Friday, December 17, 2010
Black Stratus again
"Black stratus" is the in-house jargon term for low-topped status or stratocumulus that appear darker than surrounding ground on conventional infrared satellite imagery over Interior Alaska in winter, as the cloud tops are warmer than most of the ground. This mornings' NOAA-19 POES image shows a slug of clouds that moved into the eastern Interior from the Yukon Thursday night. Underneath the clouds, valleys are mostly 15 to 30F below this morning. Elsehwere, mostly 30 to 45F below, except on the Yukon Flats, which appear in this image as obviously "whiter", i.e. colder than most other clear valleys. Fort Yukon AWOS reports 56 below this morning, the lowest of the season. The Beaver Creek and Chalkytsyik RAWS temperatures have stopped reporting, but they are probably around -60F.