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 2619. StormTrackerScott:
I think the NHC is wrong in saying Chantal will degenerate in 24 hrs. I am no expert but I just don't see her degenerating anytime soon.



You are a typical FL wish caster. Look at all your "sound the alarm" posts lol
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Previous forecast had it at 17.7n and 72.3w at this time, so they were off by 85 miles on a 12 hour forecast.
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I think this maybe RI down the road.
Member Since: July 2, 2013 Posts: 0 Comments: 1523
Quoting 2623. RTSplayer:
Memorable facts about Chantal:

Totally unpredictable size and intensity.
Abnormally high pressure vs wind speeds.
Possibly the most disorganized TS on record.


Not too shabby for a premature cape verde system.
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C'mon Dr. Masters, put up a new update. Can't wait!! lol
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It will have 12HR on water so maybe it can get back up to TS before S FL
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Quoting 2627. SouthernIllinois:
Time to move onto the next system....

Nope,still a ts right now.
Member Since: July 2, 2013 Posts: 0 Comments: 1523
Quoting 2616. leofarnsworth:
Chantal getting severely disrupted is making the storm very shallow.  This should impact the steering currents previously thought to be in play.  My guess is Chantal will stay on a track westward under Cuba and emerge in GOM.  In GOM conditions should be much more favorable for RI. If I am right, what steering currents will impact Chantal in GOM? Where will she go from there?


Disagree, as noted earlier by Drakeon and many other reliable bloggers, even a tropical wave will feel the northward weakness from the gap in the two highs. None of the reliable models are forecasting this to get into the western gulf at the current time. (Bamm and Clips are not reliable models).
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2626. 62901IL
Chantal's DOOM:CON for florida is a three by my standards.
Member Since: June 14, 2013 Posts: 2 Comments: 2003
Quoting 2609. WxLogic:
Well... I going to say it... she's pulling a Fay.


As in Fay done away. (sorry about that, don't know what came over me).
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Memorable facts about Chantal:

Totally unpredictable size and intensity.
Abnormally high pressure vs wind speeds.
Possibly the most disorganized TS on record.
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If the cone keep moving West, w coast FL may have a direct hit from a, well, low pressure area.

Of course if it moves too far west, it could be a much larger storm.

There was a post way early on, days ago about how Kingston should get ready. I must admit, I never thought that would be an issue, but look now, watches going up for Jamaica.
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Quoting 2517. Levi32:
Chantal will still have a chance to restrengthen later. If one looks at the visible loop below, the trade winds slow in speed greatly north of 17N west of Chantal, and have started backing from W to WNW in front of her. Once in this region of the NW Caribbean, the low-level flow into the system will then be convergent, meaning air would be piling up and potentially rising. This would be favorable for restrengthening, but then modest upper-level wind shear and interaction with mountainous Cuba would be the negative factors that could potentially kill her off for good. Even beyond that, she may have another chance in the eastern gulf in the face of a retrograding upper low. It's not over, but for now Chantal has ceased to be an immediately significant threat except for heavy rainfall.



I noticed you said 'Eastern GOM'. Does that put all the east coast doom casters to rest now?
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I think the NHC is wrong in saying Chantal will degenerate in 24 hrs. I am no expert but I just don't see her degenerating anytime soon.
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2618. IKE

Quoting mikatnight:


Hi Ike,

Glad to see another of The Old Ones still around. How are things in the GOM, feel like regenerating a wave?
Doing good.
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Chantal getting severely disrupted is making the storm very shallow.  This should impact the steering currents previously thought to be in play.  My guess is Chantal will stay on a track westward under Cuba and emerge in GOM.  In GOM conditions should be much more favorable for RI. If I am right, what steering currents will impact Chantal in GOM? Where will she go from there?
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2615. WxLogic
Quoting 2613. FIUStormChaser:


Or an Ernesto lol.


LOL
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Quoting 2609. WxLogic:
Well... I going to say it... she's pulling a Fay.


Or an Ernesto lol.
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Quoting 2601. Dakster:


Where did you read that?


About half way down in the #11 advisory discussion.
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Moving west well over 20mph....gonna make fools outta the long range models
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Quoting 2597. IKE:
CHANTAL IS FORECAST TO WEAKEN TO A TROPICAL DEPRESSION OR
DEGENERATE INTO A TROPICAL WAVE DURING THE NEXT 24 HOURS.


