Next System Brings Rain Through Thursday, Then Weather Improves

 FastCast—Tuesday, Sept. 28 to Monday, Oct. 4:

After over an inch of rain for most of the region from Sunday to Tuesday, we’ll have a bit of a break through Wednesday afternoon. Showers increase by Wednesday evening, and rain will fall until late Thursday afternoon, with up to 0.75” of rain possible south of Everett. Partly to mostly cloudy and dry conditions begin on Friday. Daily highs increase from the low 60s on Thursday to the upper 60s/low 70s on Sunday and Monday. Expect lows in the mid 40s to low 50s.

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Continue reading the full blog below!

Our next weather system is ahead, after a short break. Rain will arrive by Wednesday evening, and continue through Thursday afternoon, punctuated by a frontal passage midday Thursday.

Below is the UW forecast for rain from Wednesday to early Friday.

Expect 0.5-0.75 inches around the metro area, with more in the foothills (up to 1.25”), and significantly more (1.25-2”) north of Everett, and 1.25-7.5+ inches in the mountains and on the coast.

Thursday’s rain will be heaviest during a frontal passage around midday Thursday. The predicted radar image for 11 AM Thursday (from the UW model) is shown below.

This will be similar to other recent frontal passages for our area. Expect brief heavy rain, a temporary increase in winds, and a sharp decrease in temperatures.

As mentioned in the FastCast, weather improves starting Friday. The Federal Way forecast from Weather Underground is below.

Conditions get drier and gradually warmer through the weekend, with highs reaching the upper 60s by Sunday (and low 70s on Monday). Lows in the mid-upper 40s are expected, coolest on Friday night.

All our recent rain will help Western Washington to end September at least 0.5” above normal, a welcome change from a dry summer. Welcome to fall weather!

Big Cooldown & Next Storm Ahead

 FastCast—Saturday, Sept. 25 to Tuesday, Sept. 30:

After a hot day on Saturday, a major cooldown is ahead. Clouds and rain move in on Sunday, with rain reaching Puget Sound by the afternoon. Rain totals of up to 1.5 inches are expected by Tuesday. Thunderstorms are possible on Monday and Tuesday, and breezy conditions (25-35 mph) are possible at times through Tuesday. Expect highs in the upper 50s to mid 60s, and lows in the mid 40s to low 50s.

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Saturday was one of the hottest late-September days in recent years. Many locations reached the low 80s, and nearly everywhere in the Puget Sound area hit the upper 70s. Recorded highs are below.

These will be the last 80+ temperatures until sometime next spring, and even 70s get much harder to find from here on out.

A major cooldown is ahead, with high temperatures remaining in the 60s all week. Below is the Federal Way forecast from Weather Underground.

It will feel much more like fall, with temperatures below 65 degrees most of the week and frequent rain. 

The most rain will fall late Sunday to early Monday, as a front moves through. Below is the UW forecast for rain through 5 AM Tuesday.

Expect 1-1.25” from Seattle southward, and less in the rain shadow north of Seattle (0.3-0.75”). The most rain will fall on the coast (1-3”), north of Mount Vernon (1-2”), and in the mountains (1.5-7”). 

The snow level will be around 5,000-6,000 feet during this storm, so a few inches of high-elevation snow is possible as well.

Be prepared for breezy conditions at times from late Sunday to Tuesday. The 5-forecast blend for Federal Way (from the Windy App) is below.

Expect gusts of 25-35 mph at times, highest near the water and stronger north of Everett and on the coast.

There is also a slight chance of thunderstorms on Monday and Tuesday, mainly during the day, as post-frontal showers move through. Be prepared for this potential!

It is safe to say that we will end September with much more than the average monthly rainfall…much needed after such a dry summer! 

Sunny & Warm, Then Rain Returns

FastCast—Thursday, Sept. 23 to Friday, Oct. 1:

Two mostly sunny days are ahead on Friday and Saturday. Highs on Friday and Saturday will be in the mid-upper 70s, above average for this time of year. Clouds increase on Saturday evening as rain moves in. Expect up to 1.1 inches of rain by Tuesday, most on Sunday and Monday. Another system, with up to an additional inch of rain, will arrive on Wednesday evening.

