Tropical Storm Chantal: a Likely Harbinger of an Active Atlantic Hurricane Season

By: Dr. Jeff Masters , 2:02 PM GMT on July 08, 2013

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Tropical Storm Chantal is speeding westwards at 26 mph towards a Tuesday encounter with the Lesser Antilles Islands. Satellite loops show that Chantal has plenty of spin, with several well-developed low-level spiral bands that have gradually increased their heavy thunderstorm activity this morning. However, Chantal is fighting dry air associated with the Saharan Air Layer (SAL). The heavy thunderstorm activity near Chantal's center is rather thin, and there are virtually no heavy thunderstorms on the storm's north side, where upper-level northwesterly winds are creating light to moderate wind shear of 5 - 15 knots, and driving dry air into the storm. This dry air is readily apparent on water vapor satellite loops. Ocean temperatures are fairly warm, though, at 27.5 - 28°C. There have not been any hurricane hunter missions into Chantal yet, but an Air Force hurricane hunter aircraft deployed to St. Croix on Sunday, and is scheduled to investigate Chantal on Monday afternoon.


Figure 1. MODIS image of Chantal taken at approximately 10 am EDT Monday, July 8, 2013. At the time, Chantal had top winds of 45 mph. Image credit: NASA.


Figure 2. U.S. Air Force Master Sgt. Levi Denham, a WC-130J Hercules aircraft weather reconnaissance loadmaster assigned to the 53rd Reconnaissance Squadron (the Hurricane Hunters), performs pre-engine start-up inspections in St. Croix, Virgin Islands, on Sept. 16, 2010. DoD photo by Staff Sgt. Manuel J. Martinez, U.S. Air Force. Thanks go to wunderground member Patrap for pointing out this photo.

Forecast for Chantal
The 8 am EDT Monday forecast from the SHIPS model predicts that Chantal will experience low to moderate shear through Tuesday afternoon as it heads west-northwest at 25 mph towards Hispaniola. With ocean temperatures expected to warm to 28°C during that time, Chantal has the potential to intensify to a 65 mph tropical storm before hitting Hispaniola. Working against intensification will be 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, and I don't see Chantal making it to hurricane strength before interacting with the mountains of Hispaniola and/or Cuba on Tuesday night and Wednesday. This interaction may be able to destroy the storm, since wind shear is also expected to rise to the high range, 20 - 30 knots, Tuesday night through Thursday. Chantal has the potential to cause big problems for Haiti, which is highly vulnerable to flash flooding due to the lack of vegetation on the deforested mountains. However, there is a lot of dry air to the west of Chantal, which may act to keep rainfall totals in Haiti down to a manageable 2 - 4". Over 300,000 people are still homeless and living in makeshift tent camps in Haiti, three years after the great 2010 earthquake.

Once Chantal crosses Hispaniola and enters the Bahamas late this week, the trough of low pressure pulling the storm to the northwest is expected to lift out. It is unclear at this point whether or not this trough will be strong enough to pull Chantal out to sea, or whether the storm might be forced back to the northwest into the U.S. East Coast by high pressure building in.


Figure 3. There have been only thirteen tropical depressions or tropical storms that have formed July 15 or earlier that have passed through the Lesser Antilles since 1851, an average of one such tropical cyclone every thirteen years. Note that two of these storms, Dennis and Emily, occurred during the notorious Hurricane Season of 2005. There were five other pre-July 16 storms that formed east of the Lesser Antilles Islands, but did not pass through the islands (Bertha of 2009, Barry of 1989, and unnamed tropical depressions in 1967, 1978, and 2001.) Image credit: NOAA's Historical Hurricane Tracks website.

Chantal: an uncommon early-season Cape Verde-type tropical storm
Formation of a tropical storm east of the Lesser Antilles Islands in early July from an African tropical wave is an uncommon occurrence. Since Atlantic hurricane records began in 1851, there have been only thirteen tropical depressions or tropical storms that have formed July 15 or earlier that have passed through the Lesser Antilles, an average of one early-season tropical cyclone every thirteen years. Note that two of these storms, Dennis and Emily, occurred during the notorious Hurricane Season of 2005. There were five other pre-July 16 storms that formed east of the Lesser Antilles Islands, but did not pass through the islands (Bertha of 2009, Barry of 1989, and tropical depressions in 1967, 1978, and 2001 that did not become named storms.)

