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Somerset Squall

Hurricane Leslie

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The twelfth tropical depression of the Atlantic season has formed roughly midway between the Cape Verde Islands and the eastern islands of the Caribbean. Intensity is 30kts. The depression appears to be in a favourable environment characterised by low shear and very warm sea temps. There is a fair amount of dry air to the northwest of 12L, but the cyclone should be able to overcome this IMO if the shear remains low. Looks to be a fish at present with a northwestward then northward track out to sea, but this is still uncertain. If 12L overcomes the drier air to the north then we could well be looking at a strong hurricane here; NHC forecast 12L to be an 80kt hurricane in 3 days time with the potential for further strengthening after that if the environment remains favourable. That, of course, depends on just where 12L ends up.

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Just been upgraded to Tropical Storm Leslie. Worth noting that we are actually around a day ahead of the 2005 season at this point (only 1995 was more active by this date), although i doubt we'll maintain that level of activity throughout the entire season.

000

WTNT62 KNHC 301730

TCUAT2

TROPICAL STORM LESLIE TROPICAL CYCLONE UPDATE

NWS NATIONAL HURRICANE CENTER MIAMI FL AL122012

200 PM EDT THU AUG 30 2012

...TROPICAL STORM LESLIE FORMS...

DATA FROM NOAA BUOY 41041 AND SATELLITE IMAGES SHOW THAT TROPICAL

DEPRESSION TWELVE HAS BECOME A TROPICAL STORM. MAXIMUM SUSTAINED

WINDS ARE NOW 40 MPH...65 KM/H...WITH HIGHER GUSTS. NO CHANGE TO

THE TRACK OR INTENSITY FORECAST IS REQUIRED AT THIS TIME.

THIS IS THE SECOND-EARLIEST FORMATION OF THE 12TH NAMED STORM ON

RECORD IN THE ATLANTIC BASIN...ECLIPSED ONLY BY LUIS OF 1995.

SUMMARY OF 0200 PM...1800 UTC...INFORMATION

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

LOCATION...14.3N 44.3W

ABOUT 1125 MI...1810 KM E OF THE WINDWARD ISLANDS

MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H

PRESENT MOVEMENT...W OR 275 DEGREES AT 20 MPH...32 KM/H

MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES

$$

FORECASTER BLAKE

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Can't say i expected a TS this quickly but this does mean that with 8 storms this August, we are tied for the most active month with a few others.

As has been said, looks like a strong FISH at the moment although Bermuda should be wary, the caveat to this is that it is currently racing along at 20mph westward so there is a possibility it could miss the weakness left by Kirk although unlikely.

Looks impressive however and is forecast to become a 90mph hurricane..

rbtop0-lalo.jpg

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Apologies that this is pretty random, but would someone mind telling me what FISH means?

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A FISH is a storm that stays out to sea without affecting land. I think it comes from "fish spinner".

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Leslie has strengthened to 40kts this evening. The storm is organising at an impressive rate, and the storm is in an environment favourable for further intensification over the coming days.

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Convection has now become a ball rather than a spiral which is a good indicator of intensification, still racing west at 20mph at 14N.

NHC have upped the intensity forecast to 100mph.

It should be noted that the ECMWF apparently has him heading west rather than recurving after day 3.

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Sorry to sound a bit stupid, new to all this, but does that mean it could head towards the gulf coast or will it still most likely curve to the Atlantic.

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Sorry to sound a bit stupid, new to all this, but does that mean it could head towards the gulf coast or will it still most likely curve to the Atlantic.

Not at all Snowydog :). It is not likely to affect the Gulf Coast. The upper level ridge responsible for moving storms westward is forecast to be broken down over the coming days allowing Leslie to move towards the north into the resulting weakness. There are still uncertainties as ever but the chances of Leslie getting into the Gulf Of Mexico are slim to none.

Intensity has risen to 55kts this morning, and Leslie is expected to become a hurricane later today. After dealing with some shear overnight, Leslie has developed deeper convection directly over the LLC and maintains a healthy amount also in the southwestern quadrant. Further strengthening is expected over the next few days.

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Hows about the central Atlantic H.P. ending up steering Leslie into the eastern seaboard in NY State and north? That would make better T.V. than a 950mb low clobbering scotland!

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Leslie has struggled over the last day or so against unexpected shear. This has, at times, left Leslie's LLC exposed. The storm is still generating deep, concentrated convection but not directly over the LLC due to continued shear. Sustained winds are estimated to be at 60kts. The shear is forecast to become even stronger over the next day or two as Leslie moves to the north. This should weaken Leslie. However, shear is expected to ease significantly beyond 72hrs, which may allow Leslie to finally intensify into a hurricane- but this depends how well Leslie deals with the hostile environment ahead. Leslie is a strong tropical storm with a potent LLC so I think she will come through this and then go on to strengthen long term.

