The Western Puget Sound Rain Shadow

In Seattle, it was quite a wet, blustery day, but if you had taken a short ferry ride to Bainbridge Island you would have experienced hardly a drop.  To illustrate this, here is the 24hr precipitation ending 8 PM Wednesday over Puget Sound and nearby environs.

.01 inch in Bainbridge...barely enough to wet the pavement and .02 inches in Belfair on the Kitsap Peninsula.  Cross the Sound and there was over .40 inches.  In general, it was much drier on the western side of the Sound.  Yes, Sequim to Port Townsend were fairly dry too.

As you might imagine, this contrast was due to rain shadowing in the lee of the Olympics and upslope enhancement on the western side of the Cascades.   We could watch it happening in today's weather radars (showing you the radar-based 1-hr precipitation)

11 AM.  Rain shadow NW of the Olympics, consistent with SW flow.

 At 12:59 PM, the flow was in transition (becoming more westerly) and you notice an increase in precipitation on the western side of the Cascades)

This transition was even more obvious at 3:46 PM,  A broad rain shadow downstream of the Olympics was obvious, as was the substantial enhancement of rain on the western side of the Cascades.

Even more so at 5:02 PM

We did have radiosonde launch at Qullayute at 4 PM and here is the sounding of winds (barbs), temperature and dew point (the dark lines slanting to the left).  Height is in pressure units (hPa), with 700 being 10,000 ft, 850 about 5500 ft., etc.).  Winds approaching the Olympics were from the west-southwest at that time, which fits the radar pattern.

My point is that Olympic rain shadows don't only hit Sequim and environs, they can extend down the eastern slopes of the Olympics under the right conditions.  And it also illustrates that if you are weather-wise and are ready to travel an hour or so, you can often find much better weather.  Or stormier weather if you prefer.