ATL: CHANTAL - Post-Tropical

[Miami Storm Tracker]

Look at that contorted spaghetti lookin' mess after 70 w... what in the world?


[]http://i44.tinypic.com/33jqqev.jpg[/img]

Looking at those ensembles I see a system getting trapped under a developing Bermuda High at the end forcing a west or southwest turn, which is in line with how things have looked this year. This is a different pattern than years past. We may unfortunately see a lot of this coming up.

Is this what happened to Betsy in '65?

Betsy was late august, I don't see this getting that far north due to the strong high keeping the flow east to west, at least until it nears S. Fla.
This is only my opinion and not based on any real data, anything is possible in the tropics.

[CrazyC83]

one system last season take same track want by eastern cuba got weaker

That was Isaac last year.

[jinftl]

Best shot of reaching 'cane status is in 48 hours...and then it is only currently given a 27% chance for that.

[Bocadude85]

I wonder why they weaken the system on day 5? I understand land interaction will be a major problem but they do show Chantal emerging Cuba as a tropical storm.

[wxman57]

Lots of uncertainty. I think increased wind shear, dry air and increased low-level trades in the eastern Caribbean will weaken it there - even before it reaches any significant land. Should it survive past the DR then I think conditions may be good north of Cuba. I don't believe the HWRF and GFDL as far as I can throw them. They've been pretty bad of late. Look for a recurve around 75W. I think NHC's track looks good, as I said. Just question intensity forecast next few days.

I'd certainly make sure all my supplies were in order if I lived in Florida or north through the Carolinas.

[meriland23]

I never trust the NHC forecast this far out... they tend to be pretty far off more often than not, but that is just me. I will be interested in seeing what GFS and EURO expects..

[floridasun78]

Isaac was fast mover too

[TheStormExpert]

Like I mentioned before, this situation is definitely very similar to about identical to TS Emily from 2011. It's moving very fast, and has basically an almost identical track to Emily. Emily also experienced it's circulation outrunning the convection due to it's fast movement. I'm not concerned about Chantal until it gets due south of Hispaniola and still looks like it can survive the journey across Cuba and some of Hispaniola, than I will start to watch it more closely.

[gatorcane]

000
WTNT43 KNHC 080317
TCDAT3

TROPICAL STORM CHANTAL DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL032013
1100 PM EDT SUN JUL 07 2013

CONVENTIONAL AND MICROWAVE SATELLITE IMAGES SHOW THAT DEEP
CONVECTION ASSOCIATED WITH THE STRONG TROPICAL WAVE OVER THE
CENTRAL TROPICAL ATLANTIC HAS INCREASED IN ORGANIZATION SINCE THIS
AFTERNOON. A RECENT ASCAT PASS INDICATED THAT THE CIRCULATION HAD
BECOME BETTER DEFINED SINCE THIS MORNING....WITH SEVERAL
UNCONTAMINATED 35-KT WIND VECTORS OVER THE EASTERN PORTION OF THE
CIRCULATION. BASED ON THE ASCAT AND AFOREMENTIONED SATELLITE
DATA...THE SYSTEM IS UPGRADED TO A 35-KT TROPICAL STORM.

THE INITIAL MOTION ESTIMATE IS 275/23. A STRONG SUBTROPICAL HIGH
OVER THE CENTRAL ATLANTIC IS EXPECTED TO STEER CHANTAL ON A
WESTWARD AND THEN WEST-NORTHWESTWARD TRACK FOR THE NEXT FEW DAYS
WITH LITTLE DECREASE IN FORWARD SPEED. A SECOND SUBTROPICAL RIDGE
OVER THE WESTERN ATLANTIC SHOULD KEEP CHANTAL ON THE SAME HEADING
UNTIL A WEAKNESS BEGINS TO DEVELOP OVER EASTERN NORTH AMERICA LATE
IN THE PERIOD. AS A RESULT...THE TRACK OF CHANTAL SHOULD BEND MORE
NORTHWESTWARD AND THEN POSSIBLY NORTHWARD AND DECELERATE BY DAYS 4
AND 5. THE TRACK GUIDANCE IS IN GOOD AGREEMENT ON THIS SCENARIO
THROUGH 48 TO 72 HOURS BUT THEN BEGINS TO DIVERGE AFTER THAT TIME.
THE OFFICIAL NHC TRACK FORECAST IS CLOSE TO THE MULTI-MODEL
CONSENSUS THROUGHOUT THE FORECAST PERIOD.

