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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This wishcasting stuff is getting old. Just make sure your forecast is in harmony with the current data. Wen people get too biased to satisfy their outcome--that is wishcasting, regardless if they want a storm to hit them or not.

The thing is, there's so much uncertainty in the models that almost any guess that doesn't have Bill going into the Gulf is a possibility. The cone, as wide as it is, only represents a 2/3rds probability. That means, for example, that there's about a 1/6th chance that Bill will strike west of the cone. Not a huge chance, but not particularly comforting, either. To put it another way, look at the GFS ensemble models. In the last run, one of them went straight through Boston.

Is this likely? Not really. Should Boston residents just assume they're safe? No to that either. Anyone on the east coast who (foolishly) didn't do their hurricane preparations earlier ought to take the time to do so now. Get those dead limbs off those trees, restock your emergency supplies, etc.
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Scary Loop:

NW Atlantic RGB Flash Loop
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Quoting lawntonlookers:
I wounder how the HCH are enjoying this flight? Flying through aa storm for several hours and only seeing the sunlight when they enter the eye of the storm.


Doesn't sound real fun, does it? I have the greatest respect for the pilots who take on these missions. The plane is now making its run through the northeastern quadrant, which has consistently been the strongest sector of the storm. We should have a good gauge of its current maximum sustained winds shortly.
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Quoting katzanddogz:


Yep, and a bill for the opps! LOL


Yeah, I got one of those too...LOL

It's easier to read when you take a few pks
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HWRF and GFDL 12Z

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Make a wish upon a shooting Hurricane.
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My first blog
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Quoting rwdobson:


Oh come on, reed, you know you're a Newcaster...always cape cod this and coast of maine that...lol


Excuse me? I'm just going by what I see with the pattern and steering. I'm not a wishcaster in any way, I back up my stuff with evidence. If you believe I'm a "Newcaster", call StormW that because he's been thinking the same thing as I am. StormW is an excellent storm tracker. As I mentioned earlier, I'm not forecasting a landfall!
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Well hey, hey everyone! I haven't been on Dr. Master's blog since tracking Ike last year.
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Quoting IKE:


Doing fine. How's about U?


Been better, been worse...about normal for this time of year...LOL
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Quoting TampaSpin:
Gettin might close to the Coastline....HUM.



The timing of that trough is going to be critical.. I also see there that Bill is trying to bust through the trough just off Long Island.
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I wounder how the HCH are enjoying this flight? Flying through aa storm for several hours and only seeing the sunlight when they enter the eye of the storm.
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Quoting TampaSpin:
Gettin might close to the Coastline....HUM.



Looks to be something in the GOM at the end of that........
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Quoting reedzone:


I'm gonna make my track soon as well. NOT hitting the East Coast, which means I'm not a west or wishcaster lol


This wishcasting stuff is getting old. Just make sure your forecast is in harmony with the current data. Wen people get too biased to satisfy their outcome--that is wishcasting, regardless if they want a storm to hit them or not.
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Sure wish it would turn now, the closer it gets to the US, the harder it will be to paddle out. My old bones could not take 5-10' breakers in a moderate or close period swell. Sat morning looks to be the call, light offshores with full impact swell hitting Florida. Goin' to be a thrashing, thank goodness for meds for us old guys....
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Gettin might close to the Coastline....HUM.

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Quoting reedzone:


I'm gonna make my track soon as well. NOT hitting the East Coast, which means I'm not a west or wishcaster lol


Oh come on, reed, you know you're a Newcaster...always cape cod this and coast of maine that...lol
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Quoting AllStar17:


Thank you. I will probably make another one around 4 or 5.


I'm gonna make my track soon as well. NOT hitting the East Coast, which means I'm not a west or wishcaster lol
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Quoting Sting13:
Does anyone know when the canadian hurricane center will start issueing statements? thanks


Canadian Hurricane Centre

Tropical Cyclone Information Statements

We issue information statements when a tropical cyclone is expected to bring tropical-storm force winds (gales 63-117 km/h) into Canadian territory or territorial waters within 72 hours (3 days).
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Quoting PortABeachBum:
Off to let an adjuster view damage from a fender-bender a few days ago. BBL BTW Things were a lot different in Inchon in '48 than when your dad was there!!


Yeah, he said it was loud and distinctly unfriendly; at least when he got a little ways inland...

See you after a while, PortA
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I think Environment Canada starts putting warnings out 72 in advance.... not that I'd wait that long to have a plan in place
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Quoting WatchingThisOne:


That seems to be the general sentiment around here ... i.e. the NHC is calling it right.


yea i believe the NHC has the right track always where ya posting from? I'm wondering just how "close" this damn thing will "brush" here
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Quoting apocalyps2:


West did you say west?
Not a surprise i think so.


A bit, as in <1 degree.
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Quoting Sting13:
Does anyone know when the canadian hurricane center will start issueing statements? thanks
when its within 48 hrs out from southern banks of nova scotia
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Quoting reedzone:


I think it's good for now, especially when there's no line.. It could go anywhere in that cone. Nice job.


Thank you. I will probably make another one around 4 or 5.
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anybody have that link that mandyFSU created for us showing the past HWRF runs.
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Quoting Floodman:




Sorry to hear that...pk's and gauze I take it? That's what I got when I heard that dreadful phrase


Yep, and a bill for the opps! LOL
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294. IKE
Quoting Floodman:


You think? LOL

How have you been, Ike?


