Know your Terrain!

GOES-R IFR Probabilities (Upper left), GOES Brightness Temperature Difference (10.7 – 3.9 ) (Upper Right), color-enhanced Topography (Lower Left), Window Channel Infrared (10.7 ) (Lower Right).  Imagery from 0715, 1015 and 1415 UTC 18 December 2012.

Interpretation of the GOES-R IFR probability must include a consideration of terrain height, because a cloud bank that exists over a valley as elevated stratus can quickly become fog or low stratus as the ground rises into the fog on the sides of the valleys.  This happens with some frequency over the Sierra Nevada next to California’s San Joaquin valley, but it is also apparent in the images above over the higher terrain of central Idaho near the Snake River Valley.  A strong IFR Probability signal develops over central Idaho and also over eastern Idaho/northwest Wyoming where high terrain exists.

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