Bill weakens, but still generating huge waves

By: Dr. Jeff Masters , 2:29 PM GMT on August 20, 2009

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Hurricane Bill has peaked in intensity, and now shows signs of weakening. Visible and infrared satellite imagery show that the hurricane is no longer as symmetric as it once was, with an oval instead of circular shape to its cloud pattern. Upper-level cirrus clouds are restricted on the storm's southwest side, indicating that upper-level winds from the southwest are shearing the storm. The University of Wisconsin CIMSS wind shear analysis shows about 10 - 15 knots of wind shear impacting Bill. The latest 8:18am EDT eye report from the Hurricane Hunters indicated that the eyewall had a gap in its southwest side, and the pressure had risen 2 mb since last night, to 951 mb. Maximum winds at the surface observed by the SFMR instrument were only Category 2 strength, though winds measured at the aircraft flight level of 10,000 feet still suggested Bill may be a Category 3 hurricane.

Wind shear is forecast to remain low to moderate, 5 - 15 knots, for the next three days, and it is possible Bill may see a relaxation of the wind shear affecting it, allowing re-intensification to Category 4 status. Sea Surface Temperatures (SSTs) will be plenty warm over the next three days, as Bill traverses a region of ocean with SSTs of 28 - 29°C. Total ocean heat content is at a maximum today, and will gradually decline over the next three days.


Figure 1. Visible satellite image of Bill at 1:33 pm EDT Thursday 8/20/09. Bill had an oval shape oriented SW - NE, and was missing upper-level cirrus clouds on the southwest side, indicating that wind shear from strong upper-level southwesterly winds was affecting it.

Water vapor satellite loops continue to show two small "short-wave" troughs of low pressure to the northwest of Bill, and these troughs are continuing to steer Bill to the northwest. The short wave troughs (so called because they have a relatively small amplitude and wavelength) are not strong enough to turn Bill due north, so Bill is expected to miss Bermuda. The official NHC forecast has the radius of tropical storm force winds from Bill barely reaching Bermuda on Saturday, so the island can expect sustained winds in the 35 - 45 mph range for a few hours on Saturday if the hurricane follows the NHC forecast track.


Figure 2. Visible satellite image of Bill's eye zoomed in, taken from NASA's Aqua spacecraft at 10:15am EDT Wednesday August 19, 2009. Image credit: NASA GSFC.

An unusually strong "long wave" trough of low pressure (called long wave because of its large amplitude and wavelength) is expected to develop along the U.S. East Coast this weekend. This trough will turn Bill to the north, and also bring high levels of wind shear in the 40 - 65 knot range on Sunday. The models have moved the forecast landfall point of Bill several hundred miles back and forth to the east and west over the past few days, but mostly agree that Cape Cod and Maine will probably miss a direct hit by Bill. However, these regions are still at the edge of Bill's cone of uncertainty, and a direct strike by Bill at Category 1 or 2 strength is a possibility. However, it is more likely that Bill will come ashore over the Canadian provinces of Nova Scotia or Newfoundland. Bill will be weakening rapidly as it makes landfall, and is likely to be a Category 1 hurricane if it hits Nova Scotia, or strong tropical storm if it hits Newfoundland. If Bill follows the official NHC forecast path, winds on Cape Cod and in eastern Maine are likely to remain below tropical storm force (below 39 mph).

Bill's waves
Hurricane Bill is generating huge waves, thanks to its enormous size and major hurricane intensity. Bill passed about 75 miles southwest of Buoy 41044 this morning, and the buoy recorded sustained winds of 67 mph, gusting to 92 mph, with a significant wave height (the height of the average 1/3 highest waves) of 38.8 feet. Output from NOAA's Wavewatch III model suggests that significant wave heights near Bill's center will peak at 50 feet by Saturday. Large swells from Bill will reach Bermuda this afternoon, increasing seas to 5 - 9 feet, according to the Bermuda Weather Service. Seas will increase to 10 - 20 feet on Friday and 20 - 30 feet on Saturday as Bill makes its closest approach to the island.

