Extratropical Storm Chantal: last CHC advisory issued

[CrazyC83]

Maybe if it was a threat to Canada (if might knick Newfoundland) but otherwise the hunters don't feel like flying into it I guess.

I believe Environment Canada has acquired a similar aircraft and may take flights in as it gets closer...

[MiamiensisWx]

Chantal's window of opportunity may close within 12 hours. Recent structural trends indicate Chantal is transitioning to a frontal ET low - look here. The convection is anemic and a distinct sfc frontal signature has been forming over the past few hours. Winds should decrease soon - I would not expect more advisories from the TPC as the trend continues. It should encounter colder oceanic heat content and merge with the trough over Nova Scotia.

[HURAKAN]

This storm only liked the overnight hours and morning hours. Now the center becoming exposed.

[Brent]

This storm only liked the overnight hours and morning hours. Now the center becoming exposed.

A BEAUTIFUL swirl.

[AnnularCane]

A BEAUTIFUL swirl.

Good, I'm not the only one who thinks so.

What's the matter, Chantal? Are afternoons too sunny for you?

[RL3AO]

Water is probably getting pretty cold and the sun is giving her a headache.

[Cyclone1]

This looks almost exactly like the noname last year.

[RL3AO]

It had some impressive strengthening this morning and puts 99L to shame.

[AnnularCane]

Water is probably getting pretty cold and the sun is giving her a headache.

They need to send the hurricane hunters out there to drop a couple of aspirins into her.

[CrazyC83]

WOCN31 CWHX 311800
TROPICAL STORM CHANTAL INFORMATION STATEMENT ISSUED BY THE
CANADIAN HURRICANE CENTRE OF ENVIRONMENT CANADA AT 3.30 PM NDT
TUESDAY 31 JULY 2007.

THE NEXT STATEMENT WILL BE ISSUED BY 9.30 PM NDT

... HEAVY RAIN FROM CHANTAL EXPECTED FOR NEWFOUNDLAND...

1. CURRENT POSITION, STRENGTH, CENTRAL PRESSURE AND MOTION

AT 3.30 PM NDT... TROPICAL STORM CHANTAL WAS LOCATED NEAR
LATITUDE 40.9 N AND LONGITUDE 61.8 W... ABOUT 195 NAUTICAL MILES
OR 365 KM SOUTH SOUTHWEST OF SABLE ISLAND . MAXIMUM SUSTAINED
WINDS ARE ESTIMATED AT 45 KNOTS... 83 KM/H... AND CENTRAL PRESSURE
AT 999 MB. CHANTAL IS MOVING NORTHEAST AT 26 KNOTS... 48 KM/H.

2. FORECAST POSITION, CENTRAL PRESSURE AND STRENGTH

DATE TIME LAT LON MSLP MAX WIND
NDT MB KTS KMH
JUL 31 3.30 PM 40.9N 61.8W 999 45 83
JUL 31 9.30 PM 43.0N 59.7W 998 45 83
AUG 01 3.30 AM 44.8N 56.4W 997 45 83 POST-TROPICAL
AUG 01 9.30 AM 46.9N 52.7W 997 45 83 POST-TROPICAL
AUG 01 3.30 PM 49.3N 48.6W 996 45 83 POST-TROPICAL
AUG 01 9.30 PM 51.2N 44.8W 995 50 93 POST-TROPICAL
AUG 02 3.30 AM 53.6N 40.5W 995 50 93 POST-TROPICAL

3. PUBLIC WEATHER IMPACTS AND WARNINGS SUMMARY
HEAVY RAINFALL WARNINGS HAVE BEEN ISSUED BY THE NEWFOUNDLAND
LABRADOR WEATHER OFFICE - NLWO -FOR PORTIONS OF SOUTHEASTERN
NEWFOUNDLAND.

4. MARINE WEATHER IMPACTS AND WARNINGS SUMMARY
THE ATLANTIC STORM PREDICTION CENTRE IS MAINTAINING GALE WARNINGS FOR
SOUTHEASTERN MARITIME WATERS AND EASTERN NEWFOUNDLAND WATERS
INCLUDING FUNK ISLAND BANK.

