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 Drakoen:
Looks like the Canadian Meritimes could be in for a significant system.


Yup. This Maritimer got stocked up today: non-perishables, water, candles, etc. And I have the leftovers from my prep for Kyle last year, which made landfall just about 30 km from my home, although we were lucky that he just fell to bits and damage was minimal.

Bill looks like another sort of animal altogether. Turn, baby, turn!
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It looks like Bill is undergoing some fairly rapid strengthening.

The aircraft currently investigating Bill has found that the eye has closed off, and logged 115kt flight-level winds in the SE quadrant - higher than they've been all day. More recently, it logged 140kt flight level winds in the intense northeastern eyewall, and its dropsonde found Mean Boundary Layer Winds of 139kts, and surface level winds of 122kts. That's some serious wind. It also put the extrapolated central pressure at 943.8mb. Even allowing for the fact that the vortex reading is usually a few mb higher than the lowest recorded reading, that's impressive. We started this morning at 952mb, and within the past 18 hours, it's dropped to somewhere around 946mb, dropping a millibar or so with every new reading.

It's still a fair way from Cat 5. But I expect the 11PM advisory to raise the wind speed, using this latest batch of data, to at least 125kts.
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Hi P451, thanks for your insight.
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I miss the regulars! Are they all gone for the evening and forgot to invite me?
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Quoting BaySaint:
What happened to all the people we trust? Nothing on here but a bunch of junk and God posing as stormno.


If it's not hitting Florida or New Orleans, 80% of the people who normally comment disappear.

Oh well, I survived Ike in Houston last year, and I'm headed to RI on Sunday for a few days (Bill-willing).
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Stormtop, I like it when you come here, but only for the entertainment value. You make me laugh and I like that. Doesn't matter if you are right or wrong your fun to read.
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Whoo, boy. The frame-by-frame watchers have taken over the blog.

I'll be back in the morning while these guys spend all night fretting whether Bill has been moving for the last 15 minutes at 300 degrees at 15 mph or 301 at 16mph.
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What happened to all the people we trust? Nothing on here but a bunch of junk and God posing as stormno.
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1214. alcomat
Quoting wunderkidcayman:

this is for bill
looks to me like he is trying to follow around the bottom of the southeast high,especially with the wnw turn.if that high stays put you could be looking at a westward moving bill,and the way the steering currents are set up, I wouldnt be surprised to see him get in the gulf in a week or so...texas,la???...ya never know....do ya??
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1213. scCane
Sure hard to see what direction its moving when that eye keeps shrinking
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Quoting JamesSA:


It said hurricane for Texas first of August. THAT sure didn't happen. I think it is predicting hurricanes in hurricane season for anyplace that gets hurricanes.
Agree - 'threat of hurricane' is not exactly taking a leap
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Quoting Orcasystems:


Personally I prefer a NE hit to a NS one.


Thanks, Orca. Good to have you in my corner. I know you're only really worried about the pepperoni, though. ;-)
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Quoting P451:
Ending 2315Z.
WV and FunkTop images.
WNW jog apparently short lived as in the final frames of the closeup you can see it go right back NW. Eye seems to maybe be wobbling. Maybe an EWRC as some have hinted. The erosion on the WV and FunkTop images seems to have ceased and the core band surrounding the eye seems to have rebuilt itself. Still doesn't look all that good in the north to east regions. Eye seems a bit ragged now.

FunkTop



WV



WV Closeup with L&L - you can see NW - then a WNW jog - then NW the final 2 frames again.

it is not maing a WNW jog, it is the EWRC giving the illusion of a WNW jog. It was doing it last night also which made his WNW motion seem to be more westerly.
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18z GFDL increases Bill to 144kts. (165mph)!

LINK: http://moe.met.fsu.edu/tcgengifs/
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1204. Ossqss
Quoting Drakoen:
Looks like the Canadian Meritimes could be in for a significant system.


Drak, do ya think the models are done sliding around?

