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: 1033 - 983

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

say good night oh dont look now but i see the wave off the coast and i see banning with it


Member Since: Posts: Comments:
Beauty, is in the eye of the beholder...



Rollin', rollin', rollin'
Though the streams are swollen
Keep them dogies rollin'
Rawhide!
Rain and wind and weather
Hell-bent for leather
Wishin' my gal was by my side.
All the things I'm missin',
Good vittles, love, and kissin',
Are waiting at the end of my ride
Member Since: Posts: Comments:
1031. 62901IL
Quoting 1027. StormTrackerScott:
I suspect we will have our first hurricane of the season tomorrow. Also some of the models are indicating Chantal becoming a hurricane or strong TS before slamming into the Florida east coast on Sunday.


What makes you say so? Chantal is moving way to fast for sufficent orginization.
Member Since: Posts: Comments:
Quoting 1015. MiamiHurricanes09:

Wow! Well that escalated quickly. O_o
Member Since: Posts: Comments:
1029. WWPR
Quoting 1013. RitaEvac:
Tropical Storm Watch





Member Since: Posts: Comments:
1028. sar2401
Quoting hu2007:
is chantal next?

I think Chantal is already here. 96L will be next...unless it goes right to a TS, when it will be Dorian.
Member Since: October 2, 2004 Posts: 0 Comments: 17358
I suspect we will have our first hurricane of the season tomorrow. Also some of the models are indicating Chantal becoming a hurricane or strong TS before slamming into the Florida east coast on Sunday.


Member Since: Posts: Comments:
1026. Patrap
Member Since: Posts: Comments:
Quoting 1021. Dakster:


Wow Chantal is looking much better now.
LOL
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1024. sar2401
Quoting Waltanater:
...or even Chantal!

Or even 94L!
Member Since: October 2, 2004 Posts: 0 Comments: 17358
1023. hu2007
Quoting 1013. RitaEvac:
Tropical Storm Watch



is chantal next?
Member Since: Posts: Comments:
Quoting 1006. CaribBoy:
Hello guys, is Chantal moving more WNW now?
yeah, just a tad
Member Since: Posts: Comments:
1021. Dakster
Quoting 1015. MiamiHurricanes09:


Wow Chantal is looking much better now.
Member Since: Posts: Comments:
1020. sar2401
Quoting 62901IL:

I like how you used two

I agree.
Member Since: October 2, 2004 Posts: 0 Comments: 17358
Quoting 1005. washingtonian115:
Acording to the Euro we weren't suppose to have Andrea,Barry or Chantel.We would have no storms to speak of at the moment.
...or even Chantal!
Member Since: Posts: Comments:
1018. Dakster
Quoting 1001. weatherh98:


it does what O_____O


I'd like a picture of that.
Member Since: Posts: Comments:
Quoting 1014. sar2401:

What will be special about the special advisory after the normal advisory?
because the hurricane hunters won't get there in time,then once they find their findings,they will release a special advisory.
Member Since: June 11, 2013 Posts: 20 Comments: 3383
1016. Patrap
Member Since: Posts: Comments:
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1014. sar2401
Quoting HurricaneAndre:
I think the winds will go up 50 mph at the next advisory,then a special advisory will come out.

What will be special about the special advisory after the normal advisory?
Member Since: October 2, 2004 Posts: 0 Comments: 17358
Tropical Storm Watch



Member Since: Posts: Comments:
1012. 7544
Quoting 825. hurricane23:


well if that dosent say fl bound

hows the ull doing looks like its getting larger from here
Member Since: May 6, 2007 Posts: 0 Comments: 6874
1011. 62901IL
Quoting 1009. sar2401:

Do you think that hid wave might be mentioned in the TWO, two, or do you think it might be missed because two many models miss it?

I like how you used two
Member Since: Posts: Comments:
1010. 62901IL
Quoting 1008. HurricaneAndre:
I think the winds will go up 50 mph at the next advisory,then a special advisory will come out.

And what about the special advisory? What will the winds be????????????
Member Since: Posts: Comments:
1009. sar2401
Quoting Tazmanian:




we need too watch the wave be hid are C storm

Do you think that hid wave might be mentioned in the TWO, two, or do you think it might be missed because two many models miss it?
Member Since: October 2, 2004 Posts: 0 Comments: 17358
I think the winds will go up 50 mph at the next advisory,then a special advisory will come out.
Member Since: June 11, 2013 Posts: 20 Comments: 3383
Not exhibiting good surface lift it needs to slow down and allow air to pile up and rise. Otherwise not much strengthen will occur.