The FastCast is “A short summary of upcoming weather so you’ll be prepared for what’s ahead. You'll find the FastCast at the start of each blog!”

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Continue reading the full blog post below!

A pleasant Friday and Saturday are expected, with highs in the mid-upper 70s, above average for late September! Thursday was a nice day once the fog and low clouds cleared, with highs (below) around average, in the upper 60s to low 70s.

Let’s take a look at the upcoming forecast. Below is the 5-day forecast from Weather Underground for Federal Way.

Beautiful weather on Friday and Saturday! Highs will be approximately 5-7 degrees above normal. Clouds increase Saturday evening, then by evening Sunday, rain begins.

Our next system will bring another round of substantial rainfall to the area through Wednesday morning, with the most rain falling from Sunday afternoon to Monday evening. Below is the total precipitation through 5 AM Wednesday.

Expect 0.75-1.5 inches of rain in Western Washington. More is likely north of Everett, in the mountains, and on the coast.

Breezy conditions, with winds gusting up to 30-35 mph, are possible on Monday.

Another storm is possible starting Wednesday evening as well. Fall is here!

Heat Surge on the Washington & Oregon Coasts

Introducing The_Weatherman2 FastCast: A short summary of upcoming weather so you’ll be prepared for what’s ahead. You'll find the FastCast at the start of each blog!

FastCast—Tuesday, Sept. 21 to Sunday, Sept. 26:

Expect clouds to increase overnight Tuesday. There is a chance of light showers on Wednesday, and highs will be in the mid 60s. Sun returns by midday Thursday, with sunny & pleasant conditions persisting through Saturday. Expect highs of 70-77 degrees, warmest on Saturday! Rain returns with our next system late Sunday.

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Tuesday was warmer than average across most of the Pacific Northwest. Highs in the Puget Sound area reached the mid-upper 70s, with some areas hitting the low 80s. In the Willamette Valley, highs were in the mid 80s. Surprisingly, these 80-86° highs were comparable to highs on the Washington and Oregon Coasts!

A weak system is moving toward the Pacific Northwest that will bring showers to the area on Wednesday. This system created offshore flow due to wind flowing toward lower pressure offshore. These were downslope winds. The National Weather Service graphic below shows the effect of downslope winds.

The warming effect was clearly visible today on the coast. Let’s take a look at Tuesday’s recorded highs.

81-85 degrees on the Long Beach Peninsula, 80-82 near Astoria, and 73-79 around Aberdeen & Ocean Shores! These highs were 5-10 degrees warmer than the Puget Sound area and on par with the Willamette Valley.

On a broader scale, 80s were observed along the Oregon Coast, including 85° in Florence, the same as the Portland area! 

This event was forecast by the models. Below is the UW surface temperature forecast from Monday night’s model. This forecast was for 3 PM Tuesday.

The downslope warming effect can be seen in the forecast, with warmer temperatures (mid 70s to mid 80s) downstream of the Cascade gaps and along parts of the coast.

Let’s just say it was a pretty nice (and uncharacteristically warm) day at the beach!

Temperatures will be cooler area-wide on Wednesday, as a weak system brings clouds and potential showers.

Storm Recap & A Look Ahead

The first storm of the season brought much-needed rain to Western Washington, along with gusty winds and thunderstorms.

Many people in Western Washington lost power, especially in the South Sound, mainly from Federal Way eastward. I came across a fallen tree over SE Green Valley Road east of Auburn. As you can see in the photo below, the tree brought down power lines as well, causing one of many outages around the area.

One thing I noticed all around the South Sound area was many leafy branches on the roads. This is due to the fact that trees are fully loaded and the winds easily knocked off branches. Some trees lost leaves in this storm, but the majority are still over halfway loaded. Bottom line…there is still substantial “trimming” for future windstorms to do.

Rain-wise, totals were substantial, with many locations receiving amounts close to the annual monthly rainfall from Friday to Sunday.

