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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Looks to me like the ULL nearing the Bahamas/Florida is moving a whole lot slower than Chantal -- and is very large. What do the forecasts show for track of the ULL over the next few days?

BTW, seeing the latest GFS guess (from post #786) reminds me of the sort of track 1995's Erin took.

Really would be grateful if someone could knowledgeably discuss the big ULL we are/may be awaiting here in FL.
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882. whitewabit (Mod)
Quoting 852. Patrap:
Took a lightning strike, surge protection kicked in, safed my system here.

Power was out 15 min

Restarted just now.





You got lucky !!
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Here's my forecast for Chantal... I don't think it will survive the land shear combo. It may redevelop like the 12z GFS shows though. And yes, I know the NHC doesn't use 55mph as an intensity, but I felt like that would be most accurate at that point :)

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The center is at 12N/53W now. To compare, the next forecast point had it at 12N/55W. A slight eastward adjustment could be possible. Let's see what recon finds...
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Experimental FIM-9 54 hrs.

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hurricane23, check and clear cookies. Might help.
Member Since: July 8, 2005 Posts: 259 Comments: 23641
Quoting 874. zampaz:

Is that Kermit?
Yes
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TS Chantal

RGB Loop

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Quoting 856. ArkWeather:

What is the NOAA plane in Arkansas doing?


Research
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Quoting 856. ArkWeather:

What is the NOAA plane in Arkansas doing?

Is that Kermit?
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Quoting 868. HadesGodWyvern:


sometimes you have to un-install the old version of flash and re-download the update.

otherwise close your browser and see what happens.


I had to do that this morning.
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Quoting 864. hurricane23:
Not working levi even on different browser. Flash up to date on labtop. Eveything works but when i go to click on flash loops it wont do anything. worked few days ago


I'm sorry to say it's on your end. No problems here. Like Hades said, maybe reinstall Flash, though I personally would try restarting the computer and see if that works first.
Member Since: November 24, 2005 Posts: 635 Comments: 26566
Quoting 857. StormPro:

ok, I'll specify southeast Louisiana ;)


LOL I have a storm heading towards me in west central LA, and it's dying as it gets to me. I've my fingers crossed for some of that sky juice for my garden. The winds according to local weather are gusts of 9 mph, however the wind just almost tore the door from me when I opened it to get a package from UPS.
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TS Chantal

Rainbow Loop

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Member Since: September 2, 2009 Posts: 130 Comments: 21091
868. HadesGodWyvern (Mod)
hurricane23
Not working levi even on different browser. Flash up to date on labtop. Eveything works but when i go to click on flash loops it wont do anything. worked few days ago


sometimes you have to un-install the old version of flash and re-download the update.

otherwise close your browser and see what happens.
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Quoting 852. Patrap:
Took a lightning strike, surge protection kicked in, safed my system here.

Power was out 15 min

Restarted just now.





Good to hear you are okay. It's heading my way now. Lots of lightning and thunder. Tracking it on radar.

(I took a bad strike here a few years ago. Four figures $ damage. That stuff in dangerous and expensive. Good surge protection is well worth the money.)
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In other parts of the world...



Edit: New one just went up:

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Product: Air Force High Density (HDOB) Message (URNT15 KNHC)

Transmitted: 8th day of the month at 19:06Z
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: 05

At 19:07:30Z (last observation), the observation was 206 miles (331 km) to the ESE (117°) from San Juan, Puerto Rico (USA).

19:07:30Z 17.083N 63.267W 375.9 mb
(~ 11.10 inHg) 8,081 meters
(~ 26,512 feet) - 458 meters
(~ 1,503 feet) From 80° at 13 knots
(From the E at ~ 14.9 mph) -20.0°C
(~ -4.0°F) -47.6°C
(~ -53.7°F) 13 knots
(~ 14.9 mph) 24 knots
(~ 27.6 mph) 0 mm/hr
(~ 0 in/hr) 24.0 knots (~ 27.6 mph)
184.6%
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
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Not working levi even on different browser. Flash up to date on labtop. Eveything works but when i go to click on flash loops it wont do anything. worked few days ago
Member Since: May 14, 2006 Posts: 8 Comments: 13640
DMax waiting!!!
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Quoting 856. ArkWeather:

What is the NOAA plane in Arkansas doing?
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Quoting 842. Bluestorm5:


I believe you meant hope Chantal doesn't cause lot of destruction if it makes landfall?
Ha ha correct sorry I was typing really fast.thanks
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Quoting 838. allancalderini:
Like I thought hurricane intesity might not be to far off.


To achieve Hurricane intensity while moving 20 to 25 kts would be highly impressive. While potentially not unprecedented, it would still be very impressive indeed.
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Quoting 856. ArkWeather:

What is the NOAA plane in Arkansas doing?


Spraying chemtrails.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
Quoting 847. Tazmanian:
It would. Be funny if we been tracking open wave and they don't fine a w wind

0% chance because spiral bands rotate around a closed low pressure.
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Quoting 853. aislinnpaps:


Ah, but just north of you could use a little bit.

ok, I'll specify southeast Louisiana ;)
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Quoting 809. Levi32:
My shameless plug for the day:

Instead of sorting through and mentally decoding raw recon data here on the blog or pasting it into a decoder, you can visually track today's hurricane hunter mission into Chantal on the left-hand half of this page.
What is the NOAA plane in Arkansas doing?
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855. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #15
SEVERE TROPICAL STORM SOULIK (T1307)
3:00 AM JST July 9 2013
=============================

SUBJECT: Category Two Typhoon Named Cyclone Near Marianas Islands

At 18:00 PM UTC, Severe Tropical Storm Soulik (975 hPa) located at 19.4N 141.5E has 10 minute sustained winds of 60 knots with gusts of 85 knots. The cyclone is reported as moving west at 12 knots.