In the U.S., Bill's swells will reach New York's Long Island on Friday afternoon, and seas will build to 7 - 10' on Saturday and 12 - 16' on Sunday in the near shore waters. By Friday night, Bill's swells will be affecting the entire U.S. East Coast from Florida to Cape Cod. Maximum sea heights in near shore waters over the weekend will be about 7' from Florida to South Carolina, 11 - 14' along the North Carolina coast, 8 - 11' along the mid-Atlantic coast, and 10 - 11' along the coast of Maine. The highest waves along the U.S. coast will occur at Cape Cod, Massachusetts, where waves of 18 - 23' are being forecast by NOAA for Sunday. Bill's high waves are going to cause millions of dollars in erosion damage and create very dangerous rip currents and swimming conditions along the coast.

Hurricane History of Canada
Canada is no stranger to hurricanes, and receives a hit by a Category 1 or stronger hurricane several times per decade, on average. The most recent hurricane strike on Canada occurred in 2008, when Hurricane Kyle struck the southwestern tip of Nova Scotia, just north of Yarmouth. Kyle was rated a Category 1 hurricane with 75 mph winds at landfall, but damage was limited to uprooted trees, scattered power outages, and minor street flooding in Shelburne. The other hurricane to hit Nova Scotia this decade was much more serious. In 2003, Hurricane Juan made landfall at Halifax, Nova Scotia, as a Category 2 hurricane with 100 mph winds. A record storm surge of 4.9 feet inundated the city's waterfront, resulting in extensive flooding of the Halifax and Dartmouth waterfront properties. A buoy just outside Halifax Harbor measured a significant wave height of 9 meters (30 feet), and maximum wave heights of 20 meters (65 feet). Four people died in the storm. Juan downed a phenomenal number of trees--agriculture specialists estimate that 50 - 100 million trees blew down in Nova Scotia in two hours, with one million downed in Halifax alone. The Canadian Hurricane Center has a nice historical hurricane page with more information and photos.


Figure 3. Close up view of the damage at the Bedford Yacht Club after Hurricane Juan in 2003. Photo: Gary Dunbrack. Image credit: Environment Canada website on Hurricane Juan.

Elsewhere in the tropics
There are no threat areas in the Atlantic worth mentioning today, and no reliable models are calling for tropical cyclone development over the next seven days.

I'll have an update Friday morning.

Jeff Masters

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Funny the steering maps just updated...LOL the High has already weakened alot in the last 3 hrs.
Member Since: September 2, 2007 Posts: 179 Comments: 20450
Argh, dang system doesn't want me to post... trying again.

@625 - Galveston is really working on it. They've got the beach looking better than it did pre-Ike, and from the outside the town looks pretty whole. However, there's still a lot of repairs going on and a lot of abandoned homes. I heard that the Flagship owner rode out the storm in the hotel, but that may just have been a rumor. They're also rebuilding some of the businesses out on piers like Murdoch's, but sadly the Balinese room is gone forever.
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Quoting TampaSpin:
Here is the Steering map for Bill.......that trough better start tapping away at that VERY STRONG building High on the EAST coast or things will be changing abruptly real fast...

Steering Layer 250-850mb or

940-949mb pressure 112-122 kt storms

Changing how ?
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Quoting dolphingalrules:
wilma hit between north miami and delray bch.


From Wikipedia:
Wilma crossed the state in about 4.5 hours and weakened to winds of 110 mph (175 km/h) after entering the Atlantic Ocean near Jupiter, Florida
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Quoting RickWPB:


Yep, my experience as well. Frances was huge and very slooowww moving. Jeanne a bit stronger, but since it was smaller, didn't seem as bad here in West Palm Beach area. Wilma was the worst for us. As you say, the backside was a surprise!

What I remember from TV coverage after H. Jeanne was that Hutchinson Island had broken concrete power polls. That area really got slammed really hard twice in 3 weeks. Two storms made landfall within 1 mile of each other at Sewells Point.