On a broad scale, the most rain fell in the mountains and from approximately Tacoma southward and north of Everett. (Amounts from Friday to Sunday below)

Focusing in on the Central Sound, amounts were near or slightly less than forecast, with most of the area receiving 0.7-2.1 inches, more in the foothills and Kitsap Peninsula westward.

So…what’s next? This week’s weather will be calm and pleasant. A weak system will move through on Wednesday, but it doesn’t look like it’ll produce more than a few light showers. The Federal Way forecast from Weather Underground is below.

Expect partly to mostly cloudy skies and highs in the mid-upper 60s on Monday, Wednesday, and Thursday. Tuesday and Friday will be great days, with highs in the mid 70s and sunny skies! Expect morning lows in the upper 40s to low 50s this week.

Enjoy the calm weather while it’s here! Storm season is fast approaching…

Friday Evening Storm Update

Update 9:10 PM: The cold front remains mostly offshore. It is more likely that the front will move through the metro area after 10 PM.

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It has already rained across most of Western Washington today, with the most rain on the coast and north of Everett (0.3-1.2”). The Puget Sound area received 0.01-0.2”, most from Seattle southward.

This morning’s rain has moved into the Cascades, a heavier round of rain is moving in from the coast. Between approximately 9 and 10 PM, an strong cold front will move through Western Washington, followed by more rain. 

At 9 PM, the heavy rain band is heading into the Seattle area, as seen in the UW forecast below.

By 10 PM the cold front will have moved through the eastern parts of the metro area.

This will be an heavy band of rain, also called a NCFR (narrow cold frontal rainband), with 0.25-0.5 inches of rain falling within ~3 hours. Winds will gust 30-40 mph, higher near Puget Sound.

Keep in mind that the threat for tree damage and power outages will be highest during and in the few hours after the frontal passage.

Additionally, there is a potential for urban flooding during frontal passage and through the weekend, especially near clogged storm drains.

There is also a slight chance of thunderstorms as the front moves through. Be prepared for lightning & thunder!

What about rain totals? Below is the UW high-resolution forecast for rain totals through Sunday morning.

It is likely that most of the Puget Sound area to receive 1-2 inches of rain, with amounts varying locally. Much higher amounts are likely in the mountains.

Thunderstorms are still possible as rain becomes more showery on the weekend. Any showers this weekend have a potential to produce thunder, lightning, and potential hail, all the usual threats with post-frontal showers.

In short…an active weekend is in store, starting tonight! Stay updated by clicking the Twitter icon on the right side of the blog. This takes you to my Twitter page.

You can access the latest weather information from the UW forecast models by clicking here and on the right side of the blog.

Storm Update: Heavy Rain, Gusty Winds Ahead

Update by 5 PM Friday with latest details & forecast.

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We are less than 24 hours from the start of the first significant storm of the season. Heavy rain, gusty winds, and a chance of thunderstorms are all in the cards.

The rain shield of the incoming system will reach the coast early Friday morning, with rain falling in the Puget Sound area soon after. Expect some rain in the morning, then a potential break in the rain during the afternoon.

Then, on Friday evening, the real action begins. An area of very moist air will move over Western Washington, with a current of air heavy with water vapor directed right at the Puget Sound area.

The UW forecast above is for 8 PM Friday, as heavy rain will be falling in the Puget Sound lowlands. 

Below are 24 hour totals from 5 AM Friday to 5 AM Saturday from the UW model.

From Seattle southward, expect 24-hour totals of 1-2 inches. Up to 2.5 inches near Olympia, and massive amounts of 6-7.5+ inches in the Olympics & Cascades. Notice the prevalent rain shadow northeast of the Olympics. These areas, including North Seattle and Everett, will receive lesser totals of 0.3-1 inches.

This isn’t the end…the rain continues well into Sunday, just becoming more showery. Additional rainfall of 0.5-1.1 inches is expected through Sunday evening.

Make sure that your gutters and storm drains are cleared before the heaviest rain arrives. If you haven’t done this yet, you have until Friday evening!

