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Posted at 11:40 AM ET, 08/20/2009

Hurricane Bill to Bring Big Swells to East Coast

By Capital Weather Gang

But track should keep storm center away from U.S.

* Still Hot & Humid: Full Forecast | Hurricane Tracking Center *
* NatCast | A/C or No A/C? | Hurricane-Climate Change Debate *

Updated: Thursday Aug. 20 @ 3:20 p.m.

By Dr. Greg Postel, Hurricane Expert

Latest track forecast for Hurricane Bill, as of 2 p.m. Thursday. Courtesy National Hurricane Center.

Talk about a well-placed track, at least for now. The center of Hurricane Bill, a Category 3 storm currently about 645 miles south of Bermuda, is on course to track well west of Bermuda and well east of most of the U.S. East Coast.

Still, since Bill is a large tropical cyclone with hurricane-force winds (74 mph or higher) extending outward roughly 105 miles from its center and tropical storm-force winds (39-73 mph) out to about 260 miles, Bermuda could easily see tropical storm-force winds and is under a Hurricane Watch. In addition, the Bahamas, Bermuda and most of the East Coast, including the mid-Atlantic this weekend, will likely experience "extremely dangerous surf and life-threatening rip currents," according to the National Hurricane Center.

Keep reading more for more on Hurricane Bill...

Satellite view of Hurricane Bill at 11:15 a.m. today. Courtesy NOAA.

At the moment, Bill is moving northwestward over the western Atlantic. Though some of the computer models have recently nudged its projected track a little closer to North America, a strong midlatitude low-pressure system migrating southeastward from Canada into the Ohio Valley will reach the East Coast in 3-4 days. This system is expected to strengthen winds from the southwest along and east of the Appalachians. This air flow should steer the storm itself safely away from the Lower 48. At this time, it appears Bill's most significant impact on the U.S. will be the agitation of the coastal waters.

By Sunday and Monday, Bill could pose a more direct threat to the Canadian provinces of Nova Scotia and Newfoundland, though there's a good deal of uncertainty to the storm's track at that time frame.

Recent reconnaissance flights into Bill's inner circulation have shown well-defined features characteristic of a major hurricane, with flight-level winds (~10,000 feet) of 139 mph (121 knots). It is difficult to gauge the wind strength at the 10-meter level (the official height at which intensity is defined), owing to various factors influencing the vertical structure of the wind field. But based on some of the measurements of the boundary layer, it's probably in the 105-120 mph (95-105 knot) range.

In looking at the flow characteristics surrounding Bill, it seems as though the hurricane is situated in an environment not ideally suited for much further intensification. In particular, there is a noticeable north-south elongation in the cloud presentation. This suggests the circulation is being tugged northward by a nearby band of winds from the southwest.

In addition, the reconnaissance also noticed numerous swaths of relatively dry air at many levels close to the core, which is not too surprising given its close proximity to a Saharan air layer.

At this time, it appears that neither the local shearing effects associated with the nearby southwesterly current, nor the presence of arid surroundings, will be strong enough to trigger a significant weakening of this large and well-organized tropical cyclone. This will have to wait a few days until the system moves over cooler waters at about 40°N latitude and encounters much stronger winds aloft associated with the approach of the East Coast system.

So Long Ana?

Tropical cyclone Ana effectively disintegrated over (or near) the Antilles a couple of days ago. The system never developed a long-lived core, and instead remained a small, shallow circulation that was unable to fight off the shear, dry-air layers, and land mass it encountered. The last advisory on Ana posted by the National Hurricane Center placed the center of the swirl just south of the Dominican Republic late Monday. Now, an upper-level cyclonic circulation (unfavorable for storm development) occupies the very same region where we believe Ana's remains lie.

By Capital Weather Gang  | August 20, 2009; 11:40 AM ET
Categories:  Tropical Weather  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati   Google Buzz   Previous: Forecast: More Heat, Humidity & Storm Chances
Next: PM Update: More Showers & Storms for Some


Hrm. We were thinking of going to Rehoboth Beach this weekend. Bad idea?

Posted by: Hemisphire | August 20, 2009 12:20 PM | Report abuse

There will be a front in the vicinity, so Tstorm risk will be there (unrelated to Bill). As far as effects from the hurricane ... big waves and rip currents. If you like those conditions ... :)

Posted by: gregpostel | August 20, 2009 12:50 PM | Report abuse

So what's the NATS CAST for SATURDAY?

There's a picnic for season ticket holders from 1-4

Then the game at night!

Posted by: CALSGR8 | August 20, 2009 1:09 PM | Report abuse

Should be perfect surfing conditions. Huge swells under sunny skies hopefully.

Posted by: dsk097 | August 20, 2009 1:22 PM | Report abuse

Cracks me up when all the media (TV and print) gets the gasping pants about any hurricane that might manage to make it to the shores of the US. I sincerely hope Bermuda does not suffer badly.

I would think it's been a good thing that we've had no monster hurricanes for a long time. I don't think Bill will turn out to be bad and there really isn't anything else on the horizon right now. Oh dear, oh dear, the weather news is so dull!

Posted by: OregonStorm | August 20, 2009 1:25 PM | Report abuse

Mmmm. Big swells. Hope they're breaking reasonably deep. Double overhead and a shorebreak is not fun. If they are breaking reasonably deep then I'll be hauling out the longboard.

Sunday is looking really good:

Posted by: wiredog | August 20, 2009 2:08 PM | Report abuse

The media, I think, does have a responsibility to alert the public to impending meteorological hazards. However, the profit motive can indeed obstruct honest reporting/journalism in a way that can be a nuisance at best, and dangerous at worst.

