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 1772. washingtonian115:
Looking good Chantal looking good.Can't wait to see what she looks like in the morning.
Yea! last night DMAX did wonders for it know as the sunset a deep convection is starting to fire with really impressive TS winds. Cant wait for morning.
Member Since: May 25, 2012 Posts: 0 Comments: 2043
Quoting 1767. Levi32:
This 60kt wind spike on SFMR isn't really real. It's clearly rain-contaminated, whether it was marked as such or not on the raw data.



The best estimate is and always will be the flight-level wind minus ~20%, which puts us at 50-55 mph.



Levi do you think the 1010 Mb pressure is legit?
Member Since: June 20, 2012 Posts: 0 Comments: 2159
Quoting 1774. Patrap:
ULL Rain Bands



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1780. 7544
so 50 or 60 mph at 8pm any guesses
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Quoting 1759. ncstorm:


not till you take a bite :) then I will remove it
LOL well I had mine yesterday for being wrong about not having a storm in July. So I will pass on seconds. :-P

By the way in case you guys were wondering this was the FIM-9 at 126hrs.

Member Since: June 30, 2013 Posts: 12 Comments: 8566
Quoting 1770. all4hurricanes:

This is just not true, an N named storm in July?
there was never a Hurricane or Tropical Storm Natalie according to wikipedia



Link
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Quoting 1770. all4hurricanes:

This is just not true, an N named storm in July?
there was never a Hurricane or Tropical Storm Natalie according to wikipedia


http://en.wikipedia.org/wiki/1964_Pacific_hurrica ne_season#Hurricane_Natalie

EPAC!
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1776. whitewabit (Mod)
It would be a shame to not be able to post in the middle of a storm ..
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Typhoon Soulik



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1774. Patrap
ULL Rain Bands

Member Since: July 3, 2005 Posts: 426 Comments: 128871
i really wish you guys would stop posting off topic photos when we have a storm



where are the mods they sould be re moveing the post
Member Since: May 21, 2006 Posts: 5091 Comments: 115252
Looking good Chantal looking good.Can't wait to see what she looks like in the morning.
Member Since: August 14, 2010 Posts: 10 Comments: 17151
Quoting 1767. Levi32:
This 60kt wind spike on SFMR isn't really real. It's clearly rain-contaminated, whether it was marked as such or not on the raw data.



The best estimate is and always will be the flight-level wind minus ~20%, which puts us at 50-55 mph.

Plenty of decent 45-50kt SFMR data though, which would coincide perfectly with the flight-level winds after they're reduced.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting 1658. sar2401:

Yep. TS Natalie, July, 1964. No hurricane though.

This is just not true, an N named storm in July?
there was never a Hurricane or Tropical Storm Natalie according to wikipedia
Member Since: Posts: Comments:


Dinner is served here at WU- you'll just have to use your imagination (crow pie and all that).
Member Since: September 22, 2005 Posts: 18 Comments: 2343
Quoting 1753. redwagon:

Is Chantal in danger of breaking a record for the fastest run from classification to landfall?


Not even close.
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1767. Levi32
This 60kt wind spike on SFMR isn't really real. It's clearly rain-contaminated, whether it was marked as such or not on the raw data.



The best estimate is and always will be the flight-level wind minus ~20%, which puts us at 50-55 mph.

Member Since: Posts: Comments:
Quoting 1753. redwagon:

Is Chantal in danger of breaking a record for the fastest run from classification to landfall?


Not sure, but I think Humberto's got that one. I get your point though, until it hits a wall at about 15n! :)
Member Since: July 9, 2006 Posts: 184 Comments: 29610
1765. AztecCe

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Quoting 1752. stormchaser19:


Yeah, even more than this.
Looks like she's becoming a Chant-ball.
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1763. Patrap
At 23:17:30Z (last observation), the observation was 364 miles (585 km) to the E (92°) from Bridgetown, Barbados.

Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 8th day of the month at 23:16Z
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: 30

23:17:30Z 12.900N 54.217W 966.4 mb
(~ 28.54 inHg) 419 meters
(~ 1,375 feet) 1013.9 mb
(~ 29.94 inHg) - From 126° at 47 knots
(From the SE at ~ 54.0 mph) 21.8°C
(~ 71.2°F) 19.8°C
(~ 67.6°F) 49 knots
(~ 56.3 mph) 39 knots
(~ 44.8 mph) 1 mm/hr
(~ 0.04 in/hr) 37.4 knots (~ 43.0 mph)
Tropical Storm 79.6%
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: July 3, 2005 Posts: 426 Comments: 128871
Quoting 1755. MiamiHurricanes09:
Maybe a little bit of 3D too lol.

