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: 1483 - 1433

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

Quoting 1477. Ameister12:

Looks like Georgia.
Beryl part deux?
Member Since: Posts: Comments:
Open wave? Ha!!!
Member Since: June 20, 2012 Posts: 0 Comments: 2169
A very interesting IR simulation by the GFS 147 hours out.

Member Since: Posts: Comments:
Quoting 1468. SFLWeatherman:
18Z GFS it going into N FL

Looks like Georgia.
Member Since: Posts: Comments:
Quoting 1454. jeffreeysweetypie:
Tonds of dry air and high wnd shear will keep storms at bay for at least the next 4 to 6 weeks if not the whole season just watch

Dry air may be factor for some of the storms come off Africa; but the current predictions are for the wind shear to fall off.
Member Since: Posts: Comments:
Member Since: May 23, 2012 Posts: 0 Comments: 4984
I told ya'll 92L is being reincarnated into each of these waves and trynna get back at the NHC.
Member Since: August 14, 2010 Posts: 10 Comments: 17838
the tropical wave back of Tropical Storm CHANTAL will be a big tropical storm to watch or be invest96L
Member Since: Posts: Comments:
1472. bwi
Weaker than expected Chantal might end up further west/south of forecast points.
Member Since: Posts: Comments:
Quoting 1454. jeffreeysweetypie:
Tonds of dry air and high wnd shear will keep storms at bay for at least the next 4 to 6 weeks if not the whole season just watch


It's not dry air and shear. My magic voodoo is what is responsible for everything that happens this year.
Member Since: Posts: Comments:
1470. txjac
Quoting 1464. SouthernIllinois:

I agree. West she goes into the Gulf. And stays weak. I don't see this amounting to all too much.


We'll take her here in Texas
Member Since: Posts: Comments:
Camille33 is free to blog whatever he wants, he's not a troll, but 94L a Cat4 major? And now Chantal a Cat4 over Haiti? Every example is of some monster from past years. It's fine and all, but he wants to be taken seriously and communicates as if he wants us to think he knows what he's talking about. If that's the case he should probably back off the non-stop, every storm is doom bound. His forecast for the season was 24/21/18. :) I made the last sentence up.
Member Since: Posts: Comments:
18Z GFS it going into N FL
Member Since: May 23, 2012 Posts: 0 Comments: 4984
Quoting 1454. jeffreeysweetypie:
Tonds of dry air and high wnd shear will keep storms at bay for at least the next 4 to 6 weeks if not the whole season just watch


You sound like a poster who we've had pop up under a new handle once or twice.. a day.. for the last few years.
Member Since: Posts: Comments:
Quoting 1447. MiamiHurricanes09:
LMFAO, Jason was the best poster WU has ever had hands down LOL.

"WOW!!"

-Jason
Member Since: Posts: Comments:
the recon is finding a hole lote of nothing so far they have found a sighty close low but openb too the S with a mb of 1010mb so this low is vary weak
Member Since: Posts: Comments:
Quoting 1451. Patrap:
Purty Blue RGB low Sun Angle image


Yes it is. That color looks good on Chantal.
Member Since: Posts: Comments:
6 days out, a rather intense tropical storm Chantal making landfall on the Florida/Georgia boarder with another intense tropical storm in the EATL.

Member Since: Posts: Comments:
1460. Patrap
Member Since: July 3, 2005 Posts: 428 Comments: 129903
Quoting 1424. avthunder:
Is it my imagination or are the trolls much worse this year? Seems to be one coming back with a different name every few weeks but gives himself away with the same speech (writing) patterns. Must have lots of devices and locations since I would assume bans use IP and/or MAC addresses to block.

No trolls aren't worse this year than in the past. As for banning an IP this is a little more difficult than it sounds and is usually left as a last resort effort. There have only been a couple of bad trolls this year and it will get worse; but most of the long time members know to ignore and not engage and they go away on their own. If someone in the group that you know and trust states that they suspect that someone is a troll, just put them on your ignore list and move along.
Member Since: Posts: Comments:
im starting to think dorian will be a bigger problem than chantal but i could be wrong
Member Since: Posts: Comments:
1457. hydrus
Quoting 1446. SouthernIllinois:

I don't see it either. This system shall succumb to shear and dry air.

Natalie
probably will become much weaker....Which allows the storm to cruise farther west...jmo
Member Since: Posts: Comments:
Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 8th day of the month at 22:10Z
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: 09

Mandatory Data...

Observation Time: Monday, 22:10Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 11.1N 53.8W
Location: 416 miles (670 km) to the ESE (109°) from Bridgetown, Barbados.
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 400 meters
Flight Level Wind: From 170° at 22 knots (From the S at ~ 25.3 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: 19°C
Flight Level Dew Point: 19°C
Weather (within 30 nautical miles): Thunderstorm(s)
Mean Sea Level Pressure (MSLP): 1013 mb (extrapolated)

Remarks Section - Remarks That Were Decoded...

