The CV-580 flew from Inuvik, CA to Barrow, AK and then to SHEBA ship.
The Aleutian low weakened and moved a bubble north toward SHEBA ship. Cloud cover was broken and variable along the Alaskan coast with some cirrus and some lower stratus clouds. Ice features could be seen around Barrow on the HRPT image. The denser cloud cover appeared around Barrow, while the eastern Beaufort Sea may have been clear. Over SHEBA ship, cloud cover was dense as shown on the radar. Snow was reported at 6 UT before the CV-580 arrived. However, the snow must have ended before the arrival of the aircraft because it was not reported in the weather observations of 18 UT (10 a.m. ADT) and 00 UT (4 p.m. ADT).
A mass of cirrus was moving toward SHEBA ship from the south. It could be seen on the GAC and HRPT IR images. The edge of the denser cirrus reached the ship at 02:35 UT, 18 April HRPT image.
Beaufort Sea trajectories show that most of the air came from the south, Alaska and the Pacific ocean. SHEBA ship trajectories show that air from 3 km and above came from the south, the Pacific Ocean acrossed Alaska. While the surface air came from the southeast, the Beaufort sea, and slightly above the surface, 1 to 1.5 km, the air came from the Beaufort Sea along the Alaskan coast.
