- 8 -
Slowly increasing clouds from northwest lowering Washington, north Oregon coast to m.s.l. 2,000 scattered, 3,500 broken to overcast, 7,500 overcast occasional light rain, top layers 20,000 after dark.[1]
East Washington, east Oregon clear to 25,000 thin broken, scattered cumulus 5,000 above ground level developing early afternoon dissipating during evenings, cumulus tops to 12,000- 15,000.
Mountain passes generally open. Columbia River gorge open.
Locally light icing in cumulus. Freezing level northwest Washington 3,500 sloping to 7,000 northeast Washington and to 8,500 south Oregon.
Light to locally moderate turbulence vicinity afternoon cumulus.
The terminal forecasts for Boeing Field and Seattle issued at 0845 for a 12-hour period beginning at 0900 were in part as follows:
0900 - 1800.--Four thousand scattered, 10,000 scattered, 25,000 thin broken.
There is no record of any weather briefing being provided to the crew of Logair 6541C by the personnel of the Seattle FSS following the arrival at Boeing Field.
Report as to the actual weather conditions which existed in the Seattle and Mt. Rainier areas were provided by witnesses and pilots who observed these conditions on the day of the accident.
One witness, a commercial pilot who conducts a scenic flight service in the Mt. Rainier area testified that the weather was clear during the early morning hours but that by midmorning a cumulus cloud buildup had commenced on the west face of Mt. Rainier. The cloud condition at this time was scattered to broken, with the bases at approximately 4,200 feet and the tops at approximately 8,000 feet m.s.l.
He further stated that the entire mountain was visible above the 8,000-foot level at the time. He related that the cumulus buildup continued in this area and that by noon, an overcast condition prevailed, with the bases about 4,200 feet m.s.l.
An in-flight weather observation was made by a Washington National Guard pilot who conducted a round trip flight between Gray Field, Fort Lewis, just south of Tacoma, Washington, and Yakima, Washington, approximately 90 nautical miles southeast of Seattle. The pilot stated that he departed Gray Field at 1440 for Yakima on an IFR flight plan utilizing Airway V-4. A flight along this airway passes approximately 18 miles to the northeast of the crash site on Mt. Rainier. He testified that a solid cloud deck was entered at approximately 4,700 feet, that a shallow (400 - 500 feet) clear area was encountered between 7,000 - 8,000 feet, with solid cloud conditions to his cruising altitude of 11,000 feet. He further stated that beginning near Tieton Intersection (15 nautical miles northwest of Yakima) he began breaking in and out of the rolling tops of the cloud layer. While on instruments in this layer, he encountered heavy moisture and
- ↑ After dark refers to all cloud conditions set forth in the paragraph.
