WeatherWatcher: Major changes ahead / August data graphs

Wednesday, August 9, 2017

With the high level of smoke content in the atmosphere,
I was able to capture a sun spot without using any camera filters.
Photo by Carl Dinse

  • Forecast - Major weather change
  • Record dry streak
  • August temperature graph
Forecast: The smoke is expected to stick around, at least through Friday morning. Friday afternoon and evening we have a major change in the weather pattern starting up. Thursday will possibly be our last dry day of this record long dry streak, with a high temperature in the low-mid 80's. Expect the stage one burn ban to remain in effect until at least Thursday afternoon or evening.

Friday, the transition day, on-shore flow will start to kick in during the pre-dawn hours of the morning. As a result of the on-shore flow, our widespread smoke is expected to turn into areas of smoke. Highs once again probably close to 80°F during the afternoon. Friday evening a weather disturbance will make its way into the area, bringing clouds and about a 10% chance of some light rain showers. Most importantly with this disturbance is the fact that on-shore winds will be strong enough to clear out most, if not all, of the smoke Friday night into Saturday morning.

Weekend will start with morning clouds and afternoon sun on Saturday, which will be our first day without smoke in the forecast. Highs expected to be seasonal, in the 70's. Saturday night another weak system approaches with a renewed chance of showers overnight and Sunday. Sunday is expected to start off cloudy with possible showers before clearing up a bit for partly sunny skies and highs again in the 70's. More showers expected Sunday evening.

Monday - Wednesday we return to our regularly scheduled summer, sunny skies, highs ranging in the mid-upper 70's and lows in the 50's.

Longer range is showing that we may start trending into cooler and wetter weather for the remainder of the month, so beyond next week we might get more alternating days of sun and showers here and there. It's still too uncertain to see what August 21st will look like during the solar eclipse.

Record dry streak: The last day Shoreline had recorded measurable precipitation was June 20, at 0.01 inches. This puts Shoreline at 48 days since the last measurable rain, 53 days since we've had anything over 0.01 inches.

I know we had a morning in July with a drizzle but it wasn't enough to tip the rain gauge. From various reports I've heard, however, different areas of Shoreline received heavier drizzle or no drizzle at all. The drizzle was due to a particularly heavy marine air layer that morning.

August temperature graph: Here's our daily high and low temperatures for the month of August so far. Heat wave very evident but not as bad as originally forecasted, thanks to the thick smoke.

Some area stations showed a decrease in solar radiation of 10-15%. Locations north had 50% or more reduction in solar light reaching the ground.

The big story would have been the heat. Without the smoke we could have easily reached the upper 90's or maybe even 100°F. Instead the big story became the thick wildfire smoke that was carried into our region.

Such events have happened in the past, but the smoke wasn't nearly as thick as it was this year. Some areas around Western Washington, including Shoreline, saw air quality become worse than most of the typically heavy polluted locations in the world.

August daily high and low temperatures compared to station average.

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