WeatherWatcher: Rare summer thunderstorm, this week's forecast

Lightning striking the Puget Sound September 7, 2019.
Photo by Wayne Pridemore

We had a rare and very active summer thunderstorm hit the region Saturday evening starting at about 8pm and ending sometime by midnight. For the entire region the National Weather Service counted about 2,171 cloud to ground lightning strikes, averaging about 7-8 lightning strikes per minute. 224 of those strikes in King County and 449 of those strikes to our north in Snohomish County.

Here's the radar image during the peak of the storm over Shoreline and Lake Forest Park. Yellows and reds are heavy showers, some containing hail. The heavy precipitation was short lived, with the Richmond Beach station picking up 0.21 inches of rain from this storm system. It doesn't seem like much, but nearly all of that fell within an hour, where a typical winter day might bring a half inch of rain over a 24 hour period.

Radar by the National Weather Service in Seattle

Forecast models actually had this storm system well forecasted by 5am Saturday morning. Professor Cliff Mass at the University of Washington did a good write up about the forecast and details of this storm here.

Forecast:

Forecast by the National Weather Service in Seattle

The slight threat of lightning remains in the forecast for Monday between 11am and about 8pm. Apart from that, showers are expected with a high temperature near 66°F. Monday evening we have a rain storm moving in after 8pm with steady rain expected overnight into Tuesday. Rain is expected to taper off Tuesday morning with clouds eventually breaking into mostly sunny skies.

Tuesday evening through Thursday evening the threat of showers remains in the forecast but this will likely be our driest and warmest portion of the week. Cooler weather returns Friday with again a renewed slight chance of a thunderstorm with the rain showers.

Next weekend and beyond we are looking at cool and showery weather, with our next dry spell starting possibly next Monday and lasting nearly a week, but at this point we're getting into longer range forecasts.

For current weather conditions visit www.shorelineweather.com