Wind shear has lessen ahead of it indicting its in a decent immediate environment of low shear.

Chantal need to be watch closely once it gets in the Caribbean.

Member Since: Posts: Comments:
Hello guys, is Chantal moving more WNW now?
Member Since: October 6, 2007 Posts: 0 Comments: 6455
Quoting 995. MississippiWx:


Shocker. Lol. Euro blows with tropical cyclogenesis.
Acording to the Euro we weren't suppose to have Andrea,Barry or Chantel.We would have no storms to speak of at the moment.
Member Since: Posts: Comments:
Quoting 994. will40:


i didnt make the plan just saying what it says


I know I was just saying
Member Since: Posts: Comments:
1003. Levi32
Quoting 970. TomTaylor:
Dean and Felix were both cat5s moving at ~20 MPH. As long as there is a strong gradient in the wind flow perpendicular to the storm's motion, fast trade winds on one side of the storm are not a big deal. When trade winds start accelerating ahead of the storm or when the storm is embedded in uniformly fast trade winds, then we've got more serious problems. Obviously trade winds are presenting Chantal with some problems; we still can't definitively say she's closed off her circulation. However, I don't think fast trade wind flow is as detrimental as you are making it out to be.

Personally, I am thinking a lack of upper level forcing is giving her some issues right now. Large-scale sinking surrounding the storm can be seen on chi200 and wv imagery. Additionally, no significant upper-level features in her vicinity means minimal localized vertical forcing. There is a weak ULL to her north allowing minimal outflow to the NNE. Other than that, that is it. She certainly doesn't have her own anticyclone aloft. Lack of vertical forcing largely explains the dismal satellite appearance to me.






Well, she's actually on the southeastern flank of an upper trough centered just east of the lesser Antilles, which has been hard for the GFS to see recently because no upper clouds have been in the area to generate GOES-derived upper winds. She's in a divergent upper flow at the moment, though if she overtakes the upper trough axis then she soon won't be.

You're talking about Cat 5s moving at 20mph. That's nothing. They don't care. Once something is developed it's hard to tear apart. It's the weak and tiny tropical waves like Chantal that can suffer greatly from rapid movement and trade wind divergence. We saw that with Ernesto last year and Emily the year before.

Obviously we'll see. Chantal is really on the edge of intensifying or weakening at the moment. I stuck my neck out with a forecast for a weaker TS when she was still in formative stages. After the recon mission I'll re-evaluate for tonight's forecast.
Member Since: Posts: Comments:
Most models aren't enthusiastic about this system weakening significantly over Hispaniola and in the Bahamas. I don't think it'll survive quite as well as the LGEM/SHIPS indicate, but I do think it'll remain a named storm during its crossing...especially since it'll slow down a little before Hispaniola, which may allow it to develop a more sustained/vigorous low.



If this makes it into the Gulf of Mexico as a decent system, things could get interesting...

But that's a long way out.
Member Since: Posts: Comments:
Quoting 995. MississippiWx:


Shocker. Lol. Euro blows with tropical cyclogenesis.


it does what O_____O
Member Since: Posts: Comments:
1000. sar2401
Quoting mikatnight:


Hey Sar - I was gonna mention the colors too, but everybody already knows I'm a picture freak.

Now, if only I knew what those colors meant and why those maps have all those lines all over them. :-)
Member Since: October 2, 2004 Posts: 0 Comments: 17358
Quoting 986. sar2401:

Absolutely.


I prefer the blown engine scenario. I get a little rain, the power stays on, ...
Member Since: Posts: Comments:
Quoting 970. TomTaylor:
Dean and Felix were both cat5s moving at ~20 MPH. As long as there is a strong gradient in the wind flow perpendicular to the storm's motion, fast trade winds on one side of the storm are not a big deal. When trade winds start accelerating ahead of the storm or when the storm is embedded in uniformly fast trade winds, then we've got more serious problems. Obviously trade winds are presenting Chantal with some problems; we still can't definitively say she's closed off her circulation. However, I don't think fast trade wind flow is as detrimental as you are making it out to be.

