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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Am I just hearing voices above, or are recent developments in the Atlantic basin now pointing to a potentially, "very active hurricane season?"

I hope I'm wrong, but it's also nice to be right, if that makes any sense.

As I said here yesterday in my season update(Post 2553,) "enjoy the show, but don't be happy about it."

Here's my May 29th Forecast - Post 543 ...
Quoting 543. OracleDeAtlantis:
I was going to roll this out on June 1, but it looks like the Atlantic season is starting a bit sooner than I expected. I typically will publish one or two of these a year. You can judge for yourselves how accurate I've been in the past, but considering that last year's highlighted a giant "S" for a backdrop, I hope I can safely assume that I have some bragging rights. It was, after all, an undeniable Superstorm.

The title of this forecast, which was initially published May 25, 2013 is: "Goes with the territory ..." It's based upon a dream that I had several weeks ago.

Note: There's a unique graphic and a short video that accompanies this forecast, also. See below ...



Member Since: Posts: Comments:
Wow Sar, quite the bullet you dodged. Eight boats and twenty three never accounted for, that had to be one terrifying way to go. So sorry to hear about your wife, but fate works in strange ways and your still here. What a way to go, you'd see it coming and be helpless to do anything about it.
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Quoting 2728. TropicalAnalystwx13:
Everybody repeat after me.

Tropical Storm Chantal.

Chantal.

Chantal.

ChantAl.

Lol.
Found out it was spelled that way this afternoon LOL
Member Since: September 2, 2009 Posts: 130 Comments: 21194
All aside, Chantal will be a strengthening storm as it approaches Barbados in the morning. With the sloppy south side, they may miss the TS winds. Lot's of rain however. Odd that the rain is where the lower winds are and the higher winds are in the relatively rain free zone. Likely caused by the pressure gradient.




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Everybody repeat after me.

Tropical Storm Chantal.

Chantal.

Chantal.

ChantAl.

Lol.
Member Since: July 6, 2010 Posts: 113 Comments: 32717
Member Since: June 11, 2013 Posts: 20 Comments: 3383
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2725. JRRP


less and less dry air
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2724. 7544
looks chantel and the ull may have a good dmax tonight look for more blobs tomorow imo
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We will know more from the recon in 5-6 hours.
Member Since: June 11, 2013 Posts: 20 Comments: 3383
2722. Niedjav
Link
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Well looks like we have to wait for the next TWO to see if we get any mention on those tropical waves in the far eastern atlantic.

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 AM EDT TUE JUL 9 2013

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM CHANTAL...LOCATED A COUPLE OF HUNDRED MILES EAST OF THE
WINDWARD ISLANDS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER CANGIALOSI
Member Since: June 30, 2013 Posts: 12 Comments: 8774
Quoting 2719. GTstormChaserCaleb:
CHANTAL 03L T3.0/3.0 08/2345Z Atlantic



Wind Shear increasing to 20 knots:



Gotta say I'm surprised SAB thinks Chantal looks like a T3.0...especially since it isn't the prettiest tropical storm I've ever seen lol.

To give you an idea...on the Dvorak scale, a T3.0 has winds of 45kts and a pressure of 1000mb.

http://www.ssd.noaa.gov/PS/TROP/CI-chart.html
Member Since: September 2, 2009 Posts: 130 Comments: 21194
CHANTAL 03L T3.0/3.0 08/2345Z Atlantic



Wind Shear increasing to 20 knots:



Member Since: June 30, 2013 Posts: 12 Comments: 8774
2718. JRRP
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Quoting 2716. Tazmanian:
the nhc may need two yellows out there soon






Yep I don't like this at all,3rd wave coming of too.
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the nhc may need two yellows out there soon





Member Since: May 21, 2006 Posts: 5091 Comments: 115437
2715. flsky
Quoting 2705. sar2401:
This is all pretty amazing. The last time I've seen such interest in a tropical storm at 12.4N was in 2004 for Ivan...and he was a cat 3, on the way to a cat 4 at the time. He was supposed to turn poleward, run up the Windwards and end up somewhere in Florida too. He did, just not in the way that any model predicted. If it hadn't been for the fact my wife died in 2004, we would have been living aboard our sailboat and would have been in Grenada on September 7, 2004. I would have run for the ABC's, since no hurricane ever travels west that far south. My boat speed was 11 knots and Ivan was traveling at 13 knots. We would have been overtaken in open seas and I wouldn't be here today. There are 8 yachts and 23 people who's remains have never been discovered, and they were running the same direction I would have run. Life (and models) sometimes turn out way different than you expect.

