Rapid melting snow has filled local reservoirs
In mid-April, Washington State’s snow cover was near-normal, while snow cover in the south was much higher than usual.
After that, temperatures in Washington were much warmer than normal in late April and May, as illustrated by the Olympia temperatures below (normal highs are shown in purple lines)
As a result of the warming, massive melting of Cascade ice and snow has spilled into local reservoirs, filling them to normal levels.
Consider, for example, the Yakima Reservoir system, crucial to eastern Washington agriculture (see below). During the two weeks of May, the reservoirs went from below normal to normal levels.
Or take the situation of Seattle. Just like the Yakima reservoir system, with a very rapid increase to normal levels during the past one month.
Seattle’s snow cover in the basin that supplies water to its reservoirs is shown below. OH. A dizzying decline!
To really gauge the extent of snow loss, here’s the percentage of last snow cover around the Northwest. Down to 35% or less in eastern Washington areas. But there’s still plenty of snow in southern Oregon and south.
The main problem is the temperature: while Washington is MUCH warmer than usual, California is either normal or colder than usual (see proof below)
This pattern (warm north, cool south) was advantageous: it slowed the melting of massive ice sheets across California, preventing catastrophic flooding and potential damage to lakes. contain/dam on the Golden State.
Forecast for the next ten days?
You won’t believe it. Much the same (see Central Europe forecast, which shows abnormal-than-normal temperature predictions for the next ten days). The North is warm, the South is cool. Again.
California will be saved from major flooding, which is very good news.