Storm Force Winds
==================
40 NM from the center

Gale Force Winds
===============
260 NM from the center in north quadrant
240 NM from the center in south quadrant

Dvorak Intensity: T3.5

Forecast and Intensity
=======================
24 HRS: 20.6N 136.6E - 75 knots (CAT 3/Strong Typhoon) South Of Japan
48 HRS: 21.8N 131.8E - 80 knots (CAT 3/Strong Typhoon) South Of Japan
72 HRS: 23.2N 127.0E - 85 knots (CAT 4/Very Strong Typhoon) South Of Okinawa
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Quoting 818. mikatnight:


Actually, we haven't gotten all that much this past month. Though I know most everywhere else around here has had more than enough.



BTW where did you get that precipitation report? I looked and can't seem to find it.
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Quoting 839. StormPro:


Specify Texas please, we've had enough sky juice here in South Louisiana :)


Ah, but just north of you could use a little bit.
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Took a lightning strike, surge protection kicked in, safed my system here.

Power was out 15 min

Restarted just now.



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Quoting 845. OceanMoan:



That's the truth, my nephews were able to use kayaks in their back yard a few days ago.


It has been nothing short of insane! That crazy kink in the jet stream has soaked us for over two weeks. Even a TD would be bad news here.
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Quoting CaicosRetiredSailor:


Good day Pottery

Squalling here also. ; )

We are happy to be getting some showers.
June was half the average for rainfall, July has been very dry. And hot !
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Quoting 848. Stormchaser2007:
Overall structure is improving with low level clouds showing up around the entire circulation.

Could look decent once again if it has a DMAX like last night.


What does DMAX stand for?
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Overall structure is improving with low level clouds showing up around the entire circulation.

Could look decent once again if it has a DMAX like last night.

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It would. Be funny if we been tracking open wave and they don't fine a w wind
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Quoting 818. mikatnight:


Actually, we haven't gotten all that much this past month. Though I know most everywhere else around here has had more than enough.


We're in a similar situation, we've had 25 inches so far in Jax, 7" above normal, but certainly not excessive.
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Quoting 832. nash36:
Afternoon all.

Chantal can feel free to stay away from Charleston. We are completely waterlogged and cannot handle any more significant rain.



That's the truth, my nephews were able to use kayaks in their back yard a few days ago.
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Quoting 789. pottery:
Greetings.
Showers in Trinidad today, with occasional squall conditions but nothing unusual.

Happy to see that Chantal is still being reigned-in by that dry air west of her. If it was not for that dry air, I think we would be seeing a far more dynamic storm today.


Good day Pottery

Squalling here also. ; )
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Great loop of Chantel's lifetime.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting 833. allancalderini:
yeah but they are not impossible remember Emily 2005.mmm actually the past seasons Hispaola have escape some hits since 2010 when Tomas was near they save from a direct landfall hope Chantal caused a lot of destruction if it makes landfall.


I believe you meant hope Chantal doesn't cause lot of destruction if it makes landfall?
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Found a potential analog to TS Chantal, try the 1926 Nassua Hurricane which formed 2 weeks later. "Keep in mind I'm just comparing track, not strength."

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Quoting 808. 69Viking:


I don't think there's a single part of Florida that needs the rains this could possibly bring in addition to what we've already had. Not to mention the ULL is going to give us more rain before Chantal...


Yeah...all of Florida is pretty saturated.

Link
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Quoting 829. Kumo:


Agreed, please forecast a slow moving tropical depression for those of us near the NW Gulf, we could use one of those. :)


Specify Texas please, we've had enough sky juice here in South Louisiana :)
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Quoting 831. washingtonian115:
Notice the nice sprawl bands forming on almost all sides of the storm in the last few frames.Chantel might have some tricks up her sleeve.
Like I thought hurricane intesity might not be to far off.
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Chantal larger plus tight core =
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I am really concerned however, about what this does if it re-emerges into the GOM in any form


we have a lot of west, easy, north and south shifts ahead of us. Not to mention interactions that will affect Chantal's intensity before we can become Doomcasters
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Quoting 818. mikatnight:


Actually, we haven't gotten all that much this past month. Though I know most everywhere else around here has had more than enough.



Dang, what part of Florida are you hiding from the rain in? Here in NW Florida I picked up 7 inches of rain over a 4 day period from July 3rd to July 6th! I thought most of Florida got some decent rain over the same period or just before we did.
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Quoting 824. islander101010:
yellow at 0 % why bother


Just to calm the blog down and let us know that they are aware of its presence.
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Quoting 801. FunnelVortex:


I agree. It is way too early in the season for cat 5s.
yeah but they are not impossible remember Emily 2005.
Quoting 803. PalmBeachWeatherBoy:
A Haiti and Dominican Republic strike is imminent now....I feel like this area is always under the gun.
mmm actually the past seasons Hispaola have escape some hits since 2010 when Tomas was near they save from a direct landfall hope Chantal don`t caused a lot of destruction if it makes landfall.
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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.