We live on the St. Lucie River and can see Sewall's Point from our back yard. Frances took 1/3 of our concrete dock and then Jeanne took the rest and most of our backyard. Wild ride.
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Quoting IKE:
Bill is continuing to go east of the tropical forecast points. Could be a closer call for Bermuda then forecasted.


Either that or it's trying to pull a Jeanne and loop around ... LOL ... J/K
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Flood - I hear ya. I was 8 miles north of the north wall of Andrew and south of the Hurricane Center which had 145mph gusts and that was enough for me. The day after, was checking in on our employees who lived in the area and each one told me the same story. The ones who were closest to the eye had quite literally made their piece with God before the night was out. They were positive they were going to die. I will never forget the shell-shocked look in their faces and eyes.
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Quoting Floodman:


You can end up with a cut-off low that develops into something on it's own; a cut off low is a tag end of a front that stalls and gets separated from the low itself


Oh ok, thanks!
Member Since: July 2, 2009 Posts: 0 Comments: 2811
656. slavp
Quoting SomeRandomTexan:
I hear Galveston is coming back better than ever and the structures are updated and new...

HWanderer... the song "Wake me up when September ends" comes to mind..lol
I was there for Easter week. Looked to me most everything was almost back, except on Bolivar, that is still pretty messed up.
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.
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Quoting BiloxiIsle:
WS--Rita and Dennis did not hit Miami, Katrina was a Cat 1 and Ernesto and Fay were not major hurricanes. Maybe Wilma, not sure exactly what damage occurred in Miami. It seems you really have not been through a "major" hurricane. If you had been, truly, then you would not wish them so much!
I have lived in Grand Cayman since 1973 and I was so sick and tired of hearing young folks hoping for a hurricane. I always used to tell them not to wish for that. They were the same ones crying like babies when Ivan hit in 2004 with Cat 5 winds and gusting to (I have heard) over 200mph. WS, Be careful.
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Here is the Steering map for Bill.......that trough better start tapping away at that VERY STRONG building High on the EAST coast or things will be changing abruptly real fast...

Steering Layer 250-850mb or

940-949mb pressure 112-122 kt storms

Member Since: September 2, 2007 Posts: 179 Comments: 20450
Quoting PBG00:


really guys? It must offend you greatly to feel the need to make a comment about it. Wow


That's nonsense, PBG; just someone trying to get a rise is all...the avatar is fine...now bear in mind that mine is a caricature of a rock guitarist so take my comments with a grain of salt
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I hear Galveston is coming back better than ever and the structures are updated and new...

HWanderer... the song "Wake me up when September ends" comes to mind..lol
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Member Since: Posts: Comments:
wilma hit between north miami and delray bch.
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647. PBG00
Quoting JupiterFL:


I actually really like it. It stands out and I don't have to click on it to see what it is. No offense intended.


Thanks. I actually like it too..

Later guys, nice chattin with ya!
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Quoting TexasHurricane:


ok, I'm confused what does a "strong front" or trough or whatever have to do with forming storms in the GOM or Caribean? Just curious...


You can end up with a cut-off low that develops into something on it's own; a cut off low is a tag end of a front that stalls and gets separated from the low itself
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Quoting TexasHurricane:


Don't know. I know that model we saw yesterday suggested something...other than that I hve no clue. Are you seeing something else about it?


YES i just came from Stormytops weather center desk.........LOL......NO i don't see anything yet.
Member Since: September 2, 2007 Posts: 179 Comments: 20450
Quoting guygee:
Hey Floodman - I'm wondering if 1)it will close off, 2)if it will couple with Bill. Unlikely, but I've seen stranger things happen.

...The shoe is on the hand it fits
There's really nothing much to it
Whistle through your teeth and spit
cause it's all right.

Oh well a Touch Of Grey
Kind of suits you anyway.
That was all I had to say
It's all right.

I will get by / I will get by
I will get by / I will survive


It looks like Bill is going to run it right over.
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A WHOPPER of a storm! Goes up there with Dean and Felix.

