January 04, 2015

Serious Rain and Profound Rain Shadowing

Updated 10 AM.   Here is the latest 24h amounts.  Amazing totals.
As much as 13 inches on the coast, with many locations getting 5-8 inches.  But less than a quarter of an inch in the rain shadow over parts of Puget Sound and NW Washington.   Big totals (4-6 inches) along the western slopes of the Cascades.   And a very high freezing level that is melting lots of the recent snow

Some large rain totals so far and amazing rain shadowing.  Here are the 24h totals ending 11 PM Sunday.   Notice how the heaviest amounts are in the foothills and just upstream of the terrain, where the air is initially forced to rise.  7.65  and 6.15 inches just upstream (SW) of the Olympics.  2-4 inches along the lower western slopes of the Cascades.

But ONLY .01 inch at one location on southern Whidbey Island in the rainshadow.  Amazing

It is hardly raining in Seattle, while biblical rain is hitting the mountain slopes.  Take a look at the latest radar...the profound rain shadow over Seattle is starkly apparent.

Why is the rain shadow over Seattle and not Sequim and Port Townsend?  Because the winds are westerly, causing the shadow to rotate over the city.  But look how heavy the rain is (yellow is heavy) just to the east.

The 4 PM sounding at Quillayute (Forks) on the Washington coast shows the strong westerly winds aloft and the extremely warm, moist flow.  The freezing level is now 10,000 ft and heavy rain is falling in the mountains (the height on this plot is in terms of pressure, 700 is roughly 10,000 ft; red is temperature, blue is dew point.  Where they are on top of each other the air is saturated).

The National Weather Service has flooding warning for a number of rivers.


  1. it is POURING in Port Angeles and Sequim.... hasn't let up for hours.
    Make it stop.

  2. I was very happy to be in the rain shadow when I had to walk home from the bus stop in Shoreline tonight. A bit of blowing mist is much more pleasant than a driving rain.

  3. I should have gone skiing last wee during the sunshine... I imagine the snow is all ruined now.

  4. The grass is sticking out on the Hurricane Ridge webcam

  5. Today when I visited Snoqualmie Falls to see the high river flow, I encountered a rare microclimate feature. There was heavy fog everywhere, but all the roads and surrounding area were dry except at the lodge and the overlook above the falls. At those two places, there was a heavy, fine rain (not just mist from the falls) that continued for at least a half hour even as the sun poked through the fog a little. Apparently the saturated air was cooled enough by the falls for condensation and precipitation to occur in that limited area. The road and parking lot away from the falls stayed dry the whole time.


Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

Thunderstorms Return to the Northwest

 Thunderstorms have been relatively rare this summer, but today will see some boomers over the Cascades and eastern Washington. In fact, the...