PINPOINT ALERT: Atmospheric River events begins Sunday

Some spotty showers popped up across western Washington throughout Saturday with the night ending on a rather quiet note.

A late-season atmospheric river event starts to enter the region early Sunday. With the heaviest rain falling Sunday night into Monday morning, we have a Pinpoint Alert Day for both days.

From Sunday to Tuesday here’s an estimate of total rainfall:

Lowlands: 1-2″

Mountains: 2-4″+

Coast: 2-4″

A Flood Watch is in effect from late Saturday through Wednesday morning. Snohomish, King, Pierce, Mason, and Lewis counties. River flooding and urban flooding are possible. The latest river forecast shows Snoqualmie River at Carnation nearing “minor flood stage” by Monday afternoon.

Now with these weather events comes a couple of noteworthy reminders:

  • While insignificant to most locations, some agricultural interests could be impacted by minor river flooding this time of year, especially in broad floodplain areas like the Snoqualmie Valley.
  • Unlike atmospheric river systems that have us on high alert during the fall and winter, the net result of an atmospheric river-style event in the Pacific Northwest in early June would be quite positive! This sort of soaking rainfall in the lowlands and the mountains is very unusual after May and would serve to “push out” the start of our serious wildfire concerns by quite a number of weeks

Now when it comes to wind and wind gusts, breezy conditions will increase ahead of the front areawide. These south/southwesterly winds should have minimal impacts.

A weaker system keeps rain in the forecast through Tuesday with some lingering showers possible into early Wednesday—though, a ridge of high pressure starts to amplify setting us up for a significant warm-up heading into next weekend. Highs will be in the upper 70s but pops of 80 degrees are likely next Friday and Saturday!

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