Bermuda could be hit quite hard by Leslie- it all depends on how close and how strong

The Official Forecast Track Takes Leslie Close to Bermuda This Weekend

The Official Forecast Track Takes Leslie Close to Bermuda This Weekend

I know the headline is like a memo from the department of the obvious, but it’s true. While I think that Bermuda has no way out of being impacted by Leslie, I do not know to what extent the effects will be.

Right now, the first sign of Leslie’s approach will be the increase in swells from the Atlantic. These will only get bigger and more frequent. In fact, these swells will radiate out from Leslie to impact much of the U.S. East Coast and the islands that border the northern Caribbean Sea.

Then, it looks like Leslie could really intensify over the warmer-than-normal waters of the western Atlantic. How strong remains to be seen but the upper level environment looks quite favorable and Leslie might be the first category three hurricane of the season.

The question of how close depends on the strength of the ridge which will push Leslie west some before it straightens out to a more northerly course. The timing of the north turn will ultimately result in what happens for Bermuda and how close the center tracks.

Down the road a few more days, it looks a little better for Nova Scotia and in fact the entire Northeast U.S. as Leslie should turn east enough to clear those regions. This is not by any means a done deal and any significant deviation to the west, and Leslie could bring issues to New England and the Maritimes.

I am almost at the point where I am going to decide whether or not to travel to Bermuda to intercept Leslie. I would like to take one wind tower assembly, minus the tower itself of course, plus one remotely operated cam unit. I can easily airline the Storm Case with all the gear in it and purchase a marine battery once there to power everything. I am as interested in the wind and pressure data as I am the impacts on the people there. If all went well, I would have live weather data from exceptional equipment feeding in to our iPhone app and our Client Services site. I would also have a live cam streaming for our Clients as well with frequent updates to Twitter and Facebook posted. I will know tonight if I am in fact flying to Bermuda later this week.

I’ll have more here on Leslie after the 11pm ET NHC advisory package.

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Warmer than normal water temps likely to fuel Leslie as rest of tropics stay very busy

Atlantic Sea Surface Temperature Anomalies

Atlantic Sea Surface Temperature Anomalies

Sea surface temps are running at least one degree Celsius above normal across much of the northwest Atlantic. In fact, there are large areas of plus two and three Celsius just off the Canadian Maritimes. This translates in to added heat content and Leslie is poised to take advantage of it over the next week or more.

The current NHC forecast track has Leslie moving very slowly over the next few days as steering currents remain weak. The track takes the center just to the west of Bermuda but since Leslie is a large storm with a huge wind field, the effects will be felt on the island in the way of large, battering waves, heavy rain and high winds. I suspect it won’t be too much longer until we see a hurricane watch posted for the island.

With all of this warmer than normal water around, Leslie looks like it could strengthen in to quite a strong hurricane in the models. Add to this what appears to be a very favorable upper level outflow pattern and it is possible that Leslie becomes the first category three hurricane of the season. We have been in this pattern of seeing storms/hurricanes intensify out of the deep tropics and I don’t see any reason to believe that Leslie will be any different.

In the longer range, the Euro continues its westward forecast for Leslie, taking it very close to Nova Scotia and Newfoundland. Any further west and we could be looking at a possible brush with portions of New England as well. Much of this will have to do with the way a trough is supposed to develop in the Tennessee Valley this weekend and beyond. If it is weaker or digs in farther west, even by a little, then the high pressure area over the western Atlantic can build in more and push Leslie a degree or two of longitude west. I will be watching closely to see if this trough acts to capture Leslie and swing it north-northwest or whether the trough acts to push Leslie out to the north-northeast. How this plays out will determine what, if any, landmass is directly impacted.