Edit= never mind, answered my own not so smart question :)>
Member Since: June 12, 2005 Posts: 6 Comments: 8188
IKE

BILL
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1201. JamesSA
Quoting sctonya:


I went to that site and it said the same thing for SC... Let me see if I can find it for you...Link


It said hurricane for Texas first of August. THAT sure didn't happen. I think it is predicting hurricanes in hurricane season for anyplace that gets hurricanes.
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Quoting tropicaltank:
Do you believe the storm is going to strike the east coast?
too eraly to tell, its all about the timing. IF it does, I would say just clipping Maine headinging away.
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Uh oh, I meant December. Lol. Don't wanna tempt Mother Nature.
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Quoting hunkerdown:
he is moving NW, not WNW
Do you believe the storm is going to strike the east coast?
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Quoting HaboobsRsweet:
You know the ensembles shifted to the west today and NHC still saying a WNW motion. That is making me a little nervous. I expected a NW to NNW movement already. The big models still holding to same track but htey are the eastern outliers on the ensembles.
check again, the NHC says NW on the 5:00 advisory
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Quoting hunkerdown:
he is moving NW, not WNW

ah I see that now...didnt catch the last update. Well that is a good sign then. Hopefully it keeps turning.
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Quoting HaboobsRsweet:
This is such a weird pattern, we never see fronts drop into southern MS in August. All the models point to one passing over the next few days and it is cooler than normal for this time of year.


Yep. Thats supposed to reach the Texas coast as well. I'd like to think that's a good sign for an early fall not to mention good steering patterns for us, tropically that is. But last year was dryer and cooler too. :( I can't wait for October. And Bill, go NORTH! young man!
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Quoting Tazmanian:
bill is no longer a fish storm
\]

Methinks that some will now realise that, although he never really was, what with threatening Bermuda, Nova Scotia and Newfoundland.

But, I think the late betting, right before the booth closes, is on the outsider.
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Quoting HaboobsRsweet:
2 things need to happen, the trough/front needs to start moving faster and Bill needs to turn. the longer it stays WNW from here on out, the more the models will shift to the west. Just watch
he is moving NW, not WNW
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Quoting weathercrazy40:
how often do the models update
I believe every 6 hours.
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Quoting photonchaser:
If thats true, that is really spooky
Quoting KsAvChic:
Someone posted the Almanac prediction of a hurricane hitting New York Aug 24-28 2009...if you are on here, could you post that link again? Please. Was it authentic? Kinda eerie but cool if that is true.


http://www.almanac.com/weathercenter/index.php

choose 10032 as a zip code location
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OK, I found the link. I just think this is a little freaky!
http://www.almanac.com/weatherforecast/us/2
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when are they predicting the trough will pick up Bill?
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1187. sctonya
Quoting KsAvChic:
Someone posted the Almanac prediction of a hurricane hitting New York Aug 24-28 2009...if you are on here, could you post that link again? Please. Was it authentic? Kinda eerie but cool if that is true.


I went to that site and it said the same thing for SC... Let me see if I can find it for you...Link
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how often do the models update
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2 things need to happen, the trough/front needs to start moving faster and Bill needs to turn. the longer it stays WNW from here on out, the more the models will shift to the west. Just watch
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1184. Drakoen
Looks like the Canadian Meritimes could be in for a significant system.
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18z GFDL increases Bill to 144kts. (165mph)!

LINK: http://moe.met.fsu.edu/tcgengifs/
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Quoting KsAvChic:
Someone posted the Almanac prediction of a hurricane hitting New York Aug 24-28 2009...if you are on here, could you post that link again? Please. Was it authentic? Kinda eerie but cool if that is true.
If thats true, that is really spooky
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this is for bill
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This is such a weird pattern, we never see fronts drop into southern MS in August. All the models point to one passing over the next few days and it is cooler than normal for this time of year.
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1179. Ossqss
Here is a good loop with the trough and Bill. Wide screen stuff with the whole big ball and all. LoL

http://www.atmos.washington.edu/~ovens/loops/wxloop.cgi?wv_east_enhanced+12
Member Since: June 12, 2005 Posts: 6 Comments: 8188
18z GFDL increases Bill to 144kts. (165mph)!
Member Since: Posts: Comments:
Someone posted the Almanac prediction of a hurricane hitting New York Aug 24-28 2009...if you are on here, could you post that link again? Please. Was it authentic? Kinda eerie but cool if that is true.
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1176. scCane
Quoting Tazmanian:
on the track that bill is moveing it will hit NC in about 3 to 4 days


xtrap shows if bill moved nonstop in its current direction it would hit sc if that were true my house would be in the middle of its eye, thank gosh for this trough.
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When the can start getting it correct for the local weather here I will start paying attention to them. Until then I will stick with Weather Underground and Wind Guru
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You know the ensembles shifted to the west today and NHC still saying a WNW motion. That is making me a little nervous. I expected a NW to NNW movement already. The big models still holding to same track but htey are the eastern outliers on the ensembles.
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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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