FAVORABLE ENVIRONMENTAL CONDITIONS AND WARM SEA SURFACE TEMPERATURES
SHOULD ALLOW CHANTAL TO INTENSIFY SOME DURING THE NEXT FEW DAYS.
THE POSSIBILITY OF LAND INTERACTION WITH HISPANIOLA AND CUBA IN
ABOUT 72-96 HOURS COMPLICATES THE INTENSITY FORECAST BUT IS LIKELY
TO RESULT IN WEAKENING...ESPECIALLY SINCE UPPER-LEVEL WESTERLY FLOW
IS FORECAST TO BEGIN TO AFFECT CHANTAL BY THAT TIME. THIS
INCREASING WESTERLY FLOW AND LAND INTERACTION COULD EVEN CAUSE
CHANTAL TO BECOME A REMNANT LOW OR DISSIPATE LATE IN THE FORECAST
PERIOD. THE NHC INTENSITY FORECAST IS A BLEND OF THE SHIPS/LGEM
GUIDANCE AS WELL AS THE INTENSITY CONSENSUS AIDS.


FORECAST POSITIONS AND MAX WINDS

INIT 08/0300Z 9.8N 47.2W 35 KT 40 MPH
12H 08/1200Z 10.8N 50.8W 40 KT 45 MPH
24H 09/0000Z 12.1N 55.7W 45 KT 50 MPH
36H 09/1200Z 13.9N 60.5W 50 KT 60 MPH
48H 10/0000Z 15.6N 65.1W 55 KT 65 MPH
72H 11/0000Z 18.4N 73.6W 45 KT 50 MPH
96H 12/0000Z 22.0N 77.0W 35 KT 40 MPH
120H 13/0000Z 25.0N 78.0W 30 KT 35 MPH

$$
FORECASTER KIMBERLAIN/BROWN

[gatorcane]

First NHC discussion is out calling for possible dissipation of Chantal late in the forecast period due to strong westerly shear and land interaction.

[floridasun78]

48H 10/0000Z 15.6N 65.1W 55 KT 65 MPH it look strongest will be

[AdamFirst]

I wonder why they weaken the system on day 5? I understand land interaction will be a major problem but they do show Chantal emerging Cuba as a tropical storm.

NHC discussion mentions that upper-level winds may be unfavorable for further development - the intensity forecast is highly dependent on land interaction with Hispaniola and Cuba

FAVORABLE ENVIRONMENTAL CONDITIONS AND WARM SEA SURFACE TEMPERATURES
SHOULD ALLOW CHANTAL TO INTENSIFY SOME DURING THE NEXT FEW DAYS.
THE POSSIBILITY OF LAND INTERACTION WITH HISPANIOLA AND CUBA IN
ABOUT 72-96 HOURS COMPLICATES THE INTENSITY FORECAST BUT IS LIKELY
TO RESULT IN WEAKENING...ESPECIALLY SINCE UPPER-LEVEL WESTERLY FLOW
IS FORECAST TO BEGIN TO AFFECT CHANTAL BY THAT TIME. THIS
INCREASING WESTERLY FLOW AND LAND INTERACTION COULD EVEN CAUSE
CHANTAL TO BECOME A REMNANT LOW OR DISSIPATE LATE IN THE FORECAST
PERIOD. THE NHC INTENSITY FORECAST IS A BLEND OF THE SHIPS/LGEM
GUIDANCE AS WELL AS THE INTENSITY CONSENSUS AIDS.

[Bocadude85]

Hmm the forecast discussion is interesting. Sounds like the upper level environment is going to become unfavorable in 4 to 5 days. Didn't WXMAN57 say he thought the conditions would be favorable in the Bahamas?

