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: 1983 - 1933

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

-_-
Member Since: June 2, 2013 Posts: 9 Comments: 1414
1982. whitewabit (Mod)
Quoting 1980. TylerStanfield:

WHAT THE HECK?! Was my account reset? I had over 400 comments and 3 blogs, my bio is gone and I only have pictures left? What's going on?!


Try signing out and then back in after clearing cookies ..
Member Since: Posts: Comments:
Quoting 1977. Stormchaser2007:


Wow
Member Since: Posts: Comments:
Quoting 1956. TylerStanfield:
Everything on my blog page is messed up! My bio is gone, my ignore list isn't working and my blogs have all been deleted. The only thing I have is Photos... What the heck?!

WHAT THE HECK?! Was my account reset? I had over 400 comments and 3 blogs, my bio is gone and I only have pictures left? What's going on?!
Member Since: June 2, 2013 Posts: 9 Comments: 1414
Quoting 1956. TylerStanfield:
Everything on my blog page is messed up! My bio is gone, my ignore list isn't working and my blogs have all been deleted. The only thing I have is Photos... What the heck?!
Maybe someone hack your account or something; that is very strange. Logout and Log back in or restart your browser.
Member Since: May 25, 2012 Posts: 0 Comments: 2043
1978. ncstorm
312 hours
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Quoting 1958. presslord:
Never before have the words 'may' and 'if'...and all their iterations...appeared so often...and to so little purpose...


Having a Churchill, Press? ;)
Member Since: Posts: Comments:
1975. will40
Quoting 1969. ncstorm:
300 hours



thatone is fine
Member Since: Posts: Comments:
Quoting 1948. Hurricanes305:

Too early to say that its could stay east of Florida. But you never know that is why the tropics are so fun. 


and the shear in the Caribbean doesn't look to terribly strong right now but it's pretty high
Member Since: September 8, 2010 Posts: 0 Comments: 2232
Not sure if this has been posted but I'll post it anyways.

True Colour image of Chantal.


Vortex streets coming off the Cape Verde Islands.


Closer view.


Would these be classified as just vortex streets or Kármán vortex streets?
Member Since: Posts: Comments:
1972. Gearsts
New center at 12n:
Time: 00:10:30Z
Coordinates: 12.0833N 55.2333W
Acft. Static Air Press: 966.6 mb (~ 28.54 inHg)
Acft. Geopotential Hgt: 396 meters (~ 1,299 feet)
Extrap. Sfc. Press: 1011.4 mb (~ 29.87 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 344° at 3 knots (From the NNW at ~ 3.4 mph)
Air Temp: 22.2°C (~ 72.0°F)
Dew Pt: 20.5°C (~ 68.9°F)
Peak (10s) Flt. Lvl. Wind: 4 knots (~ 4.6 mph)
SFMR Peak (10s) Sfc. Wind: 12 knots (~ 13.8 mph)
SFMR Rain Rate: 2 mm/hr (~ 0.08 in/hr)
(*) Denotes suspect data
Member Since: Posts: Comments:
1971. whitewabit (Mod)
Quoting 1951. ncstorm:


none of them are showing up?


They are ok for me ..
Member Since: Posts: Comments:
Quoting 1944. wunderkidcayman:

Nah
Disagree? Ok then tell us what you see in the pattern upstream. I know I left out some details I just know it. I forgot to account for the ULL that will split off from the trough split. That would pull it in more west, but as far as this Chantal making it into the Western Caribbean I don't see how that is feasible unless the rugged terrain of Haiti destroyed the storm leaving a remnant low.
Member Since: June 30, 2013 Posts: 12 Comments: 8774
1969. ncstorm
300 hours
Member Since: Posts: Comments:
Quoting 1955. AussieStorm:


My recon feed isn't working on GE. Anyone else have this problem?