Chantal: a likely harbinger of an active Atlantic hurricane season
Chantal's formation on July 8 is an usually early date for formation of the season's third storm, which usually occurs on August 13. A large number of early-season named storms is not necessarily a harbinger of an active season, unless one or more of these storms form in the deep tropics, south of 23.5°N. According to Phil Klotzbach and Bill Gray, leaders of Colorado State's seasonal hurricane forecasting team,

"Most years do not have named storm formations in June and July in the tropical Atlantic (south of 23.5°N); however, if tropical formations do occur, it indicates that a very active hurricane season is likely. For example, the seven years with the most named storm days in the deep tropics in June and July (since 1949) are 1966, 1969, 1995, 1996, 1998, 2005, and 2008. All seven of these seasons were very active. When storms form in the deep tropics in the early part of the hurricane season, it indicates that conditions are already very favorable for TC development. In general, the start of the hurricane season is restricted by thermodynamics (warm SSTs, unstable lapse rates), and therefore deep tropical activity early in the hurricane season implies that the thermodynamics are already quite favorable for tropical cyclone (TC) development."

Two of this season's three storms have formed in the deep tropics--Tropical Storm Barry, which formed in the Gulf of Mexico's Bay of Campeche at a latitude of 19.6°N, and now Tropical Storm Chantal, which formed at a latitude of 9.8°N. With recent runs of the GFS model predicting formation of yet another tropical storm southwest of the Cape Verde Islands early next week, it appears that the Atlantic is primed for an active hurricane season in 2013.

Jeff Masters

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Morning Baha,

Light rain and thunder in Briland this morning...looks like it will be pouring soon...sky is very dark looking towards Lutra
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3082. Grothar
Quoting 3073. BahaHurican:
BTW, I'm thinking about visiting FLL next week... should I bring you some cerasee and some life leaf? They taste like [ahem] but are supposed to be good for you... build up your blood... and other things...


Sure your friend still live by the Galleria mall?
Member Since: July 17, 2009 Posts: 71 Comments: 27208
3081. Gearsts
Shear
Member Since: August 2, 2010 Posts: 0 Comments: 2000
3079. SLU
Gusts to 54mph just reported from St. Lucia.
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Quoting 3075. AtHomeInTX:
That's the remnants of Dorian on the east coast. Don't know what's in the north Atlantic. But the other one seems to be the E storm. I don't even know what that is. Wild run.

Hello At home and good morning everyone.Omg this run is exciting it has a tc north of Honduras.
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Quoting CycloneOz:


Yo Aussie! How ya been? Good seeing you this AM in the western hemisphere.

The growing season here in Ecuador is year round...so I am always pushing up daisies up in this part of the world. :)


Did you get chased out of the States mate?
Ecuador, geez. Last year you were in NOLA for Isaac and this year your in Ecuador. Where to next year.
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Quoting 3072. CycloneOz:


Ain't that the truth. The cloud formations are breath taking. You would think that the hammer is going to come down.

Instead...a gentle rain falls with no wind.

Amazing weather! :)
Pictures... pics, man! Sounds like a photographers heaven. I've also heard you still get seasons... only they arranged by altitude, not by month... lol
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That's the remnants of Dorian on the east coast. Don't know what's in the north Atlantic. But the other one seems to be the E storm. I don't even know what that is. Wild run.

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3074. Gearsts
CURRENT WEATHER CONDITIONS

Date and Time Updated: TUESDAY 9th JULY 2013 AT 6 AM

Pressure: 1011.6 mb

Temperature: 24.2 °C

Apparent Temperature: N/A °C

Relative Humidity: 100 %

Wind Direction: E

Wind Speed: 8 KM/H

Visibility: 12 KM

Present Weather: OVERCAST/ SHOWERS

Cloud Cover:

Low: 7 /8 Medium: / /8 High: / /8
Member Since: August 2, 2010 Posts: 0 Comments: 2000
Quoting 3066. Grothar:


Baha,sorry I said Chantal was going through the Bahamas the other day. Nothing personal
BTW, I'm thinking about visiting FLL next week... should I bring you some cerasee and some life leaf? They taste like [ahem] but are supposed to be good for you... build up your blood... and other things...
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Quoting 3066. Grothar:


Baha,sorry I said Chantal was going through the Bahamas the other day. Nothing personal
I am not even going to thaw the fish I'm going to smack you with before I do it... and I'm going to wait until you are fully recovered so those nurses won't take a hit out on me....
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Quoting 3053. CycloneOz:


Morning Baha. How ya been?

