Wednesday, February 4, 2009
Dry Winter Two
There was some interest in our unusual dry periods this winter, so lets go one step further and compare the precipitation from Oct 1 to Feb 4 of this year, with some previous years (attached). The difference is clear...this year has an usual number of extended dry periods.
A few of you commented that this seemed like rainshadow year near and north of Seattle, and in fact you are right...we had extended periods of westerly flow...particularly when it was precipitating, and westerly flow tends to produce more rainshadows over central Puget Sound. (This area is to lee of the Olympic Mountains for westerly winds). On the other hand Sequim was in the rainshadow less!
Do the numbers support this? Here are the 3-month Nov08-Jan09 precipitation totals in inches and percent of normal (provided by Mark Albright):
Olympia 22.67 - 93%
Seatac 16.02 - 90%
Seattle WFO 12.91 - 80%
It does appear that the Seattle Weather Forecast Office in Sand Point, north of Seattle, was considerably lower compared to normal than SeaTac or Olympia.
Today was warmer than normal day, with temperature hitting the lower sixties in some foothills locations and mid to upper fifties filling the Sound. We do have an inversion over us (see figure) and a burn ban in Pierce County. Tomorrow day should be dry with increasing clouds. Rain moving in tomorrow night. Its been a long time.
There are rumors of lowland snow on Monday...more on that tomorrow.
For those that are interested, I will be talking tomorrow (Thursday) night at 7 PM at REI in Seattle on "Secrets of NW Weather Prediction" THis is open to the public and sponsored by the NW Ski Touring group.
Posted by Cliff Mass at 8:06 PM