Hi Ike,

Glad to see another of The Old Ones still around. How are things in the GOM, feel like regenerating a wave?
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2609. WxLogic
Well... I going to say it... she's pulling a Fay.
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Quoting 2444. gator23:
Interesting... it seems that folks from Florida are calling for a Florida landfall and folks int he Caymens/Texas are saying west. Location bias is crazy on this blog. Im guilty of it too though.
I dunno. Some of the pple calling 4 the W track are in FL and the Bahamas....
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2607. IKE

Quoting Dakster:


Where did you read that?
Public advisory.
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Tropical Storm CHANTAL
AIR FORCE RECONNAISSANCE PLANE FINDS THAT CHANTAL IS STILL A TROPICAL STORM
10:00 AM EST Wed Jul 10
Location: 16.5°N 72.0°W
Moving: W at 29 mph
Min pressure: 1011 mb
Max sustained: 45 mph

what happern its still a tropical storm
Member Since: March 12, 2013 Posts: 110 Comments: 105687
The tchp makes a difference.
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2603. LargoFl
NOTE..the waterspouts noted in this briefing gulf coast.............THIS HAZARDOUS WEATHER OUTLOOK IS FOR WEST CENTRAL AND SOUTHWEST
FLORIDA.

.DAY ONE...TODAY AND TONIGHT.

...THUNDERSTORM IMPACT...
SCATTERED TO NUMEROUS MAINLY AFTERNOON AND EVENING THUNDERSTORMS
ARE EXPECTED TODAY. THESE THUNDERSTORMS WILL BE CAPABLE OF
PRODUCING HEAVY RAINFALL...GUSTY WINDS...AND FREQUENT LIGHTNING.

...WATERSPOUT IMPACT...
WATERSPOUTS ARE POSSIBLE ALONG THE COAST TODAY. MARINERS AND THOSE
ALONG THE COAST SHOULD REMAIN VIGILANT AND BE PREPARED TO ACT TO
REACH SAFETY IN CASE OF A LANDFALLING WATERSPOUT THREAT.

...RIVER FLOOD IMPACT...
A COUPLE OF AREA RIVERS REMAIN ABOVE FLOOD STAGE. ANY ADDITIONAL
RAINFALL COULD CAUSE A FURTHER INCREASE IN WATER LEVELS AND MORE
PRONOUNCED FLOODING ALONG THE RIVERS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

...THUNDERSTORM IMPACT...
SCATTERED MAINLY AFTERNOON AND EVENING THUNDERSTORMS ARE EXPECTED
EACH DAY. THE STRONGEST STORMS WILL BE CAPABLE OF PRODUCING HEAVY
RAINFALL...GUSTY WINDS...AND FREQUENT LIGHTNING.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS SHOULD MONITOR THE WEATHER AND SELF ACTIVATE IF NEEDED.

$$

GARCIA
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2602. will40
Quoting 2597. IKE:
CHANTAL IS FORECAST TO WEAKEN TO A TROPICAL DEPRESSION OR
DEGENERATE INTO A TROPICAL WAVE DURING THE NEXT 24 HOURS.


still a rain maker which we dont need
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2601. Dakster
Quoting 2597. IKE:
CHANTAL IS FORECAST TO WEAKEN TO A TROPICAL DEPRESSION OR
DEGENERATE INTO A TROPICAL WAVE DURING THE NEXT 24 HOURS.


Where did you read that?
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2600. 62901IL

TROPICAL STORM CHANTAL DISCUSSION NUMBER 11
NWS NATIONAL HURRICANE CENTER MIAMI FL AL032013
1100 AM EDT WED JUL 10 2013

ALTHOUGH SATELLITE IMAGERY SUGGESTED THAT CHANTAL NO LONGER HAD A
CLOSED CIRCULATION THIS MORNING...THANKS TO DATA FROM AN AIR FORCE
HURRICANE HUNTER PLANE CURRENTLY INVESTIGATING CHANTAL...WE WERE
ABLE TO LOCATE ENOUGH OF A CIRCULATION TO MAINTAIN ADVISORIES.
INITIAL INTENSITY IS 40 KNOTS BUT GIVEN THE STRONG SHEAR THAT IS
EXPECTED TO PREVAIL ALONG THE PATH OF CHANTAL...ALONG WITH THE
INFLUENCE OF SURROUNDING LAND...THE OFFICIAL FORECAST CALLS FOR
GRADUAL WEAKENING. CHANTAL WILL LIKELY DISSIPATE IN 3 DAYS...OR
PERHAPS MUCH EARLIER.

