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 610. moonlightcowboy:


ULL's rarely make it to the surface. They do, but it's not a common occurrence. To answer your question directly though, a storm must have fuel and that comes from the warm waters at the surface.

And, in this case, the ULL is also in a dry-air environment.

Thank you.
Quoting 649. moonlightcowboy:



Agreed. I've been suspect of it reaching the surface myself, and have been watching surface vorticity for the last three or four days - nothing has changed, although it does look to have good vorticity at the mid-levels and has been. It's also in an area of fairly dry air as well. At best, right now I think, it'll help to moisten the atmosphere for Chantal, and if it retrogrades westwards ahead of the storm, it may help to pull/tug the storm along behind it as well as help ventilate it. :)

Appreciate your sharing ideas in this and post 610 MLC.
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Seems the center is tucked in convection again.
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Quoting 673. weathermanwannabe:
Lesser Antilles needs to take adequate precautions in spite of the current status of the storm. If you take the current advisory of 45mph winds at the core, and add the forward speed of 25, some folks in the islands (assuming it does not intensify much further before reaching them)can expect some very strong gusts in certain pockets nearing Cat 1 winds.

You should always prepare for a category above what is forecast just in case.


The 45mph maximum winds in the NHC advisory are the Earth-relative winds. You do not add the forward storm motion vector.

However, I agree about always being prepared for worse than is forecast. The tropics are dynamic and can be unpredictable, no matter how sure we are about our forecast.
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I would say maybe 50 to 55MPH but not 65MPH
Quoting 671. StormTrackerScott:
I am so glad a recon is going out to investigate as i am positive we have a 60 to 65 mph storm right now. Very impressive visible satellite.

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Quoting 671. StormTrackerScott:
I am so glad a recon is going out to investigate as i am positive we have a 60 to 65 mph storm right now. Very impressive visible satellite.



With convection being limited on the northern side of the circulation currently, I doubt it's that strong...yet. If convection can form in the northeast quadrant like it's trying to do, then maybe. The trades would also help speed up the winds on the northern side to help speed up the winds. I think 50mph is a legit strength right now. If convection can fire in the northeast and north, then yeah, 60-65mph totally possible.
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Quoting 677. GTstormChaserCaleb:
It's really pulling north now into that breakage and feeling the Coriolis Effect of the Earth.


Meaning she is getting stronger ass the day goes on.
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Quoting 670. Patrap:
TS Chantal

WV Loop

It's really pulling north now into that breakage and feeling the Coriolis Effect of the Earth.
Member Since: June 30, 2013 Posts: 11 Comments: 7473
Honestly, the storm look like 50 mph. While visible satellite is impressive, I am having hard time seeing 60 mph or more on other satellites such as rainbow and AVN. Chantal just lost the red color on AVN for first time in awhile.

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Quoting 668. aislinnpaps:
I love the use of the words "expect , believe, anticipate". It's what keeps this blog going. Of course, with nature and weather, it's an ongoing world of expecting, believing and anticipating...
Quoting a long lost poster. "Albeit"
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Lesser Antilles needs to take adequate precautions in spite of the current status of the storm. If you take the current advisory of 45mph winds at the core, and add the forward speed of 25, some folks in the islands (assuming it does not intensify much further before reaching them)can expect some very strong gusts in certain pockets nearing Cat 1 winds.

You should always prepare for a category above what is forecast just in case.
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Why hasn't NHC put a circle on the storm developing behind Chantal? It looks like it has a strong circulation? And...Thank you all for answering my questions. I am a passionate amateur, and I've been on here lurking and learning for years now. I am learning so much from everyone. Thank you for your patience at what I know must seem really dumb questions sometimes...Nothing in the world is so exciting to me as this blog when big weather starts up! It looks like we're in for a very active and exciting season...
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I am so glad a recon is going out to investigate as i am positive we have a 60 to 65 mph storm right now. Very impressive visible satellite.

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TS Chantal

WV Loop

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Quoting 636. moonlightcowboy:



The answer is yes, it can help to serve ventilation, but not if it gets too close where it would act to shear the upper level moisture tops, the CDO from the system.


Thanks.. So it's a two fold side.
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I love the use of the words "expect , believe, anticipate". It's what keeps this blog going. Of course, with nature and weather, it's an ongoing world of expecting, believing and anticipating...
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Quoting weatherlover94:
Still the same 45 mph

I was wonderng if that was the same, or a different, 45 mph.
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only thing recon is showing right now is a non tasked mission
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Quoting 647. MechEngMet:


Well I think that covers the question in post #601.



Not answering a question, just passing along what Skyepony had mentioned a few days ago. I'm an enthusiast not an expert. Nice very passive aggressive sarcasm though. The obvious rarity of ULL making it to the surface, land interaction, and less than rocket fuel SST's would be the answer. I make it a habit to let the experts, those in the field, and those well versed in the science of answer questions.
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Quoting 649. moonlightcowboy:



Agreed. I've been suspect of it reaching the surface myself, and have been watching surface vorticity for the last three or four days - nothing has changed, although it does look to have good vorticity at the mid-levels and has been. It's also in an area of fairly dry air as well. At best, right now I think, it'll help to moisten the atmosphere for Chantal, and if it retrogrades westwards ahead of the storm, it may help to pull/tug the storm along behind it as well as help ventilate it. :)


Concur: I can't disagree with any of that.
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Quoting 652. Patrap:
TS Chantal

RGB Loop

Looking good there Pat, even for the speed in which she is moving at.
Member Since: June 30, 2013 Posts: 11 Comments: 7473
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Quoting 511. Thrawst:


Levi, potential video today? Thanks in advance!!


I will record one as soon as I get home from work. It will be out sometime this evening after 6:00 CDT.
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Quoting Camille33:

Not really defying odds,I posted an intensity forecast last night,matches up fairly well.

You did? Can you repost it? Since Chantal is at 45 MPH now, I'd like to see how an intensity forecast for what hasn't happened already matches up to any other intensity forecast that hasn't happened.
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Quoting 653. wunderkidcayman:
anyone got recon data yet are they off the tarmac yet

Datanerd is the one to post all of the HH data. Was just going to ask if he was here and he started posting :)
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Quoting 650. DataNerd:
The navy solution is very interesting:



Should not be forgotten here we still have reputable southern outliers.


Chantal is going to be tough to track, I want to restate that. I think we will see quite a bit of shifitng of the consensus, so everyone needs to keep an eye on this especially those of you in Florida.

"NAVGEM" and "reputable" probably don't belong in the same category.
Member Since: July 6, 2010 Posts: 113 Comments: 31439
This is a very interesting link from the Barbados weather page, I'm assuming this is satellite estimated radar imagery, but you can see Chantal at the right. Pretty cool!

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Quoting 640. MechEngMet:


Yes I saw your post too late. The original question prefaced it getting into the gulf. I know it's little chance of doing anything at all where it is now. But the poster of the original question asked what about when it got to the GOM. (I must add "IF" it gets there...)

I am fully aware it is rare for ULLs to make it all the way down and form a warm core. ...but it has happened before. And this one seems like it is already trying to do so.

The last week of rain has significantly cooled the gulf waters on the East side. That could be considered somewhat of a hindrance (if it gets there).



G'afternoon.

The forecast of the ULL in the Bahamas was also addressed in the 11am discussion for Chantal by NHC.

A VIGOROUS MID-/UPPER-LEVEL LOW CURRENTLY JUST EAST OF
THE BAHAMAS IS EXPECTED TO MOVE WESTWARD AND MERGE WITH A
MID-LATITUDE TROUGH...CREATING A BREAK IN THE SUBTROPICAL RIDGE
OVER THE SOUTHEASTERN U.S. AND THE BAHAMAS

So, this is what will pull Chantel to the North and, eventually - after the ridge builds back in - to the N/NW.
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Good (insert word relevant to your time zone) everyone! I was curious if anyone had an idea of when the HH may be heading out? I enjoy tracking them on google Earth! Thank you!
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anyone got recon data yet are they off the tarmac yet
Member Since: June 13, 2009 Posts: 2 Comments: 10999
TS Chantal

RGB Loop

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Quoting 645. sar2401:

As ususal, links to current forecast discussion don't work. I don't know what the deal is with the NHC website in this regard.


000
WTNT43 KNHC 081501
TCDAT3

TROPICAL STORM CHANTAL DISCUSSION NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL AL032013
1100 AM AST MON JUL 08 2013

CONVECTIVE ORGANIZATION OF HAS IMPROVED SLIGHTLY IN SATELLITE
IMAGERY SINCE THE PREVIOUS ADVISORY WITH FRAGMENTED CURVED BANDS
DEVELOPING IN THE NORTHERN SEMICIRCLE...ALTHOUGH THE CORE
CONVECTION HAS WEAKENED SOME. THE INITIAL INTENSITY OF 40 KT IS
BASED ON A BLEND OF TAFB...SAB...ADT...AND AMSU SATELLITE INTENSITY
ESTIMATES. VISIBLE AND WATER VAPOR IMAGERY ALSO INDICATE THAT
CHANTAL HAS DEVELOPED SOME WEAK ANTICYCLONIC OUTFLOW.