It's working fine for me.
Member Since: Posts: Comments:



Convective structure is finally improving.
Member Since: Posts: Comments:
Quoting 1951. ncstorm:


none of them are showing up?
Never mind I saw it.But the ridge seems like it wants to build back in.
Member Since: August 14, 2010 Posts: 10 Comments: 17838
1965. FOREX
Quoting 1943. gator23:
I normally don't disagree with you because you are spot on most times so please allow me this one indulgence. If you look at the satellite floater with the forecast points on it appears to be north of the forecast points. I think overall it has evened out.

Link



I see a mostly NW movement, right in line with the NHC points.
Member Since: Posts: Comments:
Recon is flying through a remnant center that was probably ejected earlier today.

It would be funny is there wasn't something under the new convection

Member Since: Posts: Comments:
Looks like recon is heading out.
Member Since: Posts: Comments:
1962. will40
Quoting 1951. ncstorm:


none of them are showing up?
i see the 288 hr one
Member Since: Posts: Comments:
Quoting 1956. TylerStanfield:
Everything on my blog page is messed up! My bio is gone, my ignore list isn't working and my blogs have all been deleted. The only thing I have is Photos... What the heck?!


It's Sky's fault! ;P
Member Since: Posts: Comments:
1960. Gearsts
Center at 12n now?
Member Since: Posts: Comments:
Quoting 1932. GTstormChaserCaleb:
Ok let's see if I can clear this up the steering should continue on a w/wnw path with some jogs to the nw at times until it gets towards the vicinity of Puerto Rico. Then a gradual turn more towards the nw crossing over Hispaniola.

The ULL over the Bahamas is creating a weakness in the Subtropical Ridge on the Southwestern Flank and it is evident over Cuba that area of weakness is shifting eastward and will allow for this turn to occur.

Now look up over North Dakota and Minnesota notice the short wave digging there that will also come down and take a jab at the Subtropical Ridge on the Western and Northern Flank which will turn the system even more towards the North,

After that it remains to be seen if the Short Wave leaves quickly or hangs around. If it leaves quickly the Ridge builds back in and closes the weakness thus shunting the storm back towards the West, if it hangs around the storm continues its northward movement towards the Carolinas.



Very nice discernment! :) I'll come back in a bit and share why I think the current modeling isn't quite right, imho. :)
Member Since: Posts: Comments:
Never before have the words 'may' and 'if'...and all their iterations...appeared so often...and to so little purpose...
Member Since: Posts: Comments:
1957. Patrap
At 00:27:30Z (last observation), the observation was 268 miles (431 km) to the ESE (108°) from Bridgetown, Barbados.

Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 9th day of the month at 00:26Z
Date: July 9, 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: 37

00:27:30Z 11.867N 55.850W 843.5 mb
(~ 24.91 inHg) 1,590 meters
(~ 5,217 feet) 1013.4 mb
(~ 29.93 inHg) - From 54° at 7 knots
(From the NE at ~ 8.0 mph) 15.6°C
(~ 60.1°F) 14.3°C
(~ 57.7°F) 8 knots
(~ 9.2 mph) 8 knots
(~ 9.2 mph) 0 mm/hr
(~ 0 in/hr) 7.0 knots (~ 8.0 mph)
100.0%
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: 428 Comments: 129904
Everything on my blog page is messed up! My bio is gone, my ignore list isn't working and my blogs have all been deleted. The only thing I have is Photos... What the heck?!
Member Since: June 2, 2013 Posts: 9 Comments: 1414
Quoting wxchaser97:

Yes, they are going in for another center pass.


My recon feed isn't working on GE. Anyone else have this problem?
Member Since: Posts: Comments:
Chantal may very well become a hurricane tomorrow if current trend continue.
Member Since: Posts: Comments:
NHC center position as of 8pm EDT looked to be a little too far south and west. I'd put it just east of 55W and just north of 12N based on satellite imagery. Perhaps recon actually hits the center this time.
Member Since: July 6, 2010 Posts: 113 Comments: 32862
1952. gator23
I think its worth posting again. Look at the forecast point. Slightly north of them. The track has evened out.

