Good Upper Level
Posted by JAC on 9/8/2010, 7:03 am
Large updraft has created a large anti-cyclone over 91L.

At the moment, a clear low-shear path to the Carib.

Need to see how that holds up.

Interesting feature near ex-Gaston.

A nice anti-cyclone south of Hispaniola at 17N 70W and an area of subsidence centered at 18N 58W.

The anti-cyclone indicates a strong updraft and the CW winds converging at 18N 58W indicate a strong downdraft.

This is a closed, relatively small Walker Cell.  The kind of thing that killed the '09 season.

Obviously that is what it has done to Gaston as well.

UL winds flow from the updraft center to the downdraft center.

Surface winds flow from the downdraft center to the updraft center.

So, the whole vertical circulation is known as a Walker cell.

The surface winds from this circulation are blowing dry air into the remnants of Gaston and that is why he is struggling.

I wonder if we will see more of these Walker cells start to form.








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91L Starting to Rock & Roll - JAC, 9/8/2010, 6:35 am
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