I think today we reached the “tipping point” with respect to our wetter and cooler than average weather…specifically the last 10 days. Those thunderstorms dropped up to 1/2″ of rain on the west slopes of the West Hills this afternoon. That along with highs just reaching within 3-5 degrees of average really set some folks off.
There has also been a lot of false or at least somewhat incorrect information flying around on TV and in emails. For one, it’s not a record cold or wet May (as of now). We are neither in the top 5 for rainfall (so far), or temperature (we won’t be). So we’ve had colder Mays and wetter Mays for sure. It will probably end up the wettest May in at least 5 years and the coldest in about 10 years. And it’s not THAT unusual to have 9 out of 10 days wet in late May, but it only happens every 4-5 years. Scan through May rainfall totals through the last 30-40 years at PDX and it seems like that’s the “return interval” for a wet May. Basically we’re paying for those warm and sunny Mays of the past. Remember last year we had almost two solid weeks of 70-90 degree highs!
For those of us that are weather-savvy, what’s probably most noticeable is the lack of “heat waves” or at least warm spells. We have only hit 76 so far this May…back in 1991 we only hit 75…the only other time we haven’t made it to at least 76. Considering the weather maps the next 7-10 days don’t look too warm, our 80 degree record COULD be in jeopardy. The latest we’ve hit our first 80 degree temperature at PDX is June 9th. I sure don’t see an 80 degree day through at least June 2nd or so. Keep in mind that although the summer of 1991 (that chilly/wet May) took forever to get started, it lasted well into the Fall. September through mid-October had day after day of 80+ weather.
I also just now noticed the two wettest Mays ever were followed by hot summers and severe fire seasons in the Pacific Northwest.
Chief Meteorologist Mark Nelsen