It is raining this morning in Ecuador. I love living under the ITCZ. It's wonderfully ironic.
LOL... all of the rain... none of the excitement... It's good to see you in the blog, man...
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3066. Grothar
Quoting 3044. BahaHurican:
Good morning all...

Woke up this morning to light rain showers, overcast skies, and muted thunder. Feels like April out there.


Baha,sorry I said Chantal was going through the Bahamas the other day. Nothing personal
Member Since: July 17, 2009 Posts: 71 Comments: 27208
CoC is open on the south side obviously, but there are a few light showers trying to form there.

This storm is in really bad shape, and probably won't change for another 8 to 12 hours. It needs to get out of the dry air in order to intensify any.
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3064. MahFL
Convection firing.



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Quoting 3037. barbamz:
Wow, look at Soulik!

This was textbook formation... it was looking good yesterday, and pulling together much faster than Chantal...
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Quoting 3054. CycloneOz:


Not a chance. My money goes far here! :)

Plus, the women are beautiful and bronzed.



Three Chineese cheers!


Phooey! Phooey! Phooey!
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winds back up to 60 mph at the end.
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Quoting CycloneOz:
Hey Doug,

If I was still chasing, I would be able to enjoy my week in Pensacola!

OZ,,,, How are ya mate. I thought you um.... pushing up daisies. Opps, my bad.
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3058. Grothar

Member Since: July 17, 2009 Posts: 71 Comments: 27208
Quoting 3030. jeffreeysweetypie:
Extremely hard and rare for a storm comming up from the bahamas to make a drastic left turn into florida..... once they start to bend they usually follow a track around the high
That's really not so true... as recently as Jeanne a storm was headed north but looped back and hit FL. The transition may not be as abrupt as the models show, but there are numerous examples in the record.
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Quoting 3043. BahaHurican:
I hope you reported this to the powers that be already. The longer you wait, the harder it is for them to trace what happened.

Not funny.. way not funny....

Have you put up your shutters yet???



I didn't even see Tyler's comment. But I reported the same thing happened to me earlier. Thanks to whitewabbit's infinite patience explaining to me how to do that. :) Good Morning Baha.
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3052. WxLogic
Good Morning...
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Good morning. Look at that core structure on Soulik. That's just awesome:





Looks like Chantal is not doing well from reading back on the blog. The 6z GFS dropped the idea of redevelopment in the Bahamas or GOM.
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Quoting 3012. Chicklit:
SLOW STRENGTHENING IS FORECAST FOR THE NEXT 36 HOURS AS CHANTAL REMAINS OVER WARM WATER AND IN AN ENVIRONMENT OF MODERATE WIND SHEAR.

PRONOUNCED WEAKENING IS THEN EXPECTED WHEN CHANTAL MOVES OVER OR INTERACTS WITH THE RUGGED TERRAIN OF HISPANIOLA.

IF THE CYCLONE SURVIVES ITS TREK ACROSS HISPANIOLA...IT COULD RE-INTENSIFY AS THE ENVIRONMENTAL WIND PATTERN IS ANTICIPATED TO BECOME MORE FAVORABLE BY THE TIME THE SYSTEM REACHES THE BAHAMAS.

ONLY SLIGHT MODIFICATIONS WERE MADE TO THE WIND SPEED FORECAST OF THE PREVIOUS ADVISORY...AND THE LATEST NHC INTENSITY FORECAST IS MORE OR LESS IN LINE WITH THE FLORIDA STATE SUPERENSEMBLE AND THE INTENSITY MODEL CONSENSUS.

FORECAST POSITIONS AND MAX WINDS

INIT 09/0900Z 13.3N 58.4W 45 KT 50 MPH
12H 09/1800Z 14.6N 61.7W 50 KT 60 MPH
24H 10/0600Z 16.3N 65.9W 55 KT 65 MPH
36H 10/1800Z 18.2N 69.4W 60 KT 70 MPH
48H 11/0600Z 20.1N 72.0W 40 KT 45 MPH
72H 12/0600Z 23.5N 74.8W 40 KT 45 MPH
96H 13/0600Z 26.5N 76.0W 45 KT 50 MPH
120H 14/0600Z 28.5N 77.5W 50 KT 60 MPH

$$
FORECASTER CANGIALOSI/PASCH
Should be interesting to watch as Chantal waxes and wanes over the coming days. Not crazy over the 50 KT off my coast in 120 hours. Also still reading about the left turn causes some consternation but will see how it all plays out.
Morning Chick... I'm not liking this direct-to-my-doorstep track either. Hopefully (1) this remains a minimal storm all the way (2) it's the strongest storm that passes near / over either of us.

