Friday, September 30, 2011

Hurricane Ophelia and Tropical Storm Philippe: September 30, Update A

Oh great googliemooglies and blisterin’ barnacles!! Bermudians, I hope you are ready! Ophelia exceeded everyone’s expectations today.

Hurricane Ophelia
In my opinion I think the official forecast has been underestimating her for days, but none of us were expecting her to get quite this strong. Officially she is now a mid-sized cat 3 and a very good looking storm with 120mph winds (cat 3 range: 111-130mph). The eye has been clear and steady for hours, so she might actually be closer to a cat 4 I think. Here are visible and IR satellite images of the Atlantic:

Despite this being a night-time view, doesn’t Ophelia look good? We can see Bermuda is just on the northwestern edge of the outer cloud bands.

Although she is strong, there are some things that are working in Bermuda’s favour:

1.Currently her convection is not as strong as it could be – you can see stronger convective activity just north of Cuba, with that area of red in the IR image. Remember, red means that the cloud tops are cold, which means they are deep, and usually have strong thunderstorms with possible tornados thrown in here and there.

2.There is still a bit of wind shear acting on her, and you can see that because she’s not completely circular, but has a streaming mass of clouds to the northeast.

3.She will pass to the east of the island. Although the NHC did not officially shift her to a Northward track until today, she’s been heading North since yesterday from what I’ve seen, which is why her track (and the forecast track) has been shifting to the east of the forecast since yesterday. The unknown part is how much of her will clip Bermuda. Hopefully it’ll be just a bit breezy tomorrow, with a couple of pockets of rain. If you look at the IR satellite, you can see a front that is moving off the US… also heading in Bermuda’s direction. They might get clouds from that if they don’t have much from Ophelia… but at least it won’t be as windy. Meteorologically speaking, it’s all very interesting stuff!

I’ve heard from Steve on Bermuda. They have been preparing – the usual drill. Wrap things in tarps, have a drink, move things away from windows, get the candles, have a drink, make sure there is enough water, beer, wine, ice cream, have a drink, batteries for the radio, matches etc. (umm… that’s my preparation list anyway ;-)). He’d like to know if anyone has got any ideas on where to park the car?

She is currently at 25.9N, 63W and is doing a good job at following that center of cone track (now) – only moving slightly east of that center line. She is moving rapidly northward at 16mph, and has a minimum pressure of 956mb. Interestingly, the lower level convergence and upper level divergence are not as strong as they could be (or were yesterday and earlier today), which might be an indication that she might weaken as she gets closer to Bermuda (I’m not sure of this though – it could be a blip). Water temperatures for both storms are around 27-29 deg C; certainly warm enough to sustain them. Ophelia should pass Bermuda late tomorrow afternoon.

Tropical Storm Philippe
In comparison, Philippe looks like a baby. However, you can see (in the IR satellite image) that his convection is stronger than Ophelia’s, even if his structure or circulation is not as well developed. He is under considerably more wind shear than his bigger sister, and it looks like that will persist for a while. Officially he is at around 23.5N, 46.2W, moving NW at 13mph. Winds are 50mph, with a central pressure of 1004mb. I am not sure he’s moving quite that fast, but the location and direction are about right. This morning the NHC wrote in their 11am advisry: “FINALLY...WE CAN CLEARLY SEE THE CENTER OF PHILIPPE. A SERIES OF MICROWAVE PASSES FROM OVERNIGHT SUGGEST THAT THE PREVIOUSLY ESTIMATED CENTER DISSIPATED...AND A NEW CENTER FORMED FARTHER NORTH...CLOSER TO THE DEEP CONVECTION.” This confused me, because I saw a clear center yesterday. Maybe they don’t look at their own satellite images? And the ‘previously estimated center dissipated and a new center formed’? Really? Tut tut tut. Obviously they don’t read my wonderfully enlightening blog (ahem, probably just as well really ;-))! Their ‘estimated’ center looked off to me a couple of days ago… I think they were finally beginning to move in the right direction on this one yesterday evening.

I see they finally moved his forecast track so it’s making more of a beeline for Bermuda. And why not? They are already prepared for stormy weather so what’s one more, hey? ;-) Actually, part of this is because the forecast track is following Ophelia, which is the biggest low in the Atlantic at the moment. The models will have him track towards that beacon of lowness (not a technical term! ;-)). The actual track is a little tricky for me to see, because he is surrounded by high pressure again and because the models are following Ophelia (and he will try and follow her too by the way). Maybe tomorrow or the following day it will become clearer. The NHC think he will have deteriorated into a Tropical Depression by Monday anyway.

For those whose interest was piqued by the science research cruise out there… an update from Dale on the JOIDES Resolution (which was drilling at around 22.7N, 46W): “To move out of Philippe's path we moved NE yesterday from early morning until late in the evening on a hdg of ~44 degrees, this morning we are on a heading of 145 degrees to get behind Philippe and move back onto the drill site. Colleagues on the Canary Islands report a dust storm impacting their location this morning and predict it will be over us sometime tomorrow evening around 1800 hours. So far I collected a number of microorganisms from the atmosphere. Also looking at the influence of aerosol deposition on microbial communities in surface waters...seas have been relatively smooth so far..........” Thanks Dale!

Please stay safe on Bermuda. Send me updates if you are able. I’ll check in and see what’s what tomorrow morning too.

There will be more tomorrow. Bye for now!

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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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