Bill intensifies to Category 4; globe has 5th warmest July on record

By: Dr. Jeff Masters , 3:28 PM GMT on August 19, 2009

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Category 4 Hurricane Bill is now the the fourth strongest tropical cyclone to appear on the planet so far this year, and may grow even stronger. Visible and infrared satellite imagery continue to show an impressive, well-organized, hurricane, with plenty of low-level spiral banding and upper-level outflow well-established on all sides except the west. On Bill's west side, upper-level winds from the west are creating a modest 10 knots of wind shear, which is giving the hurricane a bit of a squashed appearance there.

Wind shear is forecast to remain low to moderate, 5-15 knots, for the next four days. Sea Surface Temperatures (SSTs) will rise steadily from 28.5°C today to 29°C on Friday. Total ocean heat content is at a maximum today, and will gradually decline over the next four days. Bill should be able to take advantage of these favorable conditions a remain a major hurricane the next three days.


Figure 1. Visible satellite image from NASA's Aqua spacecraft at 12:40pm EDT Tuesday August 18, 2009. Image credit: NASA GSFC.

Water vapor satellite loops show a small "short-wave" trough of low pressure to the north-northwest of Bill, and this trough has turned Bill on a more northwesterly track over the past two days. Bill will miss the Lesser Antilles Islands, and the main impact of the hurricane on these islands will be high waves. The short wave trough (so called because it has a relatively small amplitude and wavelength) is not strong enough to turn Bill due north, and Bill is also expected to miss Bermuda. High waves and sustained winds of 20 - 30 mph are the worst that Bermuda is likely to get from Bill.


Figure 2. Visible satellite image of Bill's eye zoomed in, taken from NASA's Aqua spacecraft at 12:40pm EDT Tuesday August 18, 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 late this week. This trough will turn Bill to the north, and also bring high levels of wind shear in the 40 - 65 knot range on Sunday. Exactly where this turn occurs is still not clear. The models continue to be in two camps: an eastern camp (GFS, GFDL, HWRF, and ECMWF) that takes Bill 300 - 500 miles east of Cape Cod, and a more western camp (NOGAPS, UKMET) that bring Bill within 150 - 200 miles of Cape Cod. Both sets of models bring Bill ashore over the Canadian provinces of Newfoundland or Nova Scotia. 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.

Bill's big waves
Large swells from Bill will begin impacting the U.S. East coast from Florida to Maine beginning Friday night or Saturday morning. Seas will build to 5 - 10 feet in the offshore waters from central Florida northwards to South Carolina, and to 10 - 15 feet from North Carolina to Cape Cod. Near shore, waves will be about 40% less. This will cause a significant coastal erosion event along some portions of the coast. The latest run of the NOAA Wavewatch III model suggests that significant wave heights near Bill's center will reach 50 feet on Sunday. Since maximum wave height is typically about a factor of 1.9 greater than the significant wave height (which is the average trough-to-crest height of the top 1/3 largest waves), a few huge waves near Bill's center may reach 95 feet high.

Possible impacts to New England
The current set of computer model runs predicts that the center of Bill will pass Cape Cod, Massachusetts Sunday afternoon or evening. Tropical storm-force sustained winds of 39 mph or greater currently extend out 185 miles to the west of Bill's center, so that if Bill maintains its current wind distribution, Cape Cod could see sustained winds of about 40 mph Sunday night if the models predicting a more westerly path are correct. However, Bill will not keep this same radius of winds. The hurricane will weaken considerably beginning Sunday morning, once the storm gets caught up in the approaching long wave trough. High wind shear of 40 - 65 knots due to strong southwesterly winds aloft will act to compress the hurricane in the east-west direction, keeping the hurricane's strongest winds away from Cape Cod. The highest winds are likely to be no more than 30 mph on Cape Cod from Bill, if the storm follows the track of the western camp of models nearest to the Massachusetts. A few rain squalls may affect coastal Massachusetts, but the main impact of Bill on New England is likely to be coastal erosion from high waves.