THE INITIAL MOTION ESTIMATE REMAINS A RATHER BRISK 280/23 KT. NO
CHANGES WERE MADE TO THE PREVIOUS FORECAST TRACK. CHANTAL IS
FORECAST TO MOVE QUICKLY WEST-NORTHWESTWARD TO THE SOUTH OF A
STRONG DEEP-LAYER SUBTROPICAL RIDGE FOR THE NEXT 48 HOURS. BY DAY 3
AND BEYOND...A VIGOROUS MID-/UPPER-LEVEL LOW CURRENTLY JUST EAST OF
THE BAHAMAS IS EXPECTED TO MOVE WESTWARD AND MERGE WITH A
MID-LATITUDE TROUGH...CREATING A BREAK IN THE SUBTROPICAL RIDGE
OVER THE SOUTHEASTERN U.S. AND THE BAHAMAS. CHANTAL IS FORECAST TO
SLOW DOWN AND TURN NORTHWESTWARD BY 72 HOURS AS IT APPROACHES THIS
DEVELOPING WEAKNESS IN THE RIDGE...AND THEN MOVE SLOWLY
NORTH-NORTHWESTWARD THROUGH THE WEAKNESS ON DAYS 4 AND 5. THE
OFFICIAL FORECAST TRACK IS A LITTLE TO THE LEFT OF THE MODEL
CONSENSUS AND LIES ALONG THE SOUTHERN EDGE OF THE GUIDANCE
ENVELOPE...CLOSE TO THE GFS AND FSSE MODELS.

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. INTERACTION WITH
THE MOUNTAINOUS TERRAIN OF HISPANIOLA AND EASTERN CUBA IN ABOUT
THREE DAYS...COUPLED WITH INCREASING WESTERLY VERTICAL WIND
SHEAR...IS EXPECTED TO CAUSED TO CHANTAL TO WEAKEN CONSIDERABLY BY
DAY 3...AND CONTINUE INTO DAYS 4 AND 5 AS THE CYCLONE MOVES
UNDERNEATH AN UPPER-LEVEL TROUGH. THE OFFICIAL INTENSITY FORECAST
FOLLOWS THE ICON INTENSITY CONSENSUS MODEL AND THE FSSE MODEL.

FORECAST POSITIONS AND MAX WINDS

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
Member Since: August 1, 2011 Posts: 28 Comments: 7897
The navy solution is very interesting:



Should not be forgotten here we still have reputable southern outliers.


Chantal is going to be tough to track, I want to restate that. I think we will see quite a bit of shifitng of the consensus, so everyone needs to keep an eye on this especially those of you in Florida.
Member Since: June 24, 2012 Posts: 0 Comments: 1534
Quoting 640. MechEngMet:


Yes I saw your post too late. The original question prefaced it getting into the gulf. I know it's little chance of doing anything at all where it is now. But the poster of the original question asked what about when it got to the GOM. (I must add "IF" it gets there...)

I am fully aware it is rare for ULLs to make it all the way down and form a warm core. ...but it has happened before. And this one seems like it is already trying to do so.

The last week of rain has significantly cooled the gulf waters on the East side. That could be considered somewhat of a hindrance (if it gets there).




Agreed. I've been suspect of it reaching the surface myself, and have been watching surface vorticity for the last three or four days - nothing has changed, although it does look to have good vorticity at the mid-levels and has been. It's also in an area of fairly dry air as well. At best, right now I think, it'll help to moisten the atmosphere for Chantal, and if it retrogrades westwards ahead of the storm, it may help to pull/tug the storm along behind it as well as help ventilate it. :)
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Still the same 45 mph
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Quoting 629. Tribucanes:
Skyepony said two days ago the ULL in question would cross Florida and have a chance to develop in the Gulf before ending up near the Louisiana coast. Would be a rare sight, but this a good looking ULL. Would be amazing, and as this is shaping up to be an amazing season; it'll probably happen.


Well I think that covers the question in post #601.
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If Chantel gets a little stronger, with higher cloud tops, the ULL east of FL could be a factor in her track.

She could be dragged towards the ULL forcing a more southerly track. Perhaps?
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Quoting BaltimoreBrian:
NHC 2 p.m. advisory on Chantal.

