A heat wave of unprecedented magnitude and duration is forecast to grip the Pacific Northwest this weekend and bring dangerously high temperatures that could make life miserable into next week for a region where air conditioning is not a fixture in most households. Triple-digit temperatures are forecast throughout parts of Oregon and Washington, which includes the Interstate 5 corridor. Both Portland, Oregon, which could see the mercury crack the 110-degree mark, and Seattle, which is expected to top 100, could experience temperatures around 30 to 40 degrees above normal and challenge daily record highs. Following a cooler stretch of weather,...