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: 2483 - 2433

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

Although the circulation of Chantal is pushing the dry air forward, I can't help but feel the rapid pace of the LLC is causing the system to inhale a little of it.
Member Since: Posts: Comments:
Future "Dorian" nowhere near as intense on the 00z compared to the 18z.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
0Z GFS 84 hours

slower and stronger

Member Since: Posts: Comments:

I see 36kt winds in there.
Member Since: June 11, 2013 Posts: 20 Comments: 2984
Quoting 2475. KoritheMan:


Do you anticipate the westward turn toward Florida beyond five days?
I actually do, the model trends seem convincing enough that once the trough splits and the ULL retrogrades westward the ridge should be able to balloon westward. Not only will Chantal have a favorable environment to work with should that happen, but it will be a pretty decent moving into the southeast United States. Apart from strength, it'll be interesting to see at what latitude it makes landfall...if it does indeed curve towards the west...as it may eventually pose a threat to the Gulf. But we still have plenty of time in order to speculate.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
2478. 7544
Quoting 2465. Tropicsweatherpr:
Tropical Wave that models develop in Eastern Atlantic as been introduced at 00z analysis.





looks like the parade is about to begin sechhhh
Member Since: May 6, 2007 Posts: 0 Comments: 6812

Member Since: June 11, 2013 Posts: 20 Comments: 2984
Quoting 2455. 7544:
well so far the cone has been shifting east away from fl do the models have the new hh data yet tia

not till 06Z I think

Member Since: Posts: Comments:
Quoting 2467. MiamiHurricanes09:
I agree. Even though I consider myself to be right of the NHC cone, the GFS looks to be overdoing it a little bit.

57 hours out:



Do you anticipate the westward turn toward Florida beyond five days?
Member Since: Posts: Comments:
Quoting 2447. listenerVT:
We have been so relentlessly hammered with rain and flooding here in Vermont that on any given day we have to pick our route around orange cones, road repairs and roads closed altogether due to washouts. I do hope Chantal doesn't come north. There is nowhere at all to put the water here. Also, I was just over on the Maine coast last weekend and the Atlantic Ocean temp is the warmest I have ever experienced it (and I'm from Boston originally!). Usually it takes until sometime in August before the water is warm enough that it doesn't curl your instep. Early July and it is already like cool bathwater. If any storms come up the coast, I'm thinking they may not weaken as fast as usual from water temp.


Yeah, I grew up south of Boston back in the 60's and the water temps in June were 40-50, July 50-60, and if you were lucky they might get to 65-70 by Labor Day. Tried to go swimming In Freeport, ME in August and nearly emerged a soprano.
Member Since: Posts: Comments:
GFS 0Z staying with 18Z track through 72 hours.
Member Since: Posts: Comments:
66 hours out and we have Dorian developing.

Member Since: September 2, 2009 Posts: 130 Comments: 21193
2471. nigel20
Quoting sar2401:

Good evening, Nigel. Back to 94 humid degrees today with a 90% chance of rain. We were in the 10% area, apparently. :-)

Hey sar! It was a very hot and dry day across most of Jamaica. This is the best time to go to the beach or tour the island, If your a visitor. I think that I should take a trip to the north coast of Jamaica...I've not been there since 2007.
Member Since: November 6, 2010 Posts: 11 Comments: 8057
2470. AztecCe
so, what's everybody's long-term guess on chantal's u.s. landfall?
i'm gonna say a georgia/s. carolina hit
Member Since: Posts: Comments:
Quoting 2465. Tropicsweatherpr:
Tropical Wave that models develop in Eastern Atlantic as been introduced at 00z analysis.



that means that is may become an AOI soon,
Member Since: June 11, 2013 Posts: 20 Comments: 2984
Member Since: Posts: Comments:
Quoting 2460. KoritheMan:


A little too far right, IMO. Doesn't seem particularly realistic based on the current motion and pattern.
I agree. Even though I consider myself to be right of the NHC cone, the GFS looks to be overdoing it a little bit.