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Quoting oakland:


Wilma was a scary storm. Sailing across the Everglades and not losing any intensity. She was not fun. I was still in Ft. Lauderdale when she hit.
i was there for wilma..coming from the west..the tv said that @ 8 am it was a cat 2..my patio went at 8:10 could not have been a cat 2, maybe 3.but, 12 hours later the temp drop 30 degrees.
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Bill has definitely been riding the east side of the forecast track. Looks to miss the next point to the east again.
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Did Bill eat the ULL that was over the Appalachians and was moving down the coast to the SW ? It seems like is has virtually almost dissipated ?

I am not seeing something ?
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639. PBG00
Quoting BiloxiIsle:
WS--Rita and Dennis did not hit Miami, Katrina was a Cat 1 and Ernesto and Fay were not major hurricanes. Maybe Wilma, not sure exactly what damage occurred in Miami. It seems you really have not been through a "major" hurricane. If you had been, truly, then you would not wish them so much!


Wilma hit more north..Plam Beach county and Martin County
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Bill is Back.

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Quoting PBG00:


really guys? It must offend you greatly to feel the need to make a comment about it. Wow


I actually really like it. It stands out and I don't have to click on it to see what it is. No offense intended.
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it has to be scary to be on bermuda and seeing bill on sattelite and how close it is and the size of the storm. anybody on bermuda on here and their observations?
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Quoting Floodman:


Well, JFV...sorry, I mean Weatherstudent, none of those would ghave been direct on landfalls for you
Correct me if I am wrong but wasn't Andrew the last major to make a direct landfall in the Miami area ?
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WS--Rita and Dennis did not hit Miami, Katrina was a Cat 1 and Ernesto and Fay were not major hurricanes. Maybe Wilma, not sure exactly what damage occurred in Miami. It seems you really have not been through a "major" hurricane. If you had been, truly, then you would not wish them so much!
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Hey Floodman - I'm wondering if 1)it will close off, 2)if it will couple with Bill. Unlikely, but I've seen stranger things happen.

...The shoe is on the hand it fits
There's really nothing much to it
Whistle through your teeth and spit
cause it's all right.

Oh well a Touch Of Grey
Kind of suits you anyway.
That was all I had to say
It's all right.

I will get by / I will get by
I will get by / I will survive
Member Since: Posts: Comments:
632. flsky
Quoting medicroc:
The forecast becomes very interesting on Friday night through much of Saturday. A strong disturbance will dive into the trough from the northern Plains. The distance the strong disturbance dives south on Friday afternoon will have a significant impact on the overall track of Hurricane Bill. Current guidance generally suggest that Hurricane Bill, although much closer than forecasts had earlier suggested, will basically remain over the Atlantic Ocean. However, some guidance is now picking up on the potential for the strong disturbance diving into the Ohio Valley to intensify and force the upper level trough into a negative tilt over the Southeast. This MAY bring Hurricane Bill closer to the forecast area with more significant impacts. The exact track of Hurricane Bill is still uncertain and all individuals in the forecast area will need to monitor the track of this dangerous hurricane.
Source
http://www.nynjpaweather.com/

To say the lease - this is interesting. Thanks for posting it.
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631. slavp
Quoting TampaSpin:
AS strong as the front is that is moving thru that will pick Bill up......I bet a storm will blow up on the tail end some where either in the GOM or Caribbean in 7days or less..any thoughts.
Wouldn't surprise me at all. Look at the flareups already over LA.
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606. southfla

I've been through the eye of a three and I don't want to see a four...
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Quoting SomeRandomTexan:


quite possible to my thinking with such a strong front..


ok, I'm confused what does a "strong front" or trough or whatever have to do with forming storms in the GOM or Caribean? Just curious...
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Quoting NRAamy:
Yes there was, but this was from 1938. They didn't have everything we have now

like Cherry Garcia ice cream, and dancing purple hippos that tell lame jokes on weather blogs....
Satellites, Models, and Blogs, OH MY!
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Quoting stormpetrol:
Link
Look at that eye.


