Update: Thunderstorms, Snow, and Widespread Rain Ahead

No FastCast tonight...continue reading the full blog below!

An interesting weekend of weather is ahead for the Pacific Northwest, with a significant upper-level trough bringing colder conditions to the region. Expect weekend highs to only reach the upper 50s to low 60s, significantly below average for mid-June. 

The biggest threat will be thunderstorms, with storms possible across the region on Saturday, and possible for areas Seattle southward and east of the Cascades on Sunday. 

Let's take a look at the European model forecast lightning flash density, showing the potential areas for thunderstorms Saturday afternoon.

This forecast shows the entirety of Western Washington has a chance of thunderstorms, highest over the lowlands from Thurston to Snohomish Counties. Eastern Washington has an even higher chance of thunderstorms, especially for Okanogan, Ferry, Stevens, Pend Orielle, Spokane, and Whitman Counties.

There is also a chance of isolated thunderstorms as strong showers move in early Saturday morning, from 4-7 AM. Below is the high-resolution HRRR model forecast for lightning flash density at 6 AM.

This forecast shows a chance of thunderstorms as showers move through the region early Saturday. This chance is highest for Island and Skagit Counties.

Instability in the atmosphere will be quite high by Saturday afternoon, and this is a key metric in determining if there is a good likelihood of thunderstorms. Below is the CAPE index forecast (showing amount of instability) on Saturday afternoon from the NAM high-resolution model.

This forecast shows high CAPE for Western Washington, with values of 400-800 possible, and values of 100-500 in Eastern WA. These are significant values for the Pacific Northwest, and indicate that there is a good potential for thunderstorms.

Rain will be widespread in Western Washington this weekend, with most areas receiving rain at times. Below is the NWS NBM forecast for rain through the weekend.

This forecast shows most of Western Washington receiving 0.1-0.3" of rain, with areas under heavier showers (specifically in the Convergence Zone from the King/Snohomish County line to SE Whatcom County) receiving 0.4-0.6". The Cascades will receive 0.75-2.5", highest where Convergence Zone bands move into the mountains.

The colder nature of this system will also drive down snow levels to around 4,500 feet, bringing some accumulating snow to higher passes and recreation areas. Below is the European model forecast for total snow through the weekend.

This forecast shows Paradise and the North Cascades Highway (between Diablo and Winthrop) getting up to 3-6" of snow, with higher amounts possible at Paradise. Stevens and White Passes could see a dusting to 1" of snow.

Finally, it will be another windy day for Eastern Washington on Saturday, with breezy conditions at times for Western WA. Below is the European model forecast for peak gusts through Saturday.

This forecast shows 25-30 mph gusts in the lowlands, mainly from Seattle southward. Eastern Washington will be much windier, with gusts of 40-45 mph for most of the region, except potentially up to 50 mph around the Blue Mountains. This is of concern due to the 1,150-acre Nisqually John Fire, burning west of Clarkston along the Snake River. Winds of 40+ mph will allow this fire to potentially experience significant growth on Saturday.

Remember, with active weather ahead and a chance of thunderstorms, be prepared to seek shelter if you hear thunder/see lightning, and be prepared for gusty winds, heavy rain, and even small hail. If you're in the backcountry, be prepared for cold and potentially snowy conditions. It sure won't feel like June for a few days!

Active June Weather: Thunderstorms, Chilly Temperatures, and High Mountain Snow

 FastCast--Friday, June 14 to Tuesday, June 18:

An interesting few days of weather is ahead for the Pacific Northwest. A chilly upper-level trough will bring showers and a region-wide chance of thunderstorms this weekend, with cold air aloft bringing snow levels down to 4,500 feet as well. Across the lowlands, expect highs in the upper 50s to mid 60s from Friday to Monday, quite chilly for this time of year. Lows will generally be in the mid to upper 40s. Showers will move through at times from midday Friday through Sunday, becoming more sporadic by Sunday. Rain totals will vary wildly across the region because of where thunderstorms will move through. If thunderstorms or strong cells move through your area, expect rain totals up to 0.4-0.8" by Sunday. Areas under the Convergence Zone could have even more rain. If you don't have any storms, your totals will likely be closer to 0-0.25". Mountain areas higher than 4,500 feet (including Paradise on Mt. Rainier and the North Cascades Hwy) will receive snow, up to 4-8". By Tuesday, lowland conditions will become sunnier, with highs increasing back to the low 70s.

Remember, with any shower or thunderstorm this weekend, the threats are thunder, lightning, small hail, gusty winds, and heavy rain. Take precautions and seek shelter!

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Continue reading the full blog below!

An incoming upper-level trough will bring chilly and active weather to the Pacific Northwest over the next few days. Let's take a look at the forecast!

We'll start with thunderstorms...the upper-level trough brings very cold air aloft, which increases instability in the atmosphere, bringing a region-wide chance of thunderstorms on Saturday and Sunday (to a lesser extent). 

Below is the European model forecast for lightning flash density (the chance of lightning at a given point) for Saturday afternoon.

This is 6-hour lightning flash density, showing the chance of thunderstorms for a 6-hour period on Saturday afternoon. As you can see, the highest chance of thunderstorms is over the Okanogan Mountains of NE WA, over the lowlands from Thurston County to Vancouver BC, and over parts of the Columbia Basin.

However, the forecast above is showing an average chance of thunderstorms over a 6-hour period, so let's take a look at 1-hour lightning flash density for around 1 PM Saturday.