ABOUT 72-96 HOURS COMPLICATES THE INTENSITY FORECAST BUT IS LIKELY
TO RESULT IN WEAKENING...ESPECIALLY SINCE UPPER-LEVEL WESTERLY FLOW
IS FORECAST TO BEGIN TO AFFECT CHANTAL BY THAT TIME. THIS
INCREASING WESTERLY FLOW AND LAND INTERACTION COULD EVEN CAUSE
CHANTAL TO BECOME A REMNANT LOW OR DISSIPATE LATE IN THE FORECAST
PERIOD. THE NHC INTENSITY FORECAST IS A BLEND OF THE SHIPS/LGEM
GUIDANCE AS WELL AS THE INTENSITY

[ozonepete]

Lots of uncertainty. I think increased wind shear, dry air and increased low-level trades in the eastern Caribbean will weaken it there - even before it reaches any significant land. Should it survive past the DR then I think conditions may be good north of Cuba. I don't believe the HWRF and GFDL as far as I can throw them. They've been pretty bad of late. Look for a recurve around 75W. I think NHC's track looks good, as I said. Just question intensity forecast next few days.

I'd certainly make sure all my supplies were in order if I lived in Florida or north through the Carolinas.

Mostly agree, wxman. A lot of uncertainties with this. I don't see the dry air but there is a better than even chance of increased wind shear somewhere over the islands. I think the track makes sense as well since there will be a digging trough in the central to eastern U.S. by the end of the week and that should pull it northward. after that it could encounter better conditions for strengthening.

[Gustywind]

Tropical Storm Chantal Forms in Atlantic; Warnings Issued
Published: Jul 7, 2013, 11:15 PM EDT weather.co
http://www.weather.com/news/weather-hur ... e-20130703

Tropical Storm Chantal has formed in the tropical Atlantic Ocean and is racing west toward the Lesser Antilles. This storm could eventually affect parts of the mainland United States by the end of the workweek.

The system developed as a strong tropical wave with tropical storm force winds before finally developing a closed circulation late Sunday night, thus bypassing the tropical depression phase and becoming Tropical Storm Chantal straightaway.

Tropical storm warnings have been issued for Barbados, Dominica and Saint Lucia. A tropical storm watch is in effect for Saint Vincent. Additional islands in the Lesser Antilles may go under watches and warnings Monday as Chantal approaches.

After crossing the Lesser Antilles, Chantal is expected to affect portions of the Dominican Republic, Haiti, and Cuba.

Residents in the mainland U.S. will have to pay attention to this system. The current forecast takes the center of Chantal over the Bahamas by Friday, but given the margin of error in the forecast, parts of Florida could be affected as well at the end of the workweek.

[ozonepete]

First NHC discussion is out calling for possible dissipation of Chantal late in the forecast period due to strong westerly shear and land interaction.

Oh yeah. A weak or moderate tropical storm going over Haiti? That's a recipe for dissipation. We'll have to see.

[blp]

Look at that contorted spaghetti lookin' mess after 70 w... what in the world?


[]http://i44.tinypic.com/33jqqev.jpg[/img]

Looking at those ensembles I see a system getting trapped under a developing Bermuda High at the end forcing a west or southwest turn, which is in line with how things have looked this year. This is a different pattern than years past. We may unfortunately see a lot of this coming up.

Evening Brian,

Busy start to the season. You thinking this will take the southern verses the northern track.

Hard to say right now. The reliable models ECMWF and GFS have been clueless and showed only an open wave. There will be a weakness and considering if it is a TS it might be stacked enough to get feel the weakness but I think the weakness will short lived with a building high forcing it back west. Land interaction is big unknown with intensity. Just my opinion.

[meriland23]

06hr GFS

[floridasun78]

what time is fight?

[cycloneye]

what time is fight?

Departs at 2:15 PM EDT from St Croix and arrives to center of Chantal around 4:30 PM EDT-5 PM EDT.