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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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 1731. TropicalAnalystwx13:

Can't believe they haven't upgraded to a major hurricane yet. The storm is undergoing a serious period of explosive intensification.


Like you always said TA, the NHC is TOO conservative.
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Quoting 1730. geepy86:

ummm, where?


Sarcasm...lol.
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I don't see Chantal surviving its in high shear and has lost most of its convection when thunderstorms should be building and Hispaniola will kill it my focus is on that African wave even though its not on the two it looks vigorous.
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Quoting 1729. TomTaylor:
Chantal looking amazing right now!


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Quoting 1729. TomTaylor:
Chantal looking amazing right now!


Can't believe they haven't upgraded to a major hurricane yet. The storm is undergoing a serious period of explosive intensification.
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1730. geepy86
Quoting TomTaylor:
Chantal looking amazing right now!


ummm, where?
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Chantal looking amazing right now!

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The intensity models seem to keep it at TS strength unless you are a believer in the SHIPS 5 which takes it up to Cat. 2 strength. If she survives the shear ahead and remains a tropical system it would simply be amazing, but that is why we keep an eye on it until it is no more. You just never know what curveball mother nature will throw at you.

Member Since: June 30, 2013 Posts: 12 Comments: 8428
1727. nigel20
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1726. nigel20
Good evening/night fellow bloggers!

Weather station in Kingston

Elevation: 223 m
Temperature: 32.2 °C
Dew Point: 22.2 °C
Humidity: 56%
Wind: 12.9 km/h / from the East
Wind Gust: 0.0 km/h /
Updated: 2:46 PM EST on July 09, 2013
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Quoting 1708. AussieStorm:


Flight 4 on route now.

As of the last observation at 04:25:30Z, the plane's...

Direction of Travel: WSW (242°)
Location: 88 miles (142 km) to the SSE (152°) from San Juan, Puerto Rico (USA).

really omg your right
Member Since: June 13, 2009 Posts: 2 Comments: 12147
It may be that Chantal's circulation is too tight to be adequately picked up by this buoy, but...

Station 42059
NDBC
Location: 15.058N 67.528W
Date: Wed, 10 Jul 2013 03:50:00 UTC
Winds: ESE (120°) at 11.7 kt gusting to 15.5 kt
Significant Wave Height: 5.6 ft
Dominant Wave Period: 7 sec
Mean Wave Direction: ENE (68°)
Atmospheric Pressure: 29.97 in and steady
Air Temperature: 79.5 F
Dew Point: 75.0 F
Water Temperature: 82.8 F
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Quoting 1719. taco2me61:
well I'm out for the night gess I'll see what she looks like in the AM....


Taco :o)
Good night Taco and yes I see that vertex to the south there is also what appears to be another vertex just south of PR racing away to the wnw from the main convection.
Member Since: June 30, 2013 Posts: 12 Comments: 8428
Chantal heading into the patch of high shear shortly.

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Quoting 1715. FOREX:


dissipation
Only chance is to get north of DR and in lower shear.
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Wish I had a more recent pass...



Kinda looks like a mid-level center to the northwest of the more dominant one. Notice the faint swirl southwest of Puerto Rico.
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well I'm out for the night gess I'll see what she looks like in the AM....


Taco :o)
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Quoting 1714. CaicosRetiredSailor:


Ahem... um um... excuse me...

but...
Looks to me she has hit a brick wall and trying to fight her way through it.
Member Since: June 30, 2013 Posts: 12 Comments: 8428
Though looks can be deceiving, Chantal certainly has the appearance of an open wave. Actually it just looks like a little moist splotch with a couple of thunderstorms.
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Quoting 1709. GTstormChaserCaleb:
Chantal is going to need a really good D-MAX if she wants to be around after tomorrow. She has almost lost all her convection tonight.


In that picture it looks like the center has moved more south or she through out a Vertex to the south....

Taco :o)
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1715. FOREX
Quoting 1710. wunderkidcayman:

what you thinking central america


dissipation
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Ahem... um um... excuse me...

but...
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Quoting 1706. AussieStorm:


Is this truth or guess?
How far out into the Caribbean sea does their air space stretch?


Truth, the airspace extends to about 15-16 degrees North, depending on longitude.

Look through here Aussie:
Maritime Treaty
and match against Chantal's last recorded position of: 15.3N 66.2W
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Quoting 1710. wunderkidcayman:

what you thinking central america

I believe she will cross Cuba before heading west.
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Quoting 1708. AussieStorm:


Flight 4 on route now.

As of the last observation at 04:25:30Z, the plane's...