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3049. MahFL
Quoting 3030. jeffreeysweetypie:
Extremely hard and rare for a storm comming up from the bahamas to make a drastic left turn into florida..... once they start to bend they usually follow a track around the high


It does happen though, from time to time. Lets hope they don't call it Super Storm Chantal......
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Typhoon Soulik in true colour.




Imagine this blog if this was Chantal!!!!
Boom!!!!!
LOL
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Quoting 3045. BahaHurican:
Is that the great OZ on the blog?????


It is.
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Quoting 3041. CycloneOz:
Hey Doug,

If I was still chasing, I would be able to enjoy my week in Pensacola!



Move back.
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Is that the great OZ on the blog?????
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Good morning all...

Woke up this morning to light rain showers, overcast skies, and muted thunder. Feels like April out there.
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Quoting 2011. TylerStanfield:
Can somebody help me? I've lost everything, my blogs, my bio, and my comments. :(
I hope you reported this to the powers that be already. The longer you wait, the harder it is for them to trace what happened.

Quoting 2056. Thrawst:


MAHAHA Chantal doesn't like the Northwest Bahamas ;)
Not funny.. way not funny....

Have you put up your shutters yet???

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Update from Barbados, The eye has not passed as yet and we feared very well with hardly any rainfall just drizzles surprisingly. We are overcast at the moment but no wind, rain, thunder or lightening. We are glad but disappointed at the same time. Chantel looks frayed this morning, should start to pick up momentum and strength soon
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3040. Grothar
Member Since: July 17, 2009 Posts: 71 Comments: 27208
3039. JLPR2
Looks like 13.8N, 59.4W

Barbados Radar

And it's passing to the North of Barbados, checked the WU page for the island and no west winds have been reported, it's a good bet that Chantal doesn't have a closed LLC.
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This is Interesting. Out of NWS MOBILE this morn.


LONG TERM
THINGS UNSETTLED THROUGH THE UPCOMING WEEKEND. THE END OF THE PERIOD
REMAINS UNCERTAIN AS THE GFS NOW BUILDS A STRONG ENOUGH RIDGE OFF
THE MID ATLANTIC COAST TO TURN CHANTAL SOUTHWESTWARD ACROSS THE
FLORIDA PENINSULA AND INTO THE GULF...WHILE THE ECMWF HAS A WEAKER
RIDGE AND KEEPS THE REMNANTS OF CHANTAL WELL EAST OF THE REGION.

DEFINITELY SOMETHING TO WATCH DURING THE LATTER PART OF THE THIS
FORECAST PERIOD INTO LATE NEXT WEEK AS IT APPEARS THE TROPICS ARE
STARTING TO GET ACTIVE.M (WEDNESDAY THROUGH TUESDAY)...SHOWERS AND THUNDERSTORMS
WILL INCREASE IN COVERAGE YET AGAIN WEDNESDAY AND ESPECIALLY
THURSDAY AS AN UPPER TROF DEEPENS ACROSS THE EAST COAST AND SENDS A
SFC COLD FRONT SOUTHWARD TOWARD THE GULF COAST. MEANWHILE...A WELL
DEFINED UPPER LOW CURRENTLY OFF THE SE FLORIDA COAST WILL MOVE
WESTWARD AND BECOME ABSORBED INTO THE DEEPENING UPPER LEVEL TROF.
THE COLD FRONT WILL STALL ACROSS THE AREA ON FRIDAY AND GRADUALLY
WASH OUT THROUGH THE WEEKEND AS THE DEEP UPPER TROF ACROSS THE
REGION CUTS OFF INTO AN UPPER LOW THAT DRIFTS WESTWARD ACROSS THE
GULF COAST THROUGH THE WEEKEND. ALL OF THESE FACTORS WILL KEEP DUE TO THE WET PATTERN...CONTINUED TO GO
SLIGHTLY BELOW GUIDANCE FOR HIGH TEMPS WITH LOWS REMAINING NEAR
NORMAL.
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3037. barbamz
Wow, look at Soulik!

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Quoting 3032. jeffreeysweetypie:
i think this will be another year of pathetic storms like last year


Fast forward motion and sinking air, the past two seasons. I blame the jet stream.
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3034. Grothar
Member Since: July 17, 2009 Posts: 71 Comments: 27208
Barbados Radar showing the center pretty well..13.8 59.2

Link

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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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