57 hours out:

Member Since: September 2, 2009 Posts: 130 Comments: 21193
Member Since: Posts: Comments:
Tropical Wave that models develop in Eastern Atlantic has been introduced at 00z analysis.



Member Since: Posts: Comments:
2464. JRRP
tomorrow will be a hard day for Chantal
Member Since: Posts: Comments:
Member Since: June 11, 2013 Posts: 20 Comments: 2984
Member Since: Posts: Comments:
As in the past..beyond 72 hrs , uncertainty rules...

if the NHC uses should, may, and other such wording... we can only wait until a concensus is
reached...In the mean time I enjoy reading the variuos posts and continue to learn...tks folks...

Member Since: Posts: Comments:
Quoting 2456. MiamiHurricanes09:
GFS still pretty far to the right. Has it scraping southwestern Puerto Rico and makking landfall across the southeastern portion of the Dominican Republic.


A little too far right, IMO. Doesn't seem particularly realistic based on the current motion and pattern.
Member Since: Posts: Comments:
2459. sar2401
Quoting HurricaneAndre:
someone told me in the chat room that a 987 mb hurricane in there.

Someone told you in the chat room...well, there you go then, that's almost a reliable as a twit or FB post. Forgetting the chat room and models, what's your guess about the probability of a storm that's currently around 1010 mb getting down to 987 mb in the next three days or so?
Member Since: October 2, 2004 Posts: 0 Comments: 15354
2458. will40
Quoting 2455. 7544:
well so far the cone has been shifting east away from fl do the models have the new hh data yet tia


the info wont be in untill tomorrow at the earliest
Member Since: September 19, 2005 Posts: 2 Comments: 4241
Quoting 2454. wunderkidcayman:
looking at floater loop convection thats on the S side of the LLCOC is starting to build over the swirl
what are the winds in those tstorms.
Member Since: June 11, 2013 Posts: 20 Comments: 2984
GFS still pretty far to the right. Has it scraping southwestern Puerto Rico and making landfall across the southeastern portion of the Dominican Republic.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
2455. 7544
well so far the cone has been shifting east away from fl do the models have the new hh data yet tia
Member Since: May 6, 2007 Posts: 0 Comments: 6812
looking at floater loop convection thats on the S side of the LLCOC is starting to build over the swirl
Member Since: Posts: Comments:
Quoting 2449. HurricaneAndre:
someone told me in the chat room that a 987 mb hurricane in there.


Believing WU chat room gossip. Newbie mistake. ;)
Member Since: Posts: Comments:
GFS 0Z 48 hour

Track the same.

Member Since: Posts: Comments:
2451. sar2401
Quoting KoritheMan:


Yep.

Good evening, Nigel. Back to 94 humid degrees today with a 90% chance of rain. We were in the 10% area, apparently. :-)
Member Since: October 2, 2004 Posts: 0 Comments: 15354
Quoting 2445. RTSplayer:
To bed I god.

Tomorrow at say 6am central, most of the storm will be on radar in the Antilles, then we'll get a real look at the thing.

Right now, I'm not expecting too much, given how pathetic NW quadrant is on satellite.
it's tightening up.
Member Since: June 11, 2013 Posts: 20 Comments: 2984
Quoting 2446. sar2401:

Andre, it just started to run. Don't embarrass yourself yet.
someone told me in the chat room that a 987 mb hurricane in there.
Member Since: June 11, 2013 Posts: 20 Comments: 2984
Quoting 2438. CosmicEvents:
So you have this one going west of W-WNW eh? Why do I feel like I'm in a Three Stooges skit.

I don't have this one doing that
Chantal has me say this
Member Since: Posts: Comments:
We have been so relentlessly hammered with rain and flooding here in Vermont that on any given day we have to pick our route around orange cones, road repairs and roads closed altogether due to washouts. I do hope Chantal doesn't come north. There is nowhere at all to put the water here. Also, I was just over on the Maine coast last weekend and the Atlantic Ocean temp is the warmest I have ever experienced it (and I'm from Boston originally!). Usually it takes until sometime in August before the water is warm enough that it doesn't curl your instep. Early July and it is already like cool bathwater. If any storms come up the coast, I'm thinking they may not weaken as fast as usual from water temp.
Member Since: Posts: Comments:
2446. sar2401
Quoting HurricaneAndre:
there's a hurricane in that run.

