Global warming: New NOAA study eyes link between Arctic meltdown and extreme weather in mid-latitudes

A warming Arctic is changing the configuration of the jet stream, which affects mid-latitude weather. GRAPHIC COURTESY NOAA.

A warming Arctic is changing the configuration of the jet stream, which affects mid-latitude weather. GRAPHIC COURTESY NOAA.

‘Too soon to tell …’

Staff Report

*More Summit Voice stories on this subject are here

FRISCO — There’s been lots of speculation and some early research on a possible link between soaring temperatures in the Arctic and extreme weather in North America and Europe, but the jury is still out, according to scientists with the National Oceanic and Atmospheric Administration.

NOAA’s James Overland was part of an international team that took a close look at possible connections and concluded that more research is needed.

“We are in the pre-consensus stage of a theory that there are links between the rapid warming of the Arctic and some severe weather events since 2007,” said Overland, lead author of the new study, “The melting Arctic and Mid-latitude weather patterns: Are they connected?” Continue reading

Global warming: Risk of exposure to extreme heat waves is growing dramatically

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Warm enough!

Population growth in warm zones is a big part of the equation

Staff Report

FRISCO — Extreme heat kills more people than any other type of extreme weather, and that mortality could increase significantly in coming decades as the Earth warms under a blanket of heat-trapping greenhouse gases.

Americans’ exposure to extreme heat could increase  four- to six-fold by 2050, a new study concludes, explaining that it’s not just the heat — the country’s population is  growing especially fast in the hottest regions of the country. Continue reading

Climate: Is this year’s El Niño here to stay?

Forecasters nearly certain pattern will persist at least through the end of summer and probably to the end of the year

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Warm sea surface temperatures along the equatorial Pacific show the shape of El Niño.

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A classic El Niño sea surface temperature pattern is projected in this map from NOAA.

By Bob Berwyn

FRISCO — A developing Pacific El Niño is already affecting weather patterns across the western U.S. by bringing abundant spring moisture to the region, including late season snow and rain to parts of parched California.

And last week meteorologists with the National Oceanic and Atmospheric Administration said El Niño is likely to stick around for the summer and probably even through the end of the year, perhaps even gaining strength. More on the forecast in this NOAA El Niño blog.
Continue reading

UK scientists find big, fat global warming fingerprint

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The chance of extreme heatwaves is increased dramatically by human-caused global warming.

Greenhouse gas buildup raises chances of record-breaking warmth

Staff Report

FRISCO — There’s little doubt that global warming will lead to, well, warmer weather in most places.

But scientists in the UK said they were surprised at how clearly they could see the fingerprint of greenhouse gas emissions in a recent study that projects a big increase in the likelihood of record-breaking warm years. Continue reading

Major water woes looming in the West

Record low streamflows expected in many areas this summer

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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.

Staff Report

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

Study: Global warming not to blame for fierce winter

Findings from Swiss-American team present nuanced view of how climate change affects weather extremes

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One of this past winter’s northeastern snowstorms swirls off the coast of New England in the satellite image via NASA Earth Observatory.

Staff Report

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

Climate: Does La Niña increase the odds of tornadoes?

Finding a signal amidst the climate noise isn’t easy

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Does La Niña increase the odds of tornadoes?

A new NOAA study tracks the occurrence of seasonal tornadoes across the U.S.

Study finds links between ENSO and tornado frequency in the Southern U.S. Photo courtesy NOAA.

Staff Report

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

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