Bill weakens, but still generating huge waves

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

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


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

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1064. chrisrw
Quoting Ossqss:


This was my first mouse on a commador 800.



Commodore, I believe
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1063. Noil
I am from Nova Scotia, but living in NC now I was in Halifax 2 days after Juan went through, the city was a huge mess and many sections you couldn't get too. The part of the province I am from didn't get much from Juan mostly rain and a little bit of wind. If one looks at Halifax harbour from a map you can see there is real potential for high storm surge. In some parts of the harbour there are issues with spring tides and spring storms creating minor flooding when both occur at the same time. Point Pleasent park was the hardest hit area of Halifax if I remember correctly as far as tree damage goes, they lost trees that were over a hundred years old.
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http://www.wunderground.com/wximage/myphotos.html?album_id=3&handle=TightLines305
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Someone said yesterday that the 1938 Hurricane hit the east coast at like 60 mph!
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connie, babe, u can have a hurricane just about any time if u live in the Pines.... lol....

OK, just messin' witcha..... but, seriously....

Broward county is genuinely in line to get hit by a 'cane during any month of the season, June to November. Doesn't mean it will happen or even that it's likely, but it's possible.

But I gotta tell u girl, we got some people out here in the Bahamas praying against these hurricanes. Don't go tempin' fate with comments like that.....
Member Since: December 31, 1969 Posts: Comments:
1059. IKE
Quoting amd:
that is one powerful trough heading toward the east coast of the us. It's not everyday that a sub 1000 low is trucking through the great lakes in August.

Link


And a 54 dew point in north Texas in August....wow....
Member Since: December 31, 1969 Posts: Comments:
Quoting hydrus:
Tell her about the one that whacked Tampa,FL Nov-30-Dec-1..1925.


Shhhh...don't SCARE her...Tampa, by the way, is WAY overdue...nothing, if I recall, since Dog in 1950 (or was it 52?)
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1057. amd
that is one powerful trough heading toward the east coast of the us. It's not everyday that a sub 1000 low is trucking through the great lakes in August.

Link
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1056. Ossqss
Quoting NRAamy:
Ossqss...you sure you didn't use that with your Pong game?


No Amy, it was gnip gnop, LoL

L8R

Yikes, I see a fortran discussion coming
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Quoting Dakster:




Better than being a dumb a$$. You said when you were a young tech. BTW, we still have legacy systems in place at my current job... No mice, no color screens either...


You are correct on both scores (better a smart ass than a dumb ass and the terminals w/out mice)

The machines you're talking about are mainframe terminals. They're text command driven, like DOS (you probably don't have a good recollection of that either) so no mouse was required. Typically you saw those in banks and Universities where mainframe access was granted...it's not true that they weren't color screens; in a mainframe session you had color...typically one, orange, green or sometimes blue (the blue ones will really hurt your eyes after a while). there may be others but those are the colors I dealt with
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1054. hydrus
Quoting Floodman:


Sorry, baby; Hurricane season starts in June and ends in November; remember Wilma made landfall on 10-24-05
Tell her about the one that whacked Tampa,FL Nov-30-Dec-1..1925.
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1053. IKE
***reaches for metoprolol.***
Member Since: December 31, 1969 Posts: Comments:
Anyone heard from CycloneOz? Did he end up heading to Bermuda? Good God, I hope he and his crew stay safe!
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I'm from Orlando....I have lived in South Florida for 3 1/2 years....I never paid attention to them because nothing really came before Charlie....I am 32 years old....but i know that south florida gets a lot of them...
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1050. breald
Quoting connie1976:
I have to wait until Sept is over!?! I'm so glad that I found this site last year!! I am a wish away caster....


NOVEMBER!!!!!
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so what !!! oh cares


not evere year you see a hurricane in octer or even in SEP



this year hurricane season will end in SEP my be even by SEP 15th or so all so the cold front are be comeing stronger why you think this one is kicking bill out too sea??????


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1048. Ossqss
Quoting Dakster:
OssGss - what the heck is that thing?

I remember having a CommodeDoor and a TRaSh-80.



Its a Steampunk PC Mouse, they make all kinds of crazy looking stuff for PC's etc.

http://jakehildebrandt.com/2007/04/20/img_0616-2/
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1047. Dakster
Cunnie - When Nov. 1 rolls around, we're pretty much out of the woods. Until then, anything is possible. Wilma was a LATE October Storm that hit South Florida...
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1046. NRAamy
Connie...nuthin wrong with being a wish-away caster....

