One of the burdens of writing this blog is the necessity on some occasions to describe some unpleasant meteorological facts.
And this is one of those blogs.
Today was wonderfully warm and dry, and tomorrow will be almost as good.
But this weekend represents the high point of our autumn-– a return of such perfect conditions is highly unlikely for the rest of the cool season.
But before I discuss the big cooldown, consider today’s wonderous high temperatures (see below). Upper 70s and lower 80s over western Washington, and low 80s over much of the Columbia Basin.
The origin of this delightful period? A ridge of high pressure aloft (see 500-hPa pressure map..around 18,000 ft) for this morning at 5 AM.
Monday morning the ridge moves out and rain and cooling moves in. Take a look at the extended temperature prediction from the NOAA National Blend of Models for Seattle (below). Tomorrow is the last day that will rise into the mid-70s over the next 10 days– a period in which the sun is weakening rapidly.
The highly skillful European Center ensemble of many forecasts shows a similar pattern (through October 21)
Why can I be so sure that we won’t get into the mid-70s and 80s after this?
Climatology
Take a look at the climatology of SeaTac Airport from Oct 7 to November 25. The red shading shows record highs. The blue shows record lows.
The sun is strong enough to get into the upper 70s and even into the 80s through mid-October. But temperatures have NEVER gotten into the 80s after that. In fact never into the upper 70s.
The next ten days should be quite wet, with total precipitation exceeding 3 inches in most of the coastal terrain of Washington and SW British Columbia. Time to check on our rain gear!
Sorry….
