Monday, August 22, 2011

Hurricane Irene: August 22, Update B

Irene was upgraded just about 1.5 hours ago to a category 2 hurricane, based on aircraft observations. They estimate winds to be 100mph which makes her a weak-to-mid level cat 2 (Category 2 range: 96-110mph). The central pressure is 981mb. I would agree with the assessment that her winds are greater than 80mph, although I don’t know if she’s quite that strong yet. There is not eye, and usually at around 90-100mph wind speeds we begin to see an eye in the satellite images.   

However her convection has increased, and the upper tropospheric circulation slowly continues to improve. The only good news is that the worst weather is offshore from Hispaniola, although the Dominican Republic is getting a downpour and quite a few strong thunderstorms at the moment. I hope everyone is ok there (including you holiday-makers). Here's a satellite Infra-Red image of the area to show you:

If you somehow forgot or missed my amazingly wonderful and witty words of wisdom (move over Oscar Wilde ;-)), how to read IR satellite images is in this entry:

Umm, it looks like she has slowed down a tad and her track has shifted slightly southwards, bringing her a bit closer to Hispaniola (but currently the center will still remain off-shore). Her forward speed is now 10mph (which is still fairly decent as forward speeds go) and although she’s heading WNW still, it’s a little more westward than that (for now anyway). This translates to the Dominican Republic getting wet and windy weather for over 24 hours because she has been in that area since this morning, and hasn’t yet got to the closest point to the island in her forecast track.  

Although her current track is slightly south that before, the longer range forecast still takes her northwest through the Bahamas and to the east of Florida. It looks like the forecast curve has sharpened to more of a turn really: ‘get to Cat Island and take a right turn at the golden arches’). I think this is because the computer models are focusing on a low pressure front that is moving through the US and off the North Carolina region into the Atlantic  - that’s the target she’s aiming for (in the models). I was hoping she would be making a bit more of a definite move towards the Bahamas by this evening, but with her slowing down a bit I will, instead, be looking for that tomorrow.

The forecast also makes her a category 3 storm by tomorrow afternoon. If she remains on a WNW track and moves away from Hispaniola, I agree with that. It looks like the Bahamas are going to have a bit of a  tricky time. If she is a cat 3 as she goes through the Bahamas, I would not put it past her to decide she’d like to be a cat 4 as she gets to the Florida Current/Gulf Stream region (assuming that’s the path she takes). I know the track has her making landfall probably in the Carolina’s on Saturday. Until she moves into the Bahamas, it’s a bit tricky to assess this (from my limited information) but tomorrow I will try and make the time to hop into my time machine and have a peek at the future.

Until tomorrow,

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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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