Pineapple Express Is Here! More Rain Ahead But Mainly Dry Weekend

6pm Thursday…

Now THIS is the November weather I remember growing up with west of the Cascades…day after day of rain and mild weather. Some southerly breezes, then a bit of mountain snow. Annoying if you want to get outside, but great to see the ground saturating, reservoirs refilling, and (eventually) a building snowpack in the Cascades. Especially after a brutally hot summer and record dry spring. It’s pouring in past of the metro area right now and we are under a Flood Watch for local areas of flooding through tomorrow. What’s ahead? Read on…

KEY POINTS

  • Showers continue in the metro area and south tonight, while heavy rain continues most of night in a line from Tillamook to Longview and northward.
  • Steadier rain develops later tonight in the metro area and south, continuing through Friday afternoon. The morning commute and midday will be a soaker again!
  • Rain comes to an end all areas west of the Cascades around sunset Friday
  • Saturday should be dry
  • Rain returns north of Portland Sunday, we’ll be right on the edge of that rain line in the city. Definitely dry south and east of here Sunday too.
  • Expect another 2-4″ Coast, Coast Range, and Cascades. 1.00-1.50″ metro, and 2-3″ Longview up to Olympia the next 24 hours

This is what we’ve seen so far; a big dousing central/south Willamette Valley last night, but then heavier rain shifted north of Portland most of today. Of course mountains both east and west of us have been significantly wetter

Notice Portland is one of the driest spots. That’s not unusual. In fact check out the typical yearly rainfall in the Portland/Vancouver area. Charlie Feris retired from BPA many years ago, but continues to maintain a precipitation network of observers. He’s been doing it since about the time I was born!

Precipitable Water chart shows that we are most definitely under an atmospheric river (pineapple express) right now. Let’s just call it an “AR” so I don’t have to type it out each time. Look at that slug of tropical moisture stretching 2,500+ miles from near Hawaii to Washington!

A tool we use to analyze this situation is Integrated Water Vapor Transport (IVT). Basically how much water vapor is being transported in any one location through a cross-section of the atmosphere. Chart below is 4pm today. Numbers show total mass of water vapor passing through each square meter of the AR each second. Got that? Simpler: Bigger numbers equal more moisture moving through any one spot overhead.

You may notice there isn’t much “IVT” going on east of the Cascades. Where did all that water go? It was converted into rain. That “river of water” in the atmosphere slams into the Coast Ranges, then the Cascades. Rising air cools, and moisture must condense into droplets = rain. The heaviest rains fall where high IVT encounters a mountain range perpendicular to the flow. Westerly flow squeezes maximum rain out of these ARs with our north/south oriented mountain ranges. That’s why so much more rain falls west and east of downtown Portland compared to the city itself.

Alright, so the AR is aimed at Washington right now and through much of tonight. By tomorrow morning it has weakened just a bit, but dropping south over Oregon. But don’t worry, there’s still plenty of rain to go around

Then it has fallen apart by Saturday morning, ending the rain over most of Oregon

An even more intense AR sets up Sunday, but this time it’s aimed at Vancouver and NW Washington. We will be right on the edge of that one.

How much rain is ahead? I think the 18z ECMWF shows a good approximation of what we can expect the next 24 hours. Less than 2″ for most areas south of Longview in the lowlands. Up to another 4″ in the wettest parts of the Cascades and Coast Range

We will probably end up with 2″+ in Portland out of this event, pretty good model forecasts so far…

The final part of this AR moves south over us Monday, followed by colder air; snow levels will go below the passes Monday night. But then a relatively dry and cool-ish pattern follows much of next week. The GFS model’s ensemble forecast for Salem high/low temps gives you the general idea.

There’s no sign of a stormy pattern OR low elevation cold/snow in the next 10 days. That can happen once we hit mid-November.

That’s it for now. I’ll be on TV at 8/9pm on FOX12Plus and 10/11pm on FOX12, see you there!

