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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1186. Grothar
Really shifted west.

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Quoting 1174. Dakster:


Pinhole eye, Taz
Next question after that will be is it going annular? :P
Member Since: June 30, 2013 Posts: 12 Comments: 8416
1184. Patrap
Member Since: July 3, 2005 Posts: 426 Comments: 128609
Quoting 1150. SavannahStorm:


A all the way
Quoting 1120. opal92nwf:
Starting to imagine this could be like a Dennis track.



wishcasters are strong tonight boys, strap up.
Member Since: July 21, 2010 Posts: 0 Comments: 1176
Quoting 1113. RTSplayer:
More model mayhem, I presume.

We have 2 scenarios:

1, says between Jamaica and Cuba, possibly still headed west, supported by 2 allegedly very good models.

2, The scenario most consistent with NHC, supported by 4 of the models says Hispaniola and then LF on the east coast.




I think those 3 to 5 tenth discrepancies in position, or 10 or 15 compass degree discrepancies in heading could add up to all the difference here. It doesn't matter what steering features are ahead of the storm if the timing is totally wrong when it gets there.


Let's talk about Jamaica haircuts for a second. Or rather beardcuts if you run North of Jamaica. Wouldn't that send you careening further West with forward momentum, like you tripped over a rock?
Member Since: August 4, 2007 Posts: 0 Comments: 3263
Quoting 1170. stormpetrol:
There is a center it's just not where they expected it to be! Its further south they need to fly around 14.5 N and well west of 65W, they'll find west winds.


Concur; They are looking too far North.
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Quoting 1172. Beachfoxx:
Ecuador?



Yep...directly underneath the ITCZ. It is both ironic and wonderful.

I evacuated the USA. It is unlikely I will ever return.
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1178. Patrap


Member Since: July 3, 2005 Posts: 426 Comments: 128609
Quoting 1169. Tazmanian:
this wind shear map is showing that chantal sould be under 20kts or higher wind shear but right now am starting too wounder if there is is some in thats keeping a way the high wind shear


It's in the left exit region of the tutt jet,it's increaseing upper divergence and forming tstms in the fact of shear.
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Quoting 1087. moonlightcowboy:


LARGER VIEW SFC MAP

There will be no effect, imo, from the CONUS mid-latitude trough - see "disipating" over Kansas, and also see the tongue of GoM high pressure extending more southwesterly. The only weakness that remains is the ULL and it's retrograding more southwesterly with 1020mb ridge building back in behind it. I expect a continuing more westerly shift in track forecasts. Chantal, if she can hold it together (and I think she will), should cross over eastern-to-central Cuba, imo.

I'ma be quiet now and let some of the smarter folks explain it to us. Honestly, among many of my weaknesses, troughing and how it affects track is my weakest. No matter, hurt, even if it's flooding only, is straight ahead for some folks, somewhere soon.


;P I said I was going to be quiet. LOL. I am. I'm tired and have a long few days ahead. I'm thinking with that tongue of GoM high pressure, and with the Atlantic high filling in behind the ULL, we could see a blocking high with Chantal stuck, stalled, and having to find another route out - probably more westwards eventually in the GoM.

Yeah, ok, I've looked at loops, circles, and lines on a map too long. Y'all enjoy figuring this one out. She's a challenge, but I don't think she's going to Georgia! :)
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Look at all the lightning this one line of storms gave off.

Member Since: June 30, 2013 Posts: 12 Comments: 8416
1174. Dakster
Quoting 1171. Hurricanes101:


radar out of san juan shows the center, it is small

seems to be right in the middle of that convective flare up


Pinhole eye, Taz
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the NHC is going to have to shift everything south and west tonight
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Ecuador?

Quoting 1166. CycloneOz:


Yo foxx! I am doing well here in Ecuador! Hope you are doing well, too.
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Quoting 1161. weatherlover94:


there could be no center...not out of the question


radar out of san juan shows the center, it is small

seems to be right in the middle of that convective flare up
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There is a center it's just not where they expected it to be! Its further south they need to fly around 14.5 N and well west of 65W, they'll find west winds.
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this wind shear map is showing that chantal sould be under 20kts or higher wind shear but right now am starting too wounder if there is is some in thats keeping a way the high wind shear

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1168. Patrap
Member Since: July 3, 2005 Posts: 426 Comments: 128609
Quoting 1151. gulfbreeze:
Dennis eye went over my house 7/10/05.

Wow. It was really compact when it made landfall. Many people said it wasn't as bad as Ivan. I assume those people weren't in the eyewall of Dennis. Because it was a major hurricane..
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Quoting 1160. Beachfoxx:
Oz, Taz, Cowboy and many others... Just dropping by to say hello. Watching Chantal & hoping east coast is paying attention.
Hope y'all are doing good!


Yo foxx! I am doing well here in Ecuador! Hope you are doing well, too.
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1164. Patrap
Doh'
Member Since: July 3, 2005 Posts: 426 Comments: 128609
1163. Patrap
Member Since: July 3, 2005 Posts: 426 Comments: 128609
1162. cwf1069
Hello everybody. Lurking most of the time. First entry this season. Chantal its giving a headache since the begining. Neither NHC and models know where she go. Looks like she's putting the brakes. LLC may be further down to the sw of the first path. Around 15n and 65.3
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Quoting 1153. FutureWx6221:
105 minutes in Chantal and still no center fix, wondering if there is some instrumental failure going on in the storm.


there could be no center...not out of the question
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Oz, Taz, Cowboy and many others... Just dropping by to say hello. Watching Chantal & hoping east coast is paying attention.
Hope y'all are doing good!
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Quoting 1153. FutureWx6221:
105 minutes in Chantal and still no center fix, wondering if there is some instrumental failure going on in the storm.


