Cold Nights & A Sunny April Week Ahead

9:30pm Sunday…

I’ve been on vacation the past 9 days, a bit of bike riding down in the Moab (Utah) area with my son. Sorry, not many pictures because I was having fun. Actually I was home part of that time as well; but I’m back at work this evening. Calling it “work” is a bit of a stretch meteorologically since we are in a VERY stable weather pattern for at least the next 7 days.

THE COLD

First, the record cold this morning. We’ve seen LOTS of late season frost the past month, because we’ve seen much drier than normal weather. Keep in mind we’ve seen less than 2″ of rain in six weeks in Portland! Drier air = less cloud cover = colder nights. Basically west of the Cascades we’ve been in more of a “continental climate” than usual. Right now dewpoints are down in the 20s in the metro area. Sometimes we don’t see them get that low all April long. Our spring in Portland (so far) is similar to a typical spring you would experience east of the Cascades. Wide temperature range; nights running cooler than average, but daytime slightly warmer. Last night we saw widespread cold readings. Look at the Portland metro lows:

Lots of upper 20s, even a few mid 20s…pretty cold for mid April! Portland airport dropped to 32 degrees, the first time we’ve seen frost beyond April 10th since 1982. Quite an impressive reading considering the metro area is much larger than 40 years ago, more of an urban “heat island” now. Plus our climate has warmed a bit in general. We don’t see many record lows in Portland the last couple of decades. Record lows were also set in several other locations west of the Cascades

My peach tree is blooming and still LOOKS okay. Maybe it needed to be under 27 degrees to do significant damage, we will see within the next couple of weeks.

Tonight won’t be quite as chilly as the airmass has warmed a bit. Sure, some frost for outlying areas, but everyone should be at least 2-3 degrees warmer than last night.

AN AMAZING WEEK AHEAD

When I came in and looked at the maps/models today, it became obvious we are in for almost continuous sunshine for the next week for much of Oregon and SW Washington. That includes the coastline.

In the upper atmosphere, a ridge of high pressure (zigzag blue line) and its sinking airmass is developing just to our west and north, keeping weather systems away. But a cold pool of air (upper-level trough) is coming down the back side of that out of Canada. By Tuesday it is centered over the Idaho/Nevada/Utah area.

It’s far enough south and east of us to keep cloud cover away. But we get a relatively strong northeast flow overhead. That’s offshore flow. Even though the air starts cool, this pattern under strong April sunshine will push our temperatures above normal. By Thursday the setup is strong high pressure to the north with a low south. This can be (and will be) a very stable weather pattern. It’s called a “Rex Block”.

Then between Thursday and Saturday the warm ridge expands south and east over us as the low moves away. A warming atmosphere means high temperatures climb from just above average to MUCH above normal. We’re headed from the lower 60s tomorrow to mid-upper 70s Saturday west of the Cascades. After tonight the widespread frosts west of the Cascades should disappear as well.

Meanwhile a deep layer of offshore wind flow continues all week, although it may weaken briefly Wednesday/Thursday. Check out the WRF-GFS cross-section over Portland; Wednesday afternoon (right side) through Sunday afternoon (left side). Yellow line is around mountain pass elevation.

Offshore flow almost the entire time, plus a warming atmosphere. No cloud cover (maybe a few thin high clouds). It doesn’t get better than this anytime April through June!

At this point we don’t appear to be setting up for record high temperatures…all in the 80s mid-April and beyond. But we’ll go from a perfectly average 60, to around 70 by Wednesday/Thursday, to upper 70s Saturday and possibly Sunday. For the weather geeks, 850mb temps need to make it to at least +10 over Salem this time of year to hit 80 in Portland with perfect conditions. That COULD happen Saturday, we will see. Regardless, this 7 Day forecast is something else for mid April!

When will it end? ECMWF ensemble precipitation forecasts imply the ridge breaks down somewhat next week, so it’s safe to assume showers will appear at some point after NEXT Monday

That’s it for now, enjoy the sunshine!

Chief Meteorologist Mark Nelsen

25 Responses to Cold Nights & A Sunny April Week Ahead

  1. Roland Derksen says:

    Definetly a big change to warm dry weather here- but I’m wondering what will happen after it’s over? Sometimes it can go back to a cool showery pattern.

    • tim says:

      Nope, not this time this is the start of our long dry hot summer on the way we deserve it after a cool\wet winter at lest here in western Washington.

