Cold air builds in Alaska

December 31st, 2008 |
GOES-11 10.7 µm IR images

GOES-11 10.7 µm IR images

Very cold air was becoming established across the interior of Alaska during the last few days of December 2008. AWIPS images of the 4-km resolution GOES-11 10.7 µm IR channel (above) showed large areas exhibiting very cold IR brightness temperatures (colder than -40º C, darker blue color enhancement) which were increasing in areal coverage as the surface temperatures continued to drop. The coldest air temperature measured in Alaska on 30 December 2008 was -49º C (-57º F) at O’Brien Creek; the temperature at the Fairbanks airport dropped to -41º C (41º F), with the coldest location in the Fairbanks urban corridor (the Woodsmoke subdivision at North Pole) reaching -43º C (-46º F).

A closer look using 1-km resolution 10.8 µm IR data from the AVHRR instrument on the NOAA series of polar-orbiting satellites (below) showed remarkable detail in the cold surface temperatures, whose patterns were strongly influenced by elevation. Due to cold air drainage, the coldest surface IR temperatures (indicated by the darkest blue color enhancement) were found in lower elevations such as river valleys and the Yukon Flats area of interior Alaska — note that the Yukon Flats region (located in the lower right quadrant of the images) exhibited a progressively darker blue enhancement on these 3 IR images as the surface temperatures plummeted during that time period. The coldest IR brightness temperature seen on the 15:57 UTC image was 222º K (-51º C, or -60º F) — and the air temperature at Fort Yukon was -46º C (-51º F) at that particular time.

NOAA-15 / NOAA-17 / NOAA-18 AVHRR 10.8 µm IR images

NOAA-15 / NOAA-17 / NOAA-18 AVHRR 10.8 µm IR images

With such cold temperatures becoming established up in Alaska, parts of the Lower 48 states should be on notice for a possible arctic outbreak in the coming weeks…

— 04 JANUARY 2009 UPDATE —

The coldest temperatures during this particular streak of cold temperatures occurred on 04 January 2009, when -54º C (-65º F) was reported at O’Brien Creek. A NOAA-17 AVHRR 10.8 µm IR image (below) indicated that IR brightness temperatures in the Yukon Flats region (located in the southeastern portion of the image) were as cold as -52º C (-62º F) at 20:51 UTC (11:51 AM local time).

NOAA-17 AVHRR 10.8 µm IR image

NOAA-17 AVHRR 10.8 µm IR image

— 10 January 2009 Update —

The coldest official temperatures recorded in Alaska during this 15-day-long cold spell were -56º C (-68º F) at O’Brien Creek (on 10 January) and at Chicken (on 08 January). In Fairbanks, the temperature remained below -40º C/F for a 24-hour period on 05-06 January.