Warmup & Overall Pattern Change

FastCast—Wednesday, June 21 to Sunday, June 25:

After a few days that felt more like early spring than mid-June, a pattern change is in store for the Northwest. The troughing that brought showers, high mountain snow, and chilly temperatures is moving away, with some ridging building in its place. This will bring more sunny weather with less clouds. The pattern will be relatively steady through Sunday (and beyond), with temperatures warming up through this week. On Wednesday, expect decreasing clouds and highs in the upper 60s to low 70s. Thursday will bring more decreasing clouds and highs increasing into the low to mid 70s. Friday will be the hottest day of this week, with highs reaching the upper 70s to low 80s under mostly sunny skies. However, it is worth noting that some forecasts have shown mountain thunderstorms trying to stray into the lowlands late Friday, but that isn’t too likely. A marine push will bring more morning clouds on Saturday, decreasing through the day. Saturday’s highs will decrease to the mid 70s, but will rebound to the upper 70s on Sunday, with less morning clouds. Through Sunday, expect morning lows in the low 50s. Additionally, there is a chance of mountain thunderstorms, mainly in the afternoon, on Thursday and Friday.

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Continue reading the full blog below!

A pattern change is ahead…fittingly on Summer Solstice! The trough that has brought weather reminiscent of early spring is moving away, bringing a change to warmer and sunnier weather. Let’s take a look at the forecast!

First, the NAM high-resolution forecast for highs on Wednesday.

On Wednesday, expect highs in the mid 60s to low 70s in the lowlands, in the low to mid 60s on the coast, and in the upper 60s to upper 70s in Eastern Washington.

Thursday will be a bit warmer, as seen in the NAM high-resolution forecast below.

On Thursday, expect lowland highs in the low to mid 70s, coastal highs in the mid 60s to low 70s, and Eastern WA’s highs in the mid 70s to upper 80s. Note that the Willamette Valley will increase to the low to mid 80s on Thursday.

Next, let’s take a look at Friday’s highs, from the European model’s forecast.

On Friday, expect lowland highs in the mid 70s to low 80s, coastal highs in the low to mid 60s, and Eastern Washington’s highs in the upper 70s to low 90s. This will be the hottest day of the week.

Let’s take a look at the extended outlooks from the NWS Climate Prediction Center. First, the temperature outlook for June 26-30 (next week).

Notice a bullseye of a 33-50% probability of above average temperatures centered on Washington.

Next, the precipitation outlook for June 26-30.

This is a bit more interesting. Usually, with above-average temperatures expected, you’d expect below-average precipitation. However, in the upcoming pattern, this isn’t the case. Notice a 33-60% probability of above average precipitation, highest in SE WA, Eastern OR, and Central Idaho, along with parts of NE CA and NW NV. 

So why is this showing up in the extended outlook? The answer…thunderstorms.

Below is the European model forecast for precipitation through Friday night.

Notice how almost all the precipitation is confined to the mountains and areas immediately adjacent to them. This shows that the overall pattern favors mountain showers and thunderstorms, common on warmer days, with air rising along the mountains producing clouds, showers, and thunderstorms.

Let’s take a look at the NWS Storm Prediction Center (SPC) thunderstorm outlook for Thursday and Friday.

Below is Thursday’s thunderstorm outlook.

On Thursday, the SPC highlights a chance of thunderstorms over the Cascades and most of Eastern Washington, excluding the Columbia Basin (which makes sense, since it is removed from mountains).

Next, the SPC outlook for Friday.

Friday’s outlook specifically highlights the Cascades and areas immediately adjacent on the east & west, which is why a slight potential for lowland showers or thunderstorms on Friday was mentioned in the FastCast.

A stretch of seasonable, favorable, and relatively sunny weather looks to continue for the next 7-10 days! Stay tuned for more information!