As you can see, this forecast is much more precise, showing the potential locations of thunderstorms on Saturday afternoon. This underscores the lowlands, NE WA, and parts of the Columbia Basin as being the most likely areas for thunderstorms to develop on Saturday afternoon.

Another good metric for thunderstorm chances is to look at the forecast for amount of instability in the atmosphere. This is measured on the CAPE index (CAPE stands for Convective Available Potential Energy). Below is the NAM high-resolution CAPE forecast for Saturday afternoon.

This forecast shows respectable CAPE values of 200-800 across Western Washington, with values of 100-500 in Eastern Washington. These are good values for our neck of the woods, and they show that thunderstorms are definitely possible on Saturday, especially from ~11 AM onward.

Now, let's take a look at the rain forecast from the high-resolution NWS NBM model. This shows rain through Sunday night.

This forecast shows 0.25-0.5" of rain for most of the lowlands, with potential areas of higher precipitation (0.5-0.9") between Everett and Bellingham. The coast will get 0.5-0.75", and the Cascades will receive 1-1.5".

However, for some parts of the Cascades, the cold nature of this system will bring June snow. Below is the European model forecast for total snow through Sunday night.

This forecast shows Paradise getting up to 6-8" of snow, with the main passes getting a dusting to 2", and the North Cascades Highway getting 3-5". Be prepared for winter driving conditions if you will be in these areas, and bring traction devices as a precaution.

Finally, let's take a look at temperatures. Saturday will be the coolest day of this stretch, seen below on the NWS NBM model.

This forecast shows lowland highs only reaching the upper 50s to low 60s, with the coast reaching the mid 50s to low 60s, the Willamette Valley reaching the mid 60s, and Eastern Washington only reaching the mid 60s to low 70s. Mountain locations may not make it out of the mid 40s (or mid 30s at Paradise).

The European model forecast below shows temperature departure from average on Saturday afternoon.

This forecast shows lowland and coastal temperatures running 5-10° below average, with the Willamette Valley and Eastern WA likely 10-15° below average. The Cascades will be an impressive 15-25° below average on Saturday afternoon!

In short...quite an interesting period of weather is ahead, especially the thunderstorm potential. With that in mind, stay tuned for an update tomorrow (Friday) night!

Calm & Comfortable Weather Continues

 FastCast--Tuesday, June 11 to Saturday, June 15:

Calm and relatively comfortable weather will continue across the region through this week. Expect a chance of light showers on Tuesday morning, with some lingering showers into the afternoon for the North Sound. Conditions will likely clear up and become mostly sunny by the afternoon. Winds could gust 25-35 mph across the region on Tuesday. Wednesday will also feature morning clouds and afternoon sun, with Tuesday and Wednesday's highs in the upper 60s to low 70s. Thursday will be partly cloudy with filtered sunshine due to high clouds, but highs will reach this week's peak, in the low to mid 70s. Conditions will get cooler and cloudier on Friday, with showers moving in during the afternoon and highs dropping to the low to mid 60s. Similar conditions are expected on Saturday, with a potential for thunderstorms across the region, which bears watching. Lows throughout the week will likely be in the upper 40s. Stay tuned for more information!

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Continue reading the full blog below!

A chance of showers is expected across Western Washington to begin Tuesday, with relatively calm weather expected for the rest of the week. Let's take a look at the forecast!

Below is the NAM high-resolution model's rain forecast, showing total rain through late Tuesday.

This forecast shows light showers (0-0.1") across the lowlands, with 0.1-0.3" on the coast, and 0.25-0.5" possible in the mountains. Eastern Washington will remain dry and warm.

The entire state will see elevated winds as this system moves through on Tuesday. Below is the European model forecast for peak gusts on Tuesday.

Expect gusts of 25-35 mph across the lowlands, with isolated gusts over 35 mph. Eastern Washington will be on the windy side, with gusts of 40-45 mph possible. This is of note due to two ongoing early-season fires, the 400-acre Pioneer Fire along the northern shore of Lake Chelan, an area that could see gusts of 35-40 mph. The Training Center Fire, which burned 4,000 acres in the Yakima Training Center on Monday, is 100% contained but bears monitoring with 45+ mph gusts possible.

Now, let's take a look at temperatures for the next few days. Below is the NWS NBM forecast for highs on Tuesday.

Expect lowland highs in the mid 60s to low 70s, with the coast reaching the upper 50s to low 60s, Willamette Valley reaching the mid 70s, and Eastern Washington reaching the mid to upper 80s, except in the mid 70s for the Kittitas Valley.

Next, let's take a look at Wednesday's highs.

On Wednesday, expect highs in the mid 60s to low 70s for the lowlands, the low to mid 60s on the coast, mid 70s in the Willamette Valley, and mid 70s to low 80s in Eastern Washington (note the cooling effect of Tuesday's system).

Thursday will likely be the warmest day of the week for Western Washington, as seen below.

Expect lowland highs in the low to mid 70s, with the coast reaching the mid to upper 60s, the Willamette Valley reaching the upper 70s to low 80s, and Eastern Washington returning to the upper 70s to mid 80s.

Conditions will begin cooling statewide on Friday, as more systems and potential thunderstorms take aim at the region.

Friday's highs will reach the low to mid 60s in the lowlands, upper 50s to low 60s on the coast, low 70s in the Willamette Valley, and the mid 70s to low 80s across Eastern Washington.

There are potential chances for thunderstorms across the state on Saturday and in the following days, with Saturday being the best chance for Western Washington. Stay tuned for more information!