Cooler Pacific Ocean temps may drive tornado activity into southern U.S.
By Summit Voice
FRISCO — After studying more than 56,000 tornados, researchers at the University of Missouri say they’ve found a clear link between Pacific Ocean sea surface temperatures and the patterns of storms that spawn the violent twisters. The findings could help scientists predict the type and location of tornado activity in the U.S.
When surface sea temperatures were warmer than average, the U.S. experienced 20.3 percent more tornadoes that were rated EF-2 to EF-5 on the Enhanced Fuijta (EF) scale. (The EF scale rates the strength of tornados based on the damage they cause. The scale has six category rankings from zero to five.)
The average land-surface temperature was even warmer. At 1.89 degrees above average, it was the third-warmest June on record over the world’s land areas. Record-setting warmth was reported from many locations in northern Canada, far northwestern Russia, southern Japan, the Philippines, part of southwestern China, and central southern Africa.
SUMMIT COUNTY — Researchers say they’re getting closer to mapping how global warming will change rainfall patterns across the tropics. Their models project increases in precipitation in areas that already wet, and also in regions where temperatures increases surpass the average warming of the tropics.
Archived ocean observations help create new data set for climate models
By Summit Voice
SUMMIT COUNTY — A new set of more complete sea surface temperature data has helped scientists explain a gradual, decades-long slowdown of a key tropical atmospheric circulation, linking it with the steady increase in global temperatures during the past few decades.
“Our experiments show that the main driver of the change in the Walker circulation is the gradual change that has taken place in the surface temperature pattern toward a more El Niño-like state,” said Hiroki Tokinaga, associate researcher at the International Pacific Research Center, University of Hawaii at Manoa. “We don’t have enough data yet to say to what degree the slowdown over the last 60 years is due to a rise in man-made greenhouse gases or to natural cycles in the climate,” Tokinaga said.
Above-average temperatures to persist across much of the country
By Bob Berwyn
SUMMIT COUNTY — This year’s El Niño is likely to be one of the weaker versions of the event in recent memory, according to experts with the National Climatic Data Center, who discussed the fall outlook and reviewed the long, hot summer at teleconference last week.
That could weaken potential impacts, particularly across the southern tier of states, where an “average” El Niño often brings above-average precipitation.This could be especially important for states like New Mexico, which just experienced its driest and warmest 24-month period on record, and farther east, where Oklahoma was also parched during a record-hot summer.
During an El Niño, sea surface temperatures in the eastern and central equatorial Pacific surge to above average, often shifting the storm track to the south. It’s part of a cyclical shift in sea surface temperatures and related wind patterns that can affect weather patterns worldwide.
Sea surface temps have hovered at slightly above average the past few months in the region where El Niño formation is measured, but haven’t reached the formal threshold yet. An area of cooler water in the north Pacific may be a factor.
The North Pacific is not cooperating … there’s a cold area near Alaska. It’s not quite a perfect setup for a warm event in the tropics,” said NOAA scientist Huug van den Dool.
“It’s probably too late to get a major El Nino … it’s going to be somewhat weaker than we expected a few months ago,” he said, explaining that there’s still a chance for enhanced precipitation across the South. An average El Niño footprint would normally also result in below-average precipitation in the northern tier of states.
El Niño or not, the Climate Prediction Center says there’s a good chance the next three months will bring mostly above average temperatures to a big swath of the country, from the eastern edge of the Great Basin through the central and northern plains, up into the Great Lakes region and New England.
The three-month precipitation outlook is for near-normal total for much of the country, with a chance of above-normal rainfall in the southeast, and drier-than-normal conditions in the Pacific Northwest.
Looking back, Jake Crouch, of the NCDC, said it was the third-warmest summer on record for the U.S. and second-warmest summer for the northern hemisphere. A total of 33 states reported their warmest year to-date on record.
The year to-date is the ninth-warmest on record globally.
Researchers propose cloud-brightening to avert strong storms
By Summit Voice
SUMMIT COUNTY — While hurricanes are often feared as a destructive force of nature, they are also one of nature’s great climate regulators, helping to disperse ocean and atmospheric heat away from the equatorial region.
But some environmental scientists think it might be a good idea to reduce the intensity of hurricanes by seeding clouds to decrease sea surface temperatures when hurricanes form. Theoretically, the scientists claim the technique could reduce hurricane intensity by a category.
The team focused on the relationship between sea surface temperature and the energy associated with the destructive potential of hurricanes. Rather than seeding storm clouds or hurricanes directly, the idea is to target marine stratocumulus clouds, which cover an estimated quarter of the world’s oceans, to prevent hurricanes forming.
“Hurricanes derive their energy from the heat contained in the surface waters of the ocean,” said Dr Alan Gadian from the University of Leeds. “If we are able to increase the amount of sunlight reflected by clouds above the hurricane development region then there will be less energy to feed the hurricanes.” Continue reading “Could cloud-seeding weaken hurricanes?”→
Cooler than average readings reported from Australia, South America
SUMMIT COUNTY — Already on record as the hottest month of all time in the U.S., July 2012 will now go into the books globally as the fourth-warmest on record.
According to the global temperature analysis released today by the National Climatic Data Center, the average combined land and sea surface temperature for July was 1.12 degrees above the 20th century average. The land surface temperatures alone was the third-warmest on record at 1.66 degrees above the 20th century average.
Last month marked the 36th consecutive July with above-average temperatures and the 329th consecutive month overall with higher-than-average readings. According to the NCDC, the last time July global temps were below average was in 1976.
The warmest temps were reported from southeastern Europe, Canada and the U.S. Much cooler than average temperatures continued in Australia, northern and western Europe, eastern Russia, Alaska, and southern South America.
Even in a transition phase between a cooling La Niña and an emerging El Niño, global ocean temperatures were well above normal, with the highest monthly departure from average since July 2010.
For the year to-date, the combined average land and sea surface temperature is the 10th-warmest on record.
Information compiled from the NOAA National Climatic Data Center, State of the Climate: Global Analysis for July 2012, published online August 2012, retrieved on August 15, 2012 from http://www.ncdc.noaa.gov/sotc/global/2012/7.