Now for the wind. Since my last blog post, the forecast winds have increased. Below are 5 forecast model predictions. (How to read this: large numbers=sustained winds, small numbers=gusts, arrows=wind direction)

This forecast (for Federal Way) shows winds gusting 30-40 mph from Friday afternoon/evening through early Saturday morning. Conditions remain breezy (gusts 20-30 mph) through Saturday evening.

Expect slightly stronger winds near Puget Sound, and winds gusting 45-50 mph on the coast and from Admiralty Inlet northward. (Wind Advisory in effect for those areas).

Regarding winds, since this is the first storm of the season, trees are fully loaded and therefore more vulnerable to damage. Add on the fact that many trees have been weakened by this summer’s extreme heat, and the threat for tree damage is higher. Be prepared for scattered power outages and damaged trees.

There is one more threat worth mentioning…thunderstorms.

Behind the cold front that moves through Friday night, the air will be unstable. The best chance for thunderstorms will be midday Saturday to Sunday evening. CAPE instability values of 200-600 will be present over the Lowlands (relatively high for our area). Values of 600+ are possible at times along the WA & OR Coasts.

Wow! A lot of active weather is heading our way! Expect things to calm down by Sunday evening, with dry weather likely by Monday. Below is a recap from NWS Seattle.

Enjoy the storm & stay safe!

First Storm of the Season to Arrive on Friday

After a long, hot, and very dry summer, we are finally due for a significant storm system, with a major rain event expected! 

The first storm of this storm season will primarily be a rain-producer, but other impacts will include breezy conditions and a chance of thunderstorms. Additionally, this storm system will likely be the end of wildfire season for the Pacific Northwest, as Eastern WA & OR will cash in on rain, cooler temperatures, and much higher humidity.

Let’s start with the forecast. Below is the Weather Underground forecast for Federal Way.

A weak system will move through Western Washington late Tuesday into Wednesday. Below is the UW forecast for rain through 4 PM Wednesday.

The majority of the Puget Sound Area will receive up to 0.03” of rain, except more in the Cascades (up to 1”). A Convergence Zone band is forecast to develop between Kent and Lakewood. These areas may receive up to 0.2 inches of rain.

However, this is a tiny appetizer to the real action that starts on Friday. 

Our most significant rain since late spring is on the way, in the form of an atmospheric river, or a long & narrow current of moisture. Below is the integrated water vapor transport (amount of water vapor in the atmosphere) at 5 PM Friday.

These values, on the order of 1000-1200 over Western WA/OR, are usually seen only in the winter. This means that we will be having a winter-style atmospheric river event to kick off the storm season!

So, how much rain are we expecting? Below is the forecast for Federal Way.

Wow! Well over 1 inch of rain is expected on Friday, with up to 1.5 inches possible. Then, totals near 0.5 inches on Saturday and Sunday.

As you would expect, rain totals will be quite high, as shown in the UW extended forecast below.

Current forecasts show rainfall totals of 1-3 inches for the Lowlands, 2-4 inches on the coast, and up to 7.5 inches in the mountains. Additionally, 1-4 inches of snow are possible above 6,000 feet. 

In Eastern Washington & Oregon, totals of 0.1-1.5 inches are possible, with the most in the mountains. This rain will play a major role in the decline of wildfires.

Another detail of this storm will be breezy winds. As of Tuesday night, forecasts indicate wind gusts of 20-35 mph from midday Friday to late Sunday.

Thunderstorms are also possible behind the main cold front on Saturday. The best chance of thunderstorms is from Saturday morning to late night, with the highest instability on the coast & in the mountains.

Stay tuned for my next update (Thursday night) as details about this storm, especially regarding exact rain amounts & chance of thunderstorms, continue to change.

What Forecast Should I Use?

One of the most pressing questions regarding weather is what forecast to use. In this age of social media and widespread internet access, there are so many different forecasts to choose from. This blog will attempt to explain which forecast to choose!