Posted by: gregpostel | August 20, 2009 2:22 PM | Report abuse

Well placed track? I'm not sure that Nova Scotia and Newfundland would agree. Looks like the Canadian Maritimes will get the brunt of what makes it up there. Canadians are people too, so I hope there's not any loss of life or too great property damange.

Posted by: HokieAnnie | August 20, 2009 2:31 PM | Report abuse

I agree with your sentiment regarding the wording of "well-placed" track. I should not have used that exact text, and I'm sorry for the confusion. I sincerely hope everyone stays safe, and there's no loss of property.

Posted by: gregpostel | August 20, 2009 2:44 PM | Report abuse

what about south shore of Long Island? weekend trip planned!

Posted by: jps3 | August 20, 2009 3:13 PM | Report abuse

Long Island - big waves, rip tides. There will be a frontal zone in the area (unrelated to Bill), so Tstorms are a good bet. But the primary hurricane circulation will likely pass way off to the East.

Posted by: gregpostel | August 20, 2009 3:35 PM | Report abuse

i have been tracking hurricanes online for a couple years now and i think it is too early to call bill as a hurricane that will not make land fall in the US my bet is it will make landfall somewhere in the vicinity of new jersey so people need to be prepared

Posted by: andrew37 | August 20, 2009 3:47 PM | Report abuse

Andrew37 ... Glad you're an enthusiast !

However, it is hard to argue against the tightness of this track cluster:

But it is true that people should keep an eye on the situation regardless

Posted by: gregpostel | August 20, 2009 3:51 PM | Report abuse

I love seeing surf talk and Swellinfo links on the Post. :)

I'm planning on going out to OC/Assateague this weekend just to watch, then playing hooky early next week for actual surfing. I don't think most DelMarVa spots can hold triple overhead. And a 20-second period is nothing to mess around with.

Posted by: rallycap | August 20, 2009 4:13 PM | Report abuse

From the Weather Channel website:

Stay out of the ocean for the next 4-5 days beginning Thursday and continuing through Sunday.

In order to be safe, just stay out of the water. Simple as that. It's tempting but don't do it. You're testing your fate.

Also those fishing on rocks, walls adjacent to the ocean, and jetties should remain away from areas where an occasional high wave can wash them into the ocean.

Do we sound a bit condescending? Well, if that's what it takes to keep you and your family safe then so be it. Your safety is priority number one!

Posted by: Yellowboy | August 20, 2009 5:20 PM | Report abuse

5 p.m. update from Hurricane Center ups Bill's intensity to 125 mph.

Posted by: Andrew-CapitalWeatherGang | August 20, 2009 5:22 PM | Report abuse

I forgot to mention they're talking about the life-threatening rip currents.

Posted by: Yellowboy | August 20, 2009 5:22 PM | Report abuse

Hey, hurricanes are good for the earth. they act as a natural air conditioner, and air purifier, and cool the surface of the earth. If you happen to be in the way of one, well......too bad.

Posted by: rkayblock1 | August 20, 2009 5:32 PM | Report abuse

We are headed to Prince Edward Island in two weeks. How do the conditions that Bill is likely to bring there (Cat 1 on the east side of the island, TS for Charlottetown) compare to the winter storms that come off of the Gulf of St. Lawrence? In other words, will things be any different in PEI after this weekend?

Posted by: vtavgjoe | August 20, 2009 5:39 PM | Report abuse

This was almost an ideal setup for a good hit for places like Long Island or southern New England.. the Atlantic ridge weakness is just in a "bad spot" for those crazed hurricane fans up there.

If you want to see something really cool, check out this 25mb image of rapid scan (every minute) visible satellite yesterday afternoon into sunset.

Posted by: Ian-CapitalWeatherGang | August 20, 2009 5:44 PM | Report abuse

So, where will Bill likely hit?

In Nova Scotia, the northeast coast from Sheet Harbour to the northeast looks most likely to take a hit, probably from the weak side of the storm. Population centers most likely to be affected include Sydney, New Waterford and Glace Bay in the far northeast. Areas from Halifax to the south and west will see relatively little direct impact, but may experience a northerly gale as the storm passes.

Newfoundland would take a square hit, but the heavily-affected south coast is very sparsely populated. The major population centers from St. Johns, Gander, Grand Falls, etc. are mainly on the north side of the island, as is the main highway, Canada Route 1. These areas are inland from the expected strike point and will likely be sheltered from major impact. Cape Race is east of the expected impact site, while St. Lawrence and Grand Bank could see some action. The most affected area includes the hamlets of Francois, Burgeo and Grand Bruit, near where the center of Bill may come ashore. St. Albans may also be hit but is at the head of a fjord or sound rather far inland.

Posted by: Bombo47jea | August 20, 2009 5:51 PM | Report abuse

I'm thinking a more westerly track than the official forecast, which would bring Cape Cod into the envelope of possibilities (cone of uncertainty)

The fact I'll be at the Cape has nothing to do with this - really!

Posted by: SteveT-CapitalWeatherGang | August 20, 2009 5:59 PM | Report abuse

Andrew37 so you have been tracking hurricanes for years? How do you justify your wild prediction that Bill comes ashore at New Jersey when all of the models have been showing a curvature for days?

Posted by: MKadyman | August 20, 2009 6:14 PM | Report abuse

Fair amount of guidance with at least some shift east today. It seems to me once you start heading that way it's hard to reverse especially given a tropical cyclones proclivity to turn right at those latitudes. The EURO is not all that close at all, hard to not hug that model a bit. Surf's going to be crazy either way. Have fun, Steve.. was actually supposed to be there this weekend too but plans changed a few weeks ago.

Posted by: Ian-CapitalWeatherGang | August 20, 2009 6:14 PM | Report abuse

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