Major Flood Warnings as Pineapple Express Soaks the Pacific Northwest

A Pineapple Express is on its way to the Pacific Northwest later this week, resulting in a flood threat along small streams, rivers, and urban areas in the area, according to meteorologists at AccuWeather.

For those unaware, a Pineapple Express — aside from the Seth Rogen movie — is a phenomenon where "a warm, moisture-rich current that flows from Hawaii to the U.S. West Coast, bringing heavy rain," as described by Seattle Hashtag. This atmospheric river will spread from the island to British Columbia and Washington through Friday, according to predictions.

This meteorological event is driven by a strong heat dome over the southwestern United States, which is pushing more extreme, winter-like weather northward around warm, dry air. That heat dome, similar to the heat wave experienced in the West (mainly California) over the weekend, is set to create record high temperatures across the location for the foreseeable future.

Heavy rain is expected to soak the region towards the end of the working week, as waves of moisture move through the Pineapple Express. Estimated rainfall between western Washington and southwestern British Columbia is approximately 1-4 inches, and is expected across most lower elevations in the region, teetering on the torrential rainfall threshold. Ponding on highways and flooding of some city streets are expected, according to Accuweather's predictions.

A moderate to major-category flooding risk is potent along some rivers in northwestern Washington and southwestern British Columbia. In addition to high rainfall, the melting of high-elevation snow in the warmer weather, especially as the region draws closer to Spring, increases this potential. Significant rainfall is also possible in the Cascades and eastern Washington regions, but the rain is thought to be more sporadic, with far less of a flooding risk.