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 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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Is the dry air and shear as bad in the West Caribbean ? If she stays this ragged wouldn't you see it missing Hati/DR and head more over towards and Cuba.
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Quoting 709. weatherlover94:


Stormpetrol does it look to you like Chantal is moving more west than west north west ? and what do you think the chances are it will thread the middle between Hispaniola and Cuba ?

It is moving more due west at the moment and it wouldn't surprise me to see it go between Jamaica and Cuba, much like Charley of 04, but that's just my take for now.
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Quoting 727. Tazmanian:



he saw nothing 1st


i saw it 1st

I saw it first.
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731. FOREX
Quoting 719. heliluv2trac:
I dont understand why they keep wanting to send chantel on the east coast it is not going that way it has started back on the westward track because it is disorganized I look for a westward shift in the track taking it into the gulf and making landfall between miss and fla pandhandle but hey i stated in the holiday Inn last nite


Sounds reasonable though.
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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 westwards 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.
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Quoting 672. RTSplayer:
"Open waves" don't have 360 degrees worth of 50kts winds.

Except Chantal doesn't have 360˚ worth of 50kt winds.
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Quoting 718. EricSFL:


Grothar



he saw nothing 1st


i saw it 1st
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Thanks very much TomTaylor!
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Quoting 718. EricSFL:


Grothar
Silly me how can I forget the Grothar model.
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Quoting 721. Tazmanian:




am a good boy tonight



you can post what evere you what


You're always a good boy...just sneaky!
Member Since: October 18, 2005 Posts: 4 Comments: 3052
Quoting 707. BaltimoreBrian:


Very cool! how about 120 hours?

Doesn't seem like much of a storm.


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Quoting 713. Hurricanes101:


um you ran the Euro at zero hours, while you ran the GFs and CMC at 87 hours


To illustrate they don't even seem to show what already exists!
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Quoting 716. mikatnight:


watch out for Taz!




am a good boy tonight



you can post what evere you what
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Quoting 710. Slamguitar:


You seriously just reminded me I was going to make chocolate chip cookies tonight. Thanks WU blogs for your occasional off-topicness!!


Save some for me!

Interesting cell in Wisconsin, has had several brief tornadoes reported

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I dont understand why they keep wanting to send chantel on the east coast it is not going that way it has started back on the westward track because it is disorganized I look for a westward shift in the track taking it into the gulf and making landfall between miss and fla pandhandle but hey i stated in the holiday Inn last nite
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Quoting 712. GTstormChaserCaleb:
Remember if Chantal moves more westbound which model saw it first...you got it the NOGAPS :D


Grothar
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Quoting 714. BaltimoreBrian:
CMC 114 hours is more impressive.



The CMC is full of crap.
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Quoting 702. tornadodude:




watch out for Taz!
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CMC 114 hours is more impressive.

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Quoting 706. mikatnight:
So, CMC...


GFS...


ECMWF...?


Did somebody put peanut butter on the Euro's disk drive or something?


um you ran the Euro at zero hours, while you ran the GFs and CMC at 87 hours
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Remember if Chantal moves more westbound which model saw it first...you got it the NOGAPS :D
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Quoting 702. tornadodude:




You seriously just reminded me I was going to make chocolate chip cookies tonight. Thanks WU blogs for your occasional off-topicness!! Still won't mail any to jeffreeysweetypie though...
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Quoting 703. stormpetrol:


This is generally the time of day that these storms wane in convection, especially now that Chantal has grown in size it will be more noticeable than before, right now convection is beginning to fire near center, don't be surprised if Chantal becomes a hurricane before this HHs mission is over tonight!


Stormpetrol does it look to you like Chantal is moving more west than west north west ? and what do you think the chances are it will thread the middle between Hispaniola and Cuba ?
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Diffuse.....watch to see if that word is used in the 8PM NHC update, or whenever it's used. I've found it's use often portends a later discussion that uses the next D word...dissipation.
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Quoting 701. TomTaylor:
Yes.

48hrs




96hrs



Very cool! how about 120 hours?

