April 13, 2016

Rainshadow Sunset

Last night, even when it was raining in Seattle, there was the most amazing sunset.   Here is the view from the space needle cam looking towards the northwest, which did not do the view justice.

Here is one taken by A. J. Thompson of Greenwood.

Last night a front had moved through and their was southwesterly flow aloft.  Air sinking on the northeast side of the Olympics (the lee side in this situation) caused warming and drying, resulting in a hole of the clouds and thus the entry of the setting sun.

The visible satellite image last evening at 5 PM hinted at the rain/cloud shadow underneath.

 But the highly accurate short-term (2 hr) forecast from the HRRR model for 7 PM showed a dry zone at around 5000 ft from the sinking (light green colors)

With a hole (white) in the predicted low clouds.

Good time to plant around the garden.  Moderate temperatures and the ground is still moist.


  1. Impressive modeling by the HRRR

  2. The models frequently predict Sequim's 'blue hole', either as a gap in the clouds or more commonly a gap in the precipitation, especially in the corner seasons. Which I also find impressive.

    That's different than mid-winter. Many winter storms are strong enough to dump enough nastiness into the downslope to overwhelm it. Or so it seems to me. Result is still lighter rain than surrounding areas, but no blue sky.

    John Marshall

  3. At the Admiralty inlet we had a very nice rainbow in the East right at sunset. No special sunset noted from with the " blue hole".


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