Short Spring Heat Wave for the Pacific Northwest

 FastCast--Thursday, May 9 to Tuesday, May 14:

A spring "heat wave" is ahead for the Northwest, with the warmest temperatures seen in months likely from Friday to Sunday. In the lowlands, expect sunny conditions through midday Sunday, before partly to mostly cloudy conditions take over from midday Sunday through Tuesday. Lowland highs will reach the low to mid 70s on Thursday. Friday and Saturday will be the hottest days since late last summer, with lowland highs reaching the low to mid 80s, hottest from Seattle southward. Cooler marine air will return on Sunday, with highs dropping to the mid 70s. Continued marine air will bring temperatures down to the mid to upper 60s on Monday and Tuesday. Remember, although temperatures will be warm, the water is NOT! Water temperatures across the region are in the 40s to low 50s, with some mountain-fed rivers in the 30s! These water conditions can cause severe health emergencies or even death. Be extremely careful around water during this warm spell.

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Warm weather is here! The warmest temperatures of 2024 (so far) are expected over the next few days, from Friday to Sunday, depending on what part of the state you're in. Let's take a look at the forecast!

First, the NWS NBM model high-resolution forecast for highs on Thursday, seen below.

Expect lowland highs to reach the low to mid 70s, with areas east of I-5 and south of Olympia reaching the upper 70s. The coast will reach the mid 60s on the beaches to mid 70s just inland, and the Willamette Valley will reach the upper 70s to low 80s. Eastern Washington will reach the mid 70s to low 80s, warmest in valleys and around the Tri-Cities.

Next, let's take a look at Friday's forecast, also from the NWS NBM model.

Friday will likely be the first 80°+ day of 2024 for most areas from Everett southward. Expect highs in the low to mid 80s from Seattle southward, and in the mid 70s to low 80s from Everett northward. The hottest temperatures will be in the mid 80s, mainly in mountain valleys. The coast will reach the low 70s (hottest day in this stretch along the coast), while the Willamette Valley will reach the upper 80s, with an outside chance at the Portland area reaching the low 90s. Eastern Washington will also be quite warm, with highs across the region in the upper 70s to mid 80s, hottest in the lower Columbia Basin.

We'll continue into the weekend, taking a look at Saturday's highs below, from the NWS NBM model.

On Saturday, the lowlands will reach the mid to upper 70s north of Everett, and the low to mid 80s south of Everett. There is potential for low 80s to be more widespread across the North Sound. The Willamette Valley will reach the mid to upper 80s, while Eastern Washington will reach the low 80s near Spokane to the low 90s in the Columbia Basin. Cities like Yakima and the Tri-Cities will likely reach the low 90s. Notice that on the coast, temperatures will drop to the low 60s on the beaches and mid to upper 60s inland. That's the "natural air conditioning" of the Pacific Northwest moving in.

The effect of that "natural A/C" (and incoming clouds) will be seen west of the Cascades on Sunday, as the NWS NBM model forecast shows.

On Sunday, temperatures west of the Cascades will decrease noticeably. Expect the lowlands to drop to the low to mid 70s, while the Willamette Valley will drop to the upper 70s. The coast will be much cooler, with highs in the upper 50s to low 60s. However, notice that the cooler marine air hasn't reached Eastern Washington, where highs will remain in the low 80s near Spokane to upper 80s/low 90s for the Columbia Basin.

Temperatures statewide will decrease on Monday and Tuesday as cooler marine air moves through. However, rain remains unlikely for at least the next 7 days, possibly longer.

What is causing such a nice stretch in mid-May? That question is easily answered by looking at the European model forecast for Friday morning, showing atmospheric pressure at 18,000 feet (called 500 millibars in the weather world).

Notice the large high pressure ridge centered just offshore of the Pacific Northwest and over Southern BC. This ridge has the proper placement and strength to bring a short-lived heat wave to the region. In summer, the overall pattern favors ridges like this being larger, stronger, and lasting longer, contributing to more intense heat waves.

However, regardless of the strength of this heat wave, adverse impacts are still possible, especially if you are recreating in the water. Take a look at the very informative graphic below from NWS Seattle, showing the dangers of the region's very cold water.

Consider these reminders if you're around the water while it's hot outside. Remember how cold and dangerous our waters can be!

Stay tuned for more information about the hot weather and extended forecast!

Brief Spring Atmospheric River Bringing a Wet Weekend

 FastCast--Saturday, May 4 to Thursday, May 9:

A fast-moving atmospheric river will bring a wet weekend to the Pacific Northwest. With the majority of the atmospheric river being aimed at Oregon, Washington's rain totals will be heaviest the further south you go. In the lowlands, generally expect 0.75-1.25" from Seattle southward, and 0.4-0.8" from Seattle northward. Expect rain at times from early Saturday through Sunday, becoming more showery on Monday. Some showers may linger into Tuesday. Conditions will change on Wednesday, turning partly sunny. Mostly sunny skies are likely by Thursday. Regarding temperatures, the weekend will be chilly around the lowlands, with highs in the low to mid 50s. However, Saturday's highs north of Everett will likely reach the mid 60s. Temperatures will be in the mid to upper 50s on Monday and Tuesday, before reaching the low 60s on Wednesday. By Thursday, a warmup is likely to begin, with highs reaching the upper 60s to low 70s. Expect lows through Thursday to remain in the low to mid 40s. Even warmer conditions, likely the warmest of 2024 so far, are possible for Mother's Day weekend, so stay tuned!

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A brief spring atmospheric river is impacting the Pacific Northwest, especially Western Oregon, with significant precipitation this weekend. Let's take a look at the forecast!