Personally, I am thinking a lack of upper level forcing is giving her some issues right now. Large-scale sinking surrounding the storm can be seen on chi200 and wv imagery. Additionally, no significant upper-level features in her vicinity means minimal localized vertical forcing. There is a weak ULL to her north allowing minimal outflow to the NNE. Other than that, that is it. She certainly doesn't have her own anticyclone aloft. Lack of vertical forcing largely explains the dismal satellite appearance to me.








we need too watch the wave be hid are C storm
Member Since: Posts: Comments:
Quoting 990. washingtonian115:
Well 2012 was the year that the storms and season as a whole defied all odds.We were suppose to have 12 name storms and ended up getting 19.


and they were rather whimpy
Member Since: Posts: Comments:
Member Since: June 11, 2013 Posts: 20 Comments: 3383
Quoting 985. ncstorm:
I was away everyone so Im catching up..the Euro isnt enthusiastic about Chantal or the wave behind it it seems..


Shocker. Lol. Euro blows with tropical cyclogenesis.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting 989. weatherh98:


no way they get there in 20 minutes


i didnt make the plan just saying what it says
Member Since: September 19, 2005 Posts: 2 Comments: 4266
At 20:07:30Z (last observation), the observation was 131 miles (210 km) to the NNE (31°) from Bridgetown, Barbados.

Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 8th day of the month at 20:06Z
Date: July 8, 2013
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 302)
Storm Number: 03
Storm Name: Chantal (flight in the North Atlantic basin)
Mission Number: 1
Observation Number: 11


20:07:30Z 14.717N 58.617W 376.0 mb
(~ 11.10 inHg) 8,055 meters
(~ 26,427 feet) - 437 meters
(~ 1,434 feet) From 94° at 23 knots
(From the E at ~ 26.4 mph) -20.0°C
(~ -4.0°F) -49.4°C
(~ -56.9°F) 24 knots
(~ 27.6 mph) 13 knots
(~ 14.9 mph) 0 mm/hr
(~ 0 in/hr) 12.5 knots (~ 14.3 mph)
54.2%
Time Coordinates Aircraft
Static Air Pressure Aircraft
Geopotential Height Extrapolated
Surface Pressure D-value Flight Level Wind (30 sec. Avg.) Air Temp. Dew Point Peak (10 sec. Avg.)
Flight Level Wind SFMR
Peak (10s Avg.) Sfc. Wind SFMR
Rain Rate Estimated Surface Wind (30 sec. Avg.)
Using Estimated Reduction Factor Peak Wind at Flight Level to
Est. Surface Reduction Factor
HDOB Observations
Member Since: Posts: Comments:
Quoting 989. weatherh98:


no way they get there in 20 minutes

Yeah, no way in coke.
Member Since: Posts: Comments:
Quoting 986. sar2401:

Absolutely.

I mean that Chantal still has a closed circulation.
Member Since: Posts: Comments:
Well 2012 was the year that the storms and season as a whole defied all odds.We were suppose to have 12 name storms and ended up getting 19.
Member Since: Posts: Comments:
Quoting 976. will40:


according to the Plan Of The Day around 4:30 eastern


no way they get there in 20 minutes
Member Since: Posts: Comments:
Quoting 985. ncstorm:
I was away everyone so Im catching up..the Euro isnt enthusiastic about Chantal or the wave behind it it seems..

OK!
Member Since: Posts: Comments:
SSMI showing a well-defined eye area now.



It also estimates winds at 65kts. It looks like the first typhoon of the year is now here.
Member Since: Posts: Comments:
Quoting 62901IL:

Good. :)

Absolutely.
Member Since: October 2, 2004 Posts: 0 Comments: 17358
Quoting 975. Dakster:


I agree - IF wind shear continues to fall and falls faster than currently predicted by the models, Chantal could be stronger.


Is there any reason to think that the large area of 40 knot shear in the E Carib will disappear?
Member Since: Posts: Comments:
Member Since: Posts: Comments:

Viewing: 1033 - 983

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

Overcast
29 °F
Overcast

JeffMasters's Recent Photos

Lake Effort Snow Shower Over Windsor, Ontario
Sunset on Dunham Lake
Pictured Rocks Sunset
Sunset on Lake Huron