Elsewhere in the tropics
The remains of Tropical Storm Ana are bringing scattered heavy rain showers to the Bahamas and Florida today. The remains are disorganized, and are not likely to re-develop. The only model calling for a new tropical cyclone to develop in the Atlantic over the next seven days is the GFS model, which predicts development off the coast of Africa about 7 days from now.

Fifth warmest July on record globally; a cold July in the U.S.
The globe recorded its fifth warmest July since record keeping began in 1880, according to NOAA's National Climatic Data Center. NOAA rated the period January - July 2009 as the sixth warmest such period on record. NASA's Goddard Institute for Space Studies rated July 2009 as the 2nd warmest July on record, behind July of 1998. For the second month in a row, global ocean Sea Surface Temperatures (SSTs) in July were the warmest on record, 0.59°C (1.06°F) above the 20th century average. This broke the previous July record set in 1998. The record July SSTs were due in part to an ongoing El Niño event in the Eastern Pacific, which has substantially warmed a large stretch of the tropical Eastern Pacific Ocean. As El Niño conditions mature during the coming months, near-record global ocean and land temperatures will probably continue. Now that El Niño conditions have been well-established for three months, the atmosphere has begun to heat up in response. It typically takes up to seven months for the atmosphere to heat up in response to ocean heating from an El Niño. This may explain why June of 2009, which independent assessments by NOAA, NASA, and the UK Hadley center agreed was the 2nd or 3rd warmest June on record at the surface, recorded only average satellite-measured temperatures in the lower atmosphere. In contrast, the July satellite-measured temperatures in the lower atmosphere were the 2nd or 3rd warmest on record, in agreement with the assessments that surface temperatures were the 2nd to 5th warmest on record.


Figure 3. Departure of temperature from average for July 2009. Image credit: NOAA/NCDC.

A cold July for the U.S.
For the contiguous U.S., the average July temperature of 23.1°C (73.5°F) was the coolest since 1994, and July temperatures were the 27th coolest in the 115-year record, according to the National Climatic Data Center. Ohio, Illinois, Indiana, Pennsylvania, Iowa, and West Virginia experienced their coolest ever July. Kentucky, Missouri, Michigan, and Wisconsin recorded their second coolest July in history. A strong trough of low pressure parked itself over the eastern portion of the U.S. in July, funneling down plenty of cold air from Canada. In the western U.S., a ridge of high pressure dominated, bringing unusually hot conditions. Arizona recorded its 3rd warmest July on record, and Seattle, Washington recorded its hottest day in history on July 28, notching a 103°F reading. This was 3°F above the previous record set in 1994.

U.S. precipitation was near average in July, with the month ranking 40th wettest in the 115-year record. U.S. tornado activity was above average in July, according to NOAA's Storm Prediction Center. However, no tornado deaths occurred in July.

At the end of July, 14% of the contiguous United States was in moderate-to-exceptional drought. This is a drop from the 19% figure observed at the beginning of the year. These extreme drought regions were exclusively in South and Central Texas.

I'll have an update Thursday morning.

Jeff Masters

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Quoting TampaSpin:
Very bad weather coming to the Tennessee and Ohio Valley today........I mean some bad stuff!


what kind of "bad stuff", that is where my family is...
Member Since: Posts: Comments:
RE: Storm surge - For my area, Cape Cod, I've heard 15 foot waves. This will greatly impact where I work and live. It could wipe out a lot of business, erode our beaches even more, scare the tourists away hurting our local economy even more, and have ecological implications we don't want to think about.

As the debate here RE: Wind towers out in the Sound, how would a storm like this affect them? How much damage to them and to the area around them?

