Sunday, October 28, 2012

'Hurricane' Sandy: October 28, Update A

If you are anywhere along the coast between Virginia and New York, you should only be reading this if you have made your preparations for Sandy! Those I’ve heard from in various states are ready or preparing. If you are in a mandatory evacuation zone (or even if you are not), please heed the warnings from your local emergency managers. They really know the local area best – where it will flood, where it won’t, what roads get jammed etc.

Sandy is still off the North Carolina coast and south of Cape Hatteras, at 34N, 70.9W, but according to the forecasts, is on the verge of making the turn to the north. She is officially heading NE at 15mph, but if things go as forecast, we should see a NNE movement in the next advisory at 11pm. She did slow down between my last update and this one, and the track shifted slightly north so landfall looks like it will be in New Jersey now. Winds are still 75mph, central pressure 950mb, so no change in intensity. I still think she’s a bit weaker than this and is a Tropical Storm, but the entire situation is a little more complicated so I’ll let that part go.

Sandy is going to be quite windy with a lot of coastal flooding (including up estuaries). There will be some rain, but not the usual torrential downpours that can come along with a hurricane/tropical storm, so that won’t be the biggest issue. The winds may take down trees and tree limbs, which means potential power losses. And because she’s a hybrid storm, the low front moving in from the west is bringing cold weather with it (I am not sure about how much snow there will be – probably not as much as a normal nor’easter).

I don’t think the tropical storm side of Sandy will change too much between now and the forecast landfall (which is supposed to occur overnight on Monday/Tuesday). If she was just a tropical system, I’d say that she would weaken. Although wind shear is a little weaker, she is over sea surface water temperatures of 26 deg C, so only just about warm enough to sustain her convection. She will cross a patch where the surface water temperatures are 26-27 deg C (this is the Gulf Stream off Cape Hatteras), but then she will get back over water that is too cool to sustain her as a tropical storm. This is when she will transtition to be an extratropical storm. She still has a lot of dry air in her, which is another reason she doesn’t have too much convection. You can see this in these satellite images (visible, infra-red to show the convection, and water vapour to show the dry air):

I’m guessing that black patch in the water vapour may be levels below a certain threshold. The tricky part of this puzzle is the low pressure front and how it will interact with Sandy.  

Looking at some real observations… From the SECOORA website that I showed you a couple of days ago, the nearest buoy is now about 70 miles northwest of her center, so well within the storm bands. That has wind measurements of about 32mph, with air pressure at 969mb and still decreasing. From Tides Online, I see that the maximum storm surge so far has been at Duck, NC and assorted places in Virginia, where the peak surge was 4 ft above normal but is decreasing now (for now). Ocean City Inlet in Maryland, places in Delaware, and Cape May in New Jersey had/have water levels 3 ft above normal. North of there the water is currently 2 ft above normal at Atlantic City (NJ) and in the Hudson River and at Montauk, in New York (I used to live on Long Island years ago and loved it!), and a bit higher in Long Island Sound.

<Observations Alert> If you want to look at observations of wind, temperature, pressure etc at places that are on land, you can go to this National Weather Service site: Pick the state of interest from the drop down menu under the Automated Surface Stations. Click on a location under ‘Current Weather Conditions’, and you will get a table of wind speed, temperature, pressure etc. For example, the observed winds in Atlantic City are about 21mph at the moment. <End Observations Alert>

Here is a photo from Laura S. in New Jersey, whose home is on the Mullica River near Atlantic City:

This was her dock earlier today … that is not high tide. The water levels will continue to increase… the storm is still blowing water onshore and will do so all day tomorrow.  

Good luck to all my family, friends, and readers in the northeast! If you have a chance, let me know how things are going.  

Stay Safe!

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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.


Fiona Mac said...

Hi Jyo ! I thought I'd find you commenting on this ! Love it. You sound well and as bubbly as ever. Take care over there ! Hugs from your old schoolmate over in Blighty [living about 4 miles from Jodrell now]..... Fiona x

Jyo said...

FIONA!! Gosh! How amazing. :-) Can you find me on FB? I looked and there were a bunch of Fiona Mac's!