      • Zach says:

        The ensembles seem to be saying otherwise. Looks like we could go back to wetter starting Fri 04/23. Although I don’t want to jinx it…

        Last year we had a dry March/April/May and then June was actually pretty wet.

        • Anonymous says:

          Models have been flip-flopping on that low. It’s competing against the high level ridging. If you look at the 2m and 850 temps, you’ll see that low is basically going up against a wall of high pressure from California up to BC that weekend. There’s also two systems that keep circulating from Alaska down to California which ultimately make up that low, but it depends on where it makes landfall in Alaska and how much of the ridging still remains.

  2. W7ENK says:

    You don’t see this around here very often, at least not in April…

    https://inws.ncep.noaa.gov/a/a.php?i=56343104

    • JohnD says:

      Yeah rare for sure—such early fire danger.
      Drove up to Timberline Lodge today (32’ and windy there around 1:00 p.m.)—reminiscing—then back down 35 to Hoody. Definitely dusty throughout with the wind. Very few cars on the road. Nice that way.

    • tim says:

      Definitely a sign of what’s to come this summer.

  3. W7ENK says:

    Is that milky haze aloft dust or smoke?
    Really hoping it’s not smoke…

  4. Anonymous says:

    Any idea of when this wind will die down? The lights have already flickered once today and I’m still mentally recovering from the ice storm power outages

  5. Andy says:

    I know some of you are concerned with how dry it is already…if this continues into May…then things could be dangerous for mid and late summer. I know in the past when we started dry it turned wet in June…or some call Junuary.

    • 5OClockCharlie says:

      GFS 18z (still running though) and Euro 12z have both backed off on precipitation through at least the 23rd. If I had money on it, I would say we’re going into May relatively dry. Junuary would be a welcomed sight. I don’t mind a damp June if it means no fires (or smoke)

      • Zach says:

        That 18z run has a few good soakers there near the end…

        • tim says:

          And a strong low approaching the coast but it’s the 18z it will be gone and dry on the 00z.

        • 5OClockCharlie says:

          Tim called it. 00z is showing the low dissipating just west of the northern California coast now, no more soaker. Now it’s only a brief run in with some moisture. I would not be surprised if it all but disappears in the next few days. That said, I hope I’m wrong and we get slammed with a soaker

  6. W7ENK says:

    This wind today is something else! Having regular gusts over 30, sometimes pushing 40, increasing since about 6am. They come with quite the roar at their peak, the trees outside are absolutely screaming…

  7. 5OClockCharlie says:

    Can’t believe I’m watering the lawn this early in April.
    Euro backed off the rain in the metro area for 19-20th. GFS is promising something a bit later than that, but it too appears to be less than what it was. If we don’t get some decent rain in early May, we’re going to be in real trouble.

    Previous years we’ve been lucky in that fire season didn’t really cause state or county-wide issues until end of August by which time the September rains were brewing and brought some relief within a couple of weeks. If our fire season starts 2 months early though… could mean being blanketed in smoke for several weeks if not months. Nightmare scenario!

  8. Jason Hougak says:

    Beautiful weather but there’s always a price to pay. We need continued precipitation with mountain snow to help carry us through the dry season. It’s started way too early this year. Dust from our gravel road and being able to drive anywhere off-road without getting stuck in the mud is very unusual for April in the PNW. Another wildfire season is just around the corner and need precipitation.

  9. Joshua Lake Oswego says:

    Maybe we can be lucky enough to get our earliest red flag warning ever this week with extremely low humidity, very warm temperatures, gusty wind, and record futile precipitation. It’s going to be a loooooong fire season.

    • tim says:

      Yep, summer came early this year and there’s no sign of a wet pattern for months via climate models so get your bbq and AC ready its gonna be a long ride.

  10. lurkingsince’14 says:

    Looks amazing! ☀️ 😎

  11. Roland Derksen says:

    I’m glad to see “Rex” back in town! I’ve missed him. 🙂

  12. Terry Finley says:

    Ugh! I HATE these weather patterns more than any other! While the rest of the area enjoys amazing weather, we get the wind! I get it, we live where it’s windy, and I Don’t mind it in the winter months, but these Spring patterns that bring warm weather to everyone else while we get hammered with East wind is very frustrating! Oh well, summer isn’t far away. Can you let those of us put in your “neighborhood” know what the wind speeds are gonna be like Thursday-Saturday?! And what’s up with the weather station at the Corbett School! Not working yet again!? Sorry to rant, hope you had a nice vaca!

  13. Pat says:

    Looks perfect!

%d bloggers like this: