mardi 18 novembre 2014

Satellite View of the U.S. Wrapped in a Frozen Blanket












NOAA logo.

November 18, 2014


Image above: In this NOAA's GOES satellite infrared image taken on Nov. 18 at 7:30 a.m. EST, the cold air over the central and eastern U.S. appears to look like a blanket of white, but it's not all snow. Image Credit: NASA/NOAA GOES Project, Dennis Chesters.

As icy cold Canadian air settled over the eastern two-thirds of the U.S. bringing snow and bitter cold, NOAA's GOES-East satellite captured this infrared view of what looks like a frozen blanket over the region.

NOAA's GOES-East satellite provides visible and infrared images over the eastern U.S. and the Atlantic Ocean from its fixed orbit in space. In an infrared image taken on Nov. 18 at 12:30 UTC (7:30 a.m. EST), the cold air over the eastern and central U.S. appears to look like a blanket of white, but it's not all snow. Infrared data shows temperature, so although the eastern two-thirds of the U.S. appears to appear is if snow covers the ground, the blanket is in fact cold clouds. However, snow does lie under that blanket in the Upper Midwest, Ohio Valley, and Canada, where it will continue in those areas through Thursday, Nov. 20.

"Dozens of lakes behind dams in the Southeast USA stand out as dark spots in a grey landscape," said Dennis Chesters of NASA/NOAA's GOES Project at NASA's Goddard Space Flight Center in Greenbelt, Md. "That is because we invert the display of infrared emission to make cold cloud tops appear white, frozen land grey, and warm water dark."

NOAA's National Weather Service Weather Prediction Center said that the deep low pressure system pushing that polar air over the Eastern U.S. is centered over southeastern Canada.  On Tuesday, Nov. 18, freeze and frost warnings stretch from the upper Great Lakes to Florida. Some areas in the Upper Great Lakes are forecast to receive over two feet of snow. Well below average temperatures are forecast to reach the Gulf Coast, with most of the Mid-Atlantic States barely getting above freezing Tuesday and Wednesday. In the Midwest, periods of lake effect snow are forecast to continue south and east of the Great Lakes through Wednesday.

Artist's view of the GOES-East satellite. Image Credit: NOAA

This Arctic blast will bring temperatures as much as 20 degrees below average from the Gulf Coast and northward into the Northeast and continue Wednesday and start rising on Thursday.

In Nov. 17 and 18 a storm system brought snow to the Midwest and Great Lakes Region, where it fell in several feet. The forecast for the lee side of the Great Lakes calls for the continuation of snow with totals approaching two feet downwind of the two lakes. 

The infrared image from NOAA's GOES-East or GOES-13 satellite on Nov. 18 at 1200 UTC (7 a.m. EST) was made by NASA/NOAA's GOES Project.

To create the image, NASA/NOAA's GOES Project takes the cloud data from NOAA's GOES-East satellite and overlays it on a true-color image of land and ocean created by data from the Moderate Resolution Imaging Spectroradiometer, or MODIS, instrument that flies aboard NASA's Aqua and Terra satellites. Together, those data created the entire picture of the storm and show its movement. After the storm system passes, the snow on the ground becomes visible.

GOES satellites provide the kind of continuous monitoring necessary for intensive data analysis. Geostationary describes an orbit in which a satellite is always in the same position with respect to the rotating Earth. This allows GOES to hover continuously over one position on Earth's surface, appearing stationary. As a result, GOES provide a constant vigil for the atmospheric "triggers" for severe weather conditions such as tornadoes, flash floods, hail storms and hurricanes.

For updated information about the storm system, visit NOAA's NWS website: http://www.weather.gov

For more information about GOES satellites, visit: http://www.goes.noaa.gov/ or http://goes.gsfc.nasa.gov/

Images (mentioned), Text, Credits: NASA's Goddard Space Flight Center/Rob Gutro.

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