Surface Wind Speed (likely by SFMR): 21 knots (~ 24.2mph)

Remarks Section - Additional Remarks...

SE TURN POINT
Member Since: Posts: Comments:
Member Since: May 23, 2012 Posts: 0 Comments: 4984
The blog's down in the dumps about the very first recon pass, yet if the recon finds something even slightly more impressive than expected there will be talks about the NHC being too low with the forecast and that Florida should be prepared for a hurricane.
Member Since: Posts: Comments:
Time: 22:07:30Z
Coordinates: 11.0833N 53.95W
Acft. Static Air Press: 966.7 mb (~ 28.55 inHg)
Acft. Geopotential Hgt: 408 meters (~ 1,339 feet)
Extrap. Sfc. Press: 1012.9 mb (~ 29.91 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 170° at 21 knots (From the S at ~ 24.1 mph)
Air Temp: 21.7°C (~ 71.1°F)
Dew Pt: 19.3°C (~ 66.7°F)
Peak (10s) Flt. Lvl. Wind: 21 knots (~ 24.1 mph)
SFMR Peak (10s) Sfc. Wind: 15 knots (~ 17.2 mph)
SFMR Rain Rate: 3 mm/hr (~ 0.12 in/hr)
Member Since: Posts: Comments:
1451. Patrap
Purty Blue RGB low Sun Angle image

Member Since: July 3, 2005 Posts: 428 Comments: 129903
1449. K8eCane
Quoting 1431. TylerStanfield:

Yeah. He said it would become a hurricane tomorrow... *Facepalm*



Hey Im just gonna follow Jethroes lead and start giving headslaps
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Quoting 1437. allancalderini:
You haven`t met Jason if you think that.He was the most persistant troll I had ever met I have like 24 accounts of him on ignore XD,and the tales say he is still here watching us.
LMFAO, Jason was the best poster WU has ever had hands down LOL.
Member Since: Posts: Comments:
Congrats to Gro on getting the NHC to put the yellow on his ULL!
Member Since: September 10, 2007 Posts: 0 Comments: 11557
Quoting 1428. nash36:


Stop it!!!!! I do not want any more heavy rain! It can feel free to croak over the mountains :-)
I'm with ya.We don't need any more excessive rain here either.So Chantal get's a second chance in the Bahamas huh?
Member Since: August 14, 2010 Posts: 10 Comments: 17838
...RIP T.S. CHANTAL...
Member Since: Posts: Comments:
1441. Patrap
Member Since: July 3, 2005 Posts: 428 Comments: 129903
Quoting 1420. TylerStanfield:

A storm doesn't just simply strengthen because wind shear is low. There are many factors, and right now, the main thing that has disrupted, and will likely continue to disrupt Chantal is the Fast Trade winds. These winds will keep any strengthen very slow, and there's about a 15% chance or less of this thing becoming a Hurricane in it's lifetime. The maximum intensity this storm is capable of right now is 65 Mph...


Whoops I had the starting intensity wrong- I thought it was 60 for some reason...sorry about that...
Here's the updated:

My predicition- Prior to Hispanola- 65 mph
After Hispanola- 35 mph
Strengthen to 40 mph in the Bahamas
but shear keeps it at 40 mph.
Hit Florida at 35-40 mph depending on shear.
Madame CHantal is playing tricks on me.
Member Since: Posts: Comments:
Recon starting to pick up higher winds as it begins to head north, nothing impressive yet.
Member Since: Posts: Comments:
our storm isnt looking so good right now, probably the dry air right?
Member Since: Posts: Comments:
Quoting 1424. avthunder:
Is it my imagination or are the trolls much worse this year? Seems to be one coming back with a different name every few weeks but gives himself away with the same speech (writing) patterns. Must have lots of devices and locations since I would assume bans use IP and/or MAC addresses to block.
You haven`t met Jason if you think that.He was the most persistant troll I had ever met I have like 24 accounts of him on ignore XD,and the tales say he is still here watching us.
Member Since: Posts: Comments:
126HR
Member Since: May 23, 2012 Posts: 0 Comments: 4984
Quoting 1424. avthunder:
Is it my imagination or are the trolls much worse this year? Seems to be one coming back with a different name every few weeks but gives himself away with the same speech (writing) patterns. Must have lots of devices and locations since I would assume bans use IP and/or MAC addresses to block.


They're no different, if anything their tenures are shorter lived thanks to vastly superior moderation than in the last few seasons. Camille, albeit being rather obnoxiously over-zealous in his forecasts, isn't breaking any rules that I can see.
Member Since: Posts: Comments:
18z GFS; 5 days out.



Very impressive EATL feature.

Member Since: Posts: Comments:

Viewing: 1483 - 1433

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
44 °F
Overcast

JeffMasters's Recent Photos

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