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Leslie continues to be a sheared system. Intensity has fallen to 50kts. Leslie's LLC has kept popping out from the convection which has persisted and remained quite deep, sheared to the southeast. For the next 24hrs, shear is expected to remain at a moderate level of 20kts, preventing intensification. Thereafter, shear is expected to drop off, and with warm waters and a favourable upper level outflow pattern developing, Leslie should strengthen significantly as it crawls towards the north. Bermuda need to be extremely wary of Leslie, as NHC currently forecast Leslie to be a large cat 2 as it approaches the island to the southwest (the front right quadrant contains the highest winds and on the current track this is the quadrant that will impact Bermuda).

203900W5_NL_sm.gif

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Indeed Bermuda does seem to be in the path:

201212N.png

201212N_7G.png

Tropical Storm LESLIE: Probability of Cat 1 or above winds to 117 hours lead

201212N_5H.png

Tropical Storm LESLIE: Modelled wind field at 69 hours lead

1.track.current.png

models_storm3.jpg

ir_enhanced_storm3_1.jpg

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Tropical storm Leslie is forecast to strike Bermuda as a hurricane at about 08:00 GMT on 9 September.

Wed, 5 Sep 2012 02:50 GMT

Source: Tropical Storm Risk

Tropical storm Leslie is forecast to strike Bermuda as a hurricane at about 08:00 GMT on 9 September.Data supplied by the US National Hurricane Centersuggest that the point of landfall will be near31.7 N,65.0 W.Leslie is expected to bring 1-minute maximum sustained winds to the region of around 148 km/h (92 mph).Wind gusts in the area may be considerably higher.

According to the Saffir-Simpson damage scale the potential property damage and flooding from a storm ofLeslie'sstrength (category 1) at landfall includes:

  • Storm surge generally 1.2-1.5 metres (4-5 feet) above normal.
  • No real damage to building structures.
  • Damage primarily to unanchored mobile homes, shrubbery, and trees.
  • Some damage to poorly constructed signs.
  • Some coastal road flooding and minor pier damage.
  • There is also the potential for flooding further inland due to heavy rain.

The information above is provided for guidance only and should not be used to make life or death decisions or decisions relating to property. Anyone in the region who is concerned for their personal safety or property should contact their official national weather agency or warning centre for advice.

http://www.tropicalstormrisk.com/

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Finally, a week after formation, Leslie has become a 65kt, cat 1 hurricane. Shear has finally relaxed and Leslie has built a decent amount of convection over the centre and an eye feature. Leslie continues to crawl towards the north, trapped between two competing ridges. For the next 72hrs, this steering pattern is forecast to remain the same. Thereafter, a trough is expected to acclelerate Leslie towards the northeast. Bermuda still look in the firing line from Leslie, at near major hurricane strength as the environment is now much more conducive for accelerated intensification.

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Mark Sudduth at hurricanetrack is planning to head to Bermuda for a Hurricane Intercept

He normally focuses on landfalling US Hurricanes

Thing about a small island is that should a monster hurricane develop, maybe pass, just to the west of Bermuda, so Bermuda is in the north-east segment of the storm (usually the strongest segment) you got no escape options

Should be interesting

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Watch out West Midlands!

Tropical storm wreaking havoc in Bermuda could bring Indian summer to Coventry and Warwickshire

A TROPICAL storm threatening to wreak havoc in Bermuda could lead to an Indian summer of high temperatures and sunshine in Coventry and Warwickshire. That was the view of forecasters who predicted high pressure would dominate the first half of September – with temperatures rising above 26C (80F) this weekend.

Leon Brown, meteorologist at satellite TV’s The Weather Channel, said: “It could be very warm this weekend with glorious sunshine.†After a patchy summer, with torrential downpours followed by limited spells of sunshine, he said weather patterns had returned to a more typical system with high pressure taking charge. Bad weather fronts from the Atlantic were predicted to weaken as they reached central England with the troublesome jetstream, that has caused the prolonged spell of unsettled conditions, moving north-east towards Iceland.

Mr Brown said disturbances caused by Tropical Storm Leslie, predicted to strike Bermuda as a hurricane on Sunday, could bring warmer conditions to the UK. He added the first half of September was looking more settled and less wet than the previous four months. But he warned: “How it pans out later in the month will depend to some degree on hurricane and tropical storm tracks over the western to north Atlantic when they get caught in the jet stream. But if they continue to run to the north east then we could be in for an Indian summer and a warm September.†Provisional figures from the Met Office suggested this year was the second wettest in the UK since records began and the worst in 100 years. Only 1912 was wetter according to official records.

