A low pressure center off the coast of British Columbia, combined with a high pressure dome to the south, are directing a firehose of tropical Pacific moisture toward the Pacific Northwest. Often referred to as a Pineapple Express, this atmospheric river is expected to produce torrential rain across the lowlands and heavy snow in the mountains over the coming days.
Since the air is relatively warm, it will transport more moisture and the snowline will be high for this time of year. As a result, extensive flooding is expected across western portions of Washington and Oregon, a region that has already endured destructive floods in recent years.
While this weather phenomenon has occurred throughout recorded history, it will surely become more potent and destructive as our climate warms. Cities on coastal plains, backed by mountain ranges, are especially vulnerable.
