Showing posts with label weatherwatcher. Show all posts
Showing posts with label weatherwatcher. Show all posts

WeatherWatcher: Wind Advisory issued Monday night into Tuesday Morning

Monday, January 8, 2024

 
Graphic by National Weather Service in Seattle

The National Weather Service in Seattle has issued a Wind Advisory for the greater Seattle area including the cities of Lake Forest Park and Shoreline. The wind advisory is in effect starting Monday night from 10pm until Tuesday night at 10pm. 

At the time of this writing models suggest the strongest winds to be just before 4am Tuesday morning but all agree that it will be windy most of the day. Wind gusts could go as high as 45 to 50mph.

From the National Weather Service:
  • What: Southwest winds 25 to 35 mph with gusts up to 50 mph expected. 
  • Where: Everett and Vicinity, Tacoma Area, Bellevue and Vicinity and Seattle and Vicinity.
  • When: From 10pm Monday evening to 10pm Tuesday. 
  • Impacts: Gusty winds could blow around unsecured objects. Tree limbs could be blown down and a few power outages may result.
 

For current weather conditions visit www.shorelineweather.com


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WeatherWatcher: Active weather ahead with rain, wind, then uncertainty

 

Blustery day at Richmond Beach
Photo by Carl Dinse

We have a week of active weather in the forecast. A rainstorm moves in late Monday morning, lasting through the afternoon and evening. A windstorm follows that rain Monday evening into Tuesday. A half inch to one inch of rain is expected with the Monday night storm.

Winds Monday night and Tuesday through the afternoon are expected to be south to southwest 15-30 mph, with gusts up to 45mph especially after midnight Monday night. Winds are expected to taper off after midnight Tuesday night into Wednesday. These winds could cause some scattered power outages throughout the area.

Interesting note, the Monday/Tuesday storm has prompted the National Weather Service in Seattle to issue their first blizzard warning for the Cascade and Olympic Mountains in 12 years. 

Rain continues through Wednesday into Thursday morning. Thursday morning and beyond is when things get very uncertain. Many of the forecast models believe we will transition into an arctic outbreak, except for the American GFS model. 

I personally have had a hard time trusting the American model. For the past two years, it has not been very good at predicting more than a couple hours into the future, let alone a few days. 

That said, even on the other forecast models that are run with slightly different starting variables, have a significant disagreement on placement of where the arctic outbreak will occur over the greater Northwest (including Montana). 

Generally, several forecasts are calling for an arctic lobe or "polar vortex" to reach down the west coast and bring us very cold temperatures with snow from Thursday/Friday well through next weekend. Other models have that arctic lobe staying generally east of the Rocky Mountain range, leaving us with our usual maritime climate and lowland rain.

It is still too early to know for sure what might happen after Thursday, but cold and snow-like weather is not ruled out yet. I will do another update Tuesday night, when hopefully we will have better forecast model agreement.


For current weather conditions visit: www.shorelineweather.com

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WeatherWatcher: Winter Outlook

Wednesday, December 6, 2023

 

Snow in Lake Forest Park, February 13, 2021
Photo by Carl Dinse

I've been asked already when I expect to see our first snows this winter. It's very hard to say, but I will point out what I've been seeing with some consistency. There are a couple of sites that forecast longer range, both have been somewhat consistent with an indication of more winter type variety weather (Yes, the snow word) in the second half of December.

It’s important to remember that any of these forecasts going out beyond even a few days really start getting into the weeds of uncertainties. That is to say these forecasts start having a much higher percentage of becoming an inaccurate forecast.

Beyond a forecast, here’s my current ideas on how winter will play out for Shoreline and Lake Forest Park.

We have two main factors I generally consider. There are many more, but I like to watch the two most measured and somewhat biggest impact cycles that occur in our weather patterns. 

  • The primary one that everyone talks about is the El Niño-Southern Oscillation (ENSO) cycle. This cycle is typically annual or seasonal, switching during the spring and summer months to either El Niño, La Niña, or neutral conditions.
  • The second significant influence on our weather trends, particularly in the winter season, is the Pacific Decadal Oscillation (PDO). This cycle is not seasonal, or annual, but functions more on a 20-to-40-year cycle, flipping between a warm phase, and a cold phase.

So, this winter, we are in a strong El Niño, but we also have a moderate to strong cold phase PDO. This tells me that this winter isn't as likely to be the widely forecasted drier and warmer than normal winter pattern.