They looked where they thought it would be; North of 15.3 but it wasn't there.

I hope they are going to go find it now. Probably a bit south of 15.3

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Quoting 1152. moonlightcowboy:
A "col" - now that's a first for me. :) See, folks, we can learn something every day. Interesting.


I'm learning more here than in school.
Member Since: July 2, 2012 Posts: 101 Comments: 10317
Quoting 1143. SavannahStorm:
Wondering if recon has instrument issues- the highest flight level winds they have found were right after takeoff at St. Croix!


Here's the deal, as I see it.

Chantal had some bad luck, let's say, between 5pm and 8pm regarding it's convection, in that even though the convection has expanded a great deal in area today, the heaviest convection died out. I don't mean it disappeared, it just warmed from -70c to about -50c. This probably lead to the collapse of the rain band where the strongest winds had previously been recorded. The overall circulation is still in tact and trying to reorganize. The Puerto Rican radar is mostly over-shooting the band near the center, but you can clearly see weather on the radar at the edge of it's range, and you can also see counter-clockwise rotation.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
Current satellite data has Typhoon Soulik at 125kts



Very close to Super Typhoon Status.
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1155. Patrap
At 01:37:30Z (last observation), the observation was 155 miles (249 km) to the SSE (154°) from San Juan, Puerto Rico (USA).


Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 10th day of the month at 01:37Z
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: 18

01:37:30Z 16.400N 65.033W 842.6 mb
(~ 24.88 inHg) 1,630 meters
(~ 5,348 feet) 1016.6 mb
(~ 30.02 inHg) - From 138° at 43 knots
(From the SE at ~ 49.4 mph) 16.9°C
(~ 62.4°F) 10.8°C
(~ 51.4°F) 44 knots
(~ 50.6 mph) 34 knots
(~ 39.1 mph) 0 mm/hr
(~ 0 in/hr) 33.2 knots (~ 38.2 mph)
77.3%
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
Member Since: July 3, 2005 Posts: 426 Comments: 128609
Not really a fan of 3rd storms of the year starting with the letters "CH" coming from the Eastern Caribbean and possibly hitting FLA on the 13th. Keep reporting guys and gals and I'll be watching Chantal in the background.
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105 minutes in Chantal and still no center fix, wondering if there is some instrumental failure going on in the storm.
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A "col" - now that's a first for me. :) See, folks, we can learn something every day. Interesting.
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Quoting 1138. AussieStorm:

Possible.

Dennis eye went over my house 7/10/05.
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Quoting 1139. ackee:
where will chantal go ?


A NW over Haiti
B OVER Dominica Republic
C Between Jamaica and Cuba


A all the way
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07/09/2013 Daily Update - GOES East Infrared Hurricane Sector Animation featuring TS Chantal

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anyone have a link to the GFS and ECMWF model pages? thanks
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1147. Dakster
Quoting 1139. ackee:
where will chantal go ?


A NW over Haiti
B OVER Dominica Republic
C Between Jamaica and Cuba


Si'
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Quoting 1145. Tazmanian:



C

I don't like that track at all.
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Quoting 1139. ackee:
where will chantal go ?


A NW over Haiti
B OVER Dominica Republic
C Between Jamaica and Cuba



C
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Quoting 1139. ackee:
where will chantal go ?


A NW over Haiti
B OVER Dominica Republic
C Between Jamaica and Cuba
C.
Member Since: June 11, 2013 Posts: 20 Comments: 3177
Wondering if recon has instrument issues- the highest flight level winds they have found were right after takeoff at St. Croix!
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According to San Juan radar an outer feeder band is about to brush the south coast of PR. The CDO is just off the south end of the long range radar perhaps moving at more westward movement. Sat loop suggests that Chantal is slowing down some perhaps reorganizing.
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Quoting 1097. GTstormChaserCaleb:
South of initialization should see the ensemble members and the mean adjust to that in the next run could be more left.





Maybe a Track like this, a little more east and a weak Tropical Storm.
Member Since: May 1, 2013 Posts: 0 Comments: 774
Quoting 1114. MechEngMet:
Is recon going home? Looks like they're heading due N. Perhaps instrument issues, though I haven't seen anything in the data about it.

Hope she turns back for another pass or two, She was supposed to stay out there quite a while...


Yup they're turning back South now. (Hope they show us something that looks like a center.)
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1139. ackee
where will chantal go ?


A NW over Haiti
B OVER Dominica Republic
C Between Jamaica and Cuba
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Quoting opal92nwf:
Starting to imagine this could be like a Dennis track.

Possible.

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regardless of how strong Chantal is....the possible landfall locations is putting them all in a very dangerous situation
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1136. pottery
Quoting Pallis:
I realize that we are all connected by some kind of link and all, but is there another Guadalupe Island in the Caribbean, because the one in the Pacific is pretty far away from the affected zone in your topic. There is this ostentatious piece of land called Mexico in the way. Always looking for more geographical knowledge though, if you snuck one by me, or I cheated myself out of a piece of the globe.

Guadeloupe & Martinique are 2 French islands within the Caribbean island chain.
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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.