Thursday, August 25, 2011

Hurricane Irene & Tropical Depression 10: August 25, Update A

Hurricane Irene:
Well the good news is that wind shear took a bit out of her and although officially her winds are 115mph, making her a weak cat 3 storm (range: 111-130mph), I think she might be a bit weaker than that, but still in the strong cat 2-to-cat 3 range. Central pressure is 950mb, but she does not have a good eye at the moment and her outflow is not equal in all sectors. A hurricane is truly a combination of the ocean and atmosphere combined. As she gets closer to Florida and the eastern US her intensity will be a battle between good and evil… between the atmosphere and the ocean… between the wind shear (inhibit her development) and the deep warm ocean (allow her to develop). The wind shear looks like it will get stronger as she gets to that region, so we’ll see whether that is strong enough to prevent her from becoming a cat 4.

The 8am advisory has her at around 25.5N, 76.5W, heading NW at 13mph. The not so good news is that the high pressure that had started to redevelop has continued on that trend. Yesterday the turning point was around North Carolina. Today it extends a bit farther south, to the Georgia/S. Carolina region. This is a bit troublesome because if this trend continues, she might not make the forecast N & NNE turns, and instead continue NNW and then back to NW tomorrow/later today, which means she will head closer to S. Carolina/Georgia/Florida. What we are watching for today is that turn towards the north so she runs parallel to the Florida coastline and then later today/tomorrow for the turn to NNE.

Tropical Depression 10:
They have upgraded the Atlantic Blob to a Tropical Depression, which means it has closed circulation with winds greater than 17mph. Convection and circulation are both weak but still developing. It is currently heading W at around 10-15mph, but might slow down later today because it is surrounded by high pressure. The pressure at the moment extends to the southern Caribbean, so for now I would say it will continue to track west, and then follow a curve similar to Irene’s towards the Dominican Republic region – but it is far too early to say with any certainty.

More later,

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DISCLAIMER: These remarks are just what I think/see regarding tropical storms - not the opinion of any organization I represent. If you are making an evacuation decision, please heed your local emergency management and the National Hurricane Center's official forecast and the National Weather Service announcements. This is not an official forecast. If I "run away, run away" (Monty Python), I'll let you know.

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