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 2828. Stormchaser2007:
There probably won't be much left of Chantal by tomorrow morning if the trends continue.

Something is effectively ripping up the system

Oof


It is getting stronger per adt...your comment has 0 proof.
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Quoting 2828. Stormchaser2007:
There probably won't be much left of Chantal by tomorrow morning if the trends continue.

Something is effectively ripping up the system


I wouldn't go that far, why do you say that? Chantal looks to be organizing a bit tonight.
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Quoting 2828. Stormchaser2007:
There probably won't be much left of Chantal by tomorrow morning if the trends continue.

Something is effectively ripping up the system


Yeah, speed shear.
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2830. Skyepony (Mod)
SOULIK, Click pic for a very large quicktime movie of the TRMM pass.
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Quoting 2821. Drakoen:
Looks like she's hitting a brick wall on WV imagery.


200mb

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There probably won't be much left of Chantal by tomorrow morning if the trends continue.

Something is effectively ripping up the system

Oof

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Quoting 2824. bigwes6844:
wassup fellas I just got off and I see my predictions from last nite mite be true that the storm may enter the GOM. But i Think Dorian will be the big boy in a week! Im ready and prepared to roll out if needed if a big one comes. Gonna be a very interesting week ahead. Welcome to the season folks!


We gonna keep in touch if need be, Wes? I expect a lot of texts from you! :D
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2826. nigel20
Quoting Dakster:
IIRC, isn't the Barbados pretty hardened and ready to handle nasty Hurricanes?

I wouldn't think even a strong TS would cause a lot of damage?

Hey Dakster! I know that the infrastructure in Barbados is a lot better than that of many Caribbean islands, so a TS would not be much of a problem...they've not had a direct hit from an hurricane for sometime now...I think the last one Allen in 1980, so a strong hurricane may pose a serious threat to their infrastructure..
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2825. JLPR2
Well I'm out, good night everyone.
I'll check early in the morning what Chantal is up to.

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wassup fellas I just got off and I see my predictions from last nite mite be true that the storm may enter the GOM. But i Think Dorian will be the big boy in a week! Im ready and prepared to roll out if needed if a big one comes. Gonna be a very interesting week ahead. Welcome to the season folks!
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2823. Skyepony (Mod)

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Quoting 2815. HurricaneAndre:
Well ya'll were arguing about how Chantal is pronounced,so I went ahead and posted all the names' pronunciations.
Spelling, not pronunciation... and you really don't need to post the whole thing, ya know?
Member Since: August 1, 2011 Posts: 28 Comments: 8074
2821. Drakoen
Looks like she's hitting a brick wall on WV imagery.
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Should intensify some more for the next 36 hours before leveling off and undergoing a weakening trend for 48 hours and then intensify again.



Member Since: June 30, 2013 Posts: 12 Comments: 8774
Did anybody get the word from the navy about Chantal.
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Quoting 2812. KoritheMan:


I work in the cooler so I can get away with that fairly easily. Not anymore, though. I reserve it for breaks now.
Same here. I need to download Chrome for my phone so I can get on here during my breaks or lunches. What do you mean by not anymore?
Member Since: August 1, 2011 Posts: 28 Comments: 8074
Quoting 2803. DataNerd:



Given that, and the latest various scat data, this is concerning.

Its concerning in that unstable LLC's tend to through our current models into chaos and can result in very large scale guidance changes with not alot of warning or rhyme or reason.

If the timing of this thing getting north is delayed or it doesn't get far enough north it increases the chances of it making it to the GOM as an organized system.


Not liking this. Hopefully any reformation won't affect the overall motion too badly. But its certainly going to delay getting a proper fix on guidance which was already pretty wide.


Isaac continually reformed to the south, so I don't see why Chantal couldn't either.

As someone who lives in southeast Louisiana, and as someone who has five years of weather forecasting experience under his belt, I never take my eyes off Caribbean systems during the summer until they safely cross Hispaniola/Cuba without wobbling around too much.
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2816. Skyepony (Mod)
Quoting 2806. TropicalAnalystwx13:
Headed out for the night.

A look at Soulik -



It's hard not to just look at it..
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Quoting 2811. Bluestorm5:
Really needless to be posted...
Well ya'lnl were arguing about how Chantal is pronounced,so I went ahead and posted all the names' pronunciations.
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Quoting 2807. dfwstormwatch:
Im interested in Chantal and all, but I have more interest in the possible storm following it shown on the GFS and CMC, seems to have a lot more potential.


Agreed.
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Quoting 2793. barbadosjulie:
Whats ya'lls opinion on the effects on Barbados? We are all in our homes and just waiting...


