Calm End to May Expected, Interesting Weather on the Horizon

 FastCast--Tuesday, May 28 to Saturday, June 1:

After a mostly cloudy Memorial Day weekend, showers will return to the Northwest. On Tuesday and Wednesday expect a total of 0.1-0.2" across the lowlands, with higher totals (up to 0.5") from Everett northward. Conditions will be mostly cloudy on Tuesday and Wednesday, with highs in the upper 50s to low 60s. We will dry out from Thursday through Saturday, with highs increasing to the mid to upper 60s, warmest on Friday, which will also be partly sunny. Through Saturday, expect overnight lows in the mid 40s to low 50s (warmest later in the week). There is potential for a potent rain event toward the early part of next week, and we will discuss this probability a bit more in the blog below.

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Continue reading the full blog below!

Let's take a look at the upcoming forecast, starting with the expected rain through Wednesday. We'll look at the European model forecast, seen below.

This forecast shows 0.1-0.25" of rain across the lowlands, with areas from Everett northward getting 0.4-0.75", and the coast getting 0.3-0.7". The Cascades will receive 0.7-1.25".

Temperatures will be on the cooler side (for late May) on Tuesday and Wednesday. Below is the NWS NBM forecast for highs on Tuesday.

On Tuesday, the lowlands will only reach the upper 50s, with similar temperatures along the coast. The Willamette Valley will reach the low to mid 60s, with Eastern Washington reaching the mid 70s to low 80s.

Wednesday will be a bit different across the state, as seen in the NWS NBM forecast below.

Eastern Washington will cool substantially on Wednesday, with highs in the low 60s to low 70s. The lowlands will be in the upper 50s to low 60s, with the Willamette Valley in the mid 60s.

Showers will move out of the region by Thursday, and temperatures will begin warming up a bit, as seen below.

In the lowlands, expect Thursday's highs to reach the low to mid 60s, with the coast in the upper 50s to low 60s, the Willamette Valley in the low 70s, and Eastern Washington in the mid 60s to mid 70s.

Now...for the interesting weather potential. A large area of subtropical moisture looks to be headed for the region, mainly from Sunday to Tuesday of next week. Below is the European model forecast showing total water vapor in the atmosphere as of Sunday evening.

This forecast shows a massive plume of moisture, known as an atmospheric river, aimed at the Northwest. This is a forecast more typical of winter, and it would bring large precipitation totals to the Northwest.

Let's compare this forecast to the GFS (American) model, also for Sunday evening.

There is good agreement on this forecast between the European and GFS models, suggesting that this is a real possibility.

Regarding rain totals and duration, that isn't known yet, as we are too far out to accurately forecast that information. However, stay tuned over the next few days as we get closer to this potential event!