Posted on October 18, 2013 by Bob Berwyn
Cooler Pacific Ocean temps may drive tornado activity into southern U.S.
A tornado near Lakeview, Texas. Photo courtesy NOAA.
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.)
“Differences in sea temperatures influence the route of the jet stream as it passes over the Pacific and, eventually, to the United States,” said Laurel McCoy, an atmospheric science graduate student at the MU School of Natural Resources. “Tornado-producing storms usually are triggered by, and will follow, the jet stream. This helps explain why we found a rise in the number of tornadoes and a change in their location when sea temperatures fluctuated.” Continue reading
Filed under: climate and weather, Environment, La Niña | Tagged: climate, extreme weather, National Oceanic and Atmospheric Administration, Pacific Decadal Oscillation, Sea surface temperature, tornadoes | 1 Comment »
Posted on August 24, 2013 by Bob Berwyn
Fall and winter outlook still murky
Seasonal weather forecasters look out to sea surface temperatures in the equatorial Pacific to get an idea of what weather patterns may bring.
Without a stron El Niño or La Niña in the outlook, forecasters are not confident of projecting pronounced temperature or precipitation anomalies.
By Bob Berwyn
FRISCO — With no strong El Niño or La Niña on the horizon, forecasters are struggling even more than usual to develop seasonal outlooks for the western U.S. The periodic El Niño-La Niña cycle is a large-scale shift in the Pacific involving a complex interplay of winds, ocean currents and sea surface temperatures.
In the U.S. the warm El Niño phase is associated with wetter than average conditions in the Desert Southwest and California, and can result in below average precipitation in the Pacific Northwest.
La Niña, on the other hand, has been linked with Southwestern drought conditions and heavy precipitation in the Pacific Northwest. That persistent moist flow off the northwestern Pacific can also favor parts of Colorado with good winter snows, but the ENSO climate signal is more marginal in Colorado than in other areas. Continue reading
Filed under: climate and weather, Colorado, Drought, El Niño, La Niña, seasons, Snow and weather, Summit County snow and weather | Tagged: climate, Colorado winter snow, El Nino, ENSO, La Niña, seasonal forecast, weather | Leave a comment »
Posted on August 10, 2013 by Bob Berwyn
Hurricane Sandy as seen from NOAA’s GOES-13 satellite on October 28, 2012. Photo courtesy NOAA/NASA.
Warm ocean temps, strong West Africa rainy season boost chances for tropical formation
By Summit Voice
FRISCO — Federal weather experts this week reaffirmed their earlier projections of an active hurricane season in the Atlantic, with hemispheric patterns similar to those that have produced many active Atlantic hurricane seasons since 1995.
Ingredients for tropical storm formation include above-average Atlantic sea surface temperatures and a stronger rainy season in West Africa, which produces wind patterns that help turn storm systems there into tropical storms and hurricanes.
The peak of the Atlantic hurricane season is just ahead, from mid-August through mid-October. Continue reading
Filed under: climate and weather, La Niña, seasons, tropical storms and hurricanes | Tagged: 2013 Atlantic hurricane season, hurricanes, National Hurricane Center, Tropical cyclone, weather | Leave a comment »
Posted on August 7, 2013 by Bob Berwyn
Strongest climate signals coming from Arctic and extreme weather events
Many parts of the globe reported record and near-record temps in June 2013.
By Bob Berwyn
FRISCO — Some of the most compelling signs of global warming impacts continued to come from the Arctic in 2012, where sea ice extent reached a record low and Greenland experienced record surface melting last summer.
Another worrying sign is the warming in permafrost regions, where significant thawing could release a new surge of heat-trapping greenhouse gases that would intensify warming.
The average global temperature for the year was among the top-10 warmest on record, and other climate observations also are consistent with what to expect in a warming world, according to climate experts who released the 2012 State of the Climate report this week. Continue reading
Filed under: Arctic, climate and weather, El Niño, Environment, global warming, La Niña | Tagged: 2012 state of the climate report, American Meteorological Society, climate change, global warming, National Climatic Data Center | 1 Comment »
Posted on July 19, 2013 by Bob Berwyn
Many northern hemisphere land areas reported near-record warmth
Most areas of the globe reported temperatures running well above the 20th century average during June 2013.
By Summit Voice
FRISCO — The Globally averaged land and sea surface temperature was 1.15 degrees above the 20th century average, tying with 2006 as the fifth-warmest on record, according to the National Climatic Data Center monthly summary report released this week.
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.
The year to-date is also running hot, tied with 2003 as the seventh-warmest January to June period on record, with a combined global land and ocean average surface temperature that was 1.06 degrees above the 20th century average. Continue reading
Filed under: climate and weather, El Niño, Environment, global warming, La Niña | Tagged: climate change, global climate, global warming, Instrumental temperature record, June 2013 global temperatures, National Oceanic and Atmospheric Administration, Sea surface temperature | Leave a comment »
Posted on July 15, 2013 by Bob Berwyn
Early warning could help regional preparedness efforts
A new climate model could help project El Niño conditions a year in advance.
By Summit Voice
FRISCO — Forecasting the emergence of El Niño well in advance has long been a goal of climate scientists and a team of German researchers say they may have devised a model that extends the lead time to a year.
Published recently in the Proceedings of the National Academy of Sciences, their paper describes how the model uses high-quality data of air temperatures as the basis for making long-term projections about El Niño, a warm phase of a periodic Pacific Ocean cycle that affects climate and weather around the world.
“Enhancing the preparedness of people in the affected regions by providing more early-warning time is key to avoiding some of the worst effects of El Niño,” said Hans Joachim Schellnhuber, director of the Potsdam Institute for Climate Impact Research, who co-authored the paper with Josef Ludescher, of Justus-Liebig Universität Giessen. Continue reading
Filed under: climate and weather, El Niño, La Niña | Tagged: climate, climate projections, El Nino, ENSO, Hans Joachim Schellnhuber, Potsdam Institute for Climate Impact Research | Leave a comment »
Posted on July 1, 2013 by Bob Berwyn
Broad tree-ring record provides accurate ENSO history
Researchers say tree ring records show that El Niño activity during the 20th century has largely been outside the range of natural variability.
By Summit Voice
Climate scientists have long suspected that global warming has an influence on the Pacific Ocean El Niño- La Niña cycle (El Niño-Southern Oscillation), but instrumental records tracking the shift between above- and below average sea surface temperatures don’t go back far enough to provide context for any recent changes in the pattern.
But scientists working at the International Pacific Research Center, University of Hawaii at Manoa say a new tree ring record extending back about 700 years has helped decipher long-term trends. The tree ring samples from both the tropics and mid-latitudes in both hemispheres support the idea that the unusually high ENSO activity in the late 20th century is a footprint of global warming said Jinbao Li, lead author of the study published online in the journal Nature Climate Change. Continue reading
Filed under: climate and weather, El Niño, global warming, La Niña | Tagged: climate, El Niño-Southern Oscillation, El Nino, ENSO, global warming, tree ring record, University of Hawaiʻi at Mānoa | 6 Comments »