What a weekend it has been! Both days in the 80s west of the Cascades, no rain, sunny from sunrise to sunset, and not much wind either. Must be mid-July right? No, just mid-April.
Portland ended up with these numbers the past three days…
A marine push of cooler air arrived on the central coast yesterday, but didn’t make it the Astoria and Long Beach until early today. So a few spots hit 80 yesterday up north, but ALL areas were much cooler today. Newport couldn’t even make it to 50. Keep in mind that in these situations proximity to the ocean determines how warm a location gets. Newport’s observations are taken at the airport, very close to the beaches. Yet Tillamook airport is quite a few miles inland = warmer when the marine layer is very shallow. Just a few miles inland at Toledo it was around 70 degrees today.
Typically I’d expect lots of that marine air to pour inland tonight. Then, since it’s so early in the season, we’d wake up to low clouds and afternoon highs only reaching to 65 or so tomorrow. But while we do have some marine air pushing inland this evening, a fresh round of “cool” and dry Canadian air is surging south through Eastern Washington. This is due to an upper-level disturbance moving down the back side of the warm ridge we are under. There was a gusty WEST wind in the Gorge today with the onshore flow, but by tomorrow morning models tell us we’ll be back to 3-5 millibars EASTERLY gradient. Expect gusts 30-50 mph at Vista House the first half of the day…quite a change. Spokane’s airport just reported blowing dust and a squall this hour as the late season “arctic front” passes by. Strong northeast wind is spreading south quickly this evening. So we’re back to a mild easterly wind tomorrow = no marine push and/or low clouds. Of course we’ll still be a bit cooler, but 10-12 degrees above normal instead of 20-22 above. To summarize, we have three more beautiful days, just some high clouds at times. That will give us 11 totally dry and mainly/all sunny days. Extremely rare in April! Check out that slow temperature rise since the cool/showery 53 degree day on Saturday the 10th
It’s back to onshore flow and a cooler atmosphere Thursday through next weekend…back to normal. We’re going for this right now. Typical late April weather for next weekend.
Of course, we badly need rain, it’s now officially the driest spring (at this point) we’ve seen in Portland since at least 1940. The ground is chalky dry in my garden; although I see the woods still have moisture an inch or so below.
How much rain is ahead? Enough to wet things down for sure, but we could use a nice 2-3″ over the next two weeks to start soaking the ground again. ECMWF ensembles say most likely it begins Saturday and continues off/on through the end of the month. So wrap up your deck-staining and other outdoor activities this Thursday/Friday and assume we’re headed into a wet period.
So is this very dry spring unusual? Yes, of course. But this isn’t a trend we’ve been seeing in springtime. In fact we’ve been turning just slightly WETTER west of the Cascades in springtime compared to 100 years ago. I just checked the entire NCDC Oregon Climate Zone #2 (western valleys) for March-April-May precipitation. This average ALL climate stations in the lower elevations westside. The last three years have been a bit on the dry side, but not excessively so. One thing to keep in mind, we still have 6 weeks of “spring” left and a May soaker could make up for this very dry start.
What about temperatures? Here are spring temperatures for this same western lowlands climate zone. What really sticks out is the cyclical stuff; we go through several years of cool/wet springs (2008-2012), then warmer periods. The last 8-9 springs have been above average…we haven’t seen a “cold spring” since 2012. That’s good for gardening, but as we know, it can be bad for summer fire season. Also notice temperatures have NOT been rising dramatically at all during this spring period. Winters are warming, summers are warming, but not much with spring…so far.
That’s it for now. Enjoy a few more bright days with more comfortable temps than we’ve see the past two days. Eventually the cool showers WILL return.
Chief Meteorologist Mark Nelsen