18 November 2013

New disturbance in central Atlantic... Melissa?

It's been 25 days since the National Hurricane Center issued any advisory on an Atlantic tropical cyclone, but that streak could end shortly.  A large trough and upper-level Low pressure system has been gradually transitioning to a subtropical cyclone, and that in time could transition to a fully tropical cyclone.  The next name on the list is Melissa.

The subtropical nature is demonstrated by its origins as well as its current structure with fronts still attached to it.  The central pressure is down to 995mb, and tropical storm force winds already extend over 250 miles from the center.  It's nowhere near land... the closest reference point is Bermuda, roughly 750 miles west-northwest of this disturbance (centered near 29N 53W as of this post: see basin-scale map).

It is expected to drift slowly to the north over the next couple of days, then accelerate into the icy waters of the north Atlantic tropical cyclone graveyard.  The sea surface temperature under the storm is a comfortable 27C now, but in about 4 days, the SST will be around 20C and this system will certainly have transitioned back to an extratropical cyclone by then.

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