Chief Meteorologist Mark Nelsen

46 Responses to Pineapple Express Is Here! More Rain Ahead But Mainly Dry Weekend

  1. Anonymous says:

    Now that today’s storm is gone and the wind died down, looks like we’re in for some really boring weather for a while. I’m looking forward to the cooler nights though, it helps me sleep. Let’s hope that polar vortex starts acting up again once we hit December and maybe we’ll get lucky enough to see a nice snowstorm!

  2. Ken in Wood Village says:

    I thought our area was having issues but up North is much worse. Here is a link.

    https://www.cnn.com/2021/11/15/weather/pacific-northwest-flooding-wxn/index.html

  3. Weatherdan says:

    Received .25 so far today Now on to more typical November weather. This mild weather has been nice but I want to see some weather that feels like November. After all Christmas will be here in 40 days and a low of 60 just doesn’t feel right. Peace.

  4. Zach says:

    Incoming the valley is about to get waxed by this front.

  5. Ken in Wood Village says:

    I went outside for lunch and the winds have picked up a lot ๐ŸŒฌ๐Ÿค—

  6. Ken in Wood Village says:

    Does anyone know what kind of condition are happening along the Coast or just anywhere? I’m at work and can’t really look stuff up. I need to get the IP address for condition around the state but it’s on my laptop which is at home ๐Ÿฅบ

  7. runrain says:

    Atmospheric Wrath, Jacob BPA, the Fab Five, the FLAB Five. Good times, back in the day.

  8. Ken in Wood Village says:

    Been looking at the HRRR runs. I still see winds around 50 mph. What’s amazing is on these runs is after the front moves through, the winds change direction really fast. We will see the strong South winds the they will switch to a Northwest wind behind the front. I think this will be a drastic change in wind direction but I think temperatures will fall as well. It will feel like fall again ๐ŸŒฌ๐Ÿ

  9. Roland Derksen says:

    Steady, and at times heavy rain here today in Southern BC. it’ll be intresting to see how much my total will be at the end of the day. I don’t expect a new record for a day in November, but possibly third or second wettest.

  10. runrain says:

    Always good to see Rob back. A real pro and good guy.

    • Yes it is! It’s also nice to see you back, I think it was July when you temporarily stopped commenting? Correct me if I’m wrong.

    • Ken in Wood Village says:

      I’m with Hank, it’s nice to see you commenting again ๐Ÿค— I would like to hear your thoughts on what you see in the model runs ๐Ÿ˜‰๐Ÿค—

  11. Ken in Wood Village says:

    I was looking at the HRRR run. It’s showing some gusts in the Portland area around 55 mph. It looks like these will happen when the front comes through. It would be a very interesting day tomorrow.

    • Yeah, I also saw the HRR run, pretty windy. Tommorow might be the 4th day this fall that Salem will get a 50+ MPH gust. As long as I don’t lose branches (which i wont) and I don’t lose power, I always enjoy wind storms. I might do a blog post on it later.

  12. Not for us, but I wanted to point this out because it’s pretty rare in Montana.

    High Wind Warning from SUN 12:00 PM MST until TUE 12:00 PM MST
    Action Recommended
    Make preparations per the instructions
    Issued By
    Great Falls – MT, US, National Weather Service
    Affected Area
    Portions of central, north central, and west central Montana
    Description
    …HIGH WIND WARNING REMAINS IN EFFECT FROM NOON TODAY TO NOON MST TUESDAY…

    WHAT…Southwest winds 40 to 50 mph with gusts over 60 mph expected. Gusts over 80 mph possible along the Rocky Mountain Front

    WHERE…Portions of central, north central, and west central Montana.

    WHEN…From Noon today to Noon MST Tuesday.

    IMPACTS…Damaging winds will blow down trees and power lines. Power outages are expected. Travel will be very difficult, especially for high profile vehicles. Blowing dust may reduce visibility at times.