What does this mean for Shoreline and Lake Forest Park?

Chances of snow events will likely increase middle through late December, and I think after December our next big chances will likely be in the middle January and/or into February time frame. It could easily become another 2019 winter, where we waited until February to get all our snow. 

Our chances of a snow event for the entire winter season are slightly lower than normal, but can still happen, and can still be capable of being a large storm.

In general, I think we'll see dry stretches like the one we just finished, with stormy periods in between and heavier than normal precipitation during the active periods. We'll see if the heavier precipitation equals out the average at the end of the season or if we do end up drier, or wetter than normal.

El Niño winters with a cold phase PDO not unlike this winter that are noteworthy from Sea-Tac (unless noted):
  • 1951-52: 10 inches, in December and January
  • 1953-54: 23.3 inches, January, and March
  • 1965-66: 22 inches, December, January, and March
  • 1968-69: 67 inches, December, and January
  • 2018-19: Shoreline: 20.7 inches, February, and March (snow measured in Shoreline)

There are a lot of other El Niño winters with a cold PDO phase that produced decent snow events, so in my opinion, backed up by the data I have from Sea-Tac, it is probably more likely than not that we'll see at least one or two snow events this winter season. 

They tend to show up late December, January, and February on average for this kind of set up. Other similar years have had smaller snow events, but still, multiple snow events occurred.

Seattle's record for most snow in one winter was 1968-1969 and it was an El Niño winter, with a cold phase PDO. The only other recorded winter that comes close was 1949-1950 at 64 inches of snow. Most fell in a January blizzard (Seattle’s only officially recorded blizzard). The 1949-50 winter, however, was a La Niña winter, but also with a cold phase PDO. 


For current weather conditions visit www.shorelineweather.com

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WeatherWatcher: Wind Advisory in effect overnight; Weekly forecast

Friday, December 1, 2023

National Weather Service weather pattern timeline
The National Weather Service in Seattle has issued a wind advisory in effect beginning Friday night, December 1, 2023 at 11pm until Saturday morning at 6am. 

Winds are expected to pick up around or after midnight Friday night. The peak of the winds is expected between around 3 to 5am. The wind advisory is in effect for the greater Seattle and Puget Sound area, including the cities of Shoreline and Lake Forest Park.

From the National Weather Service:
  • What: South winds 30 to 40 mph with gusts up to 50 mph expected.
  • Where: Southwest Interior, Everett and Vicinity, Tacoma area, Admiralty Inlet area, Hood Canal area, Eastern Strait of Juan de Fuca, East Puget Sound Lowlands, Bellevue and Vicinity, Seattle and Vicinity and Bremerton and Vicinity.
  • When: From 11pm Friday evening to 6am Saturday.
  • Impacts: Gusty winds could blow around unsecured objects. Tree limbs could be blown down and a few power outages may result.
Forecast: We have begun the transition into an active weather pattern that is very typical for the late November and early December time of year here. The jet stream is pointed right at the Pacific Northwest bringing the storm train with it.

For the weekend, we have a series of colder storms moving through, bringing several rounds of heavy rain and wind to the lowland areas. Mountains are expected to be picking up a lot of snow from this first series of storms. Windstorm overnight into Saturday morning. Then another windstorm is expected Sunday afternoon or possibly later into Monday.

Next week the fun continues with a warmer series of storms and a lot of rain. Remember how I mentioned above the mountains would be getting a lot of snow this weekend? The warmer weather next week is expected to bring rain to the lowlands and the mountains. Several inches of rain could fall in the Shoreline area, and many more inches of rain in the Cascade Mountains.

River flooding is expected next week. Small streams and creeks could start to flood and cause localized urban flooding as well. The moderate to heavy rainfall is expected for the most part to last all the way through at least next Thursday with temperatures in the mid 40's to low 50's.

Further out in the forecast shows more storms are likely to move through the region. As the week progresses, I suspect we might see more windstorms show up in the forecast as well.


For current weather conditions visit www.shorelineweather.com


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WeatherWatcher: Wind Advisory in effect

Friday, November 10, 2023

Windborne water spray at Richmond Beach
Photo by Wayne Pridemore 2017

The National Weather Service in Seattle has issued a wind advisory for the greater Seattle area which includes the cities of Shoreline and Lake Forest Park. The wind advisory is in effect until 7am PST Saturday. 