My go-to site to begin choosing a forecast is Forecast Advisor. This handy site shows the accuracy of multiple forecasts over the previous month and previous year. Below is Forecast Advisor's accuracy scores for Seattle in 2020.

The Weather Channel and Weather Underground had the highest accuracy score, over 86%. AccuWeather came up just behind at 84%. Notice that the NWS forecast came in at 78.6%, about 8% below the leaders, showing that just because it is run by the government, it isn’t the most accurate forecast available, though it is still a good choice.

Now let’s see how these trends verified last month. Below are the Forecast Advisor scores for Seattle in August.

Weather Underground and The Weather Channel take the cake again, with scores around 84%. Wetter, a German company, came in third. Notice that the NWS came in with a score of 72.5%.

If you were wondering how the accuracy scores are calculated, Forecast Advisor says in their FAQ page that “The overall accuracy percent is computed from the one- to three-day out accuracy percentages for high temperature, low temperature, icon forecast precipitation (both rain and snow), and text forecast precipitation (both rain and snow). Temperature accuracy is the percentage of forecasts within three degrees. Precipitation accuracy is the percentage of correct forecasts. The forecasts are collected in the evening.”

So, what forecast should you use?

The accuracy scores suggest using Weather Underground or The Weather Channel. These companies, both owned by IBM, have a similar forecasting algorithm that has proven to be accurate over the past few years, with consistent ratings of 80+%.

These algorithms take many things into account when making a forecast. Some things include current, future, and historical conditions and weather predicted by multiple forecast models. 

You can download the Weather Underground and The Weather Channel apps on the iOS App Store and the Google Play Store. You can also find these sites on the web, at wunderground.com and weather.com.

Generally, any forecast with 75-80%+ accuracy will give you a good idea of what conditions to expect. However, if you’re able to use the most accurate forecast, do so. It’ll give you the best idea of what to expect, especially regarding temperatures and precipitation.

Significant Cooling Ahead, Rain on the Horizon

8 out of the first 9 days of September have had a high of 75+ degrees. However, that is about to change. A significant cooling trend is expected, and temperatures at or above 75 degrees aren't expected for at least the next 10 days.

Thursday's highs are below. Widespread readings of 80-84 degrees were observed, with temperatures up to 85-86 degrees in the Eastern Lowlands.

We are in for a major temperature change in the coming days. Below is the Weather Underground forecast for Federal Way.

Cooling of around 10 degrees is likely for Friday. Highs remain in the low 70s through next Tuesday, with lows in the upper 40s to low 50s, except a bit warmer on Saturday night.

Now...what you've been waiting for...rain!!!

Below is part of the extended Weather Underground forecast for Federal Way at the end of next week (9/16-18).

Rain probability increases Thursday night, peaks on Friday, and becomes more showery on Saturday. (Take the chance of thunderstorms on Saturday with a grain of salt). Forecast models show up to 1.1 inches of rain through around the 19th. Bottom line: increasing chances of rain are expected by the end of next week! 

Something to look forward to! Stay tuned!

Chance of Showers Overnight & Another Round of California Smoke

Tuesday was mostly sunny, but you probably noticed smoke aloft moving in throughout the day. It was most apparent as the sun sank lower in the sky, as seen around 7 PM in Federal Way.

The sun became increasingly red/orange, and the layer of smoke was evident on the horizon. We'll talk about smoke soon, but first the forecast.

Below is the Federal Way forecast from Weather Underground.

There is a chance of showers overnight due to a system moving through. Wednesday will be in the upper 70s to low 80s, with temperatures in the low to mid 70s from Thursday to Sunday. Low temperatures decrease from the upper 50s on Tuesday to the upper 40s by Sunday night.

Regarding that chance of showers overnight Tuesday into Wednesday, there is also a slight chance of thunderstorms from 2-8 AM Wednesday. Instability doesn't look great, so this chance isn't very likely.

However, some rain is possible. Below is the 24 hour rain forecast from the UW model, ending 5 AM Wednesday.