My comment re: going to work was not meant to be flippant. I understand how a storm can effect people. Hopefully putting it on a personal level reminds us all what's at stake.
Member Since: August 15, 2004 Posts: 23 Comments: 392
Quoting BenInHouTX:
How would Sable Island hold up to a direct hit by a cat 3 or 4 Bill?
Not sure what you mean in your question of "Hold Up" Obviously it will depend on the strenght of the wind and the hieght of the surge. If those two things are low most everything should come through pretty well. if those two are high it could do much damage.
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fyi...There are many old and close ties between Charleston and Bermuda...depending, of course, on scope of damage and needs assessment, Portlight may be doing some work there...at this point, we don't know what...or even if...and we probably won't be waving the flag about it real hard...but I thought y'all would like to know it's possible...
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Very bad weather coming to the Tennessee and Ohio Valley today........I mean some bad stuff!
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Quoting IKE:


Here's the 12Z model runs...looks like none of them have Bill going into New England with a direct hit.......look out Canada! Should be transitioning to extra-tropical by then...



I'm sorry if this is a dumb question:

About where is the "cutoff" for extra-tropical? Or does it just depend on SSTs? Is there a latitude by which you can more-or-less say, "Okay, a tropical system that comes this far north is going to be extratropical by the time it passes XYZ point"?

(Thanks for all your great info. I'm still learning!)
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2214. Ossqss
2206 -- Uh, how do those model graphics initialize at 8am and get posted as 5am ??? Top left text in them. What is up with that? I must need more coffee !
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IKE:

Thanks, but that image is at 05Z which is about 9 hours old.. :)
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How would Sable Island hold up to a direct hit by a cat 3 or 4 Bill?
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Quoting IKE:


Finally the new photo is there...
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Hurricane Watches up for Bermuda at 11:00. Bill's intensity is 105 kts. Soon to be over the warmest waters yet and the NHC states they see no reason why Bill won't continue to strengthen slowly in the near future.
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2206. IKE
Quoting IKE:




Oops...wrong one...here it is...

Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting AllStar17:




That's a heat low. it ain't gonna develop into something tropical.
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2204. Ossqss
Quoting IKE:




This one Ike :)

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Quoting IKE:




RE: African Waves. As someone noted yesterday, if Bill does turn and miss everything he's set the Atlantic up as a prime birthing room for some great storms.

Also note: "Analyses
from CIMSS at the University of Wisconsin show that Bill has been
experiencing 10-15 kt of westerly vertical wind shear. This may be
starting to diminish...as the cirrus outflow is increasing in the
western semicircle.

The initial motion is 305/16."
Member Since: August 15, 2004 Posts: 23 Comments: 392
2201. ncstorm
okay..I was looking at the 06 runs! Whew..thanks for the clarification!
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2199. IKE
Quoting Ossqss:
How do the ensembles look today?


Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting IKE:


Here's the 12Z model runs...looks like none of them have Bill going into New England with a direct hit.......



NHC thinks the models are too aggressive with that turn according to their discussion.
Member Since: July 8, 2005 Posts: 259 Comments: 24016
Quoting IMA:


So many people are interested only if it might affect them. So many are only interested if it's going to make U.S. landfall. The rest of us are interested in the science of it and realize there are always people affected (shipping interests, other areas besides our own or the U.S., the people who are working their butts off trying to forecast, etc.).


Most, like myself, fall into the "I have a job and unless this thing is coming here, I better work category". The life and death decisions of others should be based on the forecast from the NHC and their local government. This is a place of hobby and should be treated as such.
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2196. Ossqss
How do the ensembles look today?
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Quoting rarepearldesign:
Halifax is NOT taking this serious at all. It's so annoying. One of our local weather reporters said this morning "It will swing right on pass, might clip Canso but it won't be anything to worry about"

I mean, I get the don't panic thing, but after Juan when no one was ready, they should be getting in peoples heads to be prepared at least.

I know I will be shitting bricks in my house Sunday!!

My wife is in NS. I'll be crapping bricks here in North Carolina Sunday too
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2194. IKE
Quoting ncstorm:
Thanks Ike!

but looking at the past model runs..it is shifting back to the left closer and closer to the shore line..thats why I ask..hopefully that wont be the case..


