Nearly every September has a transition to fall-like weather, with no going back. We are in such a transition right now.
For Washington State, regular rains will return, 80s and 90s will be memories, and the wildfire season will be over.
Before I show you the forecast, consider the climatology of this month.
For temperature, September average maximum temperatures at Seattle (thin red line) goes from the summer-like mid-70s to the mid-60s (the vertical red line shows today). No more 90s by the end of the month. Ever.
For the probability of measurable precipitation, there is only small upward trend after the typical "moistening" of late August.
Enough climatology.....let's consider the forecast for the next week or so.
The temperature forecasts for Seattle and Pasco predict autumn-like conditions.
Seattle will stay with fall-like 60s for the next ten days.
The predicted rainfall total though Tuesday (below) forecasts light to moderate precipitation from the Cascades to the Pacific, with substantially higher values over the Rockies. Importantly, fire-prone eastern Oregon shares in the moisture.
The reason for this switch to a wet-cooler situation is because a series of upper levels will develop over or move into the West Coast, something illustrated by the upper-level (500 hPa, about 18,000 ft) weather map for Sunday afternoon.
All the reasons Cliff mentions in his second paragraph is why I love the autumn and winter seasons most. The real new year's day is September 1, the beginning of what I call "the brrs": SeptemBER, OctoBER, and so on. Very happy we are now there!
ReplyDeleteIt seems that "super-soaker" rainfall events, are becoming rare...when was the last time we experienced, say, a two day heavy rain situation, with 2-3" coming down? Maybe in November/December? These light rain episodes are more like a mist!
ReplyDeleteI believe we have had rains like that as late as last winter. In Puget Sound, we get the rain shadow effect of the Olympics but the atmospheric rivers/Pineapple express storms still are there, some years we get loads of them, some years not as much, depends if La Nina, or El Nino.
DeleteCliff soon will tell us, as he does every year, that in a month and a half, when we enter November, we'll be in the stormiest month of the year for the PNW. The soakers are coming. I just hope that they aren't too windy. The poor trees in our area already look battered after the wind/rainstorms of the past few years.
DeleteI love fall, and you are right, September is a transitional month in that temps will begin to drop into the 60's, then October is when the rains come in, in earnest, beginning with good soakers, but then the atmospheric/pineapple express type events ramp up by late Oct.
ReplyDeleteCliff, kind of a non-sequitur, but just curious how your tomatoes did this year? This was by far the worst year I can remember. I've heard similar things from neighbors and friends. I also see lots of green tomatoes as I walk around the neighborhood. Any theories? Wet June? Dry July? Seems like the temperature was not an issue in terms of heat. It's not unusual to still harvest a few in mid-Sept, but I didn't even get an August harvest! thanks
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