5. TECHNICAL DISCUSSION

A. ANALYSIS
GOOD POSITIONAL FIX FROM VISIBLE SATELLITE IMAGERY. WE INITIALIZE
CHANTAL AT 45 KNOTS IN ACCORD WITH THE NHC 15Z BULLETIN AND THE EARLY
MORNING QUIKSCAT PASS. THE LOW LEVEL CIRCULATION CENTRE HAS MOVED
OUT FROM UNDER THE UPPER CONVECTIVE SHIELD. THE UPPER LEVEL
CIRCULATION IS SOMEWHAT MISLEADING REGARDING MOTION BUT THE HALIFAX
RADAR SHOWS NO NORTHWARD MOTION AT ALL ON ECHOES TO THE SOUTH.

B. PROGNOSTIC
CHANTAL SHOULD SOON BE MOVING OVER COOLER WATERS AND HENCE BEGIN
WEAKENING TROPICALLY. ALTHOUGH BAROCLINIC FORCING WILL INCREASE
OVER THE NEXT 24 HOURS WHILE MAINTAINING STRONG CONTRIBUTIONS FROM
LATENT HEAT RELEASE AND THE GLOBAL MODELS DEVELOP CHANTAL INTO A
POWERFUL NORTH ATLANTIC STORM EAST OF NEWFOUNDLAND AND LABRADOR
WATERS.

AT FORECAST TIME WE HAVE ONLY SEEN THE CANADIAN GEM THE UKMET AND
THE GFDL. ALL WITH SIMILAR TRACKS BUT THE DIFFERENCES WILL BE
IMPORTANT FOR NEWFOUNDLAND. THE GEM AND UKMET TAKE THE STORM CENTRE
SOUTH OF THE AVALON WHEREAS THE GFDL TAKES IT THROUGH THE AVALON AND
A BIT SLOWER. THE VARIETY OF SOLUTIONS HAVE NOT CONVINCED US TO
WAVER FROM OUR PREVIOUS THINKING.

C. PUBLIC WEATHER
AS WITH THE 00Z GEM RUN THE 12Z PACKAGE 48 HOUR QPF ACCUMULATION
OVER THE AVALON REMAINS WELL IN EXCESS OF 100...WITH A MAX OF 157.
THE PREVIOUS PACKAGE HAD A MAX OF 189. WE BELIEVE THESE NUMBERS TO
BE IN LINE WITH THE GEM MASS FIELD INTENSIFICATION...OVER THE TOP...
HOWEVER THEY DO PROVIDE A CAUTIONARY NOTE THAT HIGH AMOUNTS ARE
POSSIBLE. WE REMAIN CONCERNED ABOUT THE LINGERING MOISTURE BAND WHICH
HAS REMAINED ALIGNED OVER THE BURIN PENINSULA ALL DAY AND WITH THE
MOISTURE FRM CHANTAL FEEDING IN RIGHT BEHIND THERE MAY BE NO
DISCERNIBLE BREAK BETWEEN THEM. ACCORDINGLY THE RAINFALL WARNINGS
ARE DEFINITELY JUSTIFIED.

GALES ARE POSSIBLE TO THE NORTHWEST OF THE SYSTEM AS IT PASSES
NEWFOUNDLAND AND WITH THIS TRACK PACKAGE THE AVALON COULD SEE
MARGINAL COASTAL GALES. AFTER DISCUSSION WITH THE NLWO WE ARE HOLDING
OFF ON ISSUING A TROPICAL STORM WATCH FOR TWO REASONS... WE EXPECT
THE SYSTEM TO BE MORE BAROCLINIC THAN NOT BY TOMORROW MORNING... AND
GALES IN THE NORTHWEST QUADRANT ARE LESS LIKELY. BUT WE WILL WATCH
THIS CLOSELY. STILL IF THE GFDL SOLUTION PANS OUT THEN THE AVALON
COULD BE IN FOR A WINDY MORNING TOMORROW.

D. MARINE WEATHER
THE GALE RADII WILL BECOME LESS MEANINGFUL AS CHANTAL UNDERGOES AND
THEN COMPLETES EXTRATROPICAL TRANSITION AND THE STORM BECOMES
ENTRAINED IN THE ENVIRONMENT.