Ow...
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Quoting 1745. Tazmanian:




you will have too pick 50 or 60 mph has they do not do 55mph in storms any more


Since when? :D
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1760. 7544
whats the deal with our ull is it trying to reorganize further east where its becoming a nice round ball hmmm

Link
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1759. ncstorm
Quoting 1749. Tazmanian:




i would re move that if you dont want a ban


not till you take a bite :) then I will remove it
Member Since: August 19, 2006 Posts: 13 Comments: 15743
Quoting 1752. stormchaser19:


Yeah, even more than this.




Will this make the T S more intense?
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1757. Patrap
Convection still building West of the CoC and around it in general.

Member Since: July 3, 2005 Posts: 426 Comments: 128871
Quoting 1745. Tazmanian:




you will have too pick 50 or 60 mph has they do not do 55mph in storms any more


I know Taz :o) I was messing with ya that's all....
I'll stick with 50MPH at the next TWO Advisory....But now that I say that they will probably say 60 just to mess with me :o)

Taco :o)
Member Since: July 7, 2005 Posts: 6 Comments: 3261
Maybe a little bit of 3D too lol.

Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting 1731. MiamiHurricanes09:
Playing with the satellite enhancements. This one definitely makes Chantal look the most intense. :P



Wish they would publish something on what they mean and a scale for each one.
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Quoting 1587. hydrus:
They want a piece of Georgia pie.

Is Chantal in danger of breaking a record for the fastest run from classification to landfall?
Member Since: Posts: Comments:
Quoting 1731. MiamiHurricanes09:
Playing with the satellite enhancements. This one definitely makes Chantal look the most intense. :P



Yeah, even more than this.
Member Since: June 20, 2012 Posts: 0 Comments: 2159
1751. Relix
11:20 PM GMT on July 08, 2013
Center Fix makes me feel better here at PR. Less risk and probably 170+ miles now. Good. I don't want power to be out. I was gonna go buy water and stuff but it seems it won't be needed.
Member Since: August 3, 2006 Posts: 0 Comments: 2725
1750. ncstorm
11:20 PM GMT on July 08, 2013
Quoting 1744. washingtonian115:
Oh calm down.I said "almost hit the nail".Yes I'm going to apologize on my behave for the rude remarks that I made for his forecast because I honestly thought Chantal wouldn't do anything today.


Wash..nice way to be gracious..Sar..well..this is a 24/7 job for him to dispute everybody on the blog..even about you apologizing..LOL
Member Since: August 19, 2006 Posts: 13 Comments: 15743
1749. Tazmanian
11:19 PM GMT on July 08, 2013
Quoting 1742. ncstorm:


For some of our fellow bloggers..it best to wash it down with plenty of water..






i would re move that if you dont want a ban
Member Since: May 21, 2006 Posts: 5091 Comments: 115252
1747. canehater1
11:19 PM GMT on July 08, 2013
Wide View Loop of Atlantic... fun to watch after

reading the discussion from NHC

Link
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1746. allancalderini
11:19 PM GMT on July 08, 2013
Quoting 1735. washingtonian115:
"When a tropical storm or invest looks like a shrimp.It's a pretty healthy storm."

I thought Ernesto was a troll but..Chantal is the biggest.
Quoting 1735. washingtonian115:
"When a tropical storm or invest looks like a shrimp.It's a pretty healthy storm."

I thought Ernesto was a troll but..Chantal is the biggest.
The difference is that with Ernesto is that he troll us for days and with Chantal we are just starting.
Member Since: October 15, 2011 Posts: 0 Comments: 4410
1745. Tazmanian
11:18 PM GMT on July 08, 2013
Quoting 1738. taco2me61:

since I said in a earlier post of 55 MPH do I go with 60 or down to 50 MPH?????