Seems the winds are all on the N side due to the pressure gradient and all the rain on the S side oddly enough. However, Chantal will be a "strengthening" storm approaching Barbados. I would prepare for the forecast intensity personally.



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Quoting 2808. Bluestorm5:
It's pretty much impossible for me to do that on clock as a door greeter or cashier, lol. I haven't even tried and never will try. Not worth the risk.


I work in the cooler so I can get away with that fairly easily. Not anymore, though. I reserve it for breaks now.
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Quoting 2805. HurricaneAndre:
Name pronunciation.

2013
Andrea AN-dree-uh Barry BAIR-ree Chantal shahn-TAHL Dorian DOR-ee-an Erin AIR-rin
Fernand fair-NAHN Gabrielle ga-bree-ELL Humberto oom-BAIR-toh Ingrid ING-grid
Jerry JEHR-ee
Karen KAIR-ren
Lorenzo loh-REN-zoh Melissa meh-LIH-suh
Nestor NES-tor
Olga OAL-guh
Pablo PAHB-lo
Rebekah reh-BEH-kuh Sebastien suh-BASH-chuhn Tanya TAHN-yuh
Van van
Wendy WEN-dee
Really needless to be posted...
Member Since: August 1, 2011 Posts: 28 Comments: 8074
2810. Skyepony (Mod)
Forecast reckoning with the SAL..
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2809. nigel20
Quoting barbadosjulie:


Thanks! Will try to keep you informed as the morning goes on.

Yeah, No problem!
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Quoting 2797. KoritheMan:


Must. Not. Let. Boss. Catch. Me. Phone browsing on the clock.
It's pretty much impossible for me to do that on clock as a door greeter or cashier, lol. I haven't even tried and never will try. Not worth the risk.
Member Since: August 1, 2011 Posts: 28 Comments: 8074
Im interested in Chantal and all, but I have more interest in the possible storm following it shown on the GFS and CMC, seems to have a lot more potential.
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Headed out for the night.

A look at Soulik -

Member Since: July 6, 2010 Posts: 113 Comments: 32802
Name pronunciation.

2013
Andrea AN-dree-uh Barry BAIR-ree Chantal shahn-TAHL Dorian DOR-ee-an Erin AIR-rin
Fernand fair-NAHN Gabrielle ga-bree-ELL Humberto oom-BAIR-toh Ingrid ING-grid
Jerry JEHR-ee
Karen KAIR-ren
Lorenzo loh-REN-zoh Melissa meh-LIH-suh
Nestor NES-tor
Olga OAL-guh
Pablo PAHB-lo
Rebekah reh-BEH-kuh Sebastien suh-BASH-chuhn Tanya TAHN-yuh
Van van
Wendy WEN-dee
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2804. Dakster
IIRC, isn't the Barbados pretty hardened and ready to handle nasty Hurricanes?

I wouldn't think even a strong TS would cause a lot of damage?
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Quoting 2790. JLPR2:
If Chantal really opened up like the OSCAT pass suggest it shouldn't be that hard to close off a new LLC considering the facts that it showed some 50knots barbs and convection is increasing.
Quoting 2789. ProgressivePulse:


Very ragged today and appropriate post. I along with MANY others were thinking the same thing. Long path with many road blocks ahead. She is a tenacious little "B" though, lol. Gotta watch out for those types. Good to see you Skye.



Given that, and the latest various scat data, this is concerning.

Its concerning in that unstable LLC's tend to through our current models into chaos and can result in very large scale guidance changes with not alot of warning or rhyme or reason.

If the timing of this thing getting north is delayed or it doesn't get far enough north it increases the chances of it making it to the GOM as an organized system.


Not liking this. Hopefully any reformation won't affect the overall motion too badly. But its certainly going to delay getting a proper fix on guidance which was already pretty wide.
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Quoting 2799. nigel20:

Hey Julie! It seems as if you will be getting a bit of rain a gusty winds in a couple hours time.


Thanks! Will try to keep you informed as the morning goes on.
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Quoting 2793. barbadosjulie:
Whats ya'lls opinion on the effects on Barbados? We are all in our homes and just waiting...


Gusty winds and some minor (2-4 ft) of surge on the eastern coast (1-2 ft) on the western coast. The windward side of the island is going to get more the the brunt of the storm, scattered power outages are possible there.
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Quoting 2798. Dakster:


I think Faye moved about 6 miles in 156 hours by comparison.


lol, yeah
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2799. nigel20
Quoting barbadosjulie:
Whats ya'lls opinion on the effects on Barbados? We are all in our homes and just waiting...

