November had a daunting challenge to live up to "normal" this year, and lo and behold, it reached it.
NOAA uses a 30-year average to compute "normal" temperatures and rainfall, updated every 10 years, and 2012 was the second year of using the fairly-new 1980-2010 period. Many times, the new normals are more of a tweak than a big change -- for example, March's new normal rain is 3.72", and it was 3.75" in the 1970-2000 period.
But November is a different story. After drifting between 5.60 and 5.90" as the average monthly rainfall through the decades, this current 30-year period saw a huge jump to 6.57" -- an 11 percent increase!
Why so much? Blame 2006. That year saw November not only break, but totally destroy the record for wettest month on record -- by several inches! When all was said and done, the month tallied 15.63 inches of rain, breaking the old monthly record of 10.71" and, as you saw, triple the average month.
So when that year got factored into the new 30-year period, it skewed the November averages much higher. And it means the future 1990-2020 and 2000-2030 numbers will remain rather high in November, baring a massive, extended autumn drought, with that month still factored in.
But even more amazing? With the higher bar and echoes of a since-busted El Nino forecast still reverberating, 2012's November has reached that lofty average with a few days left to spare.
As of Monday, Seattle was at 6.71" of rain. And with more rain expected Thursday and Friday, we should be over 7" by the time all is said and done. Combine that with our very wet October and the water year is off to a rousing start.
We'll see what December holds. Remember last year was one of the driest on record and barely had any rain until the week after Christmas (finishing at 2.24 inches.)