The dry air has made a slot entering from the SE side of the system all the way around and into the eye on the SW side. Penetrating the eye wall on the west side.

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Quoting WeatherStudent:




Ok, Dennis, Rita, Katrina, Wilma, Fay, and Ernesto.
Winds from these you named were NOT major hurricane. Dennis 36kts gust 44 kts/Wilma 58kts gust 80/Katrina passed Miami as a Cat 1/Fay was a TS/Ernesto Cat 1/Rita up through the Gulf side. Pleses think before you wish because the damage done by a major hurricane is not something exciting to see. It is soul breaking. I know this from experience so "Be careful what you wish for"
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SRT Yep except 2006 we have been getting hit every year since then. If we make through September I might feel a little better. Geesh!

Toaster Thanks. I wondered how it was if it went through Ike. It's sad that they're tagging it now days. I hope it and Galveston all together come back. It's a beautiful and charming city. Every time I've been there everyone was as polite as can be. Just another way hurricanes change things. :(
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Quoting WeatherStudent:



Miami, FL.


Well, JFV...sorry, I mean Weatherstudent, none of those would have been direct on landfalls for you
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623. PBG00
Quoting JupiterFL:


or perhaps that was Walmart on the phone?


really guys? It must offend you greatly to feel the need to make a comment about it. Wow
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Quoting PBG00:


Those two storms were nuts..Francis sat over us for hours and hours (my first hurricane)..then 10 days no power. Finally got it back and a few days later Jeanne came and knocked it out for another week!

Tell ya the truth thouigh, Wilma scared me most of all. That was one strong storm (for my experiences anyway, and the back side was worse that the front!)


Yep, my experience as well. Frances was huge and very slooowww moving. Jeanne a bit stronger, but since it was smaller, didn't seem as bad here in West Palm Beach area. Wilma was the worst for us. As you say, the backside was a surprise!

What I remember from TV coverage after H. Jeanne was that Hutchinson Island had broken concrete power polls. That area really got slammed really hard twice in 3 weeks. Two storms made landfall within 1 mile of each other at Sewells Point.
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Quoting GeauxGirl:


Well said. Katrina cured me of "wishing" I could experience a major hurricane. Be careful what you wish for.


Yeah me too. Living in a FEMA trailer with a wife and two kids made we wish hurricanes were never born. However, maybe it is because it has been 4 years already I don't know, but I got that itch again. I know...crazy, probably just hard headed I guess. lol
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619. IKE
Bill is continuing to go east of the tropical forecast points. Could be a closer call for Bermuda then forecasted.
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Quoting TampaSpin:
AS strong as the front is that is moving thru that will pick Bill up......I bet a storm will blow up on the tail end some where either in the GOM or Caribbean in 7days or less..any thoughts.


Don't know. I know that model we saw yesterday suggested something...other than that I hve no clue. Are you seeing something else about it?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Quoting guygee:
Any thoughts on the possible effect of the small mid-ull that looks to be trying to close off around 23N, 72W, and diving WSW towards the Bahamas? A flash in the pan?

Seems to be allowing the west side outflow of Bill to expand.


I asked about this at 12:30 today and nobody seemed interested withit or the thing south of yuca
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Quoting TampaSpin:
AS strong as the front is that is moving thru that will pick Bill up......I bet a storm will blow up on the tail end some where either in the GOM or Caribbean in 7days or less..any thoughts.


quite possible to my thinking with such a strong front..
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Quoting guygee:
Any thoughts on the possible effect of the small mid-ull that looks to be trying to close off around 23N, 72W, and diving WSW towards the Bahamas? A flash in the pan?

Seems to be allowing the west side outflow of Bill to expand.


Howdy, Guygee...I noticed it earlier but was waiting for brighter minds to mention then explain it...LOL
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Quoting TampaSpin:
AS strong as the front is that is moving thru that will pick Bill up......I bet a storm will blow up on the tail end some where either in the GOM or Caribbean in 7days or less..any thoughts.


not out the question...a little early in the season for it, but it's a strong front for this early too.
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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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