NOAA’s winter outlook offers little relief for Arizona, New Mexico
By Bob Berwyn
FRISCO — Drought conditions may persist across the southwestern U.S. this winter and may redevelop across the Southeast, according to the seasonal outlook from NOAA’s Climate Prediction Center.
“Even though we don’t have La Niña, the atmosphere across the Pacific seems to be stuck in a La Niña mode … It’s been quite surprising to us, how persistent the pattern is,” said Mike Halpert, acting director of the Climate Prediction Center.
The new study, published Nov. 11 in the Proceedings of the National Academy of Sciences, shows how emissions of heat-trapping and ozone-depleting gases affect the distribution of precipitation through two mechanisms. Increasing temperatures are expected to make wet regions wetter and dry regions drier (thermodynamic changes); and changes in atmospheric circulation patterns will push storm tracks and subtropical dry zones toward the poles.
‘We may have underestimated the efficiency of the oceans as a storehouse for heat and energy … ‘
By Summit Voice
FRISCO — There’s more evidence that the world’s ocean are taking up the heat trapped by greenhouse gases at an increasing rate, according to a new study published in Science this week.
After reconstructing Pacific Ocean temperatures from the last 10,000 years, the researchers found that the middle depths have warmed 15 times faster in the last 60 years than they did during apparent natural warming cycles in the previous 10,000 years.
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.)
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 “Climate: With no Niño — what’s a forecaster to do?”→
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.