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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Quoting 275. HurricaneAndre:
Chantal looking good.

If Good meant a squashed looking area of convection with the center partially exposed... then yeah, it looks Good.
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Quoting 270. AussieStorm:
WA chills through freezing nights

The mercury plummeted over parts of Western Australia this morning, with some places seeing their coldest nights in almost half a century.

In the Central Wheatbelt, Corrigin residents experienced the coldest night in 49 years as the mercury dropped to minus four. Beverley shivered through its coldest night since records began 44 years ago, also recording minus four.

The Central Wheatbelt was not the only place feeling the sub-zero conditions, Narrogin in the Great Southern District had it's coldest night in 32 years, while it was 16 years since Wagin experienced a night a that was as cold, dipping to minus two.

Those in the city were not spared from the nippy temperatures. Perth recorded 1.5 degrees this morning, making it the coldest minimum temperature recorded since July last year. This was also six degrees below July's average temperature of 7.6 degrees.

The cold mornings were a combined effort of a large stable high pressure system sitting over southern parts of the state, with clear skies, allowing the day time warmth to escape.

Tuesday morning will be slightly warmer as the cloud begins to build ahead of a cold front. This front will be bringing a burst of showers to the southwest from around midday, although a break in the clouds should see the day reaching a comfortable 19 degrees.

Nights from mid-week and then likely to be significantly warmer as increased cloud over the state prevents the daytime warmth from escaping.

Weatherzone 2013






As its going to feel like over 90 degrees at my house... I will be looking at those pictures to make me feel cooler :p
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Quoting 277. hydrus:
As I kowtow in an obsequious manner...:)
Much too big of word for me...
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Quoting 230. tropicalnewbee:

After growing up on seafood in New England I can't stomach it anymore but I enjoy their steak!

At your age proper English should be like breathing but good on you and the missus! :)


Don't forget. English is not my really my first language. It is my third. I first learned Old English then gradually worked by way up. :)
Member Since: July 17, 2009 Posts: 69 Comments: 25458
Quoting 268. Patrap:
The Chart

Ahh, ah ahhh, ah ahhh...



As I kowtow in an obsequious manner...:)
Member Since: September 27, 2007 Posts: 1 Comments: 20546
Quoting 266. southernema:



you may need rain but I don't think anyone needs the potential destruction that a hurricane can bring.

That's the thing. You may not understand, but we've been in drought for 3 years straight with only isolated improvements, and the only way we usually get improvement is in our rainy months of May (Where we barely saw rain) and October. In 2010 we got out of Drought with help from Hurricane Alex, Tropical Depression Two, and Tropical Storm Hermine. We haven't seen a storm since. We need a Storm, end of story, maybe not a Major Hurricane, but we need a storm.
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Chantal looking good.
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Maybe this one does not struggle with trade winds as much. Definitely moves slower on the GFS.

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Quoting 261. TylerStanfield:

We can always hope :) We need a storm in Texas. And I do mean, we NEED it. Tropical Storm or Hurricane, we need it.


We need the rain, but I will pass on the Hurricane. We do not need one of those.
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make sure you like dr master interesting blog the most ive seen during 94 days was 70.
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Quoting 256. Patrap:
I know a Bobby Hebert, but he no relation to the Box Guy.
I saw Elvis Presley last week in a Walmart in Pigeon Forge, Tn...Not sure if it was the real guy, but he dropped a bunch of bananas and I picked them up.. He said" Thank You, Thank you very much"
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WA chills through freezing nights

The mercury plummeted over parts of Western Australia this morning, with some places seeing their coldest nights in almost half a century.

In the Central Wheatbelt, Corrigin residents experienced the coldest night in 49 years as the mercury dropped to minus four. Beverley shivered through its coldest night since records began 44 years ago, also recording minus four.

The Central Wheatbelt was not the only place feeling the sub-zero conditions, Narrogin in the Great Southern District had it's coldest night in 32 years, while it was 16 years since Wagin experienced a night a that was as cold, dipping to minus two.

Those in the city were not spared from the nippy temperatures. Perth recorded 1.5 degrees this morning, making it the coldest minimum temperature recorded since July last year. This was also six degrees below July's average temperature of 7.6 degrees.

The cold mornings were a combined effort of a large stable high pressure system sitting over southern parts of the state, with clear skies, allowing the day time warmth to escape.

Tuesday morning will be slightly warmer as the cloud begins to build ahead of a cold front. This front will be bringing a burst of showers to the southwest from around midday, although a break in the clouds should see the day reaching a comfortable 19 degrees.

