 280 degrees at 27mph. 00Z models have shifted W....Tropical Atlantic
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Quoting 958. Hurricanes101:


interesting, since the nhc said at 5pm that it was possible the westward shift would continue



IF THIS WESTWARD
MODEL TREND CONTINUES IN THE NEXT CYCLE
...I WILL NOT BE SURPRISED
IF ANOTHER WESTWARD SHIFT WILL BE REQUIRED.
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At 00:37:30Z (last observation), the observation was 159 miles (255 km) to the S (181°) from San Juan, Puerto Rico (USA).

Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 10th day of the month at 00:37Z
Date: July 10, 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: 12

00:37:30Z 16.117N 66.100W 843.2 mb
(~ 24.90 inHg) 1,596 meters
(~ 5,236 feet) 1012.6 mb
(~ 29.90 inHg) - From 81° at 37 knots
(From the E at ~ 42.5 mph) 17.5°C
(~ 63.5°F) 16.4°C
(~ 61.5°F) 39 knots
(~ 44.8 mph) 35 knots
(~ 40.2 mph) 0 mm/hr
(~ 0 in/hr) 33.2 knots (~ 38.2 mph)
89.7%
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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Interesting little pressure drop.

004400 1554N 06552W 8430 01583 0095 +195 +170 094022 025 027 000 00
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Quoting 958. Hurricanes101:


interesting, since the nhc said at 5pm that it was possible the westward shift would continue


Once again......no one knows :P
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Quoting 948. MiamiHurricanes09:
And the models have shifted a little bit back to the east. [TVCN] Still west of the NHC plot.



Those models look the same from earlier.
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People waiting to poof her should practice practice patient as this is going to be a long flight.
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Quoting 948. MiamiHurricanes09:
And the models have shifted a little bit back to the east. [TVCN] Still west of the NHC plot.



interesting, since the nhc said at 5pm that it was possible the westward shift would continue
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Quoting 950. Hurricanes101:


the atcf coordinates show were for 8pm, its based on satellite, but the nhc will go with what recon says


Oh Ok cool...so if the winds don't get above 50MPH thats what they will probably go with instead then.
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Quoting 946. AussieStorm:


This blog doesn't really work with IE, New format you need to scroll down the page to quote on Chrome, but classic format there is no problems except you can't see who has 'ed your comments.







Thanks Aussie. I saw my comments were in italics (should have been a clue, huh?. I use Chrome.
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well guys I said it and almost all of ya said no and call me wishcaster and westcaster so ha
Member Since: June 13, 2009 Posts: 2 Comments: 11018
Quoting 938. Stormchaser121:
I think the models will continue to move further west. Thats the trend.


I'm inclined to agree if for no other reason than the most recent HH center fix is such a hard west turn from the advisory.

I guess two big things that are going to screw me up are the ULL has moved slower than I thought; I expected it to be a degree or so further west. Also, the very shallow convection this storm has generally maintained throughout it's existence would seem to undermine the mean steering layer product because it's pressure and convection thickness is not consistent with it's wind speeds. I'm not convinced steering is legit compared to an ordinary 60 to 65mph storm.
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Quoting weatherlover94:


Not exactly....its moving more west than north right now

It has moved more west than south since it was born. I would expect it to move even more west once it slows down, assuming it stays together long enough to matter.
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Quoting 945. Jwd41190:
How can the NHC go ahead and downgrade to 60MPH when it is over 2 hours away from 11PM and recon is not finish yet? It might only have 50MPH winds...


Because they can change their mind up until the time they issue the 11 PM advisory.
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Quoting 941. GTstormChaserCaleb:
Yep there it is just blew up in the last frame and westbound she goes.



With that west movement,it will evade the tall Hispanola mountains.
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Quoting 945. Jwd41190:
How can the NHC go ahead and downgrade to 60MPH when it is over 2 hours away from 11PM and recon is not finish yet? It might only have 50MPH winds...


the atcf coordinates show were for 8pm, its based on satellite, but the nhc will go with what recon says
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Quoting 943. spathy:






Convection sure couldnt get much less. No place to go but up. LOL


Ha ha you got that right
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And the models have shifted a little bit back to the east. [TVCN] Still west of the NHC plot.

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Quoting 927. spathy:










Cape. If you scroll way down you can be reasonably sure to post outside of the quote box. Even if you cant see it.













Thanks, I am trying that here. Voila!
CV
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Quoting Capeverde5:
And for some reason, my comment got put inside the quote box and I couldn't correct it.


This blog doesn't really work with IE, New format you need to scroll down the page to quote on Chrome, but classic format there is no problems except you can't see who has +'ed your comments.
Member Since: September 30, 2007 Posts: 9 Comments: 15932
How can the NHC go ahead and downgrade to 60MPH when it is over 2 hours away from 11PM and recon is not finish yet? It might only have 50MPH winds...
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Quoting 938. Stormchaser121:
I think the models will continue to move further west. Thats the trend.
The NHC acknowledge that in their 5pm. discussion, so you have some credibility with your post there sir.
Member Since: June 30, 2013 Posts: 11 Comments: 7473
Regardless of development it still looks like it will be a rain maker for the east coast.
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Quoting 932. ProgressivePulse:
Chantal looks like she wants to make another run at a CDO this evening. Convection is expanding and deepening over the center currently. CIMMS still shows good convergence/divergence so she should be able to maintain. Shear is currently 20kts over the center.

Yep there it is just blew up in the last frame and westbound she goes.

Member Since: June 30, 2013 Posts: 11 Comments: 7473
Kinda interested in what the 0Z run will show in the next track
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Quoting 929. Hurricane12:


Poor gal. At least spell her name right before you poof her!


Chantal may be pushing up chantrelles but I think not quite yet.

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I think the models will continue to move further west. Thats the trend.
Member Since: September 2, 2011 Posts: 0 Comments: 1143
Quoting 928. rmbjoe1954:
Hi all. It seems Chantal is struggling. I have also noticed the cone has shifted east so I imagine the models concur.


cone shifted west actually
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Convection is finally starting to rebuild
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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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