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 stormwatcherCI:
I just looked at the vis in the Caribbean and if that is how you tell then it looks like a low between the w tip of Cuba and the Yucatan. Correct me if I am wrong as I am just trying to learn.
It's the ULL that dropped South across the Bahamas and Cuba earlier this week....
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Bill is trying to beat the trough, let the air raid sound.
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Quoting TexasHurricane:


By this, he should be a Cat 2 when making landfall...I realize a cat 2 can be BAD (Ike 08) but this would definitely be better than a 4 or 5. Still hoping for a "no landfall".


Yea only if your inland away from the water
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guys can do that old ULL turn into anything that is spinnin on the west coast of cuba??? maybe that's what the models are pciking up on in the GOM???
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Quoting bajelayman2:
Looking at the Atlantic loop, it appears to me that Bill has cleaned up the dust and dry air from the Central Atlantic?

And therefore made it easier for the next couple of waves coming along.....

If this is correct, then Bill has created a bit more indirect damage in the long run, than is obvious at first glance.
I wonder about the magnitude of impacts on europe weather. This is like temporarily stopping the flaw of the dry air&dust, SAL(Saharan Air Layer) and subtropical jet stream?
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Quoting weathersp:
It won't be the first time that the first Hurricane of the season has done this sort of thing...

From August,19,1927( Today) to August,26,1927


These are the storms that made people so complacent in 1938. To be honest, there aren't really all THAT many storms that have made landfall within 100 miles of NYC.... especially not compared to the #s of those that have gone by....
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Quoting RMM34667:
That's a pretty sharp right turn forecast for Saturday. Bill is a big guy moving very fast, hope he tips over on that corner and falls flat on his face!



Maybe Bill will vanish in the bermuda triangle!!
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Quoting RMM34667:
That's a pretty sharp right turn forecast for Saturday. Bill is a big guy moving very fast, hope he tips over on that corner and falls flat on his face!



By this, he should be a Cat 2 when making landfall...I realize a cat 2 can be BAD (Ike 08) but this would definitely be better than a 4 or 5. Still hoping for a "no landfall".
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Quoting Floodman:


And being frends with me is bad in what way, my aggie friend?

That wasn't about you, but since you asked,
nah, nevermind (just teasing you Jerry)
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Quoting atmoaggie:

Link


Thanks!
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Quoting RMM34667:
That's a pretty sharp right turn forecast for Saturday. Bill is a big guy moving very fast, hope he tips over on that corner and falls flat on his face!



Whaaaa.... Nooo..

Don't let him do that! He could hydroplane and slide right into Maine!

Then I won't have any comfortable boots for winter!
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Regardless of where Bill hits in the Maritimes He is going to push a lot of water up into the Bay of Fundy ...

Tide schedule:

2009-08-23 (Sunday)
Time Height
ADT (m) (ft)
02:30 13.7 44.9
09:01 0.1 0.3
14:53 13.6 44.6
21:24 0.2 0.7

2009-08-24 (Monday)
Time Height
ADT (m) (ft)
03:16 13.4 44.0
09:46 0.4 1.3
15:39 13.2 43.3
22:11 0.6 2.0
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That's a pretty sharp right turn forecast for Saturday. Bill is a big guy moving very fast, hope he tips over on that corner and falls flat on his face!

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Quoting atmoaggie:
Oh no.
Now you've gone and made friends with him.

Back away from the keyboard, RitaEvac


And being frends with me is bad in what way, my aggie friend?
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Quoting centrfla:
thanks for the answer baha (the trough)


5 points for me!
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Quoting KarenRei:


People focus too much on the Yellowstone supervolcano. How many people know that the US has *three* active supervolcanoes? Yellowstone (northwest Wyoming), Valles (New Mexico, just west of Los Alamos), and Long Valley (California/Nevada border). And while it's dormant now, the US has the biggest single known supervolcano in Earth's history: La Garita -- 1,200 cubic miles (nearly 5 times the magnitude of the largest Yellowstone eruption, and enough material to fill Lake Michigan)


Volcano, hmmm, I am much more impressed with the New Madrid fault.

Now THAT!!

I wonder at the hype on the San Andreas Fault, when the New Madrid, from my little readings, appears much frightening, for the whole of the US.
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Quoting druseljic:


Can you give a link? Thanks! :-)

Link
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thanks for the answer baha (the trough)
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Quoting weathersp:
It won't be the first time that the first Hurricane of the season has done this sort of thing...

From August,19,1927( Today) to August,26,1927




Might be what he's gonn do, I think models are over estimating the trough, just like the high pressure ridges
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Quoting atmoaggie:
Hot tower time. Look at the last 2 frames on the IR.


