It's been nice waking up to sunshine every one of the past five days. And we'll do it for at least another five, but now it's getting a bit...weird. It's been nice, but we don't live in Sacramento. Most of our viewers live in western Oregon and Washington.
Take a look at those temperatures the past few days. We've gone from a high of 53 Saturday to 76 today in Portland...the warmest day of the year.
VERY DRY SPRING
We've only seen .09" rain so far this month and now we've reached the midpoint of meteorological spring. March-April-May is spring in the northern hemisphere (officially defined by NOAA). Take a look at the numbers...in the past 7 weeks we've seen less than 2" rain in Portland.
Assuming it doesn't rain by Sunday (it won't), this will be the driest March 1st - April 18th on record at PDX. Those numbers go back to 1940. I checked Salem, Astoria, & Olympia. Similar extremely dry numbers.
Last year was a bit dry, our 5th driest April. Luckily last year we had a wetter May and very wet June to make up for it.
I remember the flooded sports fields back in 2017 & 2018. Each year is different, but this spring (so far) is exceptionally dry.
The NWS has a Red Flag Warning out for much of western Oregon, also quite rare for April
A strong ridge of high pressure in the upper atmosphere is centered in British Columbia with a cool low just to our southeast. It's been a chilly mid-week from Boise over to western Colorado, snow in spots
That warm ridge slides down right over us by Saturday...warmer atmosphere overhead
Then it weakens a bit by Monday, but at the same time another pocket of cool air is sliding down just to our east
The result will be offshore (easterly) flow and warming temps tomorrow & Saturday. 850 millibar temps to around +12 to +13 imply we could get as high as 84, but we're going slightly conservative with a high of 82 Saturday. That would be enough to break a record for the day
Then onshore flow arrives on the coast Saturday afternoon and tries to push a bit inland Sunday. I don't think that will drop our temperature more than a degree or two Sunday. The result is a very summerlike 3 days ahead. Then as the cool air drops in to our east Monday, that's high pressure which renews the easterly flow across the region. A cooler airmass Monday, but offshore flow returns quite strong. Looks like more sunshine for Monday and Tuesday. This all adds up to five more days of sunshine.
When does the rain return? Each operational model is different, but they all suggest a pattern change later next week. The ECMWF ensemble forecast suggests not much rain Wednesday/Thursday, but by Friday and into that last full weekend of April we could be back to a more typical wet/showery weather pattern
We can't do anything about the lack of rain, so enjoy the sunshine while we have it. And there's no reason to panic thinking that we're going to have a "terrible fire season"...remember last June we had soaking rains the first part of the month.
Chief Meteorologist Mark Nelsen