Nights from mid-week and then likely to be significantly warmer as increased cloud over the state prevents the daytime warmth from escaping.

© Weatherzone 2013





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Quoting 263. MahFL:


The peak is not for another 2 months.


Well from now past the Peak of Hurricane Season it looks like the SE & Gulf Coast states are in for a pounding as I don't think we will be seeing many Fish Storms this season.
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The Chart

Ahh, ah ahhh, ah ahhh...





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Quoting 261. TylerStanfield:

We can always hope :) We need a storm in Texas. And I do mean, we NEED it. Tropical Storm or Hurricane, we need it.
I hate to say it.But you guys need a hurricane of Ike proportions to bust you all's drought.Don just vaporized and Jim Cantore seemed so dissapointed.lol.
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Quoting 261. TylerStanfield:

We can always hope :) We need a storm in Texas. And I do mean, we NEED it. Tropical Storm or Hurricane, we need it.



you may need rain but I don't think anyone needs the potential destruction that a hurricane can bring.
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I still say S. America is in for a glancing strike.
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GFS 30 hrs.

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263. MahFL
Quoting 227. StormTrackerScott:
This is not a good pattern for FL residents. Looks like a 2004 set up as we head into the peak of hurricane season.



The peak is not for another 2 months.
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A lot of rain moving toward FL as we move into Tuesday.

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Quoting 259. washingtonian115:
ncstorm do you know who the experts are?.Seems I've been tricked all these years.

I'm more interested to see what "Dorian" will do.The track will change though.So what may seem like Texas now may be it'll be L.A or M.S perhaps F.L..

We can always hope :) We need a storm in Texas. And I do mean, we NEED it. Tropical Storm or Hurricane, we need it.
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Quoting 256. Patrap:
I know a Bobby Hebert, but no relation to the Box Guy.


Bobby Hebert was thrown out of his box.

Though I'm pretty sure he has a nice one on the 50 yd line at Death Valley now.
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Quoting 250. ncstorm:
7 day sea level pressures

ncstorm do you know who the experts are?.Seems I've been tricked all these years.

I'm more interested to see what "Dorian" will do.The track will change though.So what may seem like Texas now may be it'll be L.A or M.S perhaps F.L..
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Notice the blob over the islands, moving W... What will force Chantal to move NW? Will it adjust further S its trayectory?

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Miami
NEXRAD Radar

Base Reflectivity 0.50° Elevation
Range 248 NMI

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I know a Bobby Hebert, but he no relation to the Box Guy.
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Quoting 239. PalmBeachWeather:
I stopped breathing years ago and I feel so much better,and my acne cleared up also... Give it a try.
Sorry the second part of that quote was for Gro it lumped them together I guess I didn't give it enough space or something. At any rate I hope I can make it to Gro's age, I have 6 kids and been married 15 years so I am working on it...given his age I would say about a 6th of the way there :)
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Dem some skinny bones for a TS.

AL032013 - Tropical Storm CHANTAL


Enhanced Infrared (IR) Imagery (4 km Mercator)

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Quoting 198. missionRN14:
Can anyone comment on that Cold core low pressure system just over the Bahamas that DR Jeff Masters mentioned in passing the other day about possible development....
Well last night it looked like just a dry spin and this am looks like a cloud gatherer with a potential development? Any comment. NHC is a no mention...
Please.. I'm in the need to know zone work Emergency Services...
Tks guys


According to the NHC, the cold core upper low is interacting with the northern part of a Tropical
Wave which may be enhancing the convection....
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I would remind folks that the Islands will be impacted first.........One location at a time.

We track the storms on here 24/7, which is fine, but remember Dr. Frank's rule of thumb for the general viewing public in the States; don't really need to keep an eye on what you may need to do for preparations until a storm gets near Puerto Rico. As he worked, and published papers along with Dr. Hebert, here is the wiki art again I posted last week on the two Hebert boxes:

Link

The first Hebert Box is located east of Puerto Rico over the US Virgin Islands, between 15° and 20° north latitude and 60° to 65° west longitude. This was the first area that Hebert discovered, and provides an indication for the behavior of Cape Verde type storms, which form off of the western coast of Africa near the islands of the same name. This first box is useful for storms that typically form in the early part of the Atlantic hurricane season (June through early September).