Taco :o)




you will have too pick 50 or 60 mph has they do not do 55mph in storms any more
Member Since: May 21, 2006 Posts: 5091 Comments: 115252
1744. washingtonian115
11:18 PM GMT on July 08, 2013
Quoting 1729. sar2401:

I hadn't read anything official from the NHC that Chantal has 60 mph winds, have you? Go back and look at his predictions for 94L before you start apologizing.
Oh calm down.I said "almost hit the nail".Yes I'm going to apologize on my behave for the rude remarks that I made for his forecast because I honestly thought Chantal wouldn't do anything today.
Member Since: August 14, 2010 Posts: 10 Comments: 17151
1743. wunderkidcayman
11:18 PM GMT on July 08, 2013
hey guy which one should I use first or second

B. Center Fix Coordinates: 11°38'N 54°34'W (11.6333N 54.5667W
Member Since: June 13, 2009 Posts: 2 Comments: 12180
1742. ncstorm
11:17 PM GMT on July 08, 2013
Quoting 1721. sporteguy03:
It is just a matter of patience and learning how vaulable HH data is. 5 hours ago I was reading Chantal was decoupling and game over on this blog. The NHC spoke none of that, if the HH Data shows something different from the weather data from Satelite photos and other tools the NHC will state it. Those on the blog for a long time know how valuable HH data is.


For some of our fellow bloggers..it best to wash it down with plenty of water..


Member Since: August 19, 2006 Posts: 13 Comments: 15743
1741. allancalderini
11:17 PM GMT on July 08, 2013
Quoting 1719. TylerStanfield:

I highly doubt it with the way trade winds are and based on the overall organization it will struggle. a lot.
Jeez man calm down.
Quoting 1732. Grothar:


Then we would all be a little off with those winds.


:o oh my.
Member Since: October 15, 2011 Posts: 0 Comments: 4410
1740. TropicalAnalystwx13
11:17 PM GMT on July 08, 2013
Quoting 1728. hydrus:
Chantel is a tough girl...I am impressed...I said several days ago that the wave she came from looked textbook, especially so early.

Chantal. :)

Yeah, this storm has definitely been resilient. Has been fun to track, and should continue to be over the coming days.
Member Since: July 6, 2010 Posts: 113 Comments: 32338
1739. moonlightcowboy
11:17 PM GMT on July 08, 2013
Pretty cool map. :)

CONUS WIND DIRECTION/SPEED MAP
Member Since: July 9, 2006 Posts: 184 Comments: 29610
1738. taco2me61
11:17 PM GMT on July 08, 2013
Quoting 1724. Tazmanian:




guys they dont do 55mph any more its 50 or 60mph

since I said in a earlier post of 55 MPH do I go with 60 or down to 50 MPH?????

Taco :o)
Member Since: July 7, 2005 Posts: 6 Comments: 3261
1737. SLU
11:17 PM GMT on July 08, 2013
Quoting 1707. Patrap:
At 23:07:30Z (last observation), the observation was 405 miles (652 km) to the E (92°) from Bridgetown, Barbados.

Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 8th day of the month at 23:06Z
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: 29

23:07:30Z 12.917N 53.600W 966.5 mb
(~ 28.54 inHg) 424 meters
(~ 1,391 feet) 1014.6 mb
(~ 29.96 inHg) - From 134° at 36 knots
(From the SE at ~ 41.4 mph) 22.0°C
(~ 71.6°F) 19.9°C
(~ 67.8°F) 37 knots
(~ 42.5 mph) 34 knots
(~ 39.1 mph) 1 mm/hr
(~ 0.04 in/hr) 33.1 knots (~ 38.0 mph)
91.9%
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


Center fix further south and west of the 5pm position.
Member Since: July 13, 2006 Posts: 13 Comments: 5281
1736. AllStar17
11:16 PM GMT on July 08, 2013
Quoting 1732. Grothar:


Then we would all be a little off with those winds.




LOL
Member Since: June 29, 2009 Posts: 13 Comments: 5313
1735. washingtonian115
11:16 PM GMT on July 08, 2013
"When a tropical storm or invest looks like a shrimp.It's a pretty healthy storm."

I thought Ernesto was a troll but..Chantal is the biggest.
Member Since: August 14, 2010 Posts: 10 Comments: 17151
1734. TylerStanfield
11:16 PM GMT on July 08, 2013
Quoting 1729. sar2401:

I hadn't read anything official from the NHC that Chantal has 60 mph winds, have you? Go back and look at his predictions for 94L before you start apologizing.

THANK YOU
Member Since: June 2, 2013 Posts: 8 Comments: 1347

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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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