14 September 2011

Maria strengthens slightly

Over the past two days since my last update, Maria has barely maintained intensity in the 45-50kt range, due to the strong vertical shear.  Since Tuesday morning, the central pressure fell 5 mb... the only sign of vigor it has shown lately.  At 15Z today, the intensity is 50kts and 1001mb.  The low-level center (marked by the red dot on the image below) is still on the far fringe of the deep convection in the face of 15kt shear.

At about 06Z today, Maria passed just 20 miles west of Buoy 41046, and the buoy reported a surface pressure of 1004.5mb, along with sustained winds of 33kts, gusts to 43kts, and a significant wave height of 18 feet.  The wind and pressure trace also indicates a fairly weakly-organized core, with the pressure minimum coinciding with a tiny wind minimum and surrounded closely by wind maxima.  Quite a different look than the plot I showed from Katia's passage over Buoy 41048 six days ago!

Much like Katia, Maria is about to encounter a strong mid-latitude trough... and with that comes some baroclinic enhancement and an eventual extratropical transition.  So, in the coming couple of days, the storm could approach hurricane intensity even as the shear skyrockets and the SSTs plummet.  It will recurve between Bermuda and the US, with the closest approach to Bermuda occurring Thursday morning.

Please visit my tropical Atlantic headquarters.

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