Direction of Travel: WSW (242°)
Location: 88 miles (142 km) to the SSE (152°) from San Juan, Puerto Rico (USA).

wow did not see that you are right they are on there way to her now :o)
Thanks Aussie

Taco :o)
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Quoting 1695. FOREX:


She may not cross any islands.

what you thinking central america
Member Since: June 13, 2009 Posts: 2 Comments: 12147
Chantal is going to need a really good D-MAX if she wants to be around after tomorrow. She has almost lost all her convection tonight.

Member Since: June 30, 2013 Posts: 12 Comments: 8428
Quoting cwf1069:
Anyone, at what time its the flight schedule for tomorrow. Thank u in advance.


Flight 4 on route now.

As of the last observation at 04:25:30Z, the plane's...

Direction of Travel: WSW (242°)
Location: 88 miles (142 km) to the SSE (152°) from San Juan, Puerto Rico (USA).
Member Since: September 30, 2007 Posts: 9 Comments: 15938
Quoting 1698. AussieStorm:
Any word on what happened to the HH'ers and why they ended their flight?

What time is the next HH'er plane heading out?


Refer to post #1704 Aussie, we got too close to Venezuela air space. Not allowed in there. Chantal's center lies just within.

Next plane, not sure, I don't think they've released that yet, they might wait and watch the satellite and try to determine when the "center" will rise back into international airspace.
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Quoting FOREX:


Venezuela refused to let them into their air space.


Is this truth or guess?
How far out into the Caribbean sea does their air space stretch?
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1705. 7544
hmm take a look at the nogaps intersting maybe someone could post it thanks it worth a lookie lol
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It's a shame Venezuela wouldn't let them in, but at the same time when one country has a monopoly on the hurricane business another is bound to be jealous. :p
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1703. cwf1069
Anyone, at what time its the flight schedule for tomorrow. Thank u in advance.
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Quoting 1698. AussieStorm:
Any word on what happened to the HH'ers and why they ended their flight?

What time is the next HH'er plane heading out?
Got to close to someones airspace and where told to turn around.... And If some one else has said I think in the AM but not sure

Taco :o)
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Quoting 1673. trHUrrIXC5MMX:



alright..gnite

They need to discontinue the cmc,that model is colossal waist of time.
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Quoting 1695. FOREX:


She may not cross any islands.

Im agreeing with you on this one.
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1699. FOREX
Quoting 1698. AussieStorm:
Any word on what happened to the HH'ers and why they ended their flight?

What time is the next HH'er plane heading out?


Venezuela refused to let them into their air space.
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Any word on what happened to the HH'ers and why they ended their flight?

What time is the next HH'er plane heading out?
Member Since: September 30, 2007 Posts: 9 Comments: 15938
1697. 7544
this is one confusing strom .
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Quoting 1689. 7544:
+1
Quoting 1670. L1990:
westward she blows

yep

is that good or bad for south fl tia

depends on how far west she goes but ya
Member Since: June 13, 2009 Posts: 2 Comments: 12147
1695. FOREX
Quoting 1693. washingtonian115:
Depends on what Chantal looks like after she crosses the islands.


She may not cross any islands.
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Quoting 1692. MrstormX:


The CMC has been far more consistent recently in track then the GFS has. There is this random hate for the CMC on this blog that I just can't figure out, sure the model has its quirks but so do all the other models.


I've heard it said that outside of the tropics, the CMC is actually a really good and heavily relied upon model.
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Quoting 1688. whitewabit:


The CMC has been consistent from run to run .. will be interesting if it pans out ..
Depends on what Chantal looks like after she crosses the islands.

Post 1692 that's because it always over intensifies storms and develops almost every low on the map.
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Quoting 1685. washingtonian115:
That's the CMC for ya.Always foreseeing doom.If that happened Savannah would be in series trouble.GFS only shows a depression so far.


The CMC has been far more consistent recently in track then the GFS has. There is this random hate for the CMC on this blog that I just can't figure out, sure the model has its quirks but so do all the other models.
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The GFS actually sends the upper low south over the next 48 hours. Even assuming it weakens (which is likely), that'll actually increase the net westerly shear. Not a good situation at all.
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Quoting 1686. 7544:
is that a new ull south of fla anyone?????

nope same old weakening ULL
Member Since: June 13, 2009 Posts: 2 Comments: 12147
1689. 7544
+1
Quoting 1670. L1990:
westward she blows

yep

is that good or bad for south fl tia
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1688. whitewabit (Mod)
Quoting 1685. washingtonian115:
That's the CMC for ya.Always foreseeing doom.If that happened Savannah would be in series trouble.GFS only shows a depression so far.


The CMC has been consistent from run to run .. will be interesting if it pans out ..
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1687. 7544
surpise to see no watches for andros islands
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1686. 7544
is that a new ull south of fla anyone?????
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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.