Southeast winds are expected to gust up to around 35-45mph with some gusts up to 50mph possible. Strongest winds are expected sometime after midnight and will likely start to taper off around 6am. 

The advisory has been issued as these winds are strong enough to bring down tree limbs and cause scattered power outages. Winds this strong can also blow around any unsecured objects.

As of this writing my Richmond Beach neighborhood station has already recorded a gust of 33mph at 9:17pm. So far, we have been spared rainfall but that is expected to change overnight with up to around a half inch of rain by Saturday afternoon.


For current weather conditions please visit www.shorelineweather.com


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WeatherWatcher: Thunderstorms and rain in the forecast

Monday, August 28, 2023

Lightning in Richmond Beach
Photo by Wayne Pridemore

Tuesday morning is expected to arrive with scattered thunderstorms and rain showers over the region. For the more exciting news, we are going to have a week of cool weather, cloudy skies, and rain at times. We could end next weekend with over an inch of rainfall.

Our gray and gloomy Monday was the result of a strong onshore marine air push, bringing in a shallow layer of clouds over the lowlands. Sunshine could be found at about 1,500 feet up any mountain in the area.

The Tuesday morning showers are expected to bring a little less than a tenth of an inch of rain, but higher amounts are possible from thunderstorm activity. Tuesday afternoon the shower and thunderstorm activity is expected to become more scattered and isolated with highs topping out in the 60's.

Wednesday is expected to be a mostly cloudy day, with temperatures near 70°F. A new rainmaker weather system arrives Wednesday night into Thursday. This system is expected to bring us a day of steady rain on Thursday with temperatures in the 60's. 

Friday through the weekend: A chance of showers remains in play off and on through the end of the weekend, with partly sunny skies at times, and temperatures around the mid 70's during the day. Saturday could feel extra muggy with highs near 80°F and rain showers in the mix. At those temperatures I can't rule out the possibility of another round of thunderstorms.
 

For current weather conditions visit www.shorelineweather.com


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WeatherWatcher: Heat Advisory in effect from noon Saturday until 8pm PDT Sunday

Saturday, August 26, 2023

 
Smoky sunset from Richmond Beach July 4, 2023
Photo by Carl Dinse

The National Weather Service in Seattle has issued a Heat Advisory in effect from noon Saturday until 8pm PDT Sunday.  

From the National Weather Service:
  • What: Hot conditions with temperatures of 85 to 95 degrees expected away from the water. This will pose a moderate risk of heat-related illness.
  • Where: Portions of northwest and west central Washington.
  • When: From noon Saturday to 8pm PDT Sunday.
  • Impacts: Heat will increase the risk of heat-related illnesses for those who are sensitive to heat, especially those without effective cooling or adequate hydration.  
  • Additional Details: When heat and poor air quality occur at the same time, use air conditioning and air filtration if possible. If you do not have access to air conditioning, it may not be safe to stay inside with doors and windows closed when it's hot outside. When heat and poor air quality occur at the same time, cooling should be prioritized. 
Forecast: For the Shoreline and Lake Forest Park areas, we are expecting high temperatures to reach the mid 80's both Saturday and Sunday. We are also expecting hazy and smoky conditions both days from mainly Canadian wildfires. Lows will be in the upper 50's to low 60's in the evenings.

Smoke is expected to degrade air quality to levels not quite as bad as last weekend but will make it at least to the unhealthy range for sensitive groups. If the thunderstorms that moved through the mountains and across the Olympia and Tacoma areas sparked any new fires, we could see more smoke than currently expected.
Air Quality at the Lake Forest Park Town Center
Data and graph from Puget Sound Clean Air Agency

On-shore breeze is expected to kick in Sunday afternoon and evening, helping to clear the smoke out of the region going into Monday.

We have more chances of showers and thundershowers next week around Tuesday through Thursday. 

We'll have to keep a watch on the forecast to see what could develop.


For current weather conditions visit www.shorelineweather.com


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WeatherWatcher: Excessive Heat Warning in effect until 11pm PDT Wednesday night

Tuesday, August 15, 2023

Sunny day at Richmond Beach, Shoreline.
Photo by Carl Dinse
The National Weather Service in Seattle has issued a Excessive Heat Warning for the greater Seattle area including the cities of Shoreline and Lake Forest Park. 