Hey Julie! It seems as if you will be getting a bit of rain a gusty winds in a couple hours time.
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2798. Dakster
Quoting 2795. KoritheMan:


Right now I really think she'll pass north and the tropical storm force winds will miss you guys, but since some light northwesterly shear is pushing the associated convection to the south side, you will likely be in for some heavy rain. I imagine the flooding will be mitigated relative to what it normally is during a more normal-moving storm; at speeds of 26 mph, Chantal will move 156 miles in 6 hours.


I think Faye moved about 6 miles in 156 hours by comparison.
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Quoting 2783. Dakster:


Tonight is my 'Friday' so I get to watch the remainder of the week until Friday, which is my Monday.

Anyways, I will watch Chantal for you. And then we can switch on Friday!



Must. Not. Let. Boss. Catch. Me. Phone browsing on the clock.
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Quoting 2790. JLPR2:
If Chantal really opened up like the OSCAT pass suggest it shouldn't be that hard to close off a new LLC considering the facts that it showed some 50knots barbs and convection is increasing.


Chantal will likely battle keeping the center closed until the forward speed slows down or she can drop pressure 10+mb stat.
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Quoting 2793. barbadosjulie:
Whats ya'lls opinion on the effects on Barbados? We are all in our homes and just waiting...


Right now I really think she'll pass north and the tropical storm force winds will miss you guys, but since some light northwesterly shear is pushing the associated convection to the south side, you will likely be in for some heavy rain. I imagine the flooding will be mitigated relative to what it normally is during a more normal-moving storm; at speeds of 26 mph, Chantal will move 156 miles in 6 hours.
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2794. Dakster
Quoting 2789. ProgressivePulse:


Very ragged today and appropriate post. I along with MANY others were thinking the same thing. Long path with many road blocks ahead. She is a tenacious little "B" though, lol. Gotta watch out for those types. Good to see you Skye.


Chantal been rode hard by the westerlies and put away wet for sure. But like you say she is still ready for more. These resilient storms worry me.
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Whats ya'lls opinion on the effects on Barbados? We are all in our homes and just waiting...
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2792. HadesGodWyvern (Mod)
Link

UKMET model really not confident in CHANTAL.
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Quoting 2784. HurricaneAndre:
Do you think the NHC should have two and four advisories.



I think many of us here would like an hourly update from the NHC. With all the model study, storm study, and human thinking involved, their time frame for advisories is as good as it gets.
Member Since: April 18, 2012 Posts: 0 Comments: 2437
2790. JLPR2
If Chantal really opened up like the OSCAT pass suggest it shouldn't be that hard to close off a new LLC considering the facts that it showed some 50knots barbs and convection is increasing.
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Quoting 2782. Skyepony:


Looking at it it does appear short lived & Chantal is pulling back together.

Looking a Dvorak it had the pressure come up & the T# fall there a bit but it's strengthening again.


Chantal isn't close enough to land in that pass for me to throw out the OSCAT pass.


Very ragged today and appropriate post. I along with MANY others were thinking the same thing. Long path with many road blocks ahead. She is a tenacious little "B" though, lol. Gotta watch out for those types. Good to see you Skye.
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Thank you Skyepony.
Member Since: April 18, 2012 Posts: 0 Comments: 2437
Quoting 2783. Dakster:


Tonight is my 'Friday' so I get to watch the remainder of the week until Friday, which is my Monday.

Anyways, I will watch Chantal for you. And then we can switch on Friday!

Today is my "Friday" as well. Nothing to do but track until Thursday.
Member Since: August 1, 2011 Posts: 28 Comments: 8074
2786. Skyepony (Mod)
00zCMC dooming on the Phish tour through the SE..

Tri~ I don't know.
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Quoting 2776. KoritheMan:
Darn it... This is one time I wish I didn't have to work tomorrow. I'd really rather look at Chantal than go to work when I wake up.

Waiting is always so suspenseful.
At least I'm off next two days. After that, 4 days in row with 8 1/2 hours on Saturday.
Member Since: August 1, 2011 Posts: 28 Comments: 8074
Do you think the NHC should have two and four advisories.
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2783. Dakster
Quoting 2776. KoritheMan:
Darn it... This is one time I wish I didn't have to work tomorrow. I'd really rather look at Chantal than go to work when I wake up.

Waiting is always so suspenseful.


Tonight is my 'Friday' so I get to watch the remainder of the week until Friday, which is my Monday.

Anyways, I will watch Chantal for you. And then we can switch on Friday!

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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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