December 11, 2010

The Warm Front Cometh

The latest radar shows a complex pattern, moderate to heavy rain over Puget Sound country, drying out south of Olympia, and a clear rain shadow to the NE of the Olympics.

The warm front is now moving across central Puget Sound. Take a look at Tacoma (McChord AFB) during the past 12 hours...over a period of 3 hours the temperature jumped from just above 40F to 57F! Now that is a warm front, the kind we rarely see around here.
As shown in the surface chart at 10 PM, the warm front was positioned between Tacoma and Sea-Tac Airport, with the wettest conditions to its north. The warm front has pushed farther northward along the coast.

Here is the latest precipitation totals from the Rainwatch Web site. A few areas in the lowlands have gotten above 2 inches.

1.33 inches at Sea-Tac so far .95 inches at Boeing Field, .39 inches at Paine Field. This event is not over yet....


  1. Looks like the NWRFC updated in the past hour, and for the most part the river levels on the coast at least seem to be a little less than they were earlier today.

  2. While watching the UW radar compilation loop from about 2350-0050 local I note a lower return area that remains stationary over the Sound while the stronger returns flow on to the ENE. Is this the subtle result of terrain descending to sea level from the peninsula and then rising the few hundred feet until eventually encountering the foothills -- tracing out in effect a lenticular wave train? Cooler water also comes to mind but seems unlikely over the few minutes it takes the air mass to cross the water.

  3. 1.92" of rain here on the Sammamish Plateau for 24 hours ending at 5:30 AM along with a balmy 55.4 degrees.

  4. Cliff, I was noticing on UW radar this morning how well shadowed Vancouver CA is. 'Have any cumulative data on their rain shadow? I think that it would be an interesting blog to analyze the location of our large cities in the PNW with respect to what is known now about localized climatic phenomena. Does the rise up to Beaverton rain shadow downtown Portland? What weather wisdom (if any) were the old timers using when the larger cities up here were founded?

  5. Cliff: will the new coastal radar have the capability to see/plot a cross section of atmosphere temps? It would be interesting to see a cross-section of this front up through the heights (i.e. the shape).

  6. 2.23" storm total in Normandy Park at 7:10am Sunday morning.

    Our Basement is flooding and my 500 gallons rain barrel system would have filled up 4 times over! Maybe I should increase the size!

  7. At Lake Dawn, 5 miles south of Port Angeles and 1800 ft elevation, my rain guage measured 1.60 inches by 2230 hours on 11 Dec. 2010.

    J. Wegmann


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