Weather with Cliff Mass | KNKX

Weather with Cliff Mass

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A view of Seattle's ship canal on July 10, 2020.
Tim Durkan / Tim Durkan Photography

The first week of August is generally the hottest time of the year in Washington. This year, people in the Puget Sound region already have experienced some record temperatures, with highs topping 90 degrees for the first time in 2020 on Monday. Olympia reached an eye-popping 98 degrees. Seattle made it to 94.

But a cooling trend that will continue through Monday has started, says KNKX weather expert Cliff Mass.

Tim Durkan / Tim Durkan Photography

This story originally aired Aug. 23, 2019.

Most people have had that classic summer experience of driving along a warm road and seeing a shimmering patch ahead that looks like water. But when you get there, it’s gone. This is a trick of the atmosphere, caused by different densities of the air, associated with temperature.

The Comet Neowise is seen in the night sky above several trees, Wednesday, July 15, 2020, in Olympia, Wash. The comet is expected to be visible from earth most of the rest of the month before continuing on it's nearly 7,000 year orbit around the sun.
Ted S. Warren / Associated Press


It’s that most wonderful time of the year in the Pacific Northwest, when we get to enjoy clear skies, warm yet comfortable temperatures and 9 p.m. sunsets. Summers here are the payoff for our long, dark winters. And this week, the "perfect weather" many of us like to gloat about has finally arrived.

This summer, these conditions are coinciding with the appearance of a rare comet called NEOWISE. KNKX weather expert Cliff Mass is among the astronomy enthusiasts who ventured out at 3 a.m. to see it.

KNKX weather expert Cliff Mass says big displays like this one from Seattle in 2019 are not a significant source of pollution, compared to what personal shows produce - based on the air quality data after this year's July 4th festivities.
Tim Durkan / Tim Durkan Photography

People in the Pacific Northwest sometimes jokingly call the sixth month here "Juneuary," because of the persistently gloomy weather we often face in June. Now an abundance of offshore flow — marine air coming in off the cool Pacific Ocean — has KNKX weather expert Cliff Mass calling July "Julember."

Fireworks at Gas Works Park in Seattle on July 4, 2013.
Wikimedia Commons

July 4 is upon us. Normally, that means our air quality takes a big hit. It's an issue that KNKX weather expert Cliff Mass often talks about. Mass has studied the impact of fireworks on our air quality. This year, things will be a little different. With all the major community fireworks displays canceled due to the COVID-19 pandemic.

A view from Seattle, May 3, 2020.
Tim Durkan / Tim Durkan Photography

The curse of the wet weekend is making another appearance as June comes to an end. The month sometimes referred to as "Juneuary" in the Pacific Northwest has actually included quite a few lovely summer days this year, with temperatures hitting the 80s under bluebird skies. (Just not many on weekends.)

But our somewhat soggy spring this year in Washington has nothing on what folks north of us in British Columbia have been experiencing.

A cloudy Friday night in Seattle, February 21, 2020.
Tim Durkan / Tim Durkan Photography

If you feel like you’re being punished by the weather for staying indoors during the workweek, you’re not alone. Lots of people in Western Washington have noticed a pattern of fair and sunny weather that abruptly turns to rain as soon as the weekend arrives.

Another mostly wet weekend lies ahead as an area of low pressure moves in, bringing rain and showers through Monday night.
Tim Durkan / Tim Durkan Photography

We’re in for another cool, wet weekend. Rain and rain showers dominate the forecast through Monday night. High temperatures won’t get past the mid-60s.

This is the kind of forecast most of us have come to rely on as we plan our activities, using radar viewers and other online tools to know what’s coming our way, sometimes down to the hour.

Sunset, seen from the shores of Seattle on May 28, 2020.
Tim Durkan / Tim Durkan Photography

Gray skies, rain showers and possible thunderstorms are in the forecast again. It’s a pretty typical for this time of year in the Pacific Northwest, where most people rattle off phrases such as "June Gloom" and "June-uary" to describe this kind of weather.

The exception here is thunder and lightning. Intense storms that are common in other parts of the country are rare here.

A view from Seattle on May13, 2020.
Tim Durkan / Tim Durkan Photography

After a string of warm and sunny days, residents of Western Washington were bracing for the effects of an upper level disturbance coming up from California. The weekend forecast calls for significant rain and possible thunderstorms, with temperatures dropping into the mid-60s.

