Archivo de la etiqueta: Climate

In 2015, NOAA’s Climate Program Office (CPO) invited grant proposals from sea ice and climate scientists looking to better understand and predict Arctic sea ice behavior, on timescales ranging from days to decades. This is our second story on some of the resulting research.

Welcome to meteorological spring! March kickstarts the transition season for many across the United States, and NOAA’s Climate Prediction Center has issued its monthly outlook for March 2020 temperature and precipitation.  As a reminder, these outlooks don’t predict the actual numerical temperature or the exact amount of precipitation. Instead, they predict the probability that monthly temperatures and precipitation will be in the upper or lower third of the climatological record (defined as the 1981-2010 period) for a given location. Darker colors refer to a higher chance, not more extreme conditions.

The highest chance for above-average temperatures during March is located across the lower Mississippi Valley from northeastern Arkansas and western Tennessee to the lower Great Lakes in Michigan and southern Wisconsin. However, the entire central and eastern parts of the contiguous United States have a tilt in the odds toward above-average temperatures during March. Only the Pacific Northwest sees probabilities tilted towards a cooler-than-average March.

The increased chance for above-average temperatures in the Ohio Valley region coincides with an increased probability for a wetter March, with the highest odds in the Tennessee Valley. Another area where the odds are tilted toward a wetter March is along the US/Mexico border from southern California to western Texas. February in California was quite dry, so above-average rains would be helpful to the state’s reservoirs and ecosystems. On the flip side, March is favored to be dry for Florida and the Central Plains. For Alaska maps, visit the Climate Prediction Center’s webpage.

What about elsewhere?

The areas in white on the map refer to there being an equal chance (33.3%) that monthly temperature and precipitation will be above, below, or near average. Even odds occur when forecasters see no reason to expect one outcome over another at a given location. It doesn’t mean conditions are favored to be average.

What climate factors might give forecasters a reason to think a particular climate outcome is more likely? Phenomena like El Niño or La Niña, the Arctic Oscillation, or recent trends can influence monthly temperature and precipitation patterns. If these patterns give conflicting signals to forecasters or are judged to be too weak to influence climate patterns in a given location, forecasters might declare those areas to be “equal chances”. For March 2020, that includes much of the western United States for temperature, and much of the Great Plains, East Coast, Mountain West and Pacific Northwest for precipitation.

What was on the forecasters minds?

In their discussion of this month’s outlooks, the Climate Prediction Center noted that forecasts for the large-scale pattern suggest the influence of Pacific air across the continental United States. Across the far western United States, this means troughing bringing in cooler North Pacific air to the Pacific Northwest and farther south bringing moist air from the neighboring ocean to southern California, increasing the chance for a wetter than average March for southern California and cooler than average temperatures across the Pacific Northwest. Meanwhile across the central and eastern United States, winds out of the west and southwest will result in ridging or high pressure, meaning a better chance at warmer-than-average temperatures.

Forecasters also note that variability will be high, especially across western United States, leading to the equal chance designation for temperatures across the West.

Join us on social media to let us know how your start to meteorological spring is going!

On Wednesday, February 5, climate  expert Dr. Gijs de Boer will answer questions in a Climate.gov tweet chat about ATOMIC scientific mission and his work on measuring the interactions between the clouds and ocean using an autonomous aircraft. 

The Greenland Ice Sheet contains enough stored water to raise sea level by more than 24 feet (7.2 meters) as it melts. How fast that will occur is one of the big unknowns for predicting the pace of sea level rise over the rest of the century. Glacier experts think the ice sheet was likely in balance in the decades leading up to 1990, but since then, it has been losing mass at an accelerating pace.

Adapted from the 2019 Arctic Report Card, this graph shows month-to-month changes in Greenland ice mass from April 2002–April 2019 overlaid on a NASA satellite image of the northwest coast of the island (rotated counterclockwise about 90 degrees) from July 19, 2019. Each peak in the graph shows the snow mass gained during the winter; each valley shows summer losses through surface melting and glacier thinning and retreat. The 17-year trend is estimated to be -267±3 billion tons per year, which is enough to have raised sea level by nearly 12 millimeters (0.5 inches). 

In the satellite image, sapphire blue melt ponds and streams are visible along the low elevations of the ice sheet margin which appears gray where snow has melted and dirty ice is exposed. Surface melting in summer 2019 was unusually widespread and early, according to the Arctic Report Card, starting in mid-April, 6-8 weeks sooner than average.  Under high pressure and sunny skies, roughly 95 percent of the surface experienced melting at some point in the summer, well above the 1981-2010 average of about 64 percent, equivalent to the previous record set in 2012. The highest one-day melt extent was 60.9 percent on July 31. Around the northern margin of the island, the melt season lasted at least 20 days longer than average.

Based on preliminary analysis combining observations and models since 1948, the exceptionally early and widespread melt in 2019 is likely to have led to the biggest one-year ice mass loss on record for the Greenland Ice Sheet.

This image is adapted from NOAA’s 2019 Arctic Report Card, which provides an annual update on observations from the Arctic, documenting changes in the physical environment—including sea ice, the atmosphere, snow, the Greenland Ice Sheet, and carbon stored and released by permafrost—and the impacts on people, plants, and animals that live there. This peer-reviewed collection of essays is part of NOAA’s mission to help the nation understand and prepare for the risks and opportunities of a changing climate.

On Tuesday, November 19, NOAA sea level rise expert William Sweet answered questions in a Climate.gov tweet chat about sea level rise and U.S. high-tide flooding.