Andre, it just started to run. Don't embarrass yourself yet.
Member Since: October 2, 2004 Posts: 0 Comments: 15354
To bed I god.

Tomorrow at say 6am central, most of the storm will be on radar in the Antilles, then we'll get a real look at the thing.

Right now, I'm not expecting too much, given how pathetic NW quadrant is on satellite.
Member Since: Posts: Comments:
GFS 0Z 36 hour

Maybe a little south

Member Since: Posts: Comments:
2443. sar2401
Quoting ProgressivePulse:


I think they would have had the models not diverged from the pretty good consensus they had earlier today. I wouldn't either personally. They don't even show the slightest bend to the west at the end, lol. It's all covered in the error cone though.

Although, the white line from the GFS ensembles model shows a hard left from north of the Bahamas, over Georgia, and ending right on top of my house. I wonder when we're finally get some more models in the ensemble?
Member Since: October 2, 2004 Posts: 0 Comments: 15354
Quoting 2428. Levi32:
12.3°N 56.2°W


yeah kinda looks about right

Quoting 2430. 7544:
ull is finaly dieing out ?


yes Me and another forecaster was talking about that ULL dying earlier today
Member Since: Posts: Comments:
Quoting 2439. FIUStormChaser:


New Gfs is Running... lets see....
there's a hurricane in that run.
Member Since: June 11, 2013 Posts: 20 Comments: 2984

Member Since: June 11, 2013 Posts: 20 Comments: 2984
Quoting 2432. WPBHurricane05:
GFS 0Z 15 hour



New Gfs is Running... lets see....
Member Since: Posts: Comments:
Quoting 2431. wunderkidcayman:

in all honesty W-WNW looking more on the W side though
So you have this one going west of W-WNW eh?
.
Why do I feel like I'm in a Three Stooges skit.
Member Since: Posts: Comments:
Quoting 2434. caribbeantracker01:


but whats your take on the movement ? still wnw?
yes.
Member Since: June 11, 2013 Posts: 20 Comments: 2984
2436. HadesGodWyvern (Mod)
Philippines Atmospheric Geophysical Astronomical Services and Administration
Tropical Weather Advisory
11:00 AM PhST July 9 2013
================================================

At 10:00 AM PhST, A typhoon (International Typhoon Name: "SOULIK") located at 19.7N 140.2E or 1,680 km east of Basco, Batanes outside the eastern boundary of the Philippine Area of Responsibility has 10 minute sustained winds of 65 knots with gustiness up to 80 knots. Typhoon is forecast to move west at 10 knots.

Typhoon will enter the Philippine Area of Responsibility Wednesday morning and will exit early Saturday morning north of Taiwan.

Typhoon "SOULIK" will not have any direct effect on any part of the country today and tomorrow.
Member Since: May 24, 2006 Posts: 51 Comments: 45319
Grothar I thought not. It is early for deep warm water outside the loop current in the Gulf of Mexico.
Member Since: Posts: Comments:
Quoting 2428. Levi32:
12.3°N 56.2°W



but whats your take on the movement ? still wnw?
Member Since: Posts: Comments:
Quoting 2424. ProgressivePulse:


Odd for this time of year, lol.

So tough to forecast when you "potentially" have a cut off low backing off to the SW and high pressure moving in. Timing, Timing, Timing. My gut tells me that the high has been dominant this year. Still to far out to be the least bit certain. Truthfully, it will most likely be after it crosses Hispaniola before there is decent confidence.


It really is, and that's what is quite unnerving, will it take a track like the CMC and skirt the East Coast or take a track like the GFS and cross into the Gulf.

Here's to hoping its decoupled and an Ernesto like system when it leaves Hispaniola.
Member Since: Posts: Comments:

Viewing: 2483 - 2433

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.