The Meteorology of the Kenmore Air Crash near Sucia Island

On Thursday around 5:15 PM, a Kenmore Air float plane crashed on the south side of Sucia Island in the San Juans.   An image from the final seconds (shown below) does not suggest particularly strong winds at the surface, nor any precipitation.

The weather radar at the time of the incident shows a convective/thunderstorm line just to the south, but with the crash location (indicated by the red arrow) being in the clear.

The thunderstorms in the band were associated with lightning (see map below) for the period immediately before the crash.

There was good reason that the Kenmore Air pilot, headed towards Roche Harbor, went north and east to avoid the incoming thunderstorm cells.  He appeared to be circling about, waiting for a weakness in the convective line--but I am not sure of that.

So how severe were the meteorological conditions?

Examining the wind gusts at 5 PM, there was nothing exceptional, with 23 mph near the accident site (Eastsound).

Precipitation with the thunderstorm line was variable, ranging from 0.44 to 0.04 inches on Orcas Island.

The bottom line is that meteorology (a line of thunderstorms) obviously caused a change in the route of the Kenmore aircraft, but there is no direct and obvious causal relationship to the accident.

The Weather Pattern is Stuck: Temperate, Mild Weather Ahead

Sometimes the weather gets stuck in a totally benign pattern, with little threat of heatwaves, wildfire explosions, heavy rain, or anything else of note.

During the next week or so, we will be stuck in such a boring pattern, with great benefits for our region.

To demonstrate this benign situation, consider the forecast upper-level (500 hPa pressure, about 18,000 t) for Sunday morning.   A ridge of high pressure is inland, and a trough of low pressure is off the northwest coast.

Fast forward to next Friday evening (below).  Very similar!

This pattern produces moderate, unremarkable weather over our region, with no heat waves.  

To illustrate this, below are the temperature forecasts for Seattle and the Tri-Cities for the next ten days.

BORING.   Seattle rises into the mid to upper 70s.   The Tri-Cities into the 90s.  Very typical.

The forecast upper-level pattern is associated with modest atmospheric rivers, moving moisture from the southwest to the northeast.  

To prove this to you, below are the forecast water vapor transport from Sunday and next Friday.   The moisture plumes are evident. When the moisture reaches our shores, expect rain.

There will be regional precipitation, particularly over southwestern British Columbia.  The total precipitation through Sunday evening is shown below.   The Olympics and North Cascades will get a piece of it. 

Total through next Saturday morning is impressive.   Will damp down any wildfires across southwest British Columbia.

Getting moisture this time of the year....typically the warmest and driest period for our region.. is very good news and will help this summer end with normal or below normal wildfire acreage numbers.   Also favorable for Northwest agriculture.