From the National Weather Service:
  • What: Dangerously hot conditions with daytime temperatures in the low to mid 90s and lows in the 60s and 70s expected. This will pose a major risk of heat-related illness.
  • Where: Bellevue and Vicinity and Seattle and Vicinity. 
  • When: Until 11 PM PDT Wednesday. 
  • Impacts: Major Heat Risk level poses a major risk for heat- related illnesses for anyone without effective cooling or adequate hydration.  

Forecast: We will be in a heatwave through the end of the week, the worst of it though is expected Tuesday and Wednesday. High temperatures could get into the low to mid 90's both days. What is going to make us uncomfortable are the nighttime lows, in the 70's and upper 60's.

Once we get through Wednesday, things will start a slow trend into a cooler pattern. Thursday and Friday highs are expected to come down into the low to mid 80's. 

Then, Saturday and Sunday we cool down enough to keep high temperatures in the 70's. By the weekend our overnight low temperatures will come back down into the upper 50's.

Currently there is no significant rainmaker in sight, however there are some models indicating that we might see some dry thunderstorm activity over the mountains this coming weekend. Most of the activity stays down in Oregon but the Cascade Mountain range right now is under a red flag warning. 

A red flag warning means that conditions are causing extreme fire danger. The criteria for a red flag warning is a relative humidity 15% or below, in combination with sustained or frequently gusting winds above 25mph. Both conditions have to be occurring for at least 3 hours out of a 12-hour period to issue a red flag warning.

I've been asked why the Puget Sound lowlands area, including Shoreline and Lake Forest Park, are not under a red flag warning. We don't have the consistently strong enough winds or a low enough relative humidity right now. This does not mean that fire danger isn't high, as we still have a lot of dry fuels around which is typical of late July and August in our region.

Relative humidity has been in the 40-50% area so far during this heatwave, which is a little more humid than normal, and winds have been calm, with the biggest gusts averaging around 15-18mph.


For current weather conditions visit www.shorelineweather.com



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WeatherWatcher: High temps and wildfire smoke give way to cool down and clear out later in the week

Wednesday, July 5, 2023

Photo by Carl Dinse 7-4-2023

Right now we have a light layer of Canadian wildfire smoke hanging over Puget Sound.

Wednesday and Thursday will still be hazy with the wildfire smoke aloft. High temps will be in the mid 80’s both days.

Photo by Carl Dinse 7-4-2023

Friday we get our A/C back in the form of an onshore flow. We’ll cool back down to the mid 70’s for highs and the wildfire smoke aloft will clear out.

Saturday and beyond should be a decent week weather wise, with sunny skies, highs in the 70’s, and an onshore flow with no wildfire smoke.



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WeatherWatcher: Wildfire Smoke returns, no end in sight to sunny days

Thursday, May 18, 2023

 
From the archive, Thunderstorms bubbling up over the Olympics.
Photographed from Richmond Beach August 2013 by Carl Dinse.
Believe it or not, wildfire smoke has returned to Western Washington already. This time the source of all the smoke is from wildfires in northern Alberta, Canada.

The smoke is expected to remain mostly aloft (in the upper atmosphere) this time. The smoke will, however, produce hazy days with colorful sunrises and sunsets.

Our forecast shows basically no end in sight to the sunny skies and summer like weather. There is a slight chance of some afternoon and evening thunderstorms on Thursday but beyond that, expect hazy to sunny skies and clear nights. 

Temperatures will still be above normal, reaching the upper 70's to low 80's and lows in the mid to upper 50's.

We cool down a little on Sunday, with high temperatures dropping to the upper 60's with partly sunny skies and a slight chance of showers Monday. 

Mostly sunny skies return Monday evening and continue through next Wednesday with highs back into the low 70's.

Daily high and low temperatures for the month of May
from Shoreline Weather station in Northridge / Echo Lake neighborhood
May heatwave statistics:
  • National Weather Service had issued a Heat Advisory from Saturday May 13th at 2pm until Monday May 15th at 8pm.
    • Friday May 12th: High: 80°F, Low: 51°F
    • Saturday May 13th: High: 82°F, Low: 57°F
    • Sunday May 14th: High: 89°F, Low: 63°F
    • Monday May 15th: High: 89°F, Low: 62°F
    • Tuesday May 16th: High: 79°F, Low: 57°F

For current weather conditions visit www.shorelineweather.com


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WeatherWatcher: Excessive heat watch in effect Saturday - Monday

Thursday, May 11, 2023

 
Sunny day in Shoreline on 185th near Aurora Ave. March 2019
Photo by Carl Dinse
The National Weather Service in Seattle has issued an excessive heat watch to be in effect from Saturday afternoon until Monday afternoon. This is expected to turn into a heat advisory as we get closer to the weekend.

High pressure has built up in the upper atmosphere along the west coast interior, centered over interior British Columbia, Canada. This "heat dome" or dome of high pressure is pushing sinking heating air south and west into the Puget Sound region. This brings us glorious sunny weather, clear skies, and warm temperatures.

The sunny skies and warm air are making up for our unusually cold spring. Thursday and Friday high temperatures are expected to be in the mid 70's. We could even get near or just past 80°F on Friday and into the low to mid 80's on Saturday.

Sunday and Monday are when the heat starts to crank up, with high temperatures into the mid to upper 80's, or low 90's. There's a higher chance of seeing 90°F or more if you're south of Northgate, or away from Puget Sound. I expect most of Shoreline and Lake Forest Park to be in the upper 80's to near 90°F.  Lake Forest Park might trend warmer.

At the tail end of this heatwave, as with most heat waves around here that end quickly, there is a slight chance of thunderstorms developing. An upper-level low over California might rotate some extra energy from the east up and over the Cascade Mountains. This could be enough energy combined with the cooling atmosphere to get convection started, leading to possible thunderstorm activity.

One of the dangers of this heat wave is it may drive a lot of people to go to the water. Water temperatures are still dangerously cold right now which will put a lot of people at risk of hypothermia if they spend time in the water.

If SeaTac reaches 90°F this weekend or Monday it could set the record for earliest day in the year breaking the 90°F mark. 

Beyond the weekend: Mostly sunny conditions are expected to continue through all next week, highs in the mid 70's and lows in the upper 50's. It's going to feel like summer for a while, outside of this heatwave it's probably welcomed by many after this cold and grey spring we've been having.


For current weather conditions visit www.shorelineweather.com


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WeatherWatcher: Hailstorm, cold and wet weather continues

Wednesday, April 12, 2023

 

Storm rolling in from the Puget Sound 4/11/2023
Photo by Lee Lageschulte


Tuesday afternoon turned wild when a large thunderstorm cell developed on the eastern slopes of the Olympic mountains and moved east, clipping Shoreline with its southern tail. The storm was producing lightning every 15-30 seconds and heavy downpours with hail before it crossed the Puget Sound and weakened. 

Doppler radar at about 2pm April 11, 2023

Brief accumulations of hail occurred from Shoreline through Everett causing traffic slowdowns, especially in the north end of the storm. The storm lasted about 30 minutes, as it quickly moved east. Temperatures dropped around 10-12°F within that 30-minute period as well. 

In Everett temperatures plummeted from 46°F down to 33°F with snow mixing in as the storm passed. Shoreline saw a similar temperature drop, from 50°F down to 37°F, also reports of snow mixing in as the storm moved east.

April 2023 rainfall at the North Ridge station

Rainfall this month is trending far above normal now, making up for the slightly below normal March. Temperatures, as seen below, are still trending below average. I expect temperatures to remain below average for most of April and early May.

April 2023 high and low temperatures compared to average at the North Ridge station

Forecast: Wednesday morning could see some showers; some may be mixed with wet snow. Once we get past the morning showers skies should clear up to a sunny afternoon. High temperatures Wednesday afternoon should reach near 50°F. Wednesday night is expected to be mostly clear, lows in the 30's with the potential for frost in places.

Showers return Thursday morning through Thursday evening, with Friday drying out with partly cloudy skies. More steady rain returns Saturday and continues through the weekend and into next Tuesday.


For current weather conditions visit www.shorelineweather.com


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WeatherWatcher: Unsettled Weather and March in review

Tuesday, April 4, 2023

Photo by Tim Davis

This late winter and early spring have been a classic La Niña weather pattern. We've been dominated by a northwest flow from the arctic out through the Gulf of Alaska into the region. This is creating a situation where air in the atmosphere or aloft is much colder than the air at the surface. 

The cold air above is producing the perfect conditions to bring us very unstable air, with heavy short lived rain showers, hail showers and rain/snow mix showers. Some of these showers are strong enough to produce a lightning strike and occasional rumble of thunder.

Rainfall compared to average at the Northridge Weather Station in March 2023.

Despite all the intermittent heavy rain showers we are below average on rainfall, which has been the trend most of the winter. This is somewhat unusual for La Niña, but sometimes we get too far on the cold side of the jet stream and that can limit the amount of moisture our area gets.

