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 presslord:


sorry dude..but I'm a blue water mariner...anyone with keys to a boat anywhere north of DC who doesn't know about Bill deserves what they get...

So ignorance or stupidity deserves possible death. This from a person who helps people who didn't evacuate. I'm sorry, I've always respected your comments and applaud your efforts, but that was uncalled for and may have scared the person asking a question about someone they care about.
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Evening StormW!

Models yet again shifted west today, you were right on with Bill! Great job.
Member Since: July 1, 2008 Posts: 13 Comments: 7396
1522. Dakster
Quoting presslord:


furthermore...it's morally repugnant to me to ask the Coasties to go out in that sort of thing to fetch someone who ought not be in the gene pool anyway...


Presslord, you obviously believe in adding some chlorine to the gene pool, don't you?

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Quoting naplesdoppler:


Thanks Medicroc, I should have figured that out!

No problem(keep this between us:I found out yesterday when someone else asked;)
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Photobucket
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1518. centex
We want a tropical system to stall over us? These things only break with a flood and while it does cause problems it's better to have flood than continue drought. You don't understand if you think wrong to wish for flood, it's how we survive. Common knowledge in these parts.
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Quoting stormwatcherCI:
Anyone know what conditions are in the northern islands right now ?


Sorry... fashionably late on my reply. After some dark skies and heavy rainfall earlier in the evening, it's now gotten totally still outside. No rain at all and can even see some stars. Our Met office has warned of swells of between 7-10ft today and tomorrow but I haven't checked out any beaches yet to see the condition of the surf.
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Quoting PcolaDan:

Sorry press, but I think that was kind of cold. I think a better response would be to call the Coast Guard and tell them your concerns and ask if they can be of assistance. Believe it or not, some people are clueless that Bill is even out there.

Exqueeze me. But it is a mariner's responsibility to himself and those on board to look at weather conditions before he/she leaves port. Very old rule. Recall the NFL guys that were capsized in the Gulf. 2/3 didn't make it.
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Is the NHC predicting Bill to pickup forward speed as it turns NE? Wouldn't that make bill ahead of the low pressure trough?
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1511. jdjnola
Quoting StSimonsIslandGAGuy:


Actually it's very simple. New Jersey is hundreds of miles west of the westernmost model track. And Bill will be moving at 30 kts and New Jersey will be on the weak left side of the storm. It's not rocket science. It's as easy as saying Texas will have no significant impact from Bill.

And I'm not that young, lol.


I'm just saying, a lot can change with the model track in 3 days. Especially Bill being over a thousand of miles from the east coast. Katrina was a few hundred miles south of the Gulf coast, and the models shifted about 300 miles west over two days! Also, I wasn't calling you young specifically, I meant Nostradamus in his younger prophetic days ("young Nostradamus" being an expression of speech). Don't take offense, I was just being a little facetious.
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1510. 789
Quoting StormW:
1459. medicroc 10:10 PM EDT on August 19, 2009
Quoting cajunkid:
medicroc, you might ask StormW about the models

Didn't want to bother. He's got his hands full with everyone else(he's always a gentleman and always accomodating. Don't want to take advantage).


Thanks! But ask away!!
is there another shift west coming ?
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Eye looking like a crescent moon now.

http://www.wunderground.com/tropical/tracking/at200903_sat.html#a_topad
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1507. Dakster
Quoting medicroc:
I remember reading somewhere that the margin of error in predicting landfall is much greater for a storm running paralell to a coastline than one which is coming in at a perpendicular angle. Can anyone help confirm?


That's correct, but it is because of pure mathematics/geometry. Take two storms one running almost parallel to the coast and one running perpendicular. Now let's say the track error is 50 miles off. The one perpendicular is off by only 50 miles, but the other one could be off by several hundred miles. Why? Well, because it is approaching the coast at a slight angle where a little bit off means a ton of miles. I think it was Charlie that hit west coast Florida and this happened.
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Well, it looks like Bill is going through the first stages of an eyewall replacement cycle. I wouldn't be surprised to see a cat 3 Bill by tomorrow morning and perhaps a slight bend to the west (maybe 5°) until the cycle is complete.
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Quoting PcolaDan:

Sorry press, but I think that was kind of cold. I think a better response would be to call the Coast Guard and tell them your concerns and ask if they can be of assistance. Believe it or not, some people are clueless that Bill is even out there.


sorry dude..but I'm a blue water mariner...anyone with keys to a boat anywhere north of DC who doesn't know about Bill deserves what they get...
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Bill

Bill

AOI
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Good evening y'all. I see Bill is a strong category 4 storm, but not much change on track consensus today. Looks like Atlantic Canada should prepare for Bill, though things can still change in 6 days. It is the weather, after all. Nothing much worth mentioning out there atm, though Kman did point out a weak low forming off of Africa. Not much going on with it right now, but I'll keep an eye on it anyways.
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Thanks a ton, Storm! Will take those other two into regard...
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Quoting Dakster:
Orca - A little model divergence.


Just a smidge, but I have notice over the past few days.. a few more each time being west of NS
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When Isabel came through in '03 I had an Aunt living in Va Beach who didn't evac, and ended up having an anxiety attack when the police came through telling everyone to write their SSN on their arms and legs for body ID after the storm.

I believe she high-tailed it outta there right after that.

Reality ain't real pretty sometimes.
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Quoting presslord:


if you think they are offshore on a boat with this coming, you should contact the US Coast Guard and give them your contact info...in the event remains are recovered...

Sorry press, but I think that was kind of cold. I think a better response would be to call the Coast Guard and tell them your concerns and ask if they can be of assistance. Believe it or not, some people are clueless that Bill is even out there.
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Quoting StormW:
1459. medicroc 10:10 PM EDT on August 19, 2009
Quoting cajunkid:
medicroc, you might ask StormW about the models

Didn't want to bother. He's got his hands full with everyone else(he's always a gentleman and always accomodating. Don't want to take advantage).


Thanks! But ask away!!
HH say eye open to the sw again. What does this mean is going on with Bill ?TIA
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1495. Dakster
Orca - A little model divergence.
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1494. zuglie
I dont know what you guys think ? But the last few frames of Bill looks like it's going a bit more east?
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I remember reading somewhere that the margin of error in predicting landfall is much greater for a storm running paralell to a coastline than one which is coming in at a perpendicular angle. Can anyone help confirm?
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I find it amazing how we can accurately forecast the track of Bill and not worry about it changing course. I watch it and also watch all the media and how much confidence they put on the National Hurricane Centers forecasts. It is an anomaly that will not fully be understood no matter how much research we do. Also, I still do not understand why hurricanes in general do not have more lightning around them. I know it exists but in my experience being in a place in Florida where lightning is plentiful, I cannot understand why during a hurricane why we do not have more. Rain squalls are plentiful but with no lightning. I believe we have to watch this anomaly of nature and that is why I just really like to come home and tune in to The Weather Underground site and get Dr. Masters opinion on what is happening. I also enjoy seeing all the interest and blogs from around the nation on what people think about the whole situation. So, even though I do not blog frequently, I am reading and enjoying. CSta Weatherman.
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Quoting WxLogic 1306:
Well with this DLM High strengthening...

Can't say Iv'e heard that term. Must be something obvious (WxLogical) or they would have put it here.
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Quoting watchingnva:


and why is this?....your logic?

that would prolly be 'gut feeling'
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Pick a track... any track :)
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1487. Dakster
Quoting presslord:


if you think they are offshore on a boat with this coming, you should contact the US Coast Guard and give them your contact info...in the event remains are recovered...


Presslord, always the optimist.
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Thx StormW....interesting. That's where I'm from...Dallas area. Hope he hasn't quit contributing. I remember you guys were buds. Tell him Hey! Or now he will have to say Howdy?
Thx for all your unselfish posts......
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Quoting presslord:


if you think they are offshore on a boat with this coming, you should contact the US Coast Guard and give them your contact info...in the event remains are recovered...

Yes, that was a disturbing post.
Um, they didn't notice a CAT 4 headed in their direction?
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Quoting iluvjess:
Models will should contnue to inch back to the West unfortunately.


and why is this?....your logic?
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they must be seeding Bill...lol
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I was at the OBX to surf this summer and the waves were CRAP! Now, I can't believe I'm not there!!! You OBX people are lucky this weekend...
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1481. SQUAWK
Quoting TexasGulf:
I might have to ride down and watch some of those waves.

You might want to plan ahead. You might get caught up in evacuation traffic... 5 mph, bumper to bumper, no gas in the stations, everyone trying to get boats out of the water... what a zoo.

If you plan a way in to look at the waves, think about at least 2 good routes to get out if it hits the fan.


There aren't 2 routes out of OBX.
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Quoting MelbourneTom:
One more question for StormW or anyone willing. Thoughts on Cap Code this weekend. We have family there and can not get in touch with them. Found out they are on an extended weekend and may be on their boat.


if you think they are offshore on a boat with this coming, you should contact the US Coast Guard and give them your contact info...in the event remains are recovered...
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Quoting medicroc:

Major


Thanks Medicroc, I should have figured that out!
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It would be, at most, a Sunday afternoon ride, there and back, and if it looks like anything remotely reaching evacuation levels for the OBX I will most definitly be packing up my kids, dogs, and photo albums and heading west too.

At the current track, the waves would be pretty impressive, but we won't even see rain from it.
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1476. Dakster
Quoting naplesdoppler:
Hello all, lurker for years and I do post once and a while. Not sure if it is new this year but I have never noticed it before. I understand obviously the H for Hurricane, S for Tropical Storm, and D for Depression, but what is M??? I know it is for winds 110 and higher but what is the reasoning behind the letter M?


M is for Major Hurricane...
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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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