PREDICTED WIND RADII (NM)
TIME GALES STORMS HURRICANE
NE SE SW NW NE SE SW NW NE SE SW NW
31/18Z 100 150 30 100 0 0 0 0 0 0 0 0
01/00Z 120 180 30 60 0 0 0 0 0 0 0 0
01/06Z 140 210 60 60 0 0 0 0 0 0 0 0
01/12Z 160 210 100 60 0 0 0 0 0 0 0 0
01/18Z 180 230 150 60 0 0 0 0 0 0 0 0
02/00Z 200 250 150 100 0 100 0 0 0 0 0 0
02/06Z 220 250 150 120 0 100 0 0 0 0 0 0

END PJB
_______________________________________________
http://www.atl.ec.gc.ca/weather/hurrica ... oin_e.html

[MiamiensisWx]

000
WTNT43 KNHC 312030
TCDAT3
TROPICAL STORM CHANTAL DISCUSSION NUMBER 4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032007
500 PM EDT TUE JUL 31 2007

CHANTAL IS MAINTAINING A CURVED BAND STRUCTURE ON VISIBLE SATELLITE
PICTURES...ALBEIT WITH LESS DEEP CONVECTION THAN EARLIER TODAY.
THE STORM SHOULD SOON BEGIN THE EXTRATROPICAL TRANSITION PROCESS AS
SEA SURFACE TEMPERATURES BENEATH THE STORM SOON DECREASE BELOW 70F
AND IT INTERACTS WITH COOLER AIR OVER THE CANADIAN MARITIMES.
SATELLITE CLASSIFICATIONS AND AMSU INTENSITY ESTIMATES SUPPORT
MAINTAINING THE INITIAL INTENSITY OF 45 KT. COMPUTER
MODELS...ESPECIALLY THE GFS...FORECAST THE SYSTEM TO BECOME A
STRONG EXTRATROPICAL STORM IN ABOUT 3 DAYS AND A LITTLE
STRENGTHENING IS INDICATED AT THAT TIME.

CHANTAL CONTINUES TO MOVE NORTHEASTWARD...WITH A 12 HOUR MOTION OF
ABOUT 23 KT. A DEEPENING MIDDLE-LATITUDE STORM OVER EASTERN CANADA
SHOULD CONTINUE THE STORM'S MOTION TOWARD THE NORTHEAST WITH SOME
ACCELERATION. MODEL GUIDANCE IS TIGHTLY CLUSTERED ON A TRACK
TAKING THE SYSTEM NEAR OR OVER THE AVALON PENINSULA OF NEWFOUNDLAND
AND THE OFFICIAL FORECAST REFLECT THIS SCENARIO.


FORECAST POSITIONS AND MAX WINDS

INITIAL 31/2100Z 41.7N 61.2W 45 KT
12HR VT 01/0600Z 44.5N 57.3W 45 KT...BECOMING EXTRATROPICAL
24HR VT 01/1800Z 48.6N 49.7W 45 KT...EXTRATROPICAL
36HR VT 02/0600Z 53.5N 40.5W 45 KT...EXTRATROPICAL
48HR VT 02/1800Z 57.0N 34.5W 45 KT...EXTRATROPICAL
72HR VT 03/1800Z 60.0N 27.5W 50 KT...EXTRATROPICAL
96HR VT 04/1800Z 62.0N 19.0W 40 KT...EXTRATROPICAL
120HR VT 05/1800Z 64.0N 12.0W 35 KT...EXTRATROPICAL

$$
FORECASTER BLAKE

[MiamiensisWx]

000
WTNT33 KNHC 312031
TCPAT3
BULLETIN
TROPICAL STORM CHANTAL ADVISORY NUMBER 4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032007
500 PM EDT TUE JUL 31 2007

...CHANTAL EXPECTED TO LOSE TROPICAL CHARACTERISTICS...