High and Low Temperatures compared to average at the Northridge Weather Station in March 2023.

Temperatures have for most of March trended below normal, except for a couple of rare mild days in the second half of the month. Also, not unusual for a few days to be warmer than normal to balance out a March. The average temperature for March at the Northridge station has been 44.9°F over the past 12 years. This year's average was 43.7°F so a little over 1 degree cooler than normal.

Forecast: Unsettled cooler than normal weather is expected to continue into Wednesday evening before we transition back to more seasonable temperatures. Don't expect sunny warm days soon though, more weather systems will be moving through bringing us a more winter typical steady rain event Thursday morning lasting through Friday night. Temperatures will come up to the lower 50's though with lows in the 40's.

Over the weekend we transition from rain to showers, with high temperatures climbing up into the lower 60's on Sunday. The chance of rain continues however well into the middle of next week.

Long Range Forecast: When will we start to see real spring weather? Longer range hints towards our first 70°F sunny day to be sometime out in May. April looks cooler than normal in general with more unsettled weather likely at least several times over the next 3-4 weeks.


For current weather conditions visit www.shorelineweather.com



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WeatherWatcher: Active Convergence zone may bring slushy short-lived snowfall Saturday morning

Saturday, March 25, 2023

Radar image at 11:57 PM PDT March 24, 2023.

An active Puget Sound Convergence zone is in place centered right over Shoreline and Lake Forest Park, with an east/west spread. Radar as of 11:58pm Friday night is indicating some showers are heavy enough that they are turning over to snow in localized spots. In the above radar image, green is rain, pinks are rain/snow mix, and blue is snow.

Accumulations are not expected, but if we do get accumulation, it will likely be light, confined to grassy and other cold surfaces, and very short lived. Mostly we should just expect to see snowflakes falling with rain mixed in at times or just plain rain. If there is a full changeover to snow and it does start accumulating, it will be short lived. Daytime temperatures Saturday morning should easily rise above freezing and melt anything off as soon as precipitation ends.

There is also a slight chance of a thunderstorm with this convergence zone possible overnight into Saturday morning. Colder than normal weather continues through the weekend and next week. Another chance of snow mixing with rain is possible Sunday morning as well.

There is a break in the weather expected for Monday through Wednesday evening. Sunny skies and colder than normal temperatures. Highs in the 50's with lows in the mid to upper 30's. Chance of rain showers returns next Thursday.


For current weather conditions visit www.shorelineweather.com



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Lake Forest Park startled with a hail storm on Monday afternoon

Wednesday, March 22, 2023

Photo by Gordon Snyder
Lake Forest Park was startled with a dramatic hail storm mid-afternoon on Monday, the First Day of Spring.

WeatherWatcher Carl Dinse explains:

It’s that time of year when the sun is strong enough to heat up the surface significantly, while the atmosphere is still very cold. 
This generates moderate convection strong enough to support heavy showers with hail, and sometimes lightning. 
This typically happens after a storm front moves through the area, such as what happened Monday mid-morning.

The photo is from the last time this happened, on March 3rd of this year.



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WeatherWatcher: The next snow opportunity is becoming clear in the forecast

Sunday, February 26, 2023

 

As seen in the above animated loop, our next potential for snow is developing and got quite organized today. The new storm developing came across Alaska and down the west coast out of the Arctic. It is expected by forecast models to be cold enough to bring precipitation in the form of snow for most areas, especially in elevations above 300 feet.

Timing: Monday will be much like today, partly to mostly cloudy with showers through the area. The bulk of this next storm is expected to move inland late Monday afternoon and evening. Most of the accumulating snowfall is once again expected overnight into Tuesday morning. I wouldn't be surprised if we start seeing increasing rain or snow showers earlier in the afternoon Monday given the speed at which this storm is currently moving.

What to expect: Most models are now suggesting somewhere between 2-6 inches of snow could fall through most of the Puget Sound region. Temperatures are once again marginal around the freezing mark so snow accumulations will be very dependent on your elevation and proximity to warming effects from bodies of water. Rain may be mixed in at times and will be very hyperlocal depending on where the rain/snow mix lines are.

We will treat Sunday morning's snow as an indicator of who will see the most snow Tuesday morning. Those who saw snow Sunday morning should expect to see anywhere between 2 to 6 inches of snow Tuesday morning. Daytime warming is expected so it'll be a slushy mess after the sun has been up for a few hours.