As ususal, links to current forecast discussion don't work. I don't know what the deal is with the NHC website in this regard.
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Miami
NEXRAD Radar

Velocity Azimuth Display Wind Profile ° Elevation
Range 124 NMI

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000
WTNT33 KNHC 081756
TCPAT3

BULLETIN
TROPICAL STORM CHANTAL INTERMEDIATE ADVISORY NUMBER 3A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL032013
200 PM AST MON JUL 08 2013

...RECONNAISSANCE AIRCRAFT ABOUT TO HEAD TOWARD CHANTAL...


SUMMARY OF 200 PM AST...1800 UTC...INFORMATION
----------------------------------------------
LOCATION...11.3N 52.8W
ABOUT 470 MI...760 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


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* BARBADOS
* DOMINICA
* SAINT LUCIA
* MARTINIQUE
* GUADELOUPE

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* SAINT VINCENT
* PUERTO RICO...INCLUDING VIEQUES AND CULEBRA

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA...IN THIS CASE WITHIN
24 TO 36 HOURS.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE SOMEWHERE IN THE WATCH AREA...USUALLY WITHIN 48 HOURS.

INTERESTS IN HAITI...THE DOMINICAN REPUBLIC...AND EASTERN
CUBA SHOULD MONITOR THE PROGRESS OF CHANTAL.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA WITHIN THE UNITED
STATES...PLEASE CONSULT PRODUCTS ISSUED BY YOUR LOCAL NATIONAL
WEATHER SERVICE FORECAST OFFICE. FOR INFORMATION SPECIFIC TO YOUR
AREA OUTSIDE OF THE UNITED STATES...PLEASE MONITOR PRODUCTS ISSUED
BY YOUR NATIONAL METEOROLOGICAL SERVICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 200 PM AST...1800 UTC...THE CENTER OF TROPICAL STORM CHANTAL WAS
LOCATED NEAR LATITUDE 11.3 NORTH...LONGITUDE 52.8 WEST. CHANTAL IS
MOVING TOWARD THE WEST-NORTHWEST NEAR 25 MPH...41 KM/H...AND A WEST-
NORTHWESTWARD MOTION AT ABOUT THE SAME FORWARD SPEED IS EXPECTED
OVER THE NEXT COUPLE OF DAYS. ON THE FORECAST TRACK...THE CENTER
OF CHANTAL SHOULD REACH THE LESSER ANTILLES EARLY TUESDAY...AND MOVE
INTO THE EASTERN CARIBBEAN SEA LATER ON TUESDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 45 MPH...75 KM/H...WITH HIGHER
GUSTS. SOME STRENGTHENING IS FORECAST DURING THE NEXT 48
HOURS.

TROPICAL-STORM-FORCE WINDS EXTEND OUTWARD UP TO 60 MILES...95 KM
FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB...29.68 INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...TROPICAL STORM CONDITIONS ARE EXPECTED WITHIN THE WARNING
AREA BY EARLY TUESDAY. TROPICAL STORM CONDITIONS ARE POSSIBLE IN
THE LESSER ANTILLES WATCH AREA BY EARLY TUESDAY...AND ACROSS PUERTO
RICO BY WEDNESDAY.

STORM SURGE...A STORM SURGE WILL RAISE WATER LEVELS BY AS MUCH AS
1 TO 3 FEET ABOVE NORMAL TIDE LEVELS IN THE LEEWARD ISLANDS...
WINDWARD ISLANDS...AND PUERTO RICO. NEAR THE COAST...THE SURGE
WILL BE ACCOMPANIED BY DANGEROUS WAVES.

RAINFALL...CHANTAL IS EXPECTED TO PRODUCE RAIN ACCUMULATIONS OF
2 TO 4 INCHES OVER THE LEEWARD AND WINDWARD ISLANDS...WITH MAXIMUM
AMOUNTS OF 6 INCHES POSSIBLE.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...500 PM AST.

$$
FORECASTER STEWART

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Quoting 637. TylerStanfield:

Where the heck do you get that the GFS shows 2 named storms in 160 hours. The only storm shown over the next 240 hours is the EATL Cape Verde storm. The GFS hinted at another wave passed 300+ Hours but that means nothing at this time.


I should clarify. I said one if not two, and not named necessarily.

It shows one for sure at 168 hours and a very vigorous wave behind that off the coast of Africa in the same time frame. So IF the second one developed would be a TD within this forecast period nothing stronger most likely.