The second Hebert Box is located over the Cayman Islands between 15° and 20° north latitude and 80° to 85° west longitude. This was the second discovered, and provides an indication for the behavior of storms that will move north to hit Florida. These are usually late-season storms that form in this region in late September and October, and this box is mostly concerned with them.[2]



And YES; Chantal is currently tracked to go through Hebert Box 1; thank God the intensity models keep this one at TS level............
Member Since: August 8, 2006 Posts: 0 Comments: 8834
Quoting 243. unknowncomic:
No hot water fuel, yet.
Everytime I see your name I see a guy in a funny suit with a paper bag on his head with holes for eyes......Ever read about Chuck Barris?? Who would have guessed.
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7 day sea level pressures

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Quoting 236. Camille33:

Track/Intensity I made last night check it out guys.After day 3 it get's more uncertain.

While some of the conditions are there for intensification, did you factor in the moutains of Hispaniola and Cuba? As well as the increase in shear at the time it crosses? It could thread the needle so-to-speak between the two and maintain strength given it is a small system which is very possible, but it will interact with land features causing it to not intensify or weaken. I think Cat1 isn't out of the realm of possibility, but unlikely.
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Quoting 245. Stormchaser2007:
Looking forward...

I'd say that there's a moderate chance at seeing another CV tropical system within the next seven days.

This one could be more interesting.


Could track even further West.
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Quoting 240. washingtonian115:
A lot of people wrote off Jeanne in the U.S.But it looped right back to Florida.


Yeah because of a strong Bermuda High. The Bermuda High has been deflecting troughs from penetrating across the Eastern US
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06Z GFS brings "Dorian" into the Western Gulf. *Crosses Fingers* Hopefully it makes it's way for Texas. We need all we can get.
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Looking forward...

I'd say that there's a moderate chance at seeing another CV tropical system within the next seven days.

This one could be more interesting.

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Quoting 237. scottsvb:
Guys when Stewart or any of the Dr.s from the NHC post a forecast point and strength, it's a combined effort from all the staff on where it will be and how strong. So just cause Stewart said it will be 70mph by 48hrs, it doesn't mean he's the only 1. Some might have said 80mph Hurricane, Some may have said 60MPH TS.. we don't have the technology to give windspeed yet. 70mph is the base avg of the Mets at the NHC.

LOL...well explained there. I think people find it more fun to "shoot the messenger!"
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Quoting 227. StormTrackerScott:
This is not a good pattern for FL residents. Looks like a 2004 set up as we head into the peak of hurricane season.

No hot water fuel, yet.
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Hey the Blog slowed down does that mean Chantal has slowed also :o)

Taco :o)
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Quoting 231. StormTrackerScott:
People seem to forget the NHC wrote Jeanne off after the pass of Hispanola but we all know what happened after that.

A lot of people wrote off Jeanne in the U.S.But it looped right back to Florida.
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Quoting 230. tropicalnewbee:

After growing up on seafood in New England I can't stomach it anymore but I enjoy their steak!

At your age proper English should be like breathing but good on you and the missus! :)
I stopped breathing years ago and I feel so much better,and my acne cleared up also... Give it a try.
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Boomers in Houston now! It's a welcome sound. Now just rain
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Guys when Stewart or any of the Dr.s from the NHC post a forecast point and strength, it's a combined effort from all the staff on where it will be and how strong. So just cause Stewart said it will be 70mph by 48hrs, it doesn't mean he's the only 1. Some might have said 80mph Hurricane, Some may have said 60MPH TS.. we don't have the technology to give windspeed yet. 70mph is the base avg of the Mets at the NHC.
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Track/Intensity I made last night check it out guys.After day 3 it get's more uncertain.
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Hey Levi32 isn't the type of pattern that you explained the same pattern that forced Hurricane Hugo back towards Charleston,SC after leaving Puerto Rico?
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Quoting 198. missionRN14:
Can anyone comment on that Cold core low pressure system just over the Bahamas that DR Jeff Masters mentioned in passing the other day about possible development....
Well last night it looked like just a dry spin and this am looks like a cloud gatherer with a potential development? Any comment. NHC is a no mention...
Please.. I'm in the need to know zone work Emergency Services...
Tks guys


No reliable models develop the cold core system. There may be heavy thunderstorms with small hail, locally flooding rains and gusty winds over the Florida peninsula tomorrow and Wednesday as it passes overhead.
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Quoting 228. MisipiGrl:
Walt: "Can anyone (genuinely) identify this scenario?"

I don't think ANYONE on the Mississippi Gulf Coast will ever forget the good ole TD 10, dissipated then named TD 12 scenario. :)
Does anyone think this is a similar setup to what we are looking at now...down the road?
Member Since: May 16, 2010 Posts: 0 Comments: 1455

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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.