Link
Member Since: Posts: Comments:
1951. ncstorm
Quoting 1949. washingtonian115:
I can't see anything.


none of them are showing up?
Member Since: Posts: Comments:
1950. Patrap
Member Since: July 3, 2005 Posts: 428 Comments: 129904
Quoting 1945. ncstorm:
288 hours
Right now I doubt.The ridge will build back in.
Member Since: August 14, 2010 Posts: 10 Comments: 17838

Quoting 1931. weatherlover94:
The Gulf of Mexico looks VERY favorable right now
Too early to say that its could stay east of Florida. But you never know that is why the tropics are so fun. 
Member Since: May 25, 2012 Posts: 0 Comments: 2043
@Skyepony What is going on? None of my blogs are showing up on my Blog Page...
Member Since: June 2, 2013 Posts: 9 Comments: 1414
Time: 00:16:00Z
Coordinates: 11.9167N 55.3167W
Acft. Static Air Press: 966.7 mb (~ 28.55 inHg)
Acft. Geopotential Hgt: 402 meters (~ 1,319 feet)
Extrap. Sfc. Press: 1012.1 mb (~ 29.89 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 13° at 1 knots (From the NNE at ~ 1.1 mph)
Air Temp: 22.7°C (~ 72.9°F)
Dew Pt: 19.0°C (~ 66.2°F)
Peak (10s) Flt. Lvl. Wind: 3 knots (~ 3.4 mph)
SFMR Peak (10s) Sfc. Wind: 17 knots (~ 19.5 mph)
SFMR Rain Rate: 1 mm/hr (~ 0.04 in/hr)
(*) Denotes suspect data


Pressure still up there for now.

Wouldn't expect a drop till later.

This is significant because it may mean a more westerly track. Certainly there should be some guidance changes coming.
Member Since: Posts: Comments:
1945. ncstorm
288 hours
Member Since: Posts: Comments:
Quoting 1932. GTstormChaserCaleb:
Ok let's see if I can clear this up the steering should continue on a w/wnw path with some jogs to the nw at times until it gets towards the vicinity of Puerto Rico. Then a gradual turn more towards the nw crossing over Hispaniola.

The ULL over the Bahamas is creating a weakness in the Subtropical Ridge on the Southwestern Flank and it is evident over Cuba that area of weakness is shifting eastward and will allow for this turn to occur.

Now look up over North Dakota and Minnesota notice the short wave digging there that will also come down and take a jab at the Subtropical Ridge on the Western and Northern Flank which will turn the system even more towards the North,

After that it remains to be seen if the Short Wave leaves quickly or hangs around. If it leaves quickly the Ridge builds back in and closes the weakness thus shunting the storm back towards the West, if it hangs around the storm continues its northward movement towards the Carolinas.


Nah
Member Since: June 13, 2009 Posts: 2 Comments: 12719
1943. gator23
I normally don't disagree with you because you are spot on most times so please allow me this one indulgence. If you look at the satellite floater with the forecast points on it appears to be north of the forecast points. I think overall it has evened out.

Link

Quoting 1923. MiamiHurricanes09:
Looks like the cone will need to be shifted southward to reconcile with the new position.

Member Since: Posts: Comments:
Quoting 1913. Patrap:
Itsa making good time too.