:)

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1045. IKE
Quoting TampaSpin:
Wow! This could be close on timing.......Just a 6hr delay on that trough could even put the outerbanks into play when looking at the geography of the landscape. Just 6 hrs.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEWPORT/MOREHEAD CITY NC
251 PM EDT THU AUG 20 2009


SHORT TERM /FRIDAY THROUGH SUNDAY/...
-- Changed Discussion --
AS OF 230 PM THU...UPPER RIDGE WILL CONT TO DRIFT E AND BREAK
DOWN FRI AS AN UPPER LEVEL TROUGH APPROACHES FROM THE WEST. A
LITTLE BIT BETTER CHANCE FOR SHOWERS AND THUNDERSTORMS OVER INLAND
AREAS FRI AFTERNOON INTO FRI NIGHT AS MODELS INDICATE CONVECTION
DEVELOPING WEST OF THE AREA ALONG PRE-FRONTAL TROUGH...MOVING EAST
INTO THE COASTAL PLAIN LATE AFTERNOON. WILL MAINTAIN CHANCE POPS
COASTAL PLAIN WITH LITTLE OR NO CHC IMD CST WHERE ATMS WILL BE
SIGNIFICANTLY DRIER. FORECAST SOUNDINGS INDICATE MID LEVEL
SUBSIDENCE AND DRYING OVER THE OBX FRI NIGHT AND SAT AS MJR
HURRICANE BILL BEGINS MOVING NORTH WELL OFFSHORE TO THE SE.
HAVE
CHC POPS ALL AREAS SAT NIGHT AND SUN AS FRONT SLOWLY DROPS INTO
THE REGION. WILL REMAIN HOT FRI WITH LOWER 90S INLAND...AS HGTS
DROP AND PRECIP INCREASES ON SAT HAVE HIGHS MAINLY IN THE MID TO
UPPER 80S...WILL COOL INTO THE MID 80S SUN WITH FRONT ACROSS THE
AREA.
-- End Changed Discussion --

Member Since: December 31, 1969 Posts: Comments:
Quoting WeatherStudent:



Do not strech my words out of context there, bud...


He is stretching nothing. He is absolutely correct................."Weather Student"
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Excuse me, Bill grew and now takes up TWELVE lat/long boxes...
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1042. hydrus
Quoting Ossqss:
I wonder what the forward speed of the system will be once it heads north. They tend to go very fast.
when storms track to the N.E.they tend to accelerate rapidly.It was years ago but I recall they clocked one storm moving at 75 m.p.h off of Cape Race,Newfoundland.
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I have to wait until Sept is over!?! I'm so glad that I found this site last year!! I am a wish away caster....
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Quoting breald:


Now why would you say that??


It's like the NFL announcers bragging about the RB that hasn't fumbled all year. You just know the next time he carries the ball...
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Quoting Tazmanian:
hurricane season may end in SEP like it did in 2006

Doubtful
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Whoo whee. I gotta get me some kinda battery backup or something for my DSL, cause I think I will have me a HARD time blogging during a 'cane with simple dialup.......
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Quoting connie1976:
I thought after August was over that we would be good?.... :(


Sorry, baby; Hurricane season starts in June and ends in November; remember Wilma made landfall on 10-24-05
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1035. breald
Quoting connie1976:
I thought after August was over that we would be good?.... :(


How many hurricane seasons have you been thru?

The season starts on June 1st and ends on Nov 30.

Even my BFF Amy knows this and she lives all the way in California....LOL
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My fear is that because Bill is so enormous, it's center taking up a whole lat/long box, and its circulation taking up nine, that my Jersey Coast is gonna get hammered with wind, rain and surge, even though the center will be out to sea. BTW, isn't Bill the name they replaced Bob with when it was retired?
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Quoting VAbeachhurricanes:


out flow clouds starting to reach bermuda.


And Billy boy starts his turn anytime soon, she's gonna take a beating!
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Wow! This could be close on timing.......Just a 6hr delay on that trough could even put the outerbanks into play when looking at the geography of the landscape. Just 6 hrs.
Member Since: December 31, 1969 Posts: Comments:
1030. IKE
Quoting connie1976:
Pembroke Pines, FL


You've got at least 2 1/2, maybe 3 more months.
Member Since: December 31, 1969 Posts: Comments:
hurricane season may end in SEP like it did in 2006
Member Since: December 31, 1969 Posts: Comments:
I would expect one more majoe hurricane between sept 7 through sept 27.
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It's by hollywood, fl....
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Pembroke Pines, FL
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I don't want a hurricane!! I was hoping that someone would tell me that we are ok this year!!
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1024. IKE
Quoting connie1976:
I thought after August was over that we would be good?.... :(


Where do you live?
Member Since: December 31, 1969 Posts: Comments:
1023. breald
Quoting connie1976:
South Florida survived another year without a hurricane!! I'm good luck for south florida....I moved here 3 1/2 years ago from Orlando and they haven't had a hurricane since!! :)


Now why would you say that??
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1022. aquak9
LMAO!!

is it time to plee another fifth?
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I thought after August was over that we would be good?.... :(
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1020. NRAamy
Ossqss...you sure you didn't use that with your Pong game?
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Quoting Dakster:
OssGss - what the heck is that thing?

I remember having a CommodeDoor and a TRaSh-80.



It's a 19th century marital aid
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1018. IKE
Quoting NRAamy:
Connie, honey, we haven't even gotten into the heart of the season yet...you can say things like that in October (late in October)...right now you;re just tempting fate

either that or she's related to the budster....

;)


LOL...plus if you live in south Florida this is a perfect set-up for a late season Wilma type system if the pattern holds.

People almost begging for a system....jeez....
Member Since: December 31, 1969 Posts: Comments:
1017. NRAamy
Connie, honey, we haven't even gotten into the heart of the season yet...you can say things like that in October (late in October)...right now you;re just tempting fate

either that or she's related to the budster....

;)
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I'm still sticking to 9/5/2
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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather

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