Mount St. Helen's erupts on July 22, 1980 in Washington State.
JACK SMITH / The Associated Press

“An improving trend” is in store this Memorial Day weekend. The clouds, rain and cool temperatures we’ve been experiencing over the past several days will yield to something a little less cloudy. You can expect dry conditions in most places and it will warm up considerably, to as high as 70 degrees on Monday, says KNKX Weather expert Cliff Mass.

But it will still be pretty cloudy.

A view "from Seattle with love" on May 14, 2020.
Tim Durkan / Tim Durkan Photography

After a heat wave that left many of us dreaming of summer, more typical spring weather is back in the greater Puget Sound region. That means a chance of rain pretty much every day and temperatures in the 60s, along with clouds and sun breaks.  

It also means the summer outlook for water supplies, stream flows and wildfires are looking normal to favorable, despite a scary dry spell in April.

Tim Durkan / Tim Durkan Photography

Temperatures around the Puget Sound region were shooting up Friday into the mid-to-upper 70s, after an already warm week. And the forecast for Mother’s Day weekend promises temperatures in the low 80s. It almost feels like summer.

But KNKX weather expert Cliff Mass says this kind of heat wave in mid- to late May is not that unusual for the region.

Tim Durkan / Tim Durkan Photography

As May begins, the weather continues to offer that typical grab bag of conditions that is typical for spring in the Northwest: plenty of clouds, along with showers, sunbreaks, even possible thunderstorms. And often, forecasts predict the probability of these phenomena: a 10 percent chance of rain, say — or 50 percent chance.

That sounds plausible, but it turns out most people don’t know what that actually means.

Tim Durkan / Tim Durkan Photography

After a pretty long dry spell, April showers have returned to the Puget Sound region. We’ve entered a typical phase of showers and sun breaks, with lots of instability in the atmosphere that produces dramatic clouds with light blazing through them. 

A view of Pike Place Market with Seattle's Elliott Bay on April 15, 2020.
Tim Durkan / Tim Durkan Photography

Maybe you felt a spark as you walked over carpeting and touched a doorknob. Or perhaps you noted how arid the soil was when you went out to do some gardening. These are signs of low relative humidity in the air. And Western Washington has experienced extreme levels of it — on several days this past month.

KNKX weather expert Cliff Mass says it’s been so dry, he coined a new term for it: "dry storm."

Tim Durkan / Tim Durkan Photography

Audio Pending...

It’s been warm and sunny lately with clear blue skies and great visibility in the Pacific Northwest — ideal for seeing for events like the supermoon Tuesday night. 


Contrast that with Southern California, where a pattern of rain and snow in the mountains has locked in, providing much-needed water for reservoirs, but dampening spirits for some who live there.

This contrast is due to a configuration in the atmosphere called a blocking effect, says KNKX weather expert Cliff Mass. 

Seattle's skyline, as seen on March 29, 2020.
Tim Durkan / Tim Durkan Photography

If you’ve been feeling chilly lately, you are not alone. Lots of people may have noticed on walks around their neighborhoods that spring this year has been colder than usual. And in fact, now that March is over, statistics show the month has been colder on average than January.

The decline in commercial aircraft traffic due to the new coronavirus will degrade weather forecasting, says Cliff Mass, a professor of atmospheric sciences at the Univeristy of Washington.
Ted S. Warren / The Associated Press

Sprinkles and showers are in the forecast for most of Western Washington this weekend, with temperatures hovering around 50 degrees. It’s perfect weather for gardening or maybe taking a long run or walk in your neighborhood. The skies above likely will be quieter, too.

The spread of the new coronavirus already has slowed air traffic aloft. An even more dramatic decline in commercial flight schedules is coming soon. And that could affect weather forecasting.

A Seattle Sunset as seen on March 18, 2020.
Tim Durkan / Tim Durkan Photography

The official start of spring comes a little early this year, in tandem with the vernal equinox that showed up in most U.S. calendars on March 19. Although meteorological spring began in the Pacific Northwest about a month ago with signs of warmer weather, KNKX weather expert Cliff Mass says around now is when certain typical features of spring become evident.

