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 122. islander101010:
i have not wishcasted this system yet alot of the models have her right on top of us e cen fl.

Islander I am in Titusville and have been watching this. NHC adjusted the cone slightly to the east but I think as time moves on it will shift back west due to the trough lifting out and the high pressure pushing it back west. As the Doc said this is probably Bad JuJu for us in the East Coast of FL. of things to come...
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Quoting 171. washingtonian115:
70mph in 48 hours?.NHC must know something we don't.
In err Levi's video he showed something about the Euro also taking notice of that wave that the GFS is developing.


they are the experts..
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Quoting 166. Grothar:


I don't know. I guess he doesn't want to give me credit since I "saw if first". Hey, he is a busy man. I don't know how he even finds the time to post what he does. It takes a lot of work. Has anyone even read my last blog? I worked on it for hours.


Well written blog Gro..
A thinking man's blog.. :)

Yeah I know Dr. Masters is busy and all..
Just thinking that maybe the blob would be a player in the GOM and change the dynamics some..
Just me thinking again.. :)
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Quoting 165. MAweatherboy1:
Stewart is forecasting 70mph for a peak now. Can't see it happening given Chantal's current state.

True, but small systems can fluctuate in strength wildly at times. Intensity with Chantal is going to be rather annoying the next few days any slight deviation could cause the intensity to change.
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178. SLU
I'd like if some of our fellow bloggers who have been downcasting Chantal since 2 days ago do some sort of post-storm analysis as to why the system has done the opposite to what they expected because the NHC sounds rather optimistic about Chantal relative to some of our fellow bloggers.

OTHER THAN THE FAST FORWARD SPEED OF CHANTAL...ENVIRONMENTAL
CONDITIONS ARE FAIRLY FAVORABLE FOR AT LEAST SOME MODEST
STRENGTHENING TO OCCUR DURING THE NEXT 48 HOURS OR SO WHILE THE
CYCLONE REMAINS UNDERNEATH A 200 MB RIDGE AXIS.
Member Since: July 13, 2006 Posts: 13 Comments: 5367
Quoting 162. Ameister12:
Borderline hurricane by 48 hours.

INIT 08/1500Z 10.9N 51.7W 40 KT 45 MPH
12H 09/0000Z 12.0N 55.0W 45 KT 50 MPH
24H 09/1200Z 13.6N 59.6W 50 KT 60 MPH
36H 10/0000Z 15.2N 64.1W 55 KT 65 MPH
48H 10/1200Z 16.8N 68.2W 60 KT 70 MPH
72H 11/1200Z 19.8N 74.1W 50 KT 60 MPH
96H 12/1200Z 23.3N 76.8W 35 KT 40 MPH
120H 13/1200Z 26.0N 78.1W 30 KT 35 MPH

$$
FORECASTER STEWART


It's Stewart, lol.

I find it interesting that he says this:

"OTHER THAN THE FAST FORWARD SPEED OF CHANTAL...ENVIRONMENTAL CONDITIONS ARE FAIRLY FAVORABLE FOR AT LEAST SOME MODEST STRENGTHENING TO OCCUR..."

I personally think he is brushing off the forward speed too lightly. It means a lot more than that.

Member Since: November 24, 2005 Posts: 635 Comments: 26701
176. 7544
45mph now no open wave yet lol
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Quoting 130. TylerStanfield:

I think he meant 2010, gaston wasnt in 2008, and it wasnt an El Niño.

you are right Gaston was 2010
as for 2006 African Dust created dry air that inhibited many of the storms
http://www.nasa.gov/mission_pages/hurricanes/arch ives/2006/normal_2006.html
El Nino was certainly a big factor though
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Quoting 136. viman:
And let the F5 Race BEGIN!!!
Hey Viman were in the VI are you? st.thomas stjohn or st.croix
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watch the surface winds in the bahamas today and overnight. might in for a surprise. very warm water lies downstream.
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Quoting 146. AussieStorm:


I guess no one cares about the very good looking T-wave behind Chantal. Very good for this time of year.
I wouldn't say "no one cares"; it's just that Chantal is hogging most of the attention at the moment, and deservedly so.

At any rate, there are three waves stacked up behind Chantal one over water, one coming off the African coast, and one a few days inland still:

waves
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70mph in 48 hours?.NHC must know something we don't.
In err Levi's video he showed something about the Euro also taking notice of that wave that the GFS is developing.
Member Since: August 14, 2010 Posts: 10 Comments: 17859
maybe a hurricane
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No big changes in the track forecast:

Member Since: February 11, 2012 Posts: 84 Comments: 8049
Quoting 145. Grothar:


What I want to know, is where the pulses will be which will pull Chantal North (like I've been saying for 3 days, LOL) But, more importantly, I see all the models shifting Chantal, or the remnants back towards the east coast. I still don't see what would do that yet. Any graphics???


To use the GFS as an example, at 108 hours the remnants of Chantal are evident at the 500mb level in the SE Bahamas. Note the trough digging into Virginia, which is helping to bring it northward.



However, look at how just 24 hours later, the base of that trough splits away and moves southwestward towards the north gulf coast, with the Bermuda ridge building back westward towards North Carolina. This retrograding trough split pattern can help rotate storms back NW towards the SE US, that is, if there is actually a storm in the area.

Member Since: November 24, 2005 Posts: 635 Comments: 26701
Quoting pcola57:


I care Aussie..
I would post a look at it but I don't have a good site to get the image from.. :(


I posted a true colour image of it at #118
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Quoting 143. pcola57:
Gro your blob has plenty of moisture and is starting a movement into the Bahamas now..
Curious as to why Dr. Masters gave it no mention..
Even if just to discount it..



I don't know. I guess he doesn't want to give me credit since I "saw if first". Hey, he is a busy man. I don't know how he even finds the time to post what he does. It takes a lot of work. Has anyone even read my last blog? I worked on it for hours.
Member Since: July 17, 2009 Posts: 71 Comments: 27211
Stewart is forecasting 70mph for a peak now. Can't see it happening given Chantal's current state.
Member Since: February 11, 2012 Posts: 84 Comments: 8049
...CHANTAL STRENGTHENS SLIGHTLY... ...TROPICAL STORM WATCH ISSUED FOR PUERTO RICO...
------------------------------------------------- -------------------------------

11:00 AM AST Mon Jul 8
Location: 10.9°N 51.7°W
Moving: WNW at 25 mph
Min pressure: 1005 mb
Max sustained: 45 mph
Member Since: October 15, 2012 Posts: 0 Comments: 435
Quoting 140. will40:


Link

try this link Sheri


Will Thank you I found the one I was looking for.

Sheri
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Borderline hurricane by 48 hours.

INIT 08/1500Z 10.9N 51.7W 40 KT 45 MPH
12H 09/0000Z 12.0N 55.0W 45 KT 50 MPH
24H 09/1200Z 13.6N 59.6W 50 KT 60 MPH
36H 10/0000Z 15.2N 64.1W 55 KT 65 MPH
48H 10/1200Z 16.8N 68.2W 60 KT 70 MPH
72H 11/1200Z 19.8N 74.1W 50 KT 60 MPH
96H 12/1200Z 23.3N 76.8W 35 KT 40 MPH
120H 13/1200Z 26.0N 78.1W 30 KT 35 MPH

$$
FORECASTER STEWART
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Upper Level vorticity:

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I know that we won't get proper location and movement until hurricane Hunters fly in so that may be at the 5pm Advisory or 7pm intermediate advisory
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Levi, I noticed that Allan Huffman is now doing paid subscriptions of "Tidbits" as well..the highest form of flattery is imitation..
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...CHANTAL STRENGTHENS SLIGHTLY... ...TROPICAL STORM WATCH ISSUED FOR PUERTO RICO...
11:00 AM AST Mon Jul 8
Location: 10.9°N 51.7°W
Moving: WNW at 25 mph
Min pressure: 1005 mb
Max sustained: 45 mph
Member Since: Posts: Comments:
45mph, TS Watch issued for Puerto Rico.
Member Since: July 7, 2010 Posts: 0 Comments: 5725
BULLETIN
TROPICAL STORM CHANTAL ADVISORY NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL AL032013
1100 AM AST MON JUL 08 2013

...CHANTAL STRENGTHENS SLIGHTLY...
...TROPICAL STORM WATCH ISSUED FOR PUERTO RICO...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...10.9N 51.7W
ABOUT 550 MI...885 KM ESE OF BARBADOS
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 25 MPH...41 KM/H
MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES
Member Since: February 11, 2012 Posts: 84 Comments: 8049
155. 7544
look whats goin on with ull as soon as it reach the bahammas today dont you you think it will be the same for chantel even if the nhc shows a td at that time the bahamas and north of cuba have been the hot spot so far this season this is where whats left of chantel could regenerte and grow stronger imo im no expert lol
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Quoting 139. SouthernIllinois:

Never understood that. I guess folks have way too much time on their hands. Must be summer boredom.


Or some of us are retired, wives in Europe, children all grown with lives of their own, while we sit here waiting for the nurses to give us our hourly pills. What else are we going to do?

We are in the company of intelligent,interesting people who willingly share information and a bit of humor now and then. What more could one ask for?
Member Since: July 17, 2009 Posts: 71 Comments: 27211
Quoting 133. Levi32:


That is a fairly likely scenario with a retrograding trough in the SE US ahead of Chantal. The big question is will there even be a Chantal at that time.


tibet? so whats your take on the movement of chantal?
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expect 40 mph and wnw at 11
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Quoting 143. pcola57:
Gro your blob has plenty of moisture and is starting a movement into the Bahamas now..
Curious as to why Dr. Masters gave it no mention..
Even if just to discount it..




cause that's a mid-upper level low
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Quoting 146. AussieStorm:


I guess no one cares about the very good looking T-wave behind Chantal. Very good for this time of year.