You aren't Randy from PI are you? If so, send me a WU email.
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Quoting 2710. ProgressivePulse:


That's all relative to where you believe the center position to be at this point.


2:00 AM AST Tue Jul 9
Location: 12.9°N 57.2°W
Moving: WNW at 26 mph
Min pressure: 1010 mb
Max sustained: 50 mph

radar show it further S
Member Since: June 13, 2009 Posts: 2 Comments: 12712
2713. nigel20
Quoting Civicane49:
A beautiful, but dangerous typhoon in the western Pacific:


It looks a bit similar to Igor in 2010.
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In six hours, Chantal has moved 1.1N and 2.2W.
Member Since: July 6, 2010 Posts: 113 Comments: 32717
Quoting 2705. sar2401:
This is all pretty amazing. The last time I've seen such interest in a tropical storm at 12.4N was in 2004 for Ivan...and he was a cat 3, on the way to a cat 4 at the time. He was supposed to turn poleward, run up the Windwards and end up somewhere in Florida too. He did, just not in the way that any model predicted. If it hadn't been for the fact my wife died in 2004, we would have been living aboard our sailboat and would have been in Grenada on September 7, 2004. I would have run for the ABC's, since no hurricane ever travels west that far south. My boat speed was 11 knots and Ivan was traveling at 13 knots. We would have been overtaken in open seas and I wouldn't be here today. There are 8 yachts and 23 people who's remains have never been discovered, and they were running the same direction I would have run. Life (and models) sometimes turn out way different than you expect.

well ok now you can understand why I think they may follow differently to what models are showing now
Member Since: June 13, 2009 Posts: 2 Comments: 12712
Quoting 2704. wunderkidcayman:

actually it passing S of the forecast line and if trend continue it may pass next forecast plot to its S


That's all relative to where you believe the center position to be at this point. As I said before, looks right on track to me.


2:00 AM AST Tue Jul 9
Location: 12.9N 57.2W
Moving: WNW at 26 mph
Min pressure: 1010 mb
Max sustained: 50 mph
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BULLETIN
TROPICAL STORM CHANTAL INTERMEDIATE ADVISORY NUMBER 5A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL032013
200 AM AST TUE JUL 09 2013

...CHANTAL NEARING BARBADOS...


SUMMARY OF 200 AM AST...0600 UTC...INFORMATION
----------------------------------------------
LOCATION...12.9N 57.2W
ABOUT 155 MI...250 KM E OF BARBADOS
ABOUT 285 MI...455 KM ESE OF MARTINIQUE
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 26 MPH...43 KM/H
MINIMUM CENTRAL PRESSURE...1010 MB...29.83 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* BARBADOS
* DOMINICA
* ST. LUCIA
* MARTINIQUE
* GUADELOUPE
* PUERTO RICO
* SOUTHERN COAST OF THE DOMINICAN REPUBLIC FROM CABO ENGANO TO THE
BORDER WITH HAITI

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* ST. VINCENT
* U.S. VIRGIN ISLANDS
* VIEQUES AND CULEBRA
* NORTHERN COAST OF THE DOMINICAN REPUBLIC FROM NORTH OF CABO ENGANO
TO CABO FRANCES VIEJO
* HAITI

INTERESTS IN THE REMAINDER OF THE NORTHERN LEEWARD ISLANDS...THE
SOUTHEASTERN BAHAMAS AND THE TURKS AND CAICOS SHOULD MONITOR THE
PROGRESS OF CHANTAL.

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA...GENERALLY WITHIN 36
HOURS.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS.
Member Since: June 30, 2013 Posts: 12 Comments: 8774
A beautiful, but dangerous typhoon in the western Pacific:

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Hurricane Frances - 2004

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Quoting 2674. sar2401:

Bluestorm, nice graphic, but it would be a good idea to have an "unofficial" box on it somewhere so new people dont think this came from the NHC.


I just added a box for future graphics that states: "This is an unofficial forecast from Bluestorm5 and not NHC's forecast. Please do not use this for your decisions!"
Member Since: August 1, 2011 Posts: 28 Comments: 8046
2705. sar2401
This is all pretty amazing. The last time I've seen such interest in a tropical storm at 12.4N was in 2004 for Ivan...and he was a cat 3, on the way to a cat 4 at the time. He was supposed to turn poleward, run up the Windwards and end up somewhere in Florida too. He did, just not in the way that any model predicted. If it hadn't been for the fact my wife died in 2004, we would have been living aboard our sailboat and would have been in Grenada on September 7, 2004. I would have run for the ABC's, since no hurricane ever travels west that far south. My boat speed was 11 knots and Ivan was traveling at 13 knots. We would have been overtaken in open seas and I wouldn't be here today. There are 8 yachts and 23 people who's remains have never been discovered, and they were running the same direction I would have run. Life (and models) sometimes turn out way different than you expect.
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Quoting 2701. ProgressivePulse:


Looks to be right on track to me.

actually it passing S of the forecast line and if trend continue it may pass next forecast plot to its S
Member Since: June 13, 2009 Posts: 2 Comments: 12712
NAM 84 hrs.

