15 September 2010 link 
An image timed at 0815GMT Wednesday shows Karl (far left), Igor (centre) and Julia (far right)
Igor, said to be the season's most powerful hurricane, is moving west-north-west towards Bermuda.
Julia intensified to category four on Wednesday, with winds close to 135mph.
Storm surges Karl was expected to hit the Yucatan peninsula at the Mayan ruins town of Tulum.
"A storm surge is expected to produce some coastal flooding near and to the north of where the centre makes landfall," the NHC said.
Karl may then head back out to open water and strengthen again.
At 0300GMT on Wednesday Igor was 605 miles east of the northern Leeward Islands.
Igor is not expected to make landfall for a several days but storm swells will affect Puerto Rico, the Virgin Islands, the Bahamas and the Leewards on Wednesday.
Igor's maximum winds have weakened slightly but are still at 145mph.
"Much more detail on Igor will be covered in the next few days, as it likely becomes a potential threat," the NHC said.
Julia rapidly intensified early on Wednesday but is not close to land.
UPDATE 5 AM AST: Second time in 100-years two coincident Category 4′s in the Atlantic…together, Igor and Julia have the highest coincident intensities on record.
Two major hurricanes exist simultaneously in the North Atlantic, a rare occurrence. With the current intensities of Julia and Igor, this has only happened 3-times in the past 60-years: 1950 [Dog & Easy], 1958 [Helene & Ilsa], and 1999 [Floyd & Gert]. But Igor and Julia just are not major hurricanes, they are Category 4′s.
Scientists studying sunspots for the past 2 decades have concluded that the magnetic field that triggers their formation has been steadily declining. If the current trend continues, by 2016 the sun's face may become spotless and remain that way for decades - a phenomenon that in the 17th century coincided with a prolonged period of cooling on Earth.
Sunspots appear when upwellings of the sun's magnetic field trap ionized plasma - or electrically charged, superheated gas - on the surface. Normally, the gas would release its heat and sink back below the surface, but the magnetic field inhibits this process. From Earth, the relatively cool surface gas looks like a dark blemish on the sun.
Astronomers have been observing and counting sunspots since Galileo began the practice in the early 17th century. From those studies, scientists have long known that the sun goes through an 11-year cycle, in which the number of sunspots spikes during a period called the solar maximum and drops - sometimes to zero - during a time of inactivity called the solar minimum.
The last solar minimum should have ended last year, but something peculiar has been happening. Although solar minimums normally last about 16 months, the current one has stretched over 26 months - the longest in a century. One reason, according to a paper submitted to the International Astronomical Union Symposium No. 273, an online colloquium, is that the magnetic field strength of sunspots appears to be waning.
Since 1990, solar astronomers Matthew Penn and William Livingston of the National Solar Observatory in Tucson, Arizona, have been studying the magnetic strength of sunspots using a measurement called Zeeman splitting. Named after the Dutch physicist who discovered it, the splitting is the distance that appears between a pair of lines in a spectrograph of the light given off by iron atoms in the sun's atmosphere. The wider the splitting, the greater the intensity of the magnetic field that created it. After examining the Zeeman splitting of 1500 sunspots, Penn and Livingston conclude that the average magnetic field strength of sunspots has declined from about 2700 gauss - the average strength of Earth's field is less than 1 gauss - to about 2000 gauss. The reasons for the decrease are not clearly understood, but if the trend continues, sunspot field strength will drop to 1500 gauss by as early as 2016. Because 1500 gauss is the minimum required to produce sunspots, Livingston says, at that level they would no longer be possible.
The phenomenon has happened before. Sunspots disappeared almost entirely between 1645 and 1715 during a period called the Maunder Minimum, which coincided with decades of lower-than-normal temperatures in Europe nicknamed the Little Ice Age. But Livingston cautions that the zero-sunspot prediction could be premature. "It may not happen," he says. "Only the passage of time will tell whether the solar cycle will pick up." Still, he adds, there's no doubt that sunspots "are not very healthy right now." Instead of the robust spots surrounded by halolike zones called penumbrae, as seen during the last solar maximum (photo), most of the current crop looks "rather peaked," with few or no penumbrae.
"It is a very interesting sequence of observations," says solar physicist Scott McIntosh of the National Center for Atmospheric Research in Boulder, Colorado. The researchers "have carefully analyzed their data and the trend appears to be real," he says.
Solar physicist David Hathaway of NASA's Marshall Space Flight Center in Huntsville, Alabama, agrees but with a caveat. "It's an important paper," he says. But the sunspot magnetic field calculations don't take into account a lot of small sunspots that appeared during the last solar maximum. Those sunspots have weaker magnetic fields, which, if not included, could make the average sunspot magnetic field strength seem higher than it really was.
Mexico, US and Caribbean eye trio of storms
An image timed at 0815GMT Wednesday shows Karl (far left), Igor (centre) and Julia (far right) Tropical Storm Karl is bearing down on Mexico, with two dangerous category four hurricanes - Igor and Julia - also sweeping in from the Atlantic.
Karl, packing maximum sustained winds of 65mph (100km/h), is close to the Mayan Riviera on Mexico's Yucatan peninsula.Igor, said to be the season's most powerful hurricane, is moving west-north-west towards Bermuda.
Julia intensified to category four on Wednesday, with winds close to 135mph.
Storm surges Karl was expected to hit the Yucatan peninsula at the Mayan ruins town of Tulum.