We'll start with the European model forecast for precipitable water late Friday night, showing the location of the heavier concentrations of water vapor (aka...the atmospheric river).

Notice how the highest concentrations of moisture are directed at Western Oregon, with some elevated moisture content making its way into Western Washington.

Now, let's look at rain totals. First, we'll take a look at the European model forecast for total rain through Monday night.

From Skagit County southward, this forecast shows 0.5-1" of rain, with areas from Olympia to Portland and on the coast getting 1.25-2", and the Willamette Valley and Oregon Coast being soaked by 2-2.5"! Whatcom and San Juan Counties will likely receive 0.3-0.5". Even Eastern Washington will get in on the rain, with most of the region getting 0.4-0.8", except 0.75-1.25" along and south of I-82.

We'll compare this to the NWS NBM high-resolution model forecast, seen below, also showing total rain through Monday night.

This forecast shows a similar picture for the lowlands and coast, with the Willamette Valley getting 1.4-2", and the Oregon Coast getting 1.5-2.5". Eastern Washington's highest amounts are confined to areas south of I-90 and near the Idaho border, with totals of 0.5-1.2", highest near Walla Walla and the Tri-Cities.

Temperatures will be on the cool side due to all the rain and cloud cover. Below is the NWS NBM forecast for highs on Saturday.

As rain and clouds will move from south to north, notice that highs increase as you move north through the lowlands. Areas from Everett to Tacoma will reach the mid to upper 50s, with areas north of Everett in the mid to upper 60s. From Tacoma south, expect highs in the low to mid 50s, except in the low 50s on the coast and in the Willamette Valley. Removed from the rain on Saturday, Eastern Washington will reach the upper 60s to mid 70s.

The entire region will be cool and cloudy on Sunday, as seen in the NWS NBM forecast below.

On Sunday, expect highs west of the Cascades to reach the low to mid 50s, with Eastern Washington reaching the low 50s near Spokane to low 60s near the east slopes of the Cascades. However, the Okanogan River Valley may reach the upper 60s to low 70s.

Here's the NWS NBM forecast for Monday, as the atmospheric river's associated rain begins to move out of the region.

Temperatures on Monday will remain on the cooler side, with highs in the low to mid 50s west of the Cascades, and in the upper 50s to mid 60s in Eastern Washington.

However, a significant change is possible as we move through next week. Below is the European model forecast for Thursday.

Notice the large ridge of high pressure located just north of Washington. This ridge, which will build from Wednesday onward, will set the stage for a warm end to the week and Mother's Day weekend, so stay tuned! There is a potential for the warmest conditions of 2024 so far!

Mostly Dry to Begin May, Rainy Weekend Likely

 FastCast--Wednesday, May 1 to Sunday, May 5:

After a few days of showers, a relatively dry remainder of the work week is expected. Partly sunny conditions are expected on Wednesday, with highs reaching the upper 50s to low 60s. Thursday will be the best day of the week, with mostly sunny skies and highs in the mid 60s across the region. Clouds will return on Friday, but highs will remain in the mid to upper 60s. However, rain will move in by late Friday evening, continuing at times through late Sunday. Precipitation totals look to be on the heavier side for this round of rain, with amounts of 0.5-1.5" possible, depending on which forecast we look at. Temperatures on the weekend will decrease to the mid 50s, with lows from Friday to Sunday in the mid 40s. Notably, lows on Wednesday and Thursday will be in the mid to upper 30s, with a slight chance for frost in some outlying areas on Wednesday morning. Stay tuned over the next few days for more information about the weekend forecast.

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A couple nicer days are ahead across Washington, following a few days of showers. Let's take a look at the forecast, and a look ahead to a potentially wetter weekend.

Below is the forecast for morning lows on Wednesday from the NWS NBM model.

Expect morning lows in the mid to upper 30s outside the metro area, with the cities remaining in the upper 30s to low 40s. Eastern Washington will drop to the low to mid 30s. Any areas below approximately 35-36° have a potential for frost, so be aware of this possibility.

Highs on Wednesday will be an increase from Tuesday, as seen below in the NWS NBM forecast.

On Wednesday, expect lowland highs in the upper 50s to low 60s, coastal highs in the mid 50s, Willamette Valley highs in the upper 50s, and Eastern Washington highs in the upper 50s near Spokane and Ellensburg to the mid to upper 60s in the Columbia Basin.

Next, let's take a look at highs on Thursday, which will be the sunniest day in Western Washington, albeit not the warmest. The NWS NBM forecast is below.

On Thursday, the lowlands will reach the low to mid 60s, with the Willamette Valley and coast reaching the upper 50s to low 60s. Eastern Washington will reach the low 60s near Spokane to upper 60s in the Columbia Basin.

Friday will be the warmest day for awhile, but Western Washington's skies will be mostly cloudy as our wet weekend system moves in. Below is the NWS NBM forecast.

Expect highs on Friday to reach the mid to upper 60s in the lowlands, with the coast reaching the upper 50s, the Willamette Valley reaching the upper 50s to mid 60s, and Eastern Washington reaching the mid 60s to mid 70s.

Quite a wet weekend is possible, especially on the European model forecast. We'll look into the weekend forecast more over the next few days, but below is the forecast for total rain in the 48-hour period from Friday evening to Sunday evening.

This forecast shows heavy rain totals of 1-1.5" from Seattle southward through the Willamette Valley, with 0.3-0.9” from Seattle northward. This forecast doesn’t necessarily encompass rain totals for the whole region over the entire weekend, so stay tuned for more information over the next few days!