Weather patterns tend to get "stuck" for extended periods and we have certainly seen such persistent conditions this summer. Weather patterns can be self-reinforcing and thus stay in position for many days or weeks. And oceanic forcing, such as associated with El Nino and La Nina, can cause weather patterns to "lock".
Consider the temperature situation at SeaTac Airport from May 1 to yesterday (below). The blue bars show the observed highs and lows, brown shading shows the climatological or typical ranges, red shows the record highs and blue the record lows.
.png)
The middle of May through the end of June was associated with below average temperatures, while early July has been warmer than normal. The cool (and moist) June is a one reason why wildfire acreage in our region has been below normal so far.
Looking at the latest forecast for Seattle for the 10 days, we note that the forecasts are stuck in a very boring pattern, with temperatures remaining in the low to mid 80s. Average highs for this time of the year are roughly 77-79F.
No major heatwaves are predicted and the nights cool into the lower 60s and upper 50s, so decent sleep is possible without AC.
Why are we stuck in the lower to mid 80s? To explain, below is the average upper level pattern (at 500 hPa or around 18,000 ft) for the next week. Shading shows the difference from normal.
A ridge is evident (higher heights), but centered inland. The kind of pattern that makes western Oregon and Washington warmer than normal is not associated with heatwaves warming into the 90s, such as last week (where the ridge is centered on the coast).
We are now entering the climatologically warmest and driest period of the year. Enjoy.
Collectively (to include all folks from all perspectives of the "debate") we are rather silly. Try to make sense from data recorded over ~100 years in the face of ~4.5 billion years? Let's just BBQ and enjoy the moderate summer we have this year.
ReplyDeleteIf I remember correctly...you have mentioned that our mid-summer weather, includes the fact that we are, statistically, among the driest in the nation, during a period of 6-8 weeks. We are right there with Arizona, Nevada, etc, in that regard...just not as hot, which is great! This is the reason we have so many "snowbirds", who return for our very nice summer weather, and then head southerly/Easterly in the Fall.
ReplyDelete