One effect that I have made mention of for several days now is the increasing swells that will roll in to the East Coast. The NHC continues to make mention of this in their discussions and I want to emphasize the importance of understanding how dangerous rough surf can be- even with a storm/hurricane hundreds of miles off the coast. Check out this video that I produced last year as part of a preparedness campaign with Olympus Insurance out of Florida:

Elsewhere, we now have tropical storm Michael which will be officially named at 11am ET on the NHC advisory. The small storm will be short-lived and not affect land but it will bring the total number of named storms to 13 this season. While Michael is much smaller than Leslie, it is clearly a tropical storm and is of interest to shipping lanes in the open Atlantic.

The east Pacific is calming down and I do not see any new areas of concern developing anytime soon.

I will be working on the daily video blog for our iPhone app and will have it uploaded in just a little while. We are also eagerly anticipating the first major update to the app any day now. The update will greatly enhance the app and allow for manual refresh of the video blogs. As soon as it is approved by Apple, I will add a separate blog post. Speaking of blogs, I’ll update this blog later this afternoon.

 

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Latest Euro model to raise a few eyebrows along East Coast

Euro Forecast for Leslie Shows it Getting Closer to the East Coast of U.S.

Euro Forecast for Leslie Shows it Getting Closer to the East Coast of U.S.

It looks like the weak nature of Leslie has allowed it to track a little more west than originally forecast and this may be enough to trap it under a building ridge of high pressure over the western Atlantic in the coming days.

The latest ECMWF model shows quite a significant westward shift in the track of Leslie beyond day five. In fact, the model now shows a landfall in Nova Scotia at day nine, which is a change from the curving-out-to-sea scenario that has been the norm as of late for that model.

Both the GFS and the Euro also indicate that Leslie will grow to be a powerful hurricane with nearly ideal upper level conditions over water temps that are running several degrees above normal in some places. This will lead to a substantial wave event along the East Coast and of course, Bermuda, later this week and in to the weekend. This, in and of itself, could be a big problem with days and days of pounding surf. I’ll address this more on tomorrow’s blog post.

For now, Leslie is rather disorganized and moving generally northward. We’ll see what the NHC has to say on their next forecast package. I suspect we’ll start to see some subtle shifts to the west in the track and an increase in the intensity over time.

I’ll post more here late tonight and then again tomorrow morning. For a video discussion of the tropics, be sure to pick up our iPhone app in the App Store. We have a new update coming out any day now which will greatly improve functionality and I’ll post a separate write-up about that once Apple has approved it.

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Bermuda could be impacted by Leslie as September looks to be quite busy due to lack of El Nino

Leslie Could Impact Bermuda This Weekend

Leslie Could Impact Bermuda This Weekend

TS Leslie developed some very deep convection over night with cloud tops reach an astonishing -88 degrees Celsius. Those cold cloud tops, however, did not wrap all the way around the center of the storm. This is due to the continuation of vertical wind shear which has been just enough to keep Leslie from strengthening much. I do think the burst of deep convection is a sign that Leslie will intensify given the right upper level conditions.

The current forecast track has not budged much from recent ones and it looks like a slow and steady course to the north-northwest throughout the week ahead makes the most sense considering the pattern. There will simply not be enough western Atlantic ridge to push Leslie back to the west enough to directly impact the U.S. That being said, I do believe that an increase in long period swells is coming – especially once Leslie becomes a hurricane. Its slow movement will allow for quite a build-up of energy in the ocean and this means a great surf weekend coming up for portions of the East Coast. It also means an increase in rip currents and as such, people heading to the beach need to be mindful of this hazard. We are still a few days away from the swells reaching the U.S. and I will address this again later in the week.

As for Bermuda, it looks as though Leslie could come fairly close to the island by the weekend as a strong hurricane. Some of the intensity models suggest that Leslie could approach or exceed category three intensity towards the end of the week. Interests in Bermuda need to pay close attention to the future track and strength of this storm. It also looks like Leslie will be quite large with an expanding wind field so even a brush with Bermuda could mean a period of high winds and very rough seas for the area.

Looking at the rest of the tropics, we have invest area 99L well out in the east-central Atlantic. It may develop some but is small in size and poses no threat to land areas.

In the eastern Pacific, TS John has formed to the southwest of the Baja peninsula and will move swiftly off to the northwest and not be a bother to Mexico.