    ADDITIONAL DETAILS…Winds will let up slightly overnight tonight, but will restrengthen during the day on Monday.

    PRECAUTIONARY/PREPAREDNESS ACTIONS…

    People are urged to secure loose objects that could be blown around or damaged by the wind.

  13. Wind Advisory from MON 8:00 AM PST until MON 4:00 PM PST
    Action Recommended
    Execute a pre-planned activity identified in the instructions
    Issued By
    Portland – OR, US, National Weather Service
    Affected Area
    In Washington, Greater Vancouver Area. In Oregon, Greater Portland Metro Area and Central Willamette Valley
    Description
    …WIND ADVISORY IN EFFECT FROM 8 AM TO 4 PM PST MONDAY…

    WHAT…South winds 15 to 25 mph with gusts of 40 to 50 mph expected.

    WHERE…In Washington, Greater Vancouver Area. In Oregon, Greater Portland Metro Area and Central Willamette Valley.

    WHEN…From 8 AM to 4 PM PST Monday.

    IMPACTS…Gusty winds could blow around unsecured objects. Tree limbs could be blown down and a few power outages may result.

    PRECAUTIONARY/PREPAREDNESS ACTIONS…

    Use extra caution when driving, especially if operating a high profile vehicle. Secure outdoor objects.

  14. JohnD says:

    Rob Rocks!

  15. 00z ECMWF was quite good. Chilly. Cold trough. Great run. 925s stay at -3c for the Gorge for 36 hours with persistent chilly east wind. A marginal cold pool tries to set up. Chilly. Did I mention it’s chilly? Cold enough for Socks!(c)Rob 2016.

    • Ken in Wood Village says:

      It’s been a long time since I have seen you post something Rob ๐Ÿ˜ณ it’s great to hear from you. I miss seeing your input about what the models are showing ๐Ÿฅบ

      I don’t think you mentioned it being cool or cold ๐Ÿคฃ๐Ÿคฃ the Euro model wants to bring colder air down from Alaska but the GFS keeps it bottled up for much longer. When I was looking at the GFS, for some reason it didn’t make much sense (just the overall pattern seems off). The Euro model looks more realistic on how the pattern would respond to the colder air moving forward to the PNW. We should keep an eye on how all the models do the next couple of days ๐Ÿ˜‰

      Again, great to see you again. I hope we will see more comments from you in the future ๐Ÿ˜‡๐Ÿค—

      Ken

    • It’s great to see Rob again! I love how in winter this comment section is so much more active, wnd seems like that’s going to happen soon, with alot more people coming back.

      But about the cold. That cold wave in Alaska definitely is looking like it’s going to come to the lower 48, very few models show it going to Russia. Like always, the rockies might block us, But it’s definitely looking more favorable for us than most cold waves do, I’m definitely going to keep a close eye on it. Wouldn’t mind seeing some snowflakes Thanksgiving evening.

      -Hank

      • Ken in Wood Village says:

        I know what you mean about this blog being more active. Not a whole lot is happening during the summer months unless we have a outbreak of thunderstorms (which we didn’t have at all this summer season).

        I just looked at the 12Z GFS. I was very interested in the 850hPa temperatures. Getting further into the run, you can see from Russia all the way over to North of Canada (and all the way up to the Artic Circle), temperatures reaching -40C. If this happens, temperatures at ground level will be below zero (how much below zero is the question). For now, it looks to stay up North but if the pattern changes, we could see a cold snap that we normally wouldn’t see in the month of November. That’s if it verifying.

        It’s a long ways out and a lot can change between now and then so we need to watch how the models do over the next few days.

        One thing I am sure of is we will start seeing cooler air coming in starting Monday afternoon/evening so don’t get comfortable with the mid 60’s today. It will feel like fall again very soon ๐Ÿค—๐ŸŒง๐ŸŒจ

        Ken

    • Andy says:

      I hope you post more on the models in the future. