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 jeffs713:

The trough won't have much of an ability to intensify him, as it will speed him up as it turns him (once Bill is parallel to the trough). It will actually serve to weaken him between speeding him up and inducing shear along the axis of the trough, in combination with moving him to lower SSTs.


Just adding to that...

With some tropical cyclones (i.e. IKE) the energy associated with the storm can get absorbed by a mid-latitude baroclinic (fueled by temperature difference) storm and can act to energize both storms.

However, with Bill the trough and Cyclone remain separate with Bill racing north and then northeast ahead of the trough. This should prevent any baroclinic energy from feeding into Bill which would keep it stronger for longer over colder water.
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Quoting SeVaSurfer:

That makes feel better! Your right about Wilma, she obeyed. Still gonna be cool getting towed into Bill's 12 foot faces this weekend off Hatteras Light!


Wow! That will be nuts.
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Quoting atmoaggie:
I thought we might be going into a fairly long quiet period in the Atlantic, as did others here (I remember StormW and I agreeing on this almost a week ago).

Well, we might be wrong. MJO was tracking out of our domain and weakening in amplitude. Well, it took a turn back to our domain in the last day and the GFS and the ensemble mean both bring it well back into our domain. And the both model results bring back a bit of the amplitude in the near term and a lot in the long term.

If this verifies, we will very likely have another bout of developing waves possibly just before the forecasted development 7 days from now as per Dr M's post above.

The forecast: (The large dot is the current, the thin red line is the last 20 days, the thick blue is the next 7 days forecast by GFS, the thick green is the next 7 forecasted ensemble mean)



If you can see where the Aug 12,13,14 points fall in this plot, well do you know what was going on then?


Hmm... Interesting.
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121. JeffMasters (Admin)
Quoting Fl30258713:
Figure 1. Visible satellite image from NASA's Aqua spacecraft at 12:40pm EDT Tuesday July 18, 2009. Image credit: NASA GSFC.

Oops, thanks for the update Dr Masters.

I'm pretty sure he meant August. :-)


I appreciate the correction!

Jeff Masters
103. I was hoping this guy was on to something. Now, dunno

http://www.examiner.com/x-17371-Raleigh-Climate-Examiner~y2009m8d16-MaddenJulian-Oscillation-northw ard-shift-of-westerlies-ignite-Tropics

Link
Member Since: June 12, 2005 Posts: 6 Comments: 8183
Quoting hurricanehanna:
so what's going to keep remnants of Ana from forming (other than a llc)?
]
Things against organizing:
No LLC.
No closed circulation at any level (ex-Ana is an open wave).
No organization to speak of.
Marginal upper-level winds. (at least when I checked yesterday)

Things for organizing:
Good SSTs and OHC.
Energy left over from the storm and the soon-to-be nearby front.

Overall.. things aren't looking good for ex-Ana.
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Quoting Walshy:
Saved.




From Canada with love.
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From the HCH, now entering the Vortex:

Time: 16:15:00Z
Coordinates: 18.9667N 56.5167W
Acft. Static Air Press: 696.2 mb (~ 20.56 inHg)
Acft. Geopotential Hgt: 2,710 meters (~ 8,891 feet)
Extrap. Sfc. Press: 945.9 mb (~ 27.93 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 242° at 5 knots (From the WSW at ~ 5.8 mph)
Air Temp: 18.5°C (~ 65.3°F)
Dew Pt: 11.2°C (~ 52.2°F)
Peak (10s) Flt. Lvl. Wind: 8 knots (~ 9.2 mph)
SFMR Peak (10s) Sfc. Wind: 24 knots (~ 27.6 mph)
SFMR Rain Rate: 2 mm/hr (~ 0.08 in/hr)


That pressure of 945.9 is lower than any recorded on its last run, and there'll probably be a couple of (slightly) lower readings in its next transmission, as it traverses the center of the eye itself. The Vortex Messages have been running about 3mb higher than the lowest extrapolated pressures, so I expect we'll see it down to 947-8. Still getting a little bit stronger.
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116. slavp
Quoting hurricanehanna:
so what's going to keep remnants of Ana from forming (other than a llc)?
Hopefully a LOT LOL
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Since a debate has been going on about Hurricane Isabel busting through a trough, here is a video of it. Watch what it does around :12 to :16.

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Quoting violetprofusion:
I'm kind of new to this and I have a question:

When Bill makes his northward turn, he will weaken eventually as he approaches the northern East Coast and maritime Canada. I know that this is mostly a function of the fact that he'll be over cooler northern waters and won't have as much heat to fuel him.

Trough patterns that are forecast to pull him north--do those have any effect on his strength? Could he intensify yet, or will the northward pull make him weaker in and of itself? Or is it really just a question of how much heat he has?

I'm new here, help me try to understand! You guys have great info and I am learning a lot.

The trough won't have much of an ability to intensify him, as it will speed him up as it turns him (once Bill is parallel to the trough). It will actually serve to weaken him between speeding him up and inducing shear along the axis of the trough, in combination with moving him to lower SSTs.
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@104, the trough will also increase wind shear, weakening Bill...
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so what's going to keep remnants of Ana from forming (other than a llc)?
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Quoting atmoaggie:
I thought we might be going into a fairly long quiet period in the Atlantic, as did others here (I remember StormW and I agreeing on this almost a week ago).

Well, we might be wrong. MJO was tracking out of our domain and weakening in amplitude. Well, it took a turn back to our domain in the last day and the GFS and the ensemble mean both bring it well back into our domain. And the both model results bring back a bit of the amplitude in the near term and a lot in the long term.

If this verifies, we will very likely have another bout of developing waves possibly just before the forecasted development 7 days from now as per Dr M's post above.

The forecast: (The large dot is the current, the thin red line is the last 20 days, the thick blue is the next 7 days forecast by GFS, the thick green is the next 7 forecasted ensemble mean)



If you can see where the Aug 12,13,14 points fall in this plot, well do you know what was going on then?


Hmmmm...could get interesting... I was thinking we were suppose to have a slower September, but with this that may not be the case??
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Here is a good water vapor loop of everything involved. Big, but good.
http://www.atmos.washington.edu/~ovens/loops/wxloop.cgi?wv_east_enhanced+12
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This is what happens when an unstoppable force immovable object. I think Bill will win and slightly glace Maine.
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Saved.


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These freaking storms are so beautiful but so annoying at the same time.. I just wish they moved faster. I hate the wait.. Just land somewhere or head out.. Freaking interrupting my beach weather.
Member Since: August 15, 2009 Posts: 0 Comments: 90
Quoting IKE:


You can see the trough in the central USA advancing east...


I see it.

One thing about the weather in New England is it can change over night. I remember I went to bed thinking it was going to be sunny the next day, because that is what the weatherman said. And woke up to rain all day. I hope things work out the way they think they will. Sorry Bermuda.
Member Since: May 28, 2008 Posts: 38 Comments: 5303
Quoting TexasHurricane:
From some of the posts on here earlier, I think we are suppose to have a slower September, (for hurricane development) is this correct?

Nobody really knows, actually.
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I'm kind of new to this and I have a question:

When Bill makes his northward turn, he will weaken eventually as he approaches the northern East Coast and maritime Canada. I know that this is mostly a function of the fact that he'll be over cooler northern waters and won't have as much heat to fuel him.

Trough patterns that are forecast to pull him north--do those have any effect on his strength? Could he intensify yet, or will the northward pull make him weaker in and of itself? Or is it really just a question of how much heat he has?

I'm new here, help me try to understand! You guys have great info and I am learning a lot.
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I thought we might be going into a fairly long quiet period in the Atlantic, as did others here (I remember StormW and I agreeing on this almost a week ago).

Well, we might be wrong. MJO was tracking out of our domain and weakening in amplitude. Well, it took a turn back to our domain in the last day and the GFS and the ensemble mean both bring it well back into our domain. And the both model results bring back a bit of the amplitude in the near term and a lot in the long term.

If this verifies, we will very likely have another bout of developing waves possibly just before the forecasted development 7 days from now as per Dr M's post above.

The forecast: (The large dot is the current, the thin red line is the last 20 days, the thick blue is the next 7 days forecast by GFS, the thick green is the next 7 forecasted ensemble mean)



If you can see where the Aug 12,13,14 points fall in this plot, well do you know what was going on then?
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Quoting IKE:


Look at the water vapor loop I just posted. Trough is not weak...


Not when it starts, but as it progresses eastward, it weakens according to *some* models.
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Figure 1. Visible satellite image from NASA's Aqua spacecraft at 12:40pm EDT Tuesday July 18, 2009. Image credit: NASA GSFC.

Oops, thanks for the update Dr Masters.

I'm pretty sure he meant August. :-)
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Quoting iamcanadian:
I have been following the models which indicate that Bill may make his way toward Nova Scotia. However, CBC news (per our local weather guy) is reporting that Bill will turn out to sea before he passes by (deja vu?? Juan anyone?).

So I guess the big question is if we really need to be worried about another potentially dangerous hurricane hitting Halifax?

Any thoughts from the experts?
Hey iam... It's looking iffy right now. Halifax certainly is in the zone right now. Three days out it may not be. Depends on how fast that trough moves....
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I know it's gonna recurve, but I've been predicting what I call a close call recurvature. Maybe one more small shift to the left on the models later. Again people in New England, especially Cape Cod will have to continue to monitor the storm.
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Another thing to keep in mind regarding tracks, troughs, ridges, and Coriolis force: Storms don't "want" to keep moving generally westward or whichever way they're currently traveling. They want to curve poleward. In a neutral environment, this is what most will do.

IOW, it doesn't take a powerful trough to force an unwilling storm to curve N, it simply takes the absence of a ridge/high to allow it to follow its natural inclination.

Think of a storm as a car with its front wheels badly out of alignment, so that it wants to turn right. But if it's going over terrain that's tilted so that the left side is lower than the right, that natural pull to the right can be partially or compeletly offset and the car may go actually move left, or straight, or at least less right than it would on a flat surface.

But then let a patch of flat territory come up, or territory with the oppsite tilt, and now of course the car is free to turn right as the wheels want to do anyway.
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Quoting BahaHurican:
I think I'm going to go back and read the report on Isabel. I admit I don't remember any "trough-busting" type comments made about her.

Even if so, I'd like to know what kind of trough it was she busted through. Weak? Mediocre? Strong? All troughs are not created equal. On top of that, Isobel was the one in 100 genuine article annular storm; Bill is certainly not that.

I'm not expecting any "trough-busting" with that final trough this weekend. After all, even Wilma obeyed her trough.....


That makes feel better! Your right about Wilma, she obeyed. Still gonna be cool getting towed into Bill's 12 foot faces this weekend off Hatteras Light!
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Quoting BahaHurican:
Hey! u made it through the night! Did u get any sleep? I finally quit when my forehead kept hitting the keyboard.... lol

But it does look this a.m. like Bill will take the NW course along the edge of the Antilles for the next day or two. I just hope it keeps going up the ATL the way it's forecast to.....


lol.. yeah finally pried my fingers from the keyboard and got some rest. Hoping he maintains his current path as well. Some howling winds outside and hearing some birds going nuts...other than that all appears normal for now. I'll check out the beaches sometime in the next day or so and post pics if I see any nice waves.
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95. IKE
Quoting reedzone:
I THINK.. The GFS has shifted west on the 12Z.. Also the trough looks weak, and curving..



Look at the water vapor loop I just posted. Trough is not weak...
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting 900MB:
A Cat 4, West of Bermuda in a few days is too close for comfort for this East Hampton, Long Island weather watcher! A couple of questions for those more experienced:

1- Where will that Bermuda high be in 2 days, and will Bill slip under it, or blast it.

2- What is the bias for a major hurricane? Refresh my memory, does it tend to go left or right when it is so strong? With only warmer waters and low shear ahead over next few days, it only looks to get more intense, which is why I ask about the bias. Big storms can make their own weather.

Thanks!


The models do show the powerfull effect of Bill on the weather around it. Specifically it's outflow aloft causes additional subsidence and ridging to its north - more that there otherwise would be.

Fortunately, the trough to it's west is quite a bit stronger than a normal mid-August trough and it will definitely recurve the storm. The only tough question remaining is exactly where... It is my opinion that the US will not feel much wind from Bill, but Canada could get a good wallop.
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Quoting Melagoo:



A lot is riding on that trough ...
That's the one. It still looks fairly substantial.

Something I learned with Bertha last year is that the trough actually can push the storm along in front of it, almost like a bulldozer. It's pretty interesting to watch....
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I have been following the models which indicate that Bill may make his way toward Nova Scotia. However, CBC news (per our local weather guy) is reporting that Bill will turn out to sea before he passes by (deja vu?? Juan anyone?).

So I guess the big question is if we really need to be worried about another potentially dangerous hurricane hitting Halifax?

Any thoughts from the experts?
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91. IKE
Quoting Melagoo:



A lot is riding on that trough ...


You can see the trough in the central USA advancing east...
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Quoting reedzone:
I THINK.. The GFS has shifted west on the 12Z.. Also the trough looks weak, and curving..



Yeah it does....there also looks to be 2 other areas of cocern in the Atlantic as well.
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even the "weakened" version of the trough is very deep for this time of year. you need to look at the 500 mb maps to see it.
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I THINK.. The GFS has shifted west on the 12Z.. Also the trough looks weak, and curving..

