Bill intensifies to Category 4; globe has 5th warmest July on record
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
Reader Comments
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Nice update 456!
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..
anyway, i think people in the northeastern US should certainly not consider themselves in the clear yet. florida is safe, despite apoclyps' best efforts.
Well crap. Thanks for the heads up Tim.
Yep.... and on Long Range radar from Key West, you can make out some slight rotation. Nothing even strong yet but thunderstorms are building (slightly). Something to watch today but it would have to really blow up and soon to be a player (or anything for that matter).
Link
The majority of the models had a mediocre performance so far this year. I recommend using the ECMWF
"Rest of Today
Mostly cloudy with showers and thunderstorms likely. Breezy. Locally heavy rainfall possible. Highs around 90. Southeast winds 15 to 20 mph decreasing to 10 to 15 mph later in the afternoon. Chance of rain 60 percent."
Here's their current conditions....
"Miami, Florida (Airport)
Updated: 31 min 31 sec ago
Mostly Cloudy
87 °F
Mostly Cloudy
Humidity: 69%
Dew Point: 76 °F
Wind: 13 mph from the ESE
Pressure: 30.06 in (Steady)
Heat Index: 97 °F
Visibility: 10.0 miles
UV: 8 out of 16
Clouds:
Scattered Clouds 2500 ft
Mostly Cloudy 14000 ft
(Above Ground Level)
Elevation: 7 ft".....
Here's their radar........WTH?
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'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??
And when do they expect this Tropical Cyclone to steer near the East Coast?
It's quite clear you are a west-caster.
Correct
Floodman! Great to see ya!
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..
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.
That seems to be the general sentiment around here ... i.e. the NHC is calling it right.
Howdy, Rob! How you been?
I think it's good for now, especially when there's no line.. It could go anywhere in that cone. Nice job.
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.
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
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.
What is that under Loiusiaana? Does that bear watching also?
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.
You think? LOL
How have you been, Ike?
Doing fine. How's about U?
Yep, and a bill for the opps! LOL
Thank you. I will probably make another one around 4 or 5.
A bit, as in <1 degree.
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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