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Tropical Storm Leslie - Discussion, Images, Forecasts


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How about the Canadian pines?

And the Maritimes, too!

Haha I was typing on my phone last night, so the autocorrect was working well it seems.

Notice that Leslie doesn't seem to be in any state to intensify despite the fact the shear is decreasing. The system has done a number to its SST field, and as long as Leslie continues to be nearly stationary, its unlikely the system will intensify as robustly as most of the global models are indicating.

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Haha I was typing on my phone last night, so the autocorrect was working well it seems.

Notice that Leslie doesn't seem to be in any state to intensify despite the fact the shear is decreasing. The system has done a number to its SST field, and as long as Leslie continues to be nearly stationary, its unlikely the system will intensify as robustly as most of the global models are indicating.

Ekman upwelling and mixing waves will be its downfall, the thermocline is shallow out there and only gets shallower towards Bermuda. It'll have no problem pulling up 20-24 °C water. I wonder if the GFS is even coupled with the ocean?

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Ekman upwelling and mixing waves will be its downfall, the thermocline is shallow out there and only gets shallower towards Bermuda. It'll have no problem pulling up 20-24 °C water. I wonder if the GFS is even coupled with the ocean?

The GFS and ECMWF to my knowledge are not dynamically coupled with the ocean. From my understanding the "ocean" as seen by these models are merely a Reynolds weekly average that is not updated over the model integration. Thus, things like upwelling for vertical mixing of the ocean have little representation in the model fields nor how they might translate into the TC dynamics.

Models like the GFDL and HWRF, however, are, and should provide a better gauge to storm intensity in regards to upwelling ect.

dtk can provide a much better (and perhaps more correct) answer than myself.

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surf from leslie has already spread over 1000 miles NW. swell hitting bouys near nantucket is 5.6 ft @ 14.8 seconds. That's a powerful wave and will probably suprise a few boaters. (esp since as the swell begins to hit, it can be flat for 10-15 minutes , people assume there is no surf after being in water couple mins , and seeing nothing, then a set of 6-8 foot faces slams them, in short what a impressive wave maker, must have quite a fetch

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CHC just released a bulletin for the Atlantic Provinces.

TROPICAL CYCLONE INFORMATION STATEMENT ISSUED BY THE CANADIAN

HURRICANE CENTRE OF ENVIRONMENT CANADA AT 1:01 PM ADT TUESDAY

4 SEPTEMBER 2012.

---------------------------------------------------------------------

TROPICAL CYCLONE INFORMATION STATEMENT FOR:

=NEW= ATLANTIC PROVINCES.

FOR TROPICAL STORM LESLIE.

THE NEXT STATEMENT WILL BE ISSUED BY 3:00 PM ADT WEDNESDAY.

EARLY DISCUSSION REGARDING TROPICAL STORM LESLIE AND POSSIBLE

INFLUENCE IN EASTERN CANADA.

---------------------------------------------------------------------

==DISCUSSION==

THE CANADIAN HURRICANE CENTRE WILL BE MONITORING THE DEVELOPMENT OF

TROPICAL STORM LESLIE THIS WEEK. THE STORM IS EXPECTED TO MOVE VERY

SLOWLY AND INTENSIFY GRADUALLY OVER THE NEXT SEVERAL DAYS.

COMPUTER MODELS ARE PREDICTING LESLIE TO ONLY TRAVEL 500 KILOMETRES

IN 4 DAYS WHICH IS BASICALLY A PERSON'S AVERAGE SPEED OF WALKING.

WITH SUCH A SLOW SPEED OF TRAVEL AND THE FACT THAT THE STORM IS STILL

IN ITS ORGANIZING STAGE, THERE IS MUCH (MORE THAN USUAL) UNCERTAINTY

IN THE PREDICTED PATH/INTENSITY OVER THE NEXT WEEK.

COMPUTER MODELS INDICATE THAT LESLIE COULD EVENTUALLY PUSH THROUGH

THE LARGE 'BERMUDA HIGH' AND ACELLERATE TOWARD EASTERN CANADA WITH A

RANGE OF TRACK SCENARIOS FROM MAINE TO OFFSHORE NEWFOUNDLAND.

THE MIDDLE OF THESE TRACK FORECASTS IS OVER NEWFOUNDLAND - BUT EVEN

THAT 'AVERAGE' WILL LIKELY SHIFT BY HUNDREDS OF KILOMETERS OVER TIME

WITH EACH NEW RUN OF SIMULATIONS. IF LESLIE MAKES IT TO EASTERN

CANADA, IT WOULD NOT LIKELY DO SO UNTIL EARLY NEXT WEEK.

WE WILL UPDATE THIS BULLETIN THROUGHOUT THE WEEK IF LESLIE CONTINUES

TO DEVELOP AND WILL PROVIDE INTERPRETATION OF THE POSSIBLE SCENARIOS

AND DEGREE OF PREDICTABILITY.

VISIT WWW.WEATHEROFFICE.GC.CA/HURRICANE/TRACK_E.HTML (ALL IN LOWER

CASE) FOR THE LATEST HURRICANE TRACK MAP.