Here's the 12Z model runs...looks like none of them have Bill going into New England with a direct hit.......look out Canada! Should be transitioning to extra-tropical by then...

Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting TropicTraveler:





Great photo - have been there and watched this - it's unbelievable. Can't imagine a storm surge on top of it.


I think I lost my car keys 30 feet from that same spot. Dropped them on the beach, tide came in so fast, no chance. Had to get a family member to drive 100km's to give me my other set.
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"It should be noted that Bill will
probably not turn as sharply between 72-96 hr as implied by the track graphic...and thus is likely to pass closer to New England than the graphic would suggest."

There it is! There's the out! Still have a few more days to prepare, but I keep thinking we'll turn it away from the Cape by shear FORCE OF WILL!

Turn Bill, take the bait, follow that trough... I can't miss any work, it's hard enough paying the mortgage as it is.....

And back at #735 or so we were discussing Cantore on Nantucket.
Member Since: August 15, 2004 Posts: 23 Comments: 392
Quoting AllStar17:


You will definitely get higher tides as Bill goes by to the east.
Is there any data with educated predictions?
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2190. ncstorm
Thanks Ike!

but looking at the past model runs..it is shifting back to the left closer and closer to the shore line..thats why I ask..hopefully that wont be the case..
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Great photo - have been there and watched this - it's unbelievable. Can't imagine a storm surge on top of it.
Member Since: July 24, 2007 Posts: 2 Comments: 924
2188. IKE
Quoting Chiggy007:
can somebody post a pic of African Waves! Bloody Navy site is about 5 hours behind..again!!


Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting AllStar17:


Your graphics are excellent. I really appreciate them.
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Halifax is NOT taking this serious at all. It's so annoying. One of our local weather reporters said this morning "It will swing right on pass, might clip Canso but it won't be anything to worry about"

I mean, I get the don't panic thing, but after Juan when no one was ready, they should be getting in peoples heads to be prepared at least.

I know I will be shitting bricks in my house Sunday!!
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.
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Quoting NEwxguy:
I've cleaned up my yard,secured a lot of items,so I feel pretty safe at this point,these storms are too unpredictable to wait for until the last moment.
Make sure you cover your windows and cut down any overhanging branches off trees.
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Quoting IKE:


Looks better in the last few frames.

It's going just east of the tropical forecast points again.

I see the trough edging down into northern Arkansas now.

Biggest threat areas to me...Bermuda...Canada.
I have been wondering about possible higher than normal tides up in the NYC area as he goes by. That area is like a corner of a box.
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can somebody post a pic of African Waves! Bloody Navy site is about 5 hours behind..again!!
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2181. IKE
Quoting ncstorm:


would this mean a brush with NC as well?


It won't come close to NC...maybe 300 miles east of you.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting canehater1:
Either Bill is undergoing EWRC or he just winked at me on the visible sat loop




Lol.. I was thinking the same thing..
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2179. IKE
Quoting eyesontheweather:
Good Morning Ike. I See that over night Bill has decided to take some gulps of dry air and has been on a 315* heading also been downgraded to Cat 3.


Looks better in the last few frames.

It's going just east of the tropical forecast points again.

I see the trough edging down into northern Arkansas now.

Biggest threat areas to me...Bermuda...Canada.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting ncstorm:


would this mean a brush with NC as well?


Most likely, no.
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Quoting Sting13:


Last night was the first real news report on it, stating hurricane prepairness, but no evacuation is planned, personally ill be putting plywood over the bigger windows in the house just incase.
Where are you located? Are you concerned about storm surge in your area?
If you are not already, your may wish to get on Orca's Google Earth list (wu-mail either him or zoomiami)
Glad to hear you are making preparations.
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2174. breald
Quoting TropicTraveler:


I hope there really is a wonder trough to keep the storm way offshore. There was a graphic of the GFS model that showed a second storm catching up with Bill forming a super storm off Iceland and then heading for Great Britain. That is an awesome graphic. A few pages back.


I guess it is the the older England's turn to have a perfect storm.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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