Doesn't seem like much of a storm.
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So, CMC...


GFS...


ECMWF...?


Did somebody put peanut butter on the Euro's disk drive or something?
Member Since: October 18, 2005 Posts: 4 Comments: 3052
Quoting 700. Patrap:
TS Chantal

RainBow Loop



it doesn't look to bad on the rainbow loop
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704. JRRP
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Quoting 684. weatherlover94:
the 8:00 advisory may be brought down to 60 or 50 mph


This is generally the time of day that these storms wane in convection, especially now that Chantal has grown in size it will be more noticeable than before, right now convection is beginning to fire near center, don't be surprised if Chantal becomes a hurricane before this HHs mission is over tonight!
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Quoting 694. jeffreeysweetypie:
my 3 day ago prediciton might pan out when i said chantal will die within 5 days even though all the models and everyone said it would hit florida


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Quoting 659. BaltimoreBrian:


Do you have the model image 48 or 96 hours ahead?
Yes.

48hrs




96hrs

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TS Chantal

RainBow Loop

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Quoting 697. FSUCOOPman:


I wonder how much different the chart would look if we only looked at the last 20 years worth as a sampling.


That wouldn't be a hard chart to make with accurate numbers abound.
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Quoting 691. Bluestorm5:
Look what was in my college meteorology textbook... our old friend, "The Chart".

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Quoting 691. Bluestorm5:
Look what was in my college meteorology textbook... our old friend, "The Chart".



I wonder how much different the chart would look if we only looked at the last 20 years worth as a sampling.
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At 23:27:30Z (last observation), the observation was 200 miles (322 km) to the SE (136°) from San Juan, Puerto Rico (USA).

Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 9th day of the month at 23:26Z
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: 05

23:27:30Z 16.333N 63.950W 842.9 mb
(~ 24.89 inHg) 1,622 meters
(~ 5,322 feet) 1016.2 mb
(~ 30.01 inHg) - From 137° at 43 knots
(From the SE at ~ 49.4 mph) 16.5°C
(~ 61.7°F) 11.5°C
(~ 52.7°F) 43 knots
(~ 49.4 mph) 30 knots
(~ 34.5 mph) 1 mm/hr
(~ 0.04 in/hr) 30.0 knots (~ 34.5 mph)
69.8%
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 691. Bluestorm5:
Look what was in my college meteorology textbook... our old friend, "The Chart".



I'm glad to see it's in the newest edition. I think mine is from '07. I wonder what's been updated.
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Quoting 672. RTSplayer:
"Open waves" don't have 360 degrees worth of 50kts winds.


I wouldn't put too much faith on that. Those images make a toilet flush look good.
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Look what was in my college meteorology textbook... our old friend, "The Chart".

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Quoting 652. nash36:


Hey MLC!!!

Right now, I am doubting it's survival. IF it manages to not become decoupled, then anywhere from ECFL to GA coastline.


Copycat ;) (#620)
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Quoting 550. msphar:
She's dead, Jim.


Funny. I like that. But she ain't dead neither. Matter of fact, even an ol' dummy like me, can disagree with the good and smart Doc. I've contended for a few days now that the collapsing t'storms out in front of Chantal's COC was actually helping to serve moistening the environment. Otherwise, the thing would have already choked on the all the dry air it's been through.

She's still struggling, but she's gonna make it as long as she can keep that vigorous, low-level circulation spinning. One can easily see the moisture field has grown substantially around it. She's still churning, and right now she's really trying to get her act back together at the mid-levels and where's she's really been the strongest. She's trying to get some tops, and she will with that big of a moisture field as soon as she can get a bit stronger mid-level spin going - and, that's despite the shear.
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Quoting 683. Joanie38:



On Firefox....it works YAY!!!



Yayyyyyyyyyyyyyyyyyy
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No mention yet of African wave.

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT TUE JUL 9 2013

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM CHANTAL...THAT IS CURRENTLY MOVING ACROSS THE EASTERN
CARIBBEAN SEA.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER BROWN
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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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