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Quoting JadeInAntigua:


Yeah I was one of the ones on last night. Happy to see Bill's taken a turn away from us.
Hey! u made it through the night! Did u get any sleep? I finally quit when my forehead kept hitting the keyboard.... lol

But it does look this a.m. like Bill will take the NW course along the edge of the Antilles for the next day or two. I just hope it keeps going up the ATL the way it's forecast to.....
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A lot is riding on that trough ...
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From some of the posts on here earlier, I think we are suppose to have a slower September, (for hurricane development) is this correct?
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Quoting IKE:


The trough apparently wasn't as strong as this one.

Quoting BahaHurican:
This sounds more like what I remember.....

Yeah me to, at 5 days prior they really were not sure if it was going to hit the OBX and SE VA, but it did. Gave me a whole day to prepare.
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Quoting IKE:


The trough apparently wasn't as strong as this one.



Though some models (NOGAPS, CMC, and few GFS esnembles) are weakening this trough as well.. So it's all speculation. We'll have to see what this so called "monster trough" will do. I'm still not confident on a sharp recurvature just yet, you can see models spread out at the end of there runs, which makes the NHC 5 day cone.
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Figure 2. Visible satellite image of Bill's eye zoomed in, taken from NASA's Aqua spacecraft at 12:40pm EDT Tuesday July 18, 2009.

------------------
Let's get some more photo's from this "future seeing" satellite so we know what happens NEXT month.
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Quoting klaatuborada:
Rit from Cape Cod here. Just a little wobble to the West and we might get more than a mild blow. Surfer's and wind-surfers are going to go crazy happy with it. I'm still sitting on the fence waiting to see what happens.

Even my wunderground has only gotten our weather right about 40% of the time for the past year.

The rain they say we're going to get goes to our West and North, we've barely gotten any of the rain that's predicted, but we've gotten weather that wasn't s'posed to hit us plenty. So... I'm still watching Bill.


East End of Long Island here and ditto! It has been so long since major storm, and with gypsy moths weakening so many trees over past 7 years, wind is a scary thought, a storm even scarier!
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Quoting BahaHurican:
U guys are going to get some serious wave action along the north coast all weekend, it seems.....

Glad it seems it won't be any worse.....

The surfers will have a blast over the weekend!
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Quoting BahaHurican:
Hey. Some of the Antilles-based bloggers were on last night. (Don't forget 456 lives in St. Kitts.) Dunno if anybody's about this a.m., though.


Yeah I was one of the ones on last night. Happy to see Bill's taken a turn away from us.
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Quoting rwdobson:
Looking at the archive...I don't think Isabel really "busted" a trough. Here's what NHC discussion was saying @ 5am Sept 13 2003 "IT
APPEARS THAT THE TROUGH WHICH IS CURRENTLY ERODING THE WESTERN
PORTION OF THE RIDGE WILL WEAKEN AND THE HIGH WILL EXPAND WESTWARD."

This was about 5 days before landfall....


Exactly. In fact the NHC forecast was very consistent and accurate:

"The landfall forecasts were exceptionally accurate. The track forecast errors verifying at 1800 UTC 18 September (1 h after landfall) had errors of 6, 12, 6, 16, 31, 86, and 118 n mi for the 12, 24, 36, 48, 72, 96, and 120 h forecasts, respectively."

http://www.nhc.noaa.gov/2003isabel.shtml?


Here is the track archive:

http://www.nhc.noaa.gov/archive/2003/ISABEL_graphics.shtml
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75. IKE
Quoting rwdobson:
Looking at the archive...I don't think Isabel really "busted" a trough. Here's what NHC discussion was saying @ 5am Sept 13 2003 "IT
APPEARS THAT THE TROUGH WHICH IS CURRENTLY ERODING THE WESTERN
PORTION OF THE RIDGE WILL WEAKEN AND THE HIGH WILL EXPAND WESTWARD."

This was about 5 days before landfall....




The trough apparently wasn't as strong as this one.

Member Since: June 9, 2005 Posts: 23 Comments: 37858
A Cat 4, West of Bermuda in a few days is too close for comfort for this East Hampton, Long Island weather watcher! A couple of questions for those more experienced:

1- Where will that Bermuda high be in 2 days, and will Bill slip under it, or blast it.

2- What is the bias for a major hurricane? Refresh my memory, does it tend to go left or right when it is so strong? With only warmer waters and low shear ahead over next few days, it only looks to get more intense, which is why I ask about the bias. Big storms can make their own weather.

Thanks!
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.