I care Aussie..
I would post a look at it but I don't have a good site to get the image from.. :(
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I am always wary of "Slam the door" Bermuda high tracks that shove storms back toward the coast. A majority of the few hurricanes that have hit coastal Georgia have been of this type.

1881 Georgia Hurricane

1898 Georgia Hurricane

1940 Georgia/South Carolina Hurricane


1947 "Project Cirrus" Hurricane

Member Since: September 22, 2005 Posts: 18 Comments: 2343
maybe invest 96L soon
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Quoting 130. TylerStanfield:

I think he meant 2010, gaston wasnt in 2008, and it wasnt an El Niño.
In his earlier post he was talking about 2006.So that's why I mentioned the El nino.
Member Since: August 14, 2010 Posts: 10 Comments: 17859
Quoting AussieStorm:
Fresh True Colour pass of T-Wave behind TS Chantal.



Lager image(49mb)


I guess no one cares about the very good looking T-wave behind Chantal. Very good for this time of year.
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Quoting 133. Levi32:


That is a fairly likely scenario with a retrograding trough in the SE US ahead of Chantal. The big question is will there even be a Chantal at that time.


What I want to know, is where the pulses will be which will pull Chantal North (like I've been saying for 3 days, LOL) But, more importantly, I see all the models shifting Chantal, or the remnants back towards the east coast. I still don't see what would do that yet. Any graphics???
Member Since: July 17, 2009 Posts: 71 Comments: 27211
East coast track? With this setup, and a setup which doesn't look to be changing much anytime soon? Not likely. A strong system has a difficult time pushing up against 1016mb of high pressure, much less a weak system. I expect tracks to continue to trend further west, despite the ULL, and despite even a strengthening system.

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Gro your blob has plenty of moisture and is starting a movement into the Bahamas now..
Curious as to why Dr. Masters gave it no mention..
Even if just to discount it..

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Quoting 94. Matt74:
Grothar, what would be the inhibiting factor on this ULL working it's way down to the surface? Thanks


As I wrote on the blog earlier, (so everyone will know, none of the models developed this system. The conditions are not conducive for development in the area and it probably would not have much time for development anyway. The thing is, that these systems often pose a threat to maritime interests and I would not want to be on a boat in this area right now. (Which I often am.) Also, they can absorb a lot of moisture and dump a lot of rain. Florida has seen many of these types of systems and they can cause tremendous rainfalls awful lot of flooding.

Member Since: July 17, 2009 Posts: 71 Comments: 27211
GFS 06z last frame, another possible system.
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Quoting 113. catastropheadjuster:
Good Morning everyone, I was wondering I may get this wrong, but someone posted this a year or two ago. It's looks like a compass. What I'm getting at it's hard to explain. you know how there saying it's moving at 280 degrees there's something that looks like a compass that show all the degrees and what that degree means like nwn or wnw. Do you all understand if so can some one post it agian. I lost alot of my stuff I had saved when my computer crashed. I hope this made sense.

Sheri


Link

try this link Sheri
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Quoting 113. catastropheadjuster:
Good Morning everyone, I was wondering I may get this wrong, but someone posted this a year or two ago. It's looks like a compass. What I'm getting at it's hard to explain. you know how there saying it's moving at 280 degrees there's something that looks like a compass that show all the degrees and what that degree means like nwn or wnw. Do you all understand if so can some one post it agian. I lost alot of my stuff I had saved when my computer crashed. I hope this made sense.

Sheri


Try Compass Rose:
https://en.wikipedia.org/wiki/Compass_rose




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Quoting 131. tropicfreak:


My main concern is (as for me being on the east coast) is once it reaches the Bahamas, it will begin feeding off these warm gulf stream waters, allowing it to intensify, assuming that the atmospheric environment is favorable. That has me worried.
It may be favorable with the high building in overhead another thing to notic is the slow down, almost to a stall over the Bahamas.
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136. viman
And let the F5 Race BEGIN!!!
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Quoting 107. ProgressivePulse:
Not many storms have hit FL from the east in July. Not that there will be much left of Chantal by then, just highlighting the climatology aspect if that were to happen.




It will likely go into the gom after the bahamas,as it gets caught between the bermuda high extension and a sw moving ull in the lower southeast coast.It should stall in Bahamas and then go slowly west,intensity in Bahamas is tricky.Shear may be strong...but it 5 day away!
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Quoting 124. GTstormChaserCaleb:




This is why it would be an East Coast landfall, subtropical ridge rebuild, trough lifts out, should it survive the trek through the Caribbean and across the mountainous terrain.

Nice sat. Looks like a Cape Verde parade!
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Quoting 123. Grothar:
Many of the models are turning Chantal back towards the east coast after moving through the Bahamas




That is a fairly likely scenario with a retrograding trough in the SE US ahead of Chantal. The big question is will there even be a Chantal at that time.
Member Since: November 24, 2005 Posts: 635 Comments: 26701

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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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