THE INITIAL MOTION IS HIGHLY UNCERTAIN SINCE THE CENTER DEFINITION
IS POOR. THE BEST ESTIMATE IS 280 DEGREES AT 25 KNOTS. HOWEVER...
THE STEERING CURRENTS ARE FORECAST TO WEAKEN AS THE HIGH TO THE
NORTH MOVES EASTWARD AND A MID-LEVEL TROUGH DEVELOPS OVER THE
EASTERN UNITED STATES. THIS PATTERN SHOULD RESULT IN A TURN TO THE
NORTHWEST AND NORTH OF THE CYCLONE OR ITS REMANTS DURING THE 2 TO 3
DAYS. THIS TRACK IS CONSISTENT PRIMARILY WITH THE GFS AND THE ECMWF
SOLUTIONS.


FORECAST POSITIONS AND MAX WINDS

INIT 10/1500Z 16.5N 72.0W 40 KT 45 MPH
12H 11/0000Z 18.1N 75.5W 35 KT 40 MPH
24H 11/1200Z 20.0N 78.2W 30 KT 35 MPH
36H 12/0000Z 22.5N 80.0W 25 KT 30 MPH
48H 12/1200Z 25.0N 80.5W 25 KT 30 MPH
72H 13/1200Z 30.0N 80.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 14/1200Z...DISSIPATED

$$
FORECASTER AVILA
Member Since: June 14, 2013 Posts: 2 Comments: 2003
2599. A4Guy
Quoting 2590. SouthernIllinois:
She is going to Texas Guys to give them much needed rain and then swing northeastward like Carla did and bring us beautiful rain in Southern Illinois. :)

No seriously, she is going west. Way west. This thing is Gulf bound. Will slip just to the north of Jamaica, over Cuba, and hook like Charlie. Obviously it won't pack the punch like Charlie, but will follow a similar track.

Bottom line. This beast has a mind of it's own and defies all models and great minds of NHC forecasters...

Nat


"BEAST" - ROFLMAO
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Quoting 2587. LargoFl:


curiouser and curiouser...
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2597. IKE
CHANTAL IS FORECAST TO WEAKEN TO A TROPICAL DEPRESSION OR
DEGENERATE INTO A TROPICAL WAVE DURING THE NEXT 24 HOURS.
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29mph! We can say all we want about shape, disorganized, sloppy and whatnot, but she has some serious energy with her to move at 29mph and still maintain 'TS' characteristics. I'm still waiting to see if she slows and builds back up. With that amount of energy, she could be potent. Be prepared if near the cone.
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11am
16.5n 72w
45mph
w 29mph
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Quoting 2587. LargoFl:

That track is bogus this is going into the gulf of mexico,it being steering by 850 mb flow.
Member Since: July 2, 2013 Posts: 0 Comments: 1523
2593. GetReal



Each new frame is getting more interesting, and IMO backs up where these stronger TS force winds are being found by RECON and shore observations.

Chantal continues to breath.
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I am impress! She continues to defined forecasters and bloggers.
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Quoting 2576. StormTrackerScott:
Looks like she is trying to wrap up.



Confounded storm!
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2589. Dakster
Quoting 2578. nrtiwlnvragn:
TROPICAL STORM CENTER LOCATED NEAR 16.5N 72.0W AT 10/1500Z
POSITION ACCURATE WITHIN 70 NM

Horseshoes and handgrandes LOL


And apparently we can add Hurricanes / Tropical Storms to that.
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2588. SLU
...AIR FORCE RECONNAISSANCE PLANE FINDS THAT CHANTAL IS STILL A TROPICAL STORM...

Defying all odds.
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2587. LargoFl
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2586. will40
track shifted east
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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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