END/FOGARTY

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surf from leslie has already spread over 1000 miles NW. swell hitting bouys near nantucket is 5.6 ft @ 14.8 seconds. That's a powerful wave and will probably suprise a few boaters. (esp since as the swell begins to hit, it can be flat for 10-15 minutes , people assume there is no surf after being in water couple mins , and seeing nothing, then a set of 6-8 foot faces slams them, in short what a impressive wave maker, must have quite a fetch

I was about 30 miles east of Nantucket yesterday. The swell already started to roll in by about 9am Monday. NOAA and the buoys have a good handle on it. Yesterday the SE wind helped to stack it even more it was pretty unpleasant for a few hours on the tide. Today the period is longer but the swell a bit higher, going to rock and roll out there for many, many days. We had some legitimate 5-6 footers yesterday and I see that's already occurring again today. There were several 25-27 foot boats out there that we'd almost lose entirely on the horizon between swells. Heed the advisories and stay home!

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The GFS and ECMWF to my knowledge are not dynamically coupled with the ocean. From my understanding the "ocean" as seen by these models are merely a Reynolds weekly average that is not updated over the model integration. Thus, things like upwelling for vertical mixing of the ocean have little representation in the model fields nor how they might translate into the TC dynamics.

Models like the GFDL and HWRF, however, are, and should provide a better gauge to storm intensity in regards to upwelling ect.

dtk can provide a much better (and perhaps more correct) answer than myself.

Correct.....all of the operational global NWP models are atmosphere only, and are not coupled to ocean models. The ocean is treated as a boundary condition only....where for the GFS, the SST is initialized daily and then relaxed toward a climatology (I think with an e-folding time of several days to a week, I need to check). We are working toward implementing a fully coupled ocean/atmosphere (and eventually land surface) model for the GFS (similar to what we run for the CFSv2 and CDAS). The seasonal Euro runs are similarly coupled to an ocean model (like the CFSv2).

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surf from leslie has already spread over 1000 miles NW. swell hitting bouys near nantucket is 5.6 ft @ 14.8 seconds. That's a powerful wave and will probably suprise a few boaters. (esp since as the swell begins to hit, it can be flat for 10-15 minutes , people assume there is no surf after being in water couple mins , and seeing nothing, then a set of 6-8 foot faces slams them, in short what a impressive wave maker, must have quite a fetch

On a cruise ship about 300 miles NW of Bermuda.....pretty tame so far (4-6' at best) but hoping for the ship to really be rocking on departure Friday around 5PM.

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I was about 30 miles east of Nantucket yesterday. The swell already started to roll in by about 9am Monday. NOAA and the buoys have a good handle on it. Yesterday the SE wind helped to stack it even more it was pretty unpleasant for a few hours on the tide. Today the period is longer but the swell a bit higher, going to rock and roll out there for many, many days. We had some legitimate 5-6 footers yesterday and I see that's already occurring again today. There were several 25-27 foot boats out there that we'd almost lose entirely on the horizon between swells. Heed the advisories and stay home!

bouy reports and direction show this was mostly kirk's swell abating (it was more due Easterly in nature) it can be identified as kirk's by the period and direction

the period is longer today because the first of leslie's swell (originating from further away) is hitting the bouys near nantucket and SNE and the waters off maine/ maritimes. this period will drop into the 13 second range later.

yes it is going to rock and roll swell wise for several days , alot of the swell energy is focused NNW of the storm center as it would appear the best fetch of higher winds are in in the E quadrant with screamin SSE winds for a good fetch for the last several days pointin right at RI/ Cape cod/ Maine. 50-60 mph winds can create very large ocean waves when the fetch and duration is significant. just ask hawaii

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I was about 30 miles east of Nantucket yesterday. The swell already started to roll in by about 9am Monday. NOAA and the buoys have a good handle on it. Yesterday the SE wind helped to stack it even more it was pretty unpleasant for a few hours on the tide. Today the period is longer but the swell a bit higher, going to rock and roll out there for many, many days. We had some legitimate 5-6 footers yesterday and I see that's already occurring again today. There were several 25-27 foot boats out there that we'd almost lose entirely on the horizon between swells. Heed the advisories and stay home!

Indeed, heed the advisories. Surges of 6'-9' swells through the week:

http://www.nrlmry.navy.mil/atcf_web/wavewatch/page/web/tcww3.php

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Correct.....all of the operational global NWP models are atmosphere only, and are not coupled to ocean models. The ocean is treated as a boundary condition only....where for the GFS, the SST is initialized daily and then relaxed toward a climatology (I think with an e-folding time of several days to a week, I need to check). We are working toward implementing a fully coupled ocean/atmosphere (and eventually land surface) model for the GFS (similar to what we run for the CFSv2 and CDAS). The seasonal Euro runs are similarly coupled to an ocean model (like the CFSv2).

Excellent example of how even our most high-tech global models can't capture intrinsic non-linearities of the atmosphere-ocean system. The state of the atmosphere depends on the state of the ocean, but the state of the ocean depends on the state of the atmosphere, and the GFS can't handle that.

Will be excited to see how coupling changes the GFS' accuracy, I imagine it'll be a major improvement in the end.

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Could be an historic hit for bermuda

It's difficult for a storm to become historic for bermudians. My guess is a cat 3 over or <50mi west of Bermuda could be up there. A cat 2 < than 80mi to the west or <50mi to the east could be very disruptive, though. Those are just some rough assessments...

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It's difficult for a storm to become historic for bermudians. My guess is a cat 3 over or <50mi west of Bermuda could be up there. A cat 2 < than 80mi to the west or <50mi to the east could be very disruptive, though. Those are just some rough assessments...

Some Bermudians I talked with were actually more frightened by Emily (1987) than by Fabian (2003). While only a high end Cat 1...it was a rapidly intensifying, very fast moving, microcane with embedded tornadoes. It was also a surprise...and it's major effect lasted only about an hour.

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