AT 500 PM EDT...2100Z...THE CENTER OF TROPICAL STORM CHANTAL WAS
LOCATED NEAR LATITUDE 41.7 NORTH...LONGITUDE 61.2 WEST OR ABOUT 235
MILES...375 KM...SOUTH-SOUTHEAST OF HALIFAX NOVA SCOTIA AND ABOUT
530 MILES...850 KM...SOUTHWEST OF CAPE RACE NEWFOUNDLAND.

CHANTAL IS MOVING TOWARD THE NORTHEAST NEAR 26 MPH...43 KM/HR...AND
THIS MOTION IS EXPECTED TO CONTINUE WITH SOME INCREASE IN FORWARD
SPEED TONIGHT AND WEDNESDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 50 MPH...85 KM/HR...WITH HIGHER
GUSTS. LITTLE CHANGE IN STRENGTH IS FORECAST DURING THE NEXT 24
HOURS AND CHANTAL COULD LOSE TROPICAL CHARACTERISTICS TONIGHT OR ON
WEDNESDAY.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 200 MILES...325 KM
FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 999 MB...29.50 INCHES.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR LOCAL WEATHER OFFICE.

REPEATING THE 500 PM EDT POSITION...41.7 N...61.2 W. MOVEMENT
TOWARD...NORTHEAST NEAR 26 MPH. MAXIMUM SUSTAINED WINDS...50 MPH.
MINIMUM CENTRAL PRESSURE...999 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
1100 PM EDT.

$$
FORECASTER BLAKE

[Brent]

Got about 12 hours left, it was nice knowing you.

[sunnyday]

Isn't this unusual for a storm to form there?

[AnnularCane]

This is my first attempt at posting an image, so I hope it works out and it's not too big.



Isn't she pretty? It probably doesn't mean much of anything, but she seems to have developed a little flareup around her center.

I hope our little Chantal won't be TOO quick to leave.

[RL3AO]

This is going to be a nasty little extra-tropical storm.

[HURAKAN]

Chantal, my lobbying for you paid off but now your time is about to end.

[JonathanBelles]

Nice Pic!!

[Andrew92]

Isn't this unusual for a storm to form there?

I would say the answer is probably yes AND no. It's a tough question to answer from an amateur's point of view, and maybe a pro can shed some more light on it. However, I do know a little bit about this that I will give it a shot.

As you probably know, most tropical storms and hurricanes develop from tropical waves coming off of Africa. For obvious reasons, these storms tend to develop in lower latitudes, south of the Tropic of Cancer.

Although less common, sometimes a front can leave behind a low-pressure entity that swirls around and gradually becomes warm-core, or tropical. This allows these entities to become tropical storms, usually north of the Tropic of Cancer.

That said, frontal lows transitioning into tropical storms are somewhat more prevalent in El Nino years. I believe this is because conditions are typically unfavorable in the Mean Development Region, the Caribbean, and the GOM during an El Nino. This, of course, means that tropical waves have a much harder time developing. However, frontal lows usually have an easier time because they are further away from the unfavorable conditions.

But in a neutral or La Nina year, favorable conditions are usually prevalent around the peak of hurricane season (it is NOT the peak right now, that is still a few weeks away). This allows tropical waves to develop more frequently (though of course not every even healthy-looking wave will develop).

However, many neutral or Nina years DO see some tropical activity arise from frontal lows. It has even happened in years such as 1995, 2004 (although that turned Nino in October, but I have more on that year in a bit), and 2005.

I did say that 04 turned Nino in October, but even then there were a couple storms that developed from frontal lows before then. Gaston and Hermine did so, and Alex had a rather complicated setup involving partly a frontal low and partly a tropical wave.

In short, where Chantal developed IS rather unusual for a storm to develop. But these storms DO happen, even in neutral or Nina years. Now maybe a pro can shed some more light on the "why's" of this, but that's all I have to offer on this subject.

Very good question!

-Andrew92

[Andrew92]

OH! And one last thing.....

I think a development like Chantal will be LESS likely this year. I'm not forgetting that Andrea also developed from a rather strong non-tropical entity when I say this. However, don't forget that even though Barry looked a little subtropical, his precursor was a tropical wave. And the Atlantic is slowly getting more favorable out there.

I hazard a guess that Dean will form from a tropical wave.

-Andrew92