We should see a bit of a break Wednesday with some sunny skies. Another storm starts to work its way in Wednesday night through Thursday and that has more potential to make another round of accumulating snow. For now, we'll just take this one storm at a time and when models come to agreement for the second half of the week, I'll write another update.

Longer range: A cold, wet pattern is expected to continue for the next 10-15 days. It is a typical La Niña weather pattern, but particularly locked in with less variability than normal. The jet stream is flowing from the northwest as a result, pulling the storm track up through Siberia and Alaska and back down the west coast. 

For current weather conditions visit www.shorelineweather.com


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WeatherWatcher: Winter Weather Advisory in effect, snowy period for the week ahead

Saturday, February 25, 2023

Shoreline Park December 3, 2022.
Photo by Carl Dinse


Saturday evening a snowstorm will be moving into the area. The National Weather Service in Seattle has issued a Winter Weather advisory, in effect from 6pm Saturday evening until 10am Sunday morning. The advisory forecasts 1-2 inches of snow, but this is a general forecast for all of the area including Seattle, Tacoma and Bellevue.

Significant snowfall will start to increase at around 9pm Saturday evening in the Shoreline and Lake Forest Park areas. Steady and moderate snowfall is expected until around 4am Sunday morning. 

Temperatures are expected to be near the freezing mark so the snow may be the heavy, wet variety much like what we saw at the end of last November.

Current forecasts are calling for 1-4 inches of snow; locally there is a slight chance of pockets of heavier accumulation. A convergence zone is expected, which might change the amount of additional snowfall significantly and unpredictably and Shoreline is right in the middle of that zone.

Important to note, places near the water, low in elevation will likely see less snow accumulation and possibly no snow accumulation. Lower areas of Lake Forest Park, especially around the Town Center will also likely see less snow or no snow accumulation. Anything above the 250-foot level in elevation should see some accumulation out of this event. Again, this will be not unlike the November snow event where places along the water saw little to no snow accumulation.

Snow showers are possible through Sunday evening and Monday as well, but nothing too significant in those showers is anticipated. We have another snow-maker coming in Monday evening into Tuesday that could bring more widespread snow accumulations. 

Colder air is expected to stay with us through the end of next week with several storm systems threatening precipitation with a mix of rain or snow depending on your proximity to the water.

Bottom Line: Be prepared to deal with winter weather, especially if you're traveling from sea level locations to higher areas near I-5. This winter weather has potential to last through all next week. The warm sun should help clear the roads during daytime periods but freezing is likely in the overnight hours.


For current weather conditions visit www.shorelineweather.com

Corrected: 4am Sunday

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WeatherWatcher: Surprise windstorm, cold air and a slight change of snow this week

Tuesday, February 21, 2023

 

Snow Dusting in Shoreline, WA
Photo by Carl Dinse

A significant windstorm moved into the region Monday afternoon and evening. The National Weather Service in Seattle was forecasting a breezy to windy evening, but nothing more than 40mph. They had a wind advisory in effect from 6pm Monday evening to 6am Tuesday morning. Around 2:30pm that tone changed, and the wind advisory became in effect immediately.

Wind-whipped water on the Salish Sea as the storm moved in
around Jefferson Head. Photo by Jan Hansen

The storm's first peak occurred at about 4:30-4:45pm Monday afternoon. Wind gusts in most areas reached 35mph but some exposed areas in Shoreline saw gusts up to 55mph. Paine Field in Everett (which is our closest airport weather station) recorded a peak gust of 52mph at about the same time. At the height of the storm close to 5,700 Seattle city light customers were without power, with the majority of them in the Hillwood and Richmond Beach neighborhoods.

The wind advisory remains in effect until 6am Tuesday morning, but most of the wind activity has already died down. A westerly surge of winds 45-60mph is still possible but is not expected to make it as far south as Shoreline and Lake Forest Park. 

Return of cold, with a slight chance of snow: Tuesday is a transition day with some showers and breezy winds expected. In the afternoon or evening hours the winds should change direction from southwest to north-northeast. When this direction change happens, cold air will start spilling into the region. Low temperatures Tuesday night into Wednesday are expected to drop into the 20's and any left-over showers will fall as snow. 