The April to June period was also the wettest recorded in the UK. A spokesman for Bablake Weather Station in Coventry said: ‘‘The first three months of 2012 were the driest of any year in Coventry since 1892, while the second quarter was the wettest April to June period in the city since 1878 . ‘‘Yet here we are in September after a wet summer, enjoying what may become a prolonged dry warm and sunny spell of summer-like weather in early autumn, with little sign of any rain until the middle of next week perhaps.’’

http://www.coventrytelegraph.net/news/coventry-news/2012/09/05/tropical-storm-wreaking-havoc-in-bermuda-could-bring-indian-summer-to-coventry-and-warwickshire-92746-31774925/#ixzz25gTgFr6b

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Leslie has struggled today and almost lost hurricane status. Shear increased yet again and the hurricane also became stationary. The combination of the increase in shear and the upwelling of colder water beneath Leslie due to slow motion has prevented the hurricane from intensifying. The eye dissapeared this afternoon but is reforming now. However, the majority of the convection remains to the east of the LLC due to the shear. Shear is expected to ease again and Leslie is expected to eventually accelerate northwards, but this is not expected to occur for at least another 24hrs. Leslie is unlikely to strengthen until after that time as it continues to stir up colder water. Nevertheless, Bermuda is still in the firing line from Leslie, who is still expected to become a cat 2 on approach to the island. However, the track forecast has shifted east, and although Bermuda are still in for a very rough ride, they should now miss the most dangerous front right quadrant of the hurricane.

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I have been following all these threads with a great deal of interest and learning as I go along. Haven't been posting much as I have always thought it best to lurk and learn rather than post when I don't have a clue what I am talking about.

Anyway on that note it is interesting to see that Hurricane Leslie has been re-classified as a Tropical Storm now. I gather this has happened as she has been practically stationary for some time and has used up all the energy from the water? Once she starts moving she will once again have access to hotter water and will once again intensify, I gather this is the basics of it?

I also see that TS Leslie and Hurricane Michael are projected to come together over Newfoundland. I assume that the larger of the two (Leslie) will consume Michael and both as one depression will make their way between Scotland and Iceland sometime around the 14th or 15th September?

M...

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You're right on both counts there Maitland. NHC say that Leslie has been stationary for so long the storm has cooled the waters to 23C in the area, from around 28C. This is the main reason behind the observed weakening as you say. Despite Leslie being weaker than Michael, Leslie would absorb Michael as you say because it is the larger of the two. Dependant on Michaels track speed, the two might still remain seperate.

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You're right on both counts there Maitland. NHC say that Leslie has been stationary for so long the storm has cooled the waters to 23C in the area, from around 28C. This is the main reason behind the observed weakening as you say. Despite Leslie being weaker than Michael, Leslie would absorb Michael as you say because it is the larger of the two. Dependant on Michaels track speed, the two might still remain seperate.

Appreciate the reply. I find this all absolutely fascinating. The beauty of living in Scotland is the poor weather we can have at this time of the year (and every other time of the year). It would appear however that I am the only one in a family of five that enjoys bad weather.

As I continue to learn I hope to be able to post a little bit more.

M...

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Leslie has continued to weaken and sustained winds are now 55kts. Leslie is however, now moving but only at a pretty slow 4kts. However, as shear is easing and the northward track takes Leslie out of it's self induced cold pool of water, Leslie should re-attain hurricane status as it passes east of Bermuda. Bermuda now look to escape the worst of the conditions associated with Leslie.

Interesting NHC have echoed my observations of the other day in the latest advisory LOL:

SHIP AND BUOY

OBSERVATIONS...AS WELL AS SST MICROWAVE DATA...ARE INDICATING SEA

SURFACE TEMPERATURES OF 28 AND 29 DEGREES CELSIUS TO THE NORTH OF

LESLIE. SINCE THE SHEAR HAS DECREASED...ONCE LESLIE MOVES OVER

THESE WARMER WATERS IN A DAY OR SO...THERE IS A STRONG LIKELIHOOD

THAT IT WILL REGAIN HURRICANE STRENGTH. IN FACT...MOST OF THE

CYCLONES IN THE ATLANTIC THIS YEAR THAT HAVE REACHED HURRICANE

INTENSITY HAVE DONE SO AS THEY APPROACH 30 DEGREES NORTH AND NOT IN

THE DEEP TROPICS.

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