Member Since: June 30, 2013 Posts: 12 Comments: 8774
UKMET has a general track over Hispaniola:

Member Since: June 30, 2013 Posts: 12 Comments: 8774
Quoting 2689. EricSFL:

But it appears to me it has moved almost due west in the last several frames. I would not be surprised if the center goes right over or south of Barbados.


Looks to be right on track to me.
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Wow!

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Quoting 2692. weathersp:
Lopsided.

not for long and S of 13N

Quoting 2695. nigel20:
It seems as if Chantal's circulation is improving slightly on the Bajan radar loop.


yep
Member Since: June 13, 2009 Posts: 2 Comments: 12712
wow, If the 00z GFS pans out, it would be the ole ONE-TWO for central FL. That's quite a left hook for Chantal at around hour 190. Anyone think this will happen?
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2697. Seastep
Quoting 2673. Camille33:

It is showing huricane Andrew.


No, it is not. Goodnight all.
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Quoting 2689. EricSFL:

But it appears to me it has moved almost due west in the last several frames. I would not be surprised if the center goes right over or south of Barbados.

yep and confirmed on radar its W-S of due WNW around 274 degrees
Member Since: June 13, 2009 Posts: 2 Comments: 12712
2695. nigel20
It seems as if Chantal's circulation is improving slightly on the Bajan radar loop.
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2694. flsky
I've always trusted GFS models - wow - I'm hoping they're wrong now. It looks like a very rough summer for me otherwise - sheesh!
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2693. sar2401
Quoting Bluestorm5:
I'll includes it next time. Good idea.

Of course, all us regulars know you're right, but still...:-)
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Lopsided.
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Quoting 2684. TylerStanfield:

I'm just continuing on, Not much to do besides contact programmers... I got one of my blogs back... Comments weren't fixed. just going to deal with it I guess.


Ah, thought it was just me. WU took my blogs away as well.
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Quoting 2667. Slamguitar:
That's Dorian by Bermuda in the top one (CMC) and Dorian is in the lesser Antilles in the bottom one (GFS). A bit of disagreement right now.





re: your 2 (192) hr gfs and CMC charts. CMC Dorian (to be) near Bermuda, and GFS "Dorian" near the Antilles. I guess that big L sitting over TB is Chantal? hr 192. Is that the latest two model runs for both?
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2689. EricSFL
Quoting 2681. ProgressivePulse:


The center won't be exposed for long.

But it appears to me it has moved almost due west in the last several frames. I would not be surprised if the center goes right over or south of Barbados.
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2688. nigel20
Quoting TylerStanfield:

I'm just continuing on, Not much to do besides contact programmers... I got one of my blogs back... Comments weren't fixed. just going to deal with it I guess.

Oh..Ok. I had a similar problem about 2 years ago...I lost over a 1000 comments. :(
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NOGAPS wayyy west on this run:



-_-
Member Since: June 30, 2013 Posts: 12 Comments: 8774
Sorry, just not buying modeling tracks or the CONUS trough being deep or strong enough to erode the substantially stronger high, now showing 1016mb considerably lower than Hispaniola, and even below Jamaica now.

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2685. sar2401
Quoting GTstormChaserCaleb:
Can't discount the CMC, it did well with Andrea. I said anyone from NC south along the East Coast needs to pay attention to Chantal. It all depends how long that short wave hangs around and how long it takes the Bermuda High to restrengthen.


GT, the CMC also screwed around with 94L in the Gulf for a week and never got it right, producing a 993 mb hurricane on my doorstep on 7/4. I need to see more than one bullseye before I put much faith in any model, especially in early July.
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Quoting 2640. nigel20:

Hey Tyler! Did you get help with your blog posts and comments or do you have to continue as is?

I'm just continuing on, Not much to do besides contact programmers... I got one of my blogs back... Comments weren't fixed. just going to deal with it I guess.
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In the past, the arc of the Lesser Antilles has influenced the track of some TC... making them very hard to forecast (MARILYN in 1995, JOSE 1999).

Both were supposed to follow a track similar to CHANTAL but made a hard NW turn near Barbados..
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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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