Approx 200 miles in 8 hours



This may hit or go north of Puerto Rico. Then we will have a new game on.
Member Since: September 10, 2007 Posts: 0 Comments: 11557
CARIBBEAN SEA...
A TROPICAL WAVE IS MOVING W-NW OVER THE WESTERN CARIBBEAN WITH
AXIS EXTENDING FROM 25N77W TO 13N84W. CONTINUOUS RAINSHOWERS AND
THUNDERSTORMS HAVE BEEN REPORTED OVER EASTERN CUBA AS WELL AS
NORTHERN NICARAGUA AND ACROSS HONDURAS. TRAILING HIGH LOWER
LEVELS MOISTURE FROM THE WAVE AS WELL AS UPPER LEVEL DIFFLUENCE
FROM A CYCLONIC CIRCULATION NEAR 25N76W AND A BROAD RIDGE
EXTENDING ACROSS MUCH OF THE CARIBBEAN IS SUPPORTING CONTINUOUS
RAINSHOWERS AND THUNDERSTORMS ACROSS LA HISPANIOLA. OVER THE
SOUTHERN CARIBBEAN SCATTERED MODERATE CONVECTION AND ISOLATED
THUNDERSTORMS ARE OCCURRING S OF 12N WEST OF 79W. THIS
CONVECTION IS ASSOCIATED WITH THE MONSOON TROUGH AXIS THAT MOVES
ACROSS PANAMA. OTHERWISE...TRADEWINDS OF 15-20 KT SPREAD ACROSS
THE BASIN.

ULL interacting with ridge flow and N. end of trop wave
Member Since: Posts: Comments:
1940. Grothar
Quoting 1925. Relix:


That's with the new info?


Yes, but that is only one of GFS solutions. I will post a few others.

CMC

Member Since: Posts: Comments:
1939. Relix
Quoting 1930. TropicalAnalystwx13:

You're under a Tropical Storm Warning.


I know, but what I've learned is... most of the time when they say "tropical storm conditions" nothing else happens here. I remember a few years ago (forgot the name) a Cat 4 was 100 miles north of the island and there wasn't even rain. We were supposed to get t.storm conditions :P!
Member Since: Posts: Comments:
Quoting 1913. Patrap:
Itsa making good time too.


Approx 200 miles in 8 hours

Probably a good reason why we tend to get the big ones in August and September...slower movers.
Member Since: Posts: Comments:
Is the blog messed up? My ignore list isn't working...
Member Since: June 2, 2013 Posts: 9 Comments: 1414
1936. Patrap
Member Since: July 3, 2005 Posts: 428 Comments: 129904
Quoting 1918. unknowncomic:
That's quite the left turn

Yes it is! Might be TX bound after FL.
Member Since: September 2, 2011 Posts: 0 Comments: 1149

Quoting 1913. Patrap:
Itsa making good time too.


Approx 200 miles in 8 hours

Hey Pat it getting round again and its looks like a fetus lol maybe its about to be born for real.
Member Since: May 25, 2012 Posts: 0 Comments: 2043
Hello all back on from earlier.

Was very surprised after the initial fix of the center and the patch of dead winds being found that they were able to find 64 mph winds in the NE quadrant, I didn't see anything like that intensity coming so that is significant.

Also was interesting to note the motion and the convective restructuring that is underway right now. I would expect that the pressure is just a bit high right now probably due to that very same thing, the convective restructuring, and that is why we were seeing a pressure of 1010 mb despite much higher winds.

I would expect that unless the system goes back into degradation we will see a much lower pressure show itself during the day tomorrow.


In the meantime highest winds so far found by recon:

Time: 22:40:00Z
Coordinates: 12.1167N 54.1333W
Acft. Static Air Press: 967.2 mb (~ 28.56 inHg)
Acft. Geopotential Hgt: 383 meters (~ 1,257 feet)
Extrap. Sfc. Press: 1011.2 mb (~ 29.86 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 156° at 55 knots (From the SSE at ~ 63.2 mph)
Air Temp: 19.9°C (~ 67.8°F)
Dew Pt: 19.9°C (~ 67.8°F)
Peak (10s) Flt. Lvl. Wind: 56 knots (~ 64.4 mph)
SFMR Peak (10s) Sfc. Wind: 59 knots (~ 67.8 mph)
SFMR Rain Rate: 32 mm/hr (~ 1.26 in/hr)
(*) Denotes suspect data
Member Since: Posts: Comments:

Viewing: 1983 - 1933

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
46 °F
Overcast

JeffMasters's Recent Photos

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