Just about every winter, coastal Cascadia gets slammed with a couple days like yesterday and today: flood days.

The worst flooding typically comes when heavy rains coincide with warm, subtropical air, which rapidly melts mountain snowpacks. That’s exactly what’s going on. This particular Pineapple Express, which the Canadians are calling Tropical Punch, started south of Japan and is now melting Cascadia’s headwaters and inundating its lowlands.

The drama is well told in the local media. Southwestern British Columbia has had the heaviest rains (as much as 8 inches) and the worst resulting landslides, as the Vancouver Sun reports here and especially here (subscription required for this article). Not too much better off is Western Washington, which has 12 rivers at or close to flood stage, as the Seattle Post-Intelligencernotes. Flooding is unusually widespread across western Washington, as the Seattle Timesreports.

The stories behind the drama—the slow news (pdf)–rarely gets told. To me, Tropical Punch has three "backstories."

  • First, Cascadians keep right on building in flood plains and on steep slopes, places where they can be certain that sooner or later nature will sweep their structures away.

    Second, the US federal government keeps subsidizing such development through its flood insurance, as we described last month here.

    Third, although no particular weather event can ever be proved a result of global climate change, it gives me an ominous feeling when I read in the Oregonian today that yesterday “was the warmest January day since record-keeping began in Portland in 1874—some 131 years. In addition to Portland, the highs of 67 degrees in Troutdale and 66 degrees in Vancouver set records for the both the date and the month.”

    In three ways, then, this natural disaster seems decidedly unnatural.