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

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

Share this Blog
95
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 2683 - 2633

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70Blog Index

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..
Member Since: Posts: Comments:
The European Model hopefully will shed some light and cut the tie between the GFS and CMC.
Member Since: June 30, 2013 Posts: 12 Comments: 8264
Quoting 2676. EricSFL:


The center won't be exposed for long.
Member Since: Posts: Comments:
2680. sar2401
Quoting 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.




Except for the fact Levi says the regular GFS runs and the full-res GFS runs produce lows that have pressures completely unrelated to each other. The full-res runs produce lows that are clearly hurricanes. As for the CMC, who knows?
Member Since: Posts: Comments:
Quoting 2657. MiamiHurricanes09:
00z CMC has a hurricane landfall along the Georgia/South Carolina coast in 6 days.


Seems like the Canadian is just running around in circles with it's hair on fire at this point, it also brings Dorian out to sea... I think the upgrade has pretty much screwed the model.
Member Since: Posts: Comments:
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.

Member Since: June 30, 2013 Posts: 12 Comments: 8264
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'll includes it next time. Good idea.
Member Since: August 1, 2011 Posts: 28 Comments: 8009
2676. EricSFL
Member Since: Posts: Comments:
2675. flsky
Quoting 2614. ProgressivePulse:
2 storms into the east coast of FL in July is crazy should it come to pass.


Seems to be heading straight to my place - and I just got my balcony looking nice.
Member Since: Posts: Comments:
2674. sar2401
Quoting Bluestorm5:
Forecast #3 for Chantal. Full blog update will be tomorrow early afternoon. I also posted this on my last blog in comment section as well!


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.
Member Since: Posts: Comments:
Quoting 2670. Tazmanian:
hi


i see the gfs is forcasting are D E F G and H storm may be the I and J storm two?

It is showing huricane Andrew.
Member Since: Posts: Comments:
Quoting 2662. TylerStanfield:

It brings Dorian in from the East, it has been decently consistent with it going north of the islands, and Florida will likely see something from it, whether it brush to the south, or come full steam ahead into the east coast.


Been somewhat consistent with bringing something into South Tx too.
Member Since: Posts: Comments:
2671. sar2401
Quoting TropicalAnalystwx13:

The image I posted was not the full-res GFS. I used the regular run.

OK, so, if the two lows are so completely different, what's the point of posting the regular run?
Member Since: Posts: Comments:
hi


i see the gfs is forcasting are D E F G and H storm may be the I and J storm two?
Member Since: May 21, 2006 Posts: 5091 Comments: 115096
2669. JLPR2
Quoting 2667. Slamguitar:




Well now, that would be just plain unfriendly for the NE Caribbean.
Member Since: Posts: Comments:
Forecast #3 for Chantal. Full blog update will be tomorrow early afternoon. I also posted this on my last blog in comment section as well!

Member Since: August 1, 2011 Posts: 28 Comments: 8009
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.



Member Since: July 2, 2011 Posts: 0 Comments: 1183
Quoting 2661. sar2401:

Waht are the two lows seen in the graphic you just posted then?

The image I posted was not the full-res GFS. I used the regular run.
Member Since: Posts: Comments:
2665. EricSFL
Good Lord... 00z GFS might as well replicate Stephanie Abrams's worst case scenario...
Member Since: Posts: Comments:
Quoting 2651. HurricaneAndre:
the MJO is mostly staying with us.



Thanks
Member Since: Posts: Comments:
Quoting 2654. AtHomeInTX:


Seems to be Dorian. That is the next wave the GFS is developing off Africa. And 384 hrs. 16 days I believe. Yes it's long range. Just keep an eye on everything as usual. My personal note, historically, if it passes over any part of Florida it probably won't make landfall in Texas. Has only happened once. But then Mother Nature doesn't care about climatology. lol


ok, I see. Got to keep an eye on those models.
Member Since: Posts: Comments:
Quoting 2616. CybrTeddy:
Bet this will set the blog aflame.

It brings Dorian in from the East, it has been decently consistent with it going north of the islands, and Florida will likely see something from it, whether it brush to the south, or come full steam ahead into the east coast.
Member Since: Posts: Comments:
2661. sar2401
Quoting TropicalAnalystwx13:

Dorian is a 991mb cyclone on the full-res. It crosses Florida and becomes a 976 millibar hurricane prior to hitting Texas.

What are the two lows seen in the graphic you just posted then?

Edit:
In post #2626
Member Since: Posts: Comments:
looking at the RGB night mode shortwave ir and the Barbados radar I'm putting the LLCOC near 12.7N 57.0W/57.1W moving W-WNW
Member Since: Posts: Comments:
Quoting 2653. sar2401:

Let me see if I have this straight. In 10 days, the GFS says Chantal will be in the Gulf as 1007 low and big, bad Dorian will be approaching the Windwards as 1003 low? These are the two hurricanes that are going to flatten something?

Dorian is a 991mb cyclone approaching the Leeward Islands on the full-res. It crosses Florida and becomes a 976 millibar hurricane prior to hitting Texas.
Member Since: Posts: Comments:
2658. whitewabit (Mod)
Quoting 2653. sar2401:

Let me see if I have this straight. In 10 days, the GFS says Chantal will be in the Gulf as 1007 low and big, bad Dorian will be approaching the Windwards as 1003 low? These are the two hurricanes that are going to flatten something?