That is why I said one IF NOT two.
Member Since: June 24, 2012 Posts: 0 Comments: 1534
Miami
NEXRAD Radar

Base Reflectivity 0.50° Elevation
Range 248 NMI

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Quoting 622. moonlightcowboy:


Mech, see post #610. I know, the blog is going by so fast it's difficult to keep up. :)


Yes I saw your post too late. The original question prefaced it getting into the gulf. I know it's little chance of doing anything at all where it is now. But the poster of the original question asked what about when it got to the GOM. (I must add "IF" it gets there...)

I am fully aware it is rare for ULLs to make it all the way down and form a warm core. ...but it has happened before. And this one seems like it is already trying to do so.

The last week of rain has significantly cooled the gulf waters on the East side. That could be considered somewhat of a hindrance (if it gets there).

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Quoting 627. MississippiWx:
Chantal is quickly gaining cloud cover in her NE quadrant, an area that has been mainly void of clouds throughout her lifetime. You can even see the hint of convective bands beginning to form there as well. Chantal is defying all odds and if this pace keeps up, a minimal hurricane is not too far fetched. She will be very susceptible to small changes in the environment, however, thanks to her rapid pace. We will just have to see what happens. Chantal is making a believer out of all of us, though.


Not really defying odds,I posted an intensity forecast last night,matches up fairly well.
Member Since: July 2, 2013 Posts: 0 Comments: 1356
GFS solution actually seems the most likely to me right now.

Chantal continues a bit further west for a bit longer, before making the jog NW by WNW instead of pure WNW, and then becomes stalled.

I think this is more likely because the trough that is supposed to weaken the bermuda high late in the period will probably not be strong enough to fully encroach, so its likely chantal might drift for a day before being forced un-climatologically southwest across florida and into the GOM.

Such a scenario has its faults, but GFS seems to have had a relatively good handle on things so far this season, and on this system, so for now I will stand by it.


GFS at 168hrs showing chantal in the GOM heading W by WSW with a new storm in the CATL:

Member Since: June 24, 2012 Posts: 0 Comments: 1534
Quoting 623. DataNerd:
Morning all.

Great post by Dr. Masters and it really goes to heart of the situation we find ourselves in folks.

Our third storm is here and its only the 8th! Not a good sign at all. Whether this ultimately proves ill remains to be seen of course, but with GFS forecasting at least one if not two new additional storms in the next 160 hrs its fair to say we are in for it.

Whats even more disconcerting is the very odd ridging scenario in play over the U.S. and particularly the unusually strong Bermuda high this year, following on the back of a very strange winter which lasted longer than normal, only to be followed by consistent days of record temperatures worldwide.

Even more telling is that while active, the EPAC should have gone a bit faster if we were looking at an average season ahead, and it hasn't. Tells me that more energy is staying on the Atlantic side.


All in all chantal is also going to be a slippery fish to track, right now we have some model consensus, but the steering situation governing this storm is very dynamic as proven by early runs prior to classification. Data from this afternoons recon should provide the model runs later tonight with more accuracy, and I expect a westward or southward shift of the consensus.

Needless to say, the chances of chantal making it intact to the GOM, are low given the sheer present due to the earliness of the season.

One thing that is certainly noticeable is that chantal is improving its convective appearance, evident on RGB loops and in the latest forecast discussion.


Where the heck do you get that the GFS shows 2 named storms in 160 hours. The only storm shown over the next 240 hours is the EATL Cape Verde storm. The GFS hinted at another wave passed 300+ Hours but that means nothing at this time.
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Quoting 630. hericane96:
Can an ULL venilate a TC??? Like right now theres an ULL in the bahamas, what if Chantal was able to catch up and be in range to benfit from it. Is that a possibility or will the ULL be long gone. Does this even make since? LOL..



The answer is yes, it can help to serve ventilation, but not if it gets too close where it would act to shear the upper level moisture tops, the CDO from the system.
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Quoting moonlightcowboy:


ULL's rarely make it to the surface. They do, but it's not a common occurrence. To answer your question directly though, a storm must have fuel and that comes from the warm waters at the surface.

And, in this case, the ULL is also in a dry-air environment.

Isn't this ULL also cold-cored? It would need a suface circulation, cross Florida, and get into the Gulf with enough energy left to intensify. With this season so far, I guess it's not impossible, but the odds don't favor it. If Chantal actually makes it to and survives Cuba, then this may be a different matter.
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TS Chantal

Rainbow Loop

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Quoting 628. SFLWeatherman:
Models do not have it going down to TD they have it at TS


The new ships model is projecting a cat 1 hurricane for the east coast of FL. Very interesting days ahead.
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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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