Although Karl is now a relatively weak system, it is threatening to bring heavy rain. No evacuations have so far been ordered.
The Miami-based National Hurricane Center said there could be as much as 8in (20cm) of rain in affected areas in Mexico, as well as in parts of Belize and northern Guatemala."A storm surge is expected to produce some coastal flooding near and to the north of where the centre makes landfall," the NHC said.
Igor as seen from space on Mon and Tues. Video and commentary provided by Nasa
At 0300GMT on Wednesday Igor was 605 miles east of the northern Leeward Islands.
Igor is not expected to make landfall for a several days but storm swells will affect Puerto Rico, the Virgin Islands, the Bahamas and the Leewards on Wednesday.
Igor's maximum winds have weakened slightly but are still at 145mph.
"Much more detail on Igor will be covered in the next few days, as it likely becomes a potential threat," the NHC said.
Julia rapidly intensified early on Wednesday but is not close to land.
Hurricane Julia explodes — Atlantic has two coincident Category 4 hurricanes, very rare
UPDATE 5 AM AST: Second time in 100-years two coincident Category 4′s in the Atlantic…together, Igor and Julia have the highest coincident intensities on record.
Two major hurricanes exist simultaneously in the North Atlantic, a rare occurrence. With the current intensities of Julia and Igor, this has only happened 3-times in the past 60-years: 1950 [Dog & Easy], 1958 [Helene & Ilsa], and 1999 [Floyd & Gert]. But Igor and Julia just are not major hurricanes, they are Category 4′s.
- Unprecedented: in our North Atlantic historical records, the forecast intensities of Igor and Julia during the next 12-24 hours will be unprecedented for coincident storms. The only other time (we know of) coincident Category 4+ hurricanes occurred was in 1926 with Hurricane #4 and the Great Miami Hurricane (September 26 at 06:00 UTC).
- More: At 115 knots +, Hurricane Julia is the most intense storm that far in the Eastern Atlantic [-31.8W] joining other major hurricane east of -35W including Frances 1980 and Fred 2009.
- Early morning September 15: 12-hour forecasts indicate a maximum intensity of 120 knots for Julia and 130 knots for Igor. Two coincident Category 4 hurricanes have not occurred since 1950. The only occurrence since 1900 happened on September 15, 1926 at 06Z with Hurricane 4 [115 knots] and the Great Miami Hurricane [120 knots].
- Thus, Igor and Julia will attain have attained coincident intensities that are unprecedented: Igor: 130 knots & Julia: 115 knots.
Sunspots appear when upwellings of the sun's magnetic field trap ionized plasma - or electrically charged, superheated gas - on the surface. Normally, the gas would release its heat and sink back below the surface, but the magnetic field inhibits this process. From Earth, the relatively cool surface gas looks like a dark blemish on the sun.
Astronomers have been observing and counting sunspots since Galileo began the practice in the early 17th century. From those studies, scientists have long known that the sun goes through an 11-year cycle, in which the number of sunspots spikes during a period called the solar maximum and drops - sometimes to zero - during a time of inactivity called the solar minimum.
The last solar minimum should have ended last year, but something peculiar has been happening. Although solar minimums normally last about 16 months, the current one has stretched over 26 months - the longest in a century. One reason, according to a paper submitted to the International Astronomical Union Symposium No. 273, an online colloquium, is that the magnetic field strength of sunspots appears to be waning.
Since 1990, solar astronomers Matthew Penn and William Livingston of the National Solar Observatory in Tucson, Arizona, have been studying the magnetic strength of sunspots using a measurement called Zeeman splitting. Named after the Dutch physicist who discovered it, the splitting is the distance that appears between a pair of lines in a spectrograph of the light given off by iron atoms in the sun's atmosphere. The wider the splitting, the greater the intensity of the magnetic field that created it. After examining the Zeeman splitting of 1500 sunspots, Penn and Livingston conclude that the average magnetic field strength of sunspots has declined from about 2700 gauss - the average strength of Earth's field is less than 1 gauss - to about 2000 gauss. The reasons for the decrease are not clearly understood, but if the trend continues, sunspot field strength will drop to 1500 gauss by as early as 2016. Because 1500 gauss is the minimum required to produce sunspots, Livingston says, at that level they would no longer be possible.
The phenomenon has happened before. Sunspots disappeared almost entirely between 1645 and 1715 during a period called the Maunder Minimum, which coincided with decades of lower-than-normal temperatures in Europe nicknamed the Little Ice Age. But Livingston cautions that the zero-sunspot prediction could be premature. "It may not happen," he says. "Only the passage of time will tell whether the solar cycle will pick up." Still, he adds, there's no doubt that sunspots "are not very healthy right now." Instead of the robust spots surrounded by halolike zones called penumbrae, as seen during the last solar maximum (photo), most of the current crop looks "rather peaked," with few or no penumbrae.
"It is a very interesting sequence of observations," says solar physicist Scott McIntosh of the National Center for Atmospheric Research in Boulder, Colorado. The researchers "have carefully analyzed their data and the trend appears to be real," he says.
Solar physicist David Hathaway of NASA's Marshall Space Flight Center in Huntsville, Alabama, agrees but with a caveat. "It's an important paper," he says. But the sunspot magnetic field calculations don't take into account a lot of small sunspots that appeared during the last solar maximum. Those sunspots have weaker magnetic fields, which, if not included, could make the average sunspot magnetic field strength seem higher than it really was.
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