Have you ever seen a 10 day forecast pan out ??
Member Since: August 17, 2005 Posts: 362 Comments: 31392
00z CMC has a hurricane landfall along the Georgia/South Carolina coast in 6 days.

Member Since: September 2, 2009 Posts: 130 Comments: 21193
Hoping the models are wrong, fearing they might be right. That about sums up this situation.
Member Since: Posts: Comments:
Quoting 2643. AllStar17:
To me, the model runs are becoming more and more disconcerting by the hour.



I hear the train a comin'
It's rollin' 'round the bend,
And I ain't seen the sunshine,
Since, I don't know when...

Yes it is!
Member Since: July 9, 2005 Posts: 2 Comments: 1134
Quoting 2639. TexasHurricane05:


Seeing all sorts of models here...which one is this and how far out? I know to take this with a grain of salt...just curious.


Seems to be Dorian. That is the next wave the GFS is developing off Africa. And 384 hrs. 16 days I believe. Yes it's long range. Just keep an eye on everything as usual. My personal note, historically, if it passes over any part of Florida it probably won't make landfall in Texas. Has only happened once. But then Mother Nature doesn't care about climatology. lol
Member Since: Posts: Comments:
2653. sar2401
Quoting TropicalAnalystwx13:
The northward shunt after entering the Gulf by Chantal is unrealistic. The 0z GFS sends the storm north into potent ridging, which doesn't make sense.

Choo choo...


Let me see if I have this straight. In 10 days, the GFS says Chantal will be in the Gulf as a 1007 low and big, bad Dorian will be approaching the Windwards as 1003 low? These are the two hurricanes that are going to flatten something?
Member Since: Posts: Comments:
Quoting 2644. CaribBoy:
Link

Exposed center?


Yes it is. Chantal is riding the western edge of the convection.
Member Since: Posts: Comments:
Quoting 2648. JustDucky251:


Pardon the ignorance, but what should I be seeing in the graphics?
the MJO is mostly staying with us.
Member Since: Posts: Comments:
2650. Thrawst
That 00z GFS run is the eye opener for this season.

Clearly it is showing the Cape Verde wave train becoming strong enough and atmospheric conditions favorable enough for tropical cyclone formation, back to back (potentially to back) in the Mid July time frame. I am too tired to do the research but that sounds nearly unprecendented.

Member Since: Posts: Comments:
2649. TXCWC
0Z GFS 150hr that would be a possible hurricane on Florida's doorstep



0Z GFS very long range has our next D storm in the Gulf and is well...not good...thankfully is in long range timeframe right now and will probably change...but is not looking good for the U.S. this yr if that Bermuda high is still in place later in the season

Member Since: Posts: Comments:
Quoting 2645. HurricaneAndre:




Pardon the ignorance, but what should I be seeing in the graphics?
Member Since: Posts: Comments:
2647. nigel20
Quoting washingtonian115:
Dorian is going to be a very bad bad boy that seems he wants to follow in Dean's path to retirement...

But hopefully it will not have a similar track. :)
Member Since: Posts: Comments:
Quoting 2624. WPBHurricane05:
Great Miami Hurricane-the most costly hurricane ever.
Member Since: Posts: Comments:


Member Since: Posts: Comments:
Link

Exposed center?
Member Since: Posts: Comments:
To me, the model runs are becoming more and more disconcerting by the hour.
Member Since: Posts: Comments:
Quoting 2631. hurricane23:
Extremely dangerous patttern if it comes to pass


No kidding.

I am looking at my 1 weeks supply kit here for 3 and thinking of bumping it up to 2.
Member Since: Posts: Comments:


4 panel display of the HWRF model for ‎Chantal Saturday evening.
Member Since: Posts: Comments:
2640. nigel20
Quoting TylerStanfield:

Hallelujah.

Hey Tyler! Did you get help with your blog posts and comments or do you have to continue as is?
Member Since: Posts: Comments:
Quoting 2611. AtHomeInTX:


Seeing all sorts of models here...which one is this and how far out? I know to take this with a grain of salt...just curious.
Member Since: Posts: Comments:
Look at all that MJO on the way.
Member Since: Posts: Comments:
2637. Drakoen
Quoting 2626. TropicalAnalystwx13:
The northward shunt after entering the Gulf by Chantal is unrealistic. The 0z GFS sends the storm north into potent ridging, which doesn't make sense.

Choo choo...



Looking at the upper levels, it shows Chantal reaching the weakness between the subtropical high and the continental ridge.
Member Since: Posts: Comments:
Quoting 2616. CybrTeddy:
Bet this will set the blog aflame.

THERE SHE IS HEADED TO TX!
Member Since: Posts: Comments:
Quoting 2601. Tropicsweatherpr:


The pattern looks like late August/Early September.


Absolutely! That's crazy!
Member Since: Posts: Comments:
Quoting 2620. TylerStanfield:

Hallelujah.


Lol. My reaction. Didn't know how to spell it. :)
Member Since: Posts: Comments:
2633. Levi32
Quoting 2626. TropicalAnalystwx13:
The northward shunt after entering the Gulf by Chantal is unrealistic. The 0z GFS sends the storm north into potent ridging, which doesn't make sense.

Choo choo...



It forms a second cut-off mid-level low to the north over the Carolinas that brings Chantal north, but it is a random turbulent eddy that was not present on previous runs.

Member Since: November 24, 2005 Posts: 635 Comments: 26647

Viewing: 2683 - 2633

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

Local Weather

Mostly Cloudy
83 °F
Mostly Cloudy