Tropical Storm Leslie

NOAA GOES East RGB Visible satellite image of Tropical Storm Leslie. As of the September 2nd 5pm NHC advisory, Leslie has 60mph winds and 998mb pressure. Deep convection is forming on the south side of the center and is trying to wrap around the center to its east.

All of the major forecast models today are agreeing that Leslie will have an impact on Bermuda during its existence. Although that impact ranges from just dangerous surf to a major hurricane direct-hit.  Leslie has in fact weakened today as a result of some moderate-strong northerly wind shear. This has blown most of Leslie’s convection off to the south of the center of circulation and kept the storm from organizing.

Leslie is moving slowly northwestward at 10mph and is expected to slowly continue this motion until a weakness in the Bermuda-Azores ridge of high pressure  caused by a trough coming off the US east coast allows it to take a more northerly path. However, before it completely recurves out to sea, the trough lifts out and the ridge is expected to build back in to the north of Leslie, steering it northwestward again, potentially towards Bermuda. While this happens, the upper atmospheric environment has the opportunity to become more favorable for development, and Leslie could strengthen into a hurricane or even a major hurricane. The slow motion will allow Leslie to generate huge swells that  will do some extreme beach erosion to Bermuda. These swells could be dangerous along the US East coast and the north (Atlantic) coasts of the Caribbean and Bahamas islands.

Of course, the other possibility, is that Leslie never fights off the wind shear, stays weak and recurves safely out to sea or even dissipates and is absorbed into the trough. This scenario hasn’t been a popular one for the forecast models but, Tropical Cyclones are finicky and there could be some inhibiting factor out there that the models aren’t picking up on.

The moral of this post is to keep an eye on Leslie, and be ready to start preparations if necessary. Keep an eye on the Bermuda Weather Service’s forecasts, and the National Hurricane Center’s advisories.


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