Accumulations Wednesday morning are expected to be minimal, from nothing at all to possibly a trace to an inch at most. Temperatures Wednesday will break the freezing mark and make it up to the upper 30's, with clearing skies. The sun should help clear the streets of any snow that does accumulate.

Wednesday night through Friday afternoon we are expecting clear skies, with temperatures struggling to get above freezing. Lows are expected to be near 20°F. Our next storms start to move in Friday evening and through the weekend. Cold air is expected to continue flowing into the region when these storms arrive so most of the precipitation could be in the form of snow.

We'll have to keep an eye on the forecast through mid-week to see how things develop for the coming weekend. Right now, it looks like this cold arctic-like weather pattern could continue through the first week of March. 

Bottom line: little chance of snow for now. This weekend, however could be a different story. Cold is certain, and expect freezing temperatures to be likely from Tuesday night on forward for a week or two.



For current weather conditions visit www.shorelineweather.com


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WeatherWatcher: Snow in the forecast but no advisories in effect for Shoreline or Lake Forest Park

Monday, February 13, 2023

Slight chance of a trace of snow
Photo by Martin De Grazia
Areas of snow showers are possible tonight, but Shoreline and Lake Forest Park remain outside of the winter weather advisories currently in effect. 

No accumulations are expected, but there is a slight chance of a trace to an inch overnight. Any accumulations that do occur will quickly melt off in the daylight. 

Puget Sound Convergence zone is active but south of Seattle and in the Everett area and north. 

Models suggest little to no precipitation in the areas around North King and South Snohomish County lowlands.

Currently the National Weather Service (NWS) has no watches, warnings or advisories in effect for Shoreline or Lake Forest Park.


For current weather conditions visit www.shorelineweather.com



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WeatherWatcher: Atmospheric Rivers -- we have one right now

Wednesday, January 11, 2023

 
UW WRF-GFS 4km 72 hour rainfall forecast ending at Saturday 4pm

An atmospheric river has arrived, one in a series of many that have been coming in off the Pacific ocean and mainly impacting California and Southern Oregon. There's a lot of hype implied with this type of weather system, but they are in fact very common and very normal in West Coast winters.

In the 1990's the term "Pineapple Express" was typically used to describe an atmospheric river. They are basically a plume of subtropical or tropical moisture that is pulled in by a low pressure or trough in the northeast Pacific and directed into the west coast by the jet stream

Probably at least half of our rain events through the fall, winter, and spring seasons are the result of an atmospheric river to some degree. Some atmospheric rivers bring a half inch of rain, others can bring 2-3 inches of rain during a 2-5-day single event. Some have lasted over 7 days, bringing continuous moderate rainfall to the area at the rate of a half inch to one inch per day.

The mountains often get much heavier rain in most rain events. Atmospheric rivers can cause river flooding in the lowlands due to the typically higher snow levels often associated with them. The big snowstorm we had December 26-30, 1996, ended in a long-lived atmospheric river that started as snowfall. 

Several snowstorms that week brought up to about 20 inches of accumulated snow on the ground. I recorded a low temperature of 10°F one morning that week with an analogue thermometer under the trees in the front yard. Then the atmospheric river hit bringing another 4 inches of snow. We had a total of 24 inches of accumulated snow, before that event changed everything over to rain. 

Then it warmed up to the mid 50's with several inches of rain falling over the course of the next several days. All the snow was melted within a 24-hour period. Weight of the rain-soaked snow caused a lot of roof collapses in the area.

Forecast:

For our current atmospheric river, I consider it a moderate one. It's expected to last about 3 days. During the 72-hour period ending at 4pm Saturday we are expected to get around 1.5 to 1.75 inches of rain. This is enough to get standing water in places and maybe some minor urban flooding where storm drains are blocked with debris.

Starting Wednesday evening, as of this writing, rain is expected to pick up if it hasn't already. Rain is expected to be steady and moderate through Sunday afternoon. Temperatures will range in the mid 50's for highs and lower to mid 40's for lows.

We get a bit of a break from the rain Sunday evening through Tuesday with only a chance of rain showers during that period. Temperatures cool down a bit with highs ranging in the mid to upper 40's and lows near 40°F. Tuesday night more rain is expected to return and last through Wednesday.

Longer range shows a drier pattern setting up for the last week of January. This could be a good time to get some yard work clean up done. Current model ideas show potential for colder air first week of February. That's too far off to say what might happen but it's a pattern that suggests potential for more wintery weather.


For current weather conditions visit www.shorelineweather.com



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