SST Anomalies from August 3

SST Anomalies from August 3

Checking on the current state of the El Nino, we see that it has, in fact, backed off quite a bit in recent weeks. Comparing the SST anomaly maps from August 2 and the one from today, it is clear that the warming trend has stopped and even reversed in the eastern Pacific. This means that the threat of a significant El Nino event during the hurricane season is likely minimal at best. In other words, the negative conditions that a Pacific El Nino would typically bring to the Atlantic Basin are probably not going to be there.

SST Anomalies from September 3, Notice the Decrese in SST Temps in the East Pacific

SST Anomalies from September 3, Notice the Decrese in SST Temps in the East Pacific

The reason El Nino affects the Atlantic is similar to how a large hurricane, with its well established outflow, affects other tropical waves moving across the Atlantic. Remember TS Jean which formed east of Isaac? The large scale upward motion of Isaac led to strong outflow high in the atmosphere and this literally tore Jean apart and caused it to weaken and dissipate. An El Nino event, especially strong ones, causes tropical convection to persist across a good deal of the Pacific. This upward motion on a basin-wide scale acts to spread strong upper level winds across the deep tropics of the Atlantic, much like the outflow from a hurricane. This shear stops developing Atlantic systems in their tracks. Because we are not seeing a significant El Nino event taking shape right now, I suspect that September will be quite busy with a shift in activity more towards the Caribbean Sea and Gulf of Mexico. This is a natural evolution in any season when we see the tropical waves that come off of Africa lose their punch and the build up of low pressure in the western part of the Atlantic and Caribbean leads to development there.

The long range models, and we’re talking beyond 10 days here, indicate this pattern change is coming. Once Leslie moves out, we will probably only wait a few days, if that, before we have yet another named storm.

Curiously though, we have yet to have a major hurricane this season in the Atlantic. The layer of persistent dry air has really put a lid on things, literally. I think that Leslie has a chance to become a category three hurricane as it nears Bermuda as the global models indicate what looks like a favorable upper level wind pattern for it to develop. We may have had a lot of activity, but no intense hurricanes just yet.

I will go over a lot of what I have outlined here in today’s edition of the Hurricane Outlook and Discussion video for our iPhone app. I will also post an update here in the blog this evening to reflect the very latest on Leslie and whether or not I may be taking a trip to Bermuda later this week.

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Leslie not going anywhere fast it seems, Bermuda should monitor closely

Leslie Could Track Close to Bermuda Late Next Week

Leslie Could Track Close to Bermuda Late Next Week

TS Leslie remains just below hurricane intensity as a fairly constant northerly shear pattern is in place, keeping the deep convection from wrapping around the low level center. It is quite remarkable how hostile the deep tropics have been again this season which in turn has meant that we’ve had no major hurricanes as of yet (no category three or higher hurricanes). However, the global models all show Leslie moving in to a more favorable environment over the next several days and it should become a fairly strong hurricane at that time. Ocean temps are warm and the wind shear is forecast to relax considerably.

The steering pattern is complex and could have some big implications for Bermuda as the coming week unfolds. Right now, the storm is moving along to the northwest at a fairly good pace, 15 mph. This will soon change as the flow in the atmosphere changes and Leslie gets stuck in the middle of this pattern change. There is a chance it could just meander out in the Atlantic for a couple of days. How close this happens to Bermuda remains to be seen but there is a chance that Leslie could impact the island beyond the NHC five day forecast period. Interests in Bermuda should just keep an eye on the future predictions for Leslie this coming week.

Surfers should also keep an eye as well since the farther west Leslie tracks and the stronger it gets, the more long period swell action the East Coast will see. We’ll know more about what to expect later this week but it looks like there will be some increase in the surf along parts of the East Coast by next weekend.

The remainder of the Atlantic is quiet in terms of any other issues to be concerned about. I think we are heading for a lull in the action once Leslie moves out but that could take a while as mentioned above.

I will have more here tomorrow morning.

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