Can you give a link? Thanks! :-)
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Quoting seminolesfan:
Look for a counter-clockwise spin in the clouds on VISIBLE imagery. IR or WV shows more upper level features typically, so VIS is the choice for surface.
I just looked at the vis in the Caribbean and if that is how you tell then it looks like a low between the w tip of Cuba and the Yucatan. Correct me if I am wrong as I am just trying to learn.
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Are FEMA headquarters in Washington DC? Maybe Bill is headed there. Paybacks are a b*tch.
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Quoting Floodman:


If Bill makes a track change when he's level with the Carolinas NYC will have about 6 hours warning


There would be no point in trying to evacuate at that point. It would just be deadlock.
No pun intended.
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Quoting kachina:
It appears that Bill is going to have a significant part of himself within the Hebert box unless I'm looking at the map totally wrong.


Well, I'm more concerned by the fact that he's in the Tampabayfish Box.
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Thank You!
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It won't be the first time that the first Hurricane of the season has done this sort of thing...

From August,19,1927( Today) to August,26,1927


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Hot tower time. Look at the last 2 frames on the IR.
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Quoting lydine:
Central Illinois is getting slammed right now. Quite the system. It's on its way!
Hurrah!!!

(OK, I know I'm getting a bit carried away here...)
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844. srada
Quoting all4hurricanes:

most of these tracks are taking Bill into New England let's hope that doesn't happen.


and coming close to NC too..keep shifting left..this isnt good
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Quoting keywestbrat:

LOl I was going to edit that, but computer says no.

It's not a joke, the chickens do know when to cross the road, you have to see it to believe it,
You can't make this stuff up!!!!
I was not joking. Right in the middle of town by the post office where I work she crossed her chicks on the crosswalk.
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Quoting originalLT:
Where did the map on post 808 come from?


Under computer models on the main WU Tropical / Hurricane page for Bill.
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Any chance of Bill weakening before it would make landfall (wherever that may be)?
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Central Illinois is getting slammed right now. Quite the system. It's on its way!
Quoting weatherwatcher12:

Yellowstone?


People focus too much on the Yellowstone supervolcano. How many people know that the US has *three* active supervolcanoes? Yellowstone (northwest Wyoming), Valles (New Mexico, just west of Los Alamos), and Long Valley (California/Nevada border). And while it's dormant now, the US has the biggest single known supervolcano in Earth's history: La Garita -- 1,200 cubic miles (nearly 5 times the magnitude of the largest Yellowstone eruption, and enough material to fill Lake Michigan)
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Oh no.
Now you've gone and made friends with him.

Back away from the keyboard, RitaEvac
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Quoting rwdobson:


when did i say never? just said low chance. 10% or less to hit NYC.


Pretty much, the trough would have to slow down with Bill moving really fast. Not likely.. NW movement now, I still think it has one more chance of going WNW tomorrow for a little while. The high to it's northeast (near Azores) might be able to have enough strength to push it more to the west a bit before recurving towards Canada.
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The most recent run of the reliable GFDL model puts Bill back to 70.6W before fading east
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Quoting Floodman:


What, like fire and brimstone for Sodom and Gomorrah? Don't fool yourself: a CAT 4 in "the Bight" would mean 200-300 billion in damages and a large number of caualties. If Bill makes a track change when he's level with the Carolinas NYC will have about 6 hours warning


There's go our Health Care!
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Wow Bill's Track continues to go to the left...one model has it scraping the OBX of NC?
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Quoting RitaEvac:
Would be a nice wake up call for NYC if it were to hit em head on


You cannot be serious. A head-on hit would causing trillions in damage and countless lives.

It would not be a case of a lesson, but a case of utter devastation.

Shudder.

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Quoting RitaEvac:
Would be a nice wake up call for NYC if it were to hit em head on


What, like fire and brimstone for Sodom and Gomorrah? Don't fool yourself: a CAT 4 in "the Bight" would mean 200-300 billion in damages and a large number of caualties. If Bill makes a track change when he's level with the Carolinas NYC will have about 6 hours warning
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Instructive to note that the NHC forecast has Bill at Cat 2 at latitude of Boston, and that low in part because of increased shear. Someday, a Cat 2-3 is going to show up in Brooklyn...
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828. Prgal
Link
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Quoting Floodman:
LOL *shaking head* "Hebert Box"...kinda like "Bermuda Triangle"


LOL! You're now entering a dimension not only of sight and sound.....
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Quoting RitaEvac:
Would be a nice wake up call for NYC if it were to hit em head on

Were that to happen, I'll bet they would never have anyone taking advantage of the situation by looting, violence, etc. Only New Orleans folks are capable of that....riiiiight.
(Actually, already happened in Providence in 1938. Plenty of the same.)
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I have a question, If all/most the ensemble members show one pattern, and the main one shows another pattern, which one should we trust more?
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Quoting szqrn1:

they both start with a "y" lol

lol, no problem.
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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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