Let's just say that this will be very little rain, with a trace to 0.03 inches for Puget sound and up to 0.2 inches for parts of the mountains & coast.

I don't know about you, but I am very excited for the day when we have a real rainstorm! Hopefully within a month!

Now for the smoke forecast...this is all vertically integrated smoke (smoke aloft). 

Below is 7 PM Tuesday. Moderate concentrations of smoke over Puget Sound, with more moving north.

The thickest smoke will be overhead early Wednesday morning. The forecast for 5 AM Wednesday is below.

At 5 AM, thick smoke is present over Western Washington from Puget Sound eastward. Soon after this (by 7-8 AM), westerly winds will clear out most of the smoke.

By 1 PM, the skies are almost clear, with a slight haze remaining.

Conditions get progressively better west of the Cascades, and by 7 AM Thursday, skies are free of smoke on the west side of the mountains in Oregon and Washington.

In Eastern Washington, conditions will be largely dependent on if you are downwind of a wildfire. The Schneider Springs Fire (94,206 acres, 14% contained) will likely create a large smoke plume by Wednesday evening, impacting areas from Yakima northeast. Additional (smaller) smoke plumes will be present from other fires.

Eastern Oregon and Idaho won't be as lucky, as their location relative to massive fires in California will allow smoky skies to continue.

One Year Ago (September 7-8, 2020):

Very strong winds moved through the gaps in the Cascades in Oregon and Washington, resulting in massive wildfires in Oregon & Eastern WA and a widespread power outage event in the South Sound. These winds, some of the strongest ever observed in Western WA during September, sparked the Sumner Grade Fire early on September 8th. The fire burned over 800 acres and destroyed multiple homes before reaching 95% containment on the 16th.

The photo above was taken by Bonney Lake WX on Twitter on September 8th, as the fire grew and moved southward. The area was evacuated just hours later.

I think we are all glad to not be experiencing an extreme fire weather event this year!

Fall & Winter Outlook: La Niña Likely Again

As we begin September and fall approaches, one thing on the mind of many Pacific Northwest residents is what to expect during the storm season. Fortunately, by this time of the year, we have a good idea of the general conditions and trends to expect this fall and winter. 

The weather patterns across parts of the Northern Hemisphere are influenced by the sea surface temperatures (SST) of the equatorial Pacific Ocean. These patterns are El Niño (warmer than average SST), neutral (normal SST), and La Niña (cooler than average SST).

This winter will most likely be a La Niña winter, which generally means above average rain, above average mountain snow, and a higher potential for lowland snow.

The forecast graphic below from the NWS Climate Prediction Center shows the probability of La Niña, Neutral, or El Niño in 3-month periods.

The blue bars on the graph shows the probability of La Niña increasing by August and September. La Niña probability is over 60% from approximately fall to midwinter, which has prompted a La Niña Watch to be issued by the Climate Prediction Center earlier this summer. Current forecasts show neutral conditions increasing around March, though time will tell how this evolves.

Another way to show the La Niña forecast is through a long-range forecast run by many forecast models, showing departure from average sea surface temperatures.

This forecast plot is best described as a forecast model ensemble, like we use for snow predictions, etc. during the winter. This forecast confirms the previous one, and shows that a majority of the forecast models are predicting SSTs in the equatorial Pacific to be 0.3-1.0° Celsius below average. 

The bottom line is that it’s safe to expect a La Niña winter. We’re sure to see the effects of La Niña beginning this fall.

Now for a quick look at our upcoming forecast…below is the Weather Underground forecast for Federal Way.

From Saturday through Tuesday, temperatures will be a bit warmer than they have been, with highs in the mid 70s to low 80s, warmest on Saturday, Monday, and Tuesday. Expect lows in the low-mid 50s except in the upper 50s-low 60s on Saturday night.

Below is the rain forecast from the UW model through Monday morning.

Expect 0.01-0.05 inches of rain south of Seattle, bands of 0.1-0.2” totals between Seattle and Everett, and 0.2-0.5 inches on the coast and from Arlington northward.

Enjoy our warm & mostly dry weather while it lasts!