Thursday, September 02, 2010

Hurricane Earl, Tropical Storm Fiona, and Gaston, the remanent Low: September 2, Update A

The problem with interplanetary travel is the time it takes. I wasn't able to get to a computer to get an update out because of travelling. I wish they'd hurry up and invent a teleportation device. Or better yet, I'd like a real TARDIS so I don't have to pack either. ;-)
Hurricane Earl:
He's at about 32.5N, 75.2W, officially heading N at 18mph. He'll miss the outer banks, but parts of North Carolina are getting some breezy and wet weather. It looks to me as though he may be heading NNE now, which is good because it takes his eye away from the outer banks. He weakened today (as soon as I managed to get to a properly working computer of course ;-)). This is primarily because he's experiencing heavy wind shear from the southwest (if you look at satellite images you can see more clouds to the northeast of the system than to the south). Weakening is also partly because he has started to interact with land (North Carolina).
His wind speed is 115mph, so he's still a major cat 3 hurricane (range: 111-130mph) with a central pressure of 947mb. He may pick up a bit as he gets closer to the Gulf Stream (just south of the outer banks) but it's unlikely that he'll get beyond a cat 3 storm at that point because the wind shear is so strong and there is land interaction. His vorticity is still very strong over the entire troposphere, which means that he has the potential to intensify in the future but the wind shear would have to weaken, he'd have to move away from land, and water temperatures would have to be warm enough. Surface water temperatures are currently over 29 deg C, with waters warmer than 26.5 deg C in the upper 75 meters of the water column.
Water levels along the coast are about 0.5ft above normal south of Cape Hatteras and still rising (from Tides Online, looking at North Carolina - see this for details on how to look for yourself: 
He is forecast to cross Cape Hatteras tonight, and all states north of there are under Tropical Storm or Hurricane watches and warning. He should pick up in forward speed and is forecast to reach the Massachussetts area on Saturday.
Tropical Storm Fiona:
She's at 25.6N, 66.4W, moving NNW at 17mph. Her maximum wind speeds are 50mph, making her a mid-sized Tropical Storm (range: 39-73mph). Central pressure is 1002mb. She is also under a lot of wind shear from the north, so most of her convection is south of the center - and there is a LOT of convection for such a little stormy. Water temperatures are 27-29 deg C, with 26.5 deg C or warmer water in the upper 75m. She's heading towards Bermuda, but with the wind shear as it is, she's going to struggle to be more than a Tropical Storm. There is no vorticity in the upper half of the troposphere, just the lowest half. She is forecast to cross the Bermuda region on Friday night.
Gaston, the remanent Low:
So I'm absent for a day and an Atlantic Blob that I hadn't even got around to writing about because he was so weak goes from an unamed system, to a named Tropical Storm with a forecast of a potential hurricane, back to being just a remanent Low? Golly. Life in the fast lane. Was that all in the last day? Maybe I travelled in time too? Is this a wasted name (for now), huh?
Gaston still has some decent circulation, including vorticity in the upper half of the troposphere, which means that he could re-intensify. Unlike Earl and Fiona who are being hit by wind shear, Gaston is suffering from a severe attack of the <pause for dramatic music> Saharan Air Layer! <dun dun dun> ;-) He's just not able to get that convection going at the moment. His center is at 13.5N, 39.5W, his winds are estimated to be 30mph, central pressure is estimated to be 1009mb. He's over water of 27-29 deg C and is moving W at 5mph.  
The NHC has issued their last advisory on Gaston. There's a chance he'll re-group but I won't mention him again unless it looks like he's doing something interesting.
That's the state of play at the moment. Good luck to the North Carolinas - I see you are already getting a bit of rain in some parts.
Until tomorrow,
Blog archives at

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 was there and was going to "run away, run away" (Monty Python), I'll let you know.

No comments: