9pm Thursday…
Today was a cold one, at least by recent standards. Actually I think today was a long overdue cold and showery spring day! Take a look at the rain totals since midnight:
And the 24 hour totals on the eastside show we’ve seen a real nice soaking:
That’s about it for rain now as we head into another unusually warm (hot?) pattern for a few days.
Strong high pressure builds over the Pacific Northwest Saturday and Sunday, giving us our 3rd consecutive mild and dry weekend.
How warm this time around?
We’re forecasting temperatures very similar to the record-setting weather we just saw 7 days ago:
You might be wondering how we arrive at a forecast that seems to be warmer than other forecasts (as of Thursday evening)? Our reasoning (both Liana & I negotiated the numbers!):
- 850mb temps reach +17 to +18 deg C. over Salem late Sunday and early Monday; exactly what was forecast last time around (it ended up hitting +20).
- Solid sun Sunday and Monday
- Easterly flow (3-5 millibars gradient through the Gorge) all day Sunday and most of Monday too. Gradients go flat late Monday, but no onshore flow
- 9 days farther into the spring = slightly more heat from the sun and slightly easier to break overnight inversions
- Last time around PDX & East Metro high temps were kept down slightly by the very strong east wind. That gradient should not be nearly as strong this time around so I expect these locations to be more similar to the other locations that were in the 87-90 degree range last time.
There you go, that’s the plan. The possible thunderstorms on Tuesday or Wednesday are a huge question mark. It depends on the orientation of an upper-low as it swings north and knocks down the ridge early next week.
By the way, records are 79/80/80 for Sunday/Monday/Tuesday at PDX. I’m quite confident we’ll bust two of those records, but Tuesday is a huge guess depending on timing of a big marine push coming behind the warm weather. We HAVE seen 5 80+ days in one April (2004) but it has only happened once. Otherwise we’ve never seen more than 3 80+ days.
One more thing, before you attribute THIS APRIL (and this April only) to warming springtime temps, that’s definitely not the case. Yes, our summer and early fall temps have definitely been getting warmer. But until the last few years we were seeing lots of chilly April temps. Look at the 90 year chart and you’ll see we’ve seen warmer periods than cooler periods. Interesting that spring, unlike other seasons around here, has not been consistently warming eh?
Chief Meteorologist Mark Nelsen
Posted by Mark Nelsen 