Mount Rainier showing off March 8, with some lenticular cloud action.
Tim Durkan / Time Durkan Photography

Mount Rainier looms on horizons in the region like no other, dominating views when visible – or “out” as locals like to say. This massive 14,000-foot peak is an active volcano that inspires awe in visitors to the region and stands as one of our most recognizable icons.

It also has a profound effect on the weather around it – because of its size.

An early springtime view of Port Townsend Bay , as seen from the Larry Scott memorial trail on March 1, 2020.
Bellamy Pailthorp / KNKX

Do you doubt that spring has arrived in the Pacific Northwest? With cool temperatures and copious rain dousing much of the region lately, it can be hard to believe.

Just a couple of weeks ago, KNKX weather expert Cliff Mass talked about the typical arrival of "meteorological spring," when big storms cease and other weather changes indicate that for all practical purposes, winter has ended. It happens here a full month prior to the end of winter on the East Coast.

A view from Seattle on Feb 21, 2020.
Tim Durkan / Tim Durkan Photography

People in Western Washington have enjoyed plenty of mild, warm days and sunshine lately — typical weather for late winter and early spring. Suddenly, we’re shedding layers and searching for our sunglasses.

But in Eastern Washington and Oregon, early spring marks the onset of what can be a terrifying phenomenon: Northwest dust storms that dramatically reduce visibility and air quality when winds pick up.

A view from Seattle on Thursday, Feb. 20, 2020.
Tim Durkan / Tim Durkan Photography

The mornings have been cold and crisp under clear skies this week in many parts of the Pacific Northwest, with lows around freezing in places. But powerful sunbeams have pushed afternoon highs into the pleasant realm of the 50s.

KNKX weather expert Cliff Mass says this is in keeping with what he calls “meteorological spring,” when the weather stops delivering storms and cold temperatures that are the hallmarks of winter. Instead, trees and shrubs start sprouting green buds, crocuses push through the soil and people begin shedding layers of clothing needed in colder weather as they enjoy warmer temperatures.

Rain is in the forecast this weekend, but don't worry. Sun is on the horizon starting Monday.
Parker Miles Blohm / KNKX

The rain just keeps coming. Our reservoirs are above normal now, and it looks like there’s more rain on its way all weekend long. But can you trust that forecast? KNKX weather expert Cliff Mass says some weather apps are often the most acurate source — and anyone can check their reliability.

A flood watch continues till 4 o'clock Friday. The National Weather Service says although the rain had tapered down earlier in the morning and most area rivers were expected to crest in the afternoon, flooding will continue into Saturday.

Eleven people were evacuated from an apartment complex in Issaquah Thursday, with standing water causing road closures all around the region. 

This kind of flooding does happen regularly in western Washington, especially in areas that are connected to rivers that drain off the Cascade Mountains.
But KNKX weather expert Cliff Mass says the rainfall people have experienced here this week has been exceptionally intense. It’s because of the angle at which the atmospheric river that’s causing the precipitation has come in.

A pedestrian makes his way along a waterfront as downtown Seattle is partially hidden in a steady rain beyond Monday, Nov. 18, 2019.
Elaine Thompson / The Associated Press

It’s been a wet month in Western Washington, with few breaks from steady, and sometimes heavy, rain.

“We’ve just tied the record for number of rainy days at Seattle and at this point, Seattle got about eight inches of rain so far this month,” KNKX weather expert Cliff Mass said on Friday morning. “Typically, we only have about five and a half. So, it’s been a wet period.”

Tim Durkan / Tim Durkan Photography

Washington’s mountain ranges not only produce spectacular vistas and recreational activities year-round. Their location near the Pacific Ocean also creates a variety of unique weather features that add to the special atmosphere in the Northwest.

“You have to love the meteorology of this region. I certainly do,” says KNKX weather expert Cliff Mass, who teaches atmospheric sciences at the University of Washington and wrote a popular book on the subject.

Bellamy Pailthorp / KNKX

Forecasting technology has come a long way since KNKX weather expert Cliff Mass first got his start in the field. He often marvels at how precisely most events can be predicted, using powerful computers that run ensembles of modeling programs that meteorologists compare before they decide what to tell the public. The aim is helping people prepare, especially for potentially dangerous weather.

But in the Northwest, snow – especially the kind that hit parts of Western Washington this week – is notoriously difficult to forecast. Mass agrees, this past week was a case study in that challenge.