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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I think the Recon instruments are malfunctioning we should just get some rest right now I am utterly speechless.
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heading home sweet home.
Member Since: September 7, 2005 Posts: 7 Comments: 1516
Let's hope DMAX works in Chantal's favor, or whatever is left of it, for that matter.
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1433. ncstorm
Quoting 1430. washingtonian115:
Told ya'll to watch for downcasting today.


but the local met said that one..
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The latest discussion for Chantal explained why they never entered the southern part of the storm; apparently there are air space restrictions, so they could not cross 15 N.
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11:00 PM AST Tue Jul 9
Location: 15.3°N 66.2°W
Moving: WNW at 28 mph
Min pressure: 1009 mb
Max sustained: 60 mph

LOCATION...15.4N 64.9W
ABOUT 220 MI...360 KM SSE OF SAN JUAN PUERTO RICO
ABOUT 395 MI...635 KM ESE OF SANTO DOMINGO DOMINICAN REPUBLIC
MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 26 MPH...43 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCH, kinda dumbfounded here, movement still WNW, ???
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Quoting 1422. ncstorm:
how can the storm be dying and have max winds of 60mph..
Told ya'll to watch for downcasting today.
Member Since: August 14, 2010 Posts: 10 Comments: 17156
1428. Dakster
Quoting 1417. SouthernIllinois:

Okay Okay. Then maybe I misunderstood the statement earlier. She is a sloppy hot mess!


Are you still talking about the weather?
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Not to strong for 50 mph wind ???


Martinique 09072013
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and they are going home...
Member Since: September 7, 2005 Posts: 7 Comments: 1516
1425. Patrap


Member Since: July 3, 2005 Posts: 426 Comments: 128874
Chantal is on schedule.. a jog due west this evening, midlevel trough is causing sinking air on her NW side. Pressure is at 1009 that I posted 20 min ago but winds are a unreliable 60mph...more like 40-45mph. HH's left for the evening.
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1423. Gearsts
Quoting 1418. wunderkidcayman:
I think recon is flyin in the wrong spot it Need to fly south
-_-
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1422. ncstorm
how can the storm be dying and have max winds of 60mph..
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look out florida i think if the upper level low moves away as fast as it has if its west of florida it will move across the keys and up the western coast
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1420. whitewabit (Mod)
Recon's headed home ..
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Recon done early... must be something going on with the plane.
Member Since: August 1, 2011 Posts: 28 Comments: 8032
I think recon is flyin in the wrong spot it Need to fly south
Member Since: June 13, 2009 Posts: 2 Comments: 12180
Quoting 1382. ProgressivePulse:
And there you go, lol. Local MET says she is dying. HH having trouble finding center let alone tropical storm force winds. Lil Red ball is gone.


And that could be worse, because it might stay more south and be weaker being drawn north later possibly as far west as the Gulf of Mexico, and then who knows how much it could strengthen then. We'll need to monitor this.
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Quoting 1396. stormpetrol:
IMO they have to fly further west and south to identify the center, its slightly below 15N. They have to fly southwest below 15N to get the west winds , just my take. Plz keep the punches light :) JMO


No I agree. Their route is ridiculous and looks quite foolish by now. They wanted a second pass at the NW quadrant, fine I get that, but they've been out there 2 hours and never once flew on the south side of the storm.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
1414. Patrap
At 02:37:30Z (last observation), the observation was 109 miles (175 km) to the SSE (157°) from San Juan, Puerto Rico (USA).

Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 10th day of the month at 02:44Z
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: 24

02:37:30Z 16.967N 65.417W 670.5 mb
(~ 19.80 inHg) 3,566 meters
(~ 11,699 feet) 1016.7 mb
(~ 30.02 inHg) - From 118° at 39 knots
(From the ESE at ~ 44.8 mph) 6.9°C
(~ 44.4°F) 3.5°C
(~ 38.3°F) 40 knots
(~ 46.0 mph) - - - -
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: 128874
Toast?
Maybe spared the Haitian tent people.
Member Since: August 2, 2011 Posts: 0 Comments: 2065
Looks like recon may be heading home. They cut off the instruments for a 43 mile stretch and ascended. I'm still thinking instrument probs.
Member Since: September 22, 2005 Posts: 18 Comments: 2343
I predict that I will be happy with the new track at 11pm.
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Quoting 1402. SouthernIllinois:

I thought so too, but then someone said that's really not the case so much with established systems. It only applied to TD's or waves.


I wouldn't call Chantal an established system though. I believe Levi meant stronger storms, like Emily in 2005.
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Recon leaving.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
1407. ncstorm
Quoting 1400. WPBHurricane05:
NHC hasn't given up yet.


no only this blog...
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now the NHC barley shows any strengthening after Cuba and Hispaniola.....im done with this for the night....good night everybody
Member Since: September 8, 2010 Posts: 0 Comments: 2209
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Very interested to read the discussion.
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Hey, if anyone knows this song, + please.
Warning* I changed the lyrics a bit.

Just sitting out here watching airplanes
take off, and Fly!!!
Trying to figure out where your center is,
And why!!!You don't strengthen, Chantal...


Just sitting out here, watching airplanes.
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where they going now...lol
Member Since: September 7, 2005 Posts: 7 Comments: 1516
NHC hasn't given up yet.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
1399. Dakster
11pm is out.
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There is one thing for sure that can definitely be noted without Hurricane Hunter data (although hurricane hunters had a radar detected center at 14.9 N and 65 W at one point), that the center of Tropical Storm Chantal is definitely south and west of the previous position and the last updated track. Am expecting a westward shift not only to account for current storm position but to account for model trends.
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what is going on? Recon is not really flying into the convection yet.
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IMO they have to fly further west and south to identify the center, its slightly below 15N. They have to fly southwest below 15N to get the west winds , just my take. Plz keep the punches light :) JMO
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Max sustained: 60 mph
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i think shes moving more westerly now
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1393. Dakster
Quoting 1383. weatherlover94:
this thing could be dying on us i guess


It has entered the dead zone. Levi explained this the other day. I wouldn't say that this is unexpected.
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1392. beell
Still trucking along though. Probably an elongated center-mostly S/N
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Quoting 1376. congaline:
Who flies into Asian pacific storms like Soulik to gather data?


Maybe I'm wrong, but I think they had some accidents and quit doing it, at least that was my understanding. Somebody correct me if they know better.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
1390. will40
3,566 meters
(~ 11,699 feet)

flight level high too
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Quoting 1382. ProgressivePulse:
And there you go, lol. Local MET says she is dying. HH having trouble finding center let alone tropical storm force winds. Lil Red ball is gone.



radar shows a pretty well defined center
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I really want to know what the 11:00 update is going to hold
Member Since: September 8, 2010 Posts: 0 Comments: 2209
1387. FOREX
Quoting 1339. cchsweatherman:
Any particular reason why there has been an absence of data for nearly a half hour now from the Hurricane Hunters?


Bermuda Triangle.
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Quoting 1358. cchsweatherman:
Given the lack of hurricane hunter data except for in the northwest quadrant and the advisory coming within the next 20 minutes, I'd expect that the NHC will maintain continuity with the intensity of Chantal until they get better data and then may do a special advisory later if there are any changes.
They've sampled both the northwestern and northeastern octants with extremely unimpressive winds.
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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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