Posted on April 10, 2015 by Bob Berwyn
Record low streamflows expected in many areas this summer
Precipitation for the 2015 water year- to-date is now below normal over most of the West except for some northwestern areas. The dry March has significantly affected this picture since a month ago, when far more of the West was near normal.
FRISCO —Federal water watchers say their April 1 readings show that precipitation thus far in the 2015 water year (beginning October 1, 2014) is now below normal over most of the West except for some northwestern areas and coastal Alaska.
Snowpack has declined significantly since last month throughout the West due to the warm and dry March. Only high- elevation areas in the Rocky Mountains and Interior Alaska retain somewhat near normal snowpack.
Streamflow forecasts have dropped since last month due to a lack of snow accumulation during March and an early snowmelt, with most regions now expecting below normal streamflow. Reservoir storage is currently below normal in the Southwest and Nevada, with near to above normal storage elsewhere. Continue reading
Filed under: climate and weather, Drought, El Niño, extreme weather, global warming | Tagged: climate change, drought, extreme weather, global warming, streamflow forecast, Western United States | 1 Comment »
Posted on March 27, 2015 by Bob Berwyn
Findings from Swiss-American team present nuanced view of how climate change affects weather extremes
One of this past winter’s northeastern snowstorms swirls off the coast of New England in the satellite image via NASA Earth Observatory.
FRISCO — Adding more fuel to the debate over climate change and extreme weather, Swiss and American scientists this week said their new study shows that global warming tends to reduce temperature variability.
The cold and snowy weather that gripped much of the eastern U.S. this winter was probably not linked to Arctic amplification and increased waviness of the jet stream, according to the scientists with ETH Zurich and the California Institute of Technology.
Changes in the north-south difference in temperatures play a greater role in modifying temperature variability than changes in the jet stream, the researchers said. Continue reading
Filed under: climate and weather, extreme weather, global warming | Tagged: climate change, extreme weather, global warming, Jet stream | 2 Comments »
Posted on March 17, 2015 by Bob Berwyn
Finding a signal amidst the climate noise isn’t easy
Does La Niña increase the odds of tornadoes?
Study finds links between ENSO and tornado frequency in the Southern U.S. Photo courtesy NOAA.
FRISCO — Teasing out a link between large-scale atmospheric patterns and specific weather events isn’t easy against the backdrop of natural variability.
But a new study of the El Niño-La Niña cycle in the Pacific Ocean suggests that La Niña — the cool phase of the cycle — increases the frequency of tornadoes and hail storms in some of the most susceptible regions of the United States.
During La Niña, both vertical wind shear and surface warmth and moisture increase significantly in the southern states, making conditions favorable to severe storm occurrence.
The study, published in the current issue of the journal Nature Geoscience, may help provide more information for medium- and long-range extreme weather forecasts. Continue reading
Filed under: climate and weather, extreme weather, global warming | Tagged: climate, El Nino, ENSO, extreme weather, La Niña, tornadoes | Leave a comment »
Posted on March 14, 2015 by Bob Berwyn
‘The risk of high-impact heat waves is likely to increase’
Monsoonal summer thunderstorms help regulate heatwaves. bberwyn photo.
FRISCO — Summer heatwaves, already getting longer and hotter because of human-caused global warming, are set to get even worse, as the overall climate-warming trend disrupts atmospheric circulations that bring relief from long spells of hot weather.
A recent study by scientists with the Potsdam Institute for Climate Impact Research one measurement of accumulated summer storm energy has already declined by 10 percent since 1979. The researchers linked the findings to changes in the Arctic caused by man-made global warming. Continue reading
Filed under: Arctic, climate and weather, extreme weather, global warming | Tagged: Arctic sea ice, extreme weather, global warming, heatwaves | 1 Comment »
Posted on March 12, 2015 by Bob Berwyn
A NASA visualization of Hurricane Floyd approaching the Florida coast in 1999. Hurricane Floyd formed from a tropical wave moving off the coast of Africa to become one of the largest and strongest Atlantic Hurricanes on record.
Spatial cloud coverage offers clues to tropical storm formation
FRISCO — Closely monitoring thunderstorms over Africa may help meteorologists develop better forecasts for Atlantic hurricane development.
“Eighty-five percent of the most intense hurricanes affecting the U.S. and Canada start off as disturbances in the atmosphere over Western Africa,” said Tel Aviv University Prof. Colin Price, who recently published a new study on hurricane formation in Geophysical Research Letters. “We found that the larger the area covered by the disturbances, the higher the chance they would develop into hurricanes only one to two weeks later.”
Working with graduate student Naama Reicher of the Department of Geosciences at TAU’s Faculty of Exact Science, Price analyzed satellite images of cloud cover to track the variability in cloud cover blocking the earth’s surface in West Africa during hurricane season.Using infrared cloud-top temperature data gathered from satellites, Prof. Price assessed the temperatures of the cloud tops, which grow colder the higher they rise. He then compared his cloud data with hurricane statistics — intensity, date of generation, location, and maximum winds — from the same period using the National Hurricane Center data base. Continue reading
Filed under: climate and weather, extreme weather, tropical storms and hurricanes | Tagged: Atlantic hurricanes, Cape Verde hurricanes, climate, extreme weather, hurricane forecasting, hurricane formation, tropical storms | Leave a comment »
Posted on February 12, 2015 by Bob Berwyn
A NOAA satellite image of Hurricane Bob, which raked the New England coast in 1991.
Historic record shows series of intense storms during eras of warmer sea surface temps
FRISCO — Climate researchers say New England’s coastal communities may need to prepare for major hurricane strikes sooner rather than later as the Atlantic Ocean continues to warm.
“We may need to begin planning for a category 3 hurricane landfall every decade or so rather than every 100 or 200 years,” said Jeff Donnelly, a scientist at Woods Hole Oceanographic Institution in Massachusetts, explaining that new research findings show that a string of giant storms pummeled the region during the first millennium, from the peak of the Roman Empire into the height of the Middle Ages. Continue reading
Filed under: climate and weather, extreme weather, global warming | Tagged: climate change, extreme weather, global warming, hurricanes, New England | Leave a comment »
Posted on February 11, 2015 by Bob Berwyn
Warmer atmosphere means more moisture, more rain
FRISCO — After carefully reviewing data from hundreds of stream gauges, University of Iowa scientists say they’ve identified a clear trend of increasing floods during the past 50 years.
“It’s not that big floods are getting bigger, but that we have been experiencing a larger number of big floods,” said Gabriele Villarini, a civil and environmental engineer and corresponding author on the paper, published Feb. 9 in the advance online edition of the journal Nature Climate Change. Continue reading
Filed under: climate and weather, extreme weather, global warming | Tagged: climate change, extreme weather, flooding, Midwest floods, NASA, University of Iowa | Leave a comment »