Doing fine. How's about U?
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The MDR will be active over the following weeks, as the MJO sticks around.

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292. IKE
Heavy rains in Miami....? Now watch the radar fill in and make me eat crow.....

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Quoting IKE:


It's quite clear you are a west-caster.


You think? LOL

How have you been, Ike?
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Quoting Floodman:


By the way, I like your avatar...my dad was in Inchon in the early 50s...he wasn't leaving the port though; he and his luggage were heading inland LOL
Off to let an adjuster view damage from a fender-bender a few days ago. BBL BTW Things were a lot different in Inchon in '48 than when your dad was there!!
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Quoting CybrTeddy:


150 with a pressure around 935 would be my guess.
However 160 Category 5 certainly is possible as the SSTs increase.
bill will be the atlantic's first cat five cane of 09 season
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Does anyone know when the canadian hurricane center will start issueing statements? thanks
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Quoting futuremet:


The 12Z GFS expects a mid level high to develop and steer a tropical cyclone toward the east coast. It also tries to develop a quasi-permanent troughing pattern over the east coast for the next two weeks, which would likely curve any TCs out to sea. The ECMWF has been showing an analogous pattern, but has been eroding the trough over the past runs..


Indeed... I will doubt that we'll have another trough as strong as this one for a couple weeks... now once we head into mid to late Sept... then I would definitely expect a lot more of those troughs specially if El Nino sticks around.
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Quoting TampaSpin:
We need to watch this spin at 24N 84W NAM has it developing i do believe it old ANA.



What is that under Loiusiaana? Does that bear watching also?
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And when do they expect this Tropical Cyclone to steer near the East Coast?

To be honest, that forecast seem contradictory, for the GFS develops anomalous long term troughing pattern over the east coast during the next two weeks or so. Thus, such a system would likely go out to sea, and I find odd that the typically poleward biased GFS curve this system SWestward. Regardless, it is a long range forecast and should not be trusted. However, it does look like the majority of late august will experience a troughing pattern over the east coast.

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12Z GFDL shifted a bit, farthest west:

HOUR: 78.0 LONG: -70.60 LAT: 34.36 MIN PRESS (hPa): 942.49 MAX SURF WIND (KNOTS):103.68


12Z HWRF farthest west:

HOUR: 78.0 LONG: -68.90 LAT: 33.30 MIN PRESS (hPa): 936.00 MAX SURF WIND (KNOTS): 95.00
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Quoting AllStar17:
reed, what do you think about this path? I made it at 9 am. I definitely should have included Bermuda in the cone, but follow the center line....what do you think?



I always here on the news to never follow the center line. But since that's your cone, anyway looks accurate like the one NHC has.
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He's more of a Floridacaster.
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Quoting AllStar17:
reed, what do you think about this path? I made it at 9 am. I definitely should have included Bermuda in the cone, but follow the center line....what do you think?


I think it's good for now, especially when there's no line.. It could go anywhere in that cone. Nice job.
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Quoting RobDaHood:
Not been posting here much lately, but have to come out of work/lurk mode for this one!

Floodman! Great to see ya!


Howdy, Rob! How you been?
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Quoting K8eCane:
Ok time for advice

i'm here in wilmington nc (cape fear) and i'm watching Bill. the local forcasters are all over it too. They are basically saying we are clear from a direct hit but are not ruling out tropical storm conditions just yet. What say ye??


That seems to be the general sentiment around here ... i.e. the NHC is calling it right.
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Quoting IKE:


I looked at the 12Z GFS. I see a low that crosses that Atlantic that winds up east of the USA at 384 hours, never affecting any land(like Ike).


LOL... remember I never said it was hitting land but having an IKE type system. Sorry if the vague statement led you to believe an actual land fall somewhere.
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275. IKE
Quoting nrtiwlnvragn:
263. IKE


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
1054 AM EDT WED AUG 19 2009

.UPDATE...
THE COVERAGE OF SHOWERS AND THUNDERSTORMS HAS BEEN MUCH LESS THAN
ORIGINALLY ANTICIPATED -- ESPECIALLY ACROSS THE SOUTHWESTERN
HALF OF THE FORECAST AREA. IT APPEARS THAT A LOW-LEVEL INVERSION
SEEN IN THE 12Z MFL RAOB AND LIMITED DIURNAL HEATING BENEATH A
BROAD CIRRUS DECK ARE BOTH RESPONSIBLE FOR THIS. HOWEVER...PWAT
VALUES DO REMAIN VERY HIGH...EVEN FOR LATE AUGUST...AND WITH A
MID-LEVEL TROUGH IN THE VICINITY OF SOUTH FLORIDA AND POTENTIAL
FOR ADDITIONAL WARMING THIS AFTERNOON...AM RELUCTANT TO LOWER POPS
BELOW 60 PERCENT. THIS CHANGE WILL BE NOTED IN FORTHCOMING ZFPMFL
PRODUCT.


I was just going to post that. They should update their forecast. They could do a better job at that weather office.

Here's the afternoon forecast from Key West...."This Afternoon: A 30 percent chance of showers and thunderstorms. Partly cloudy, with a high near 87. Southeast wind around 10 mph."....

Slight difference? lol..

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Not been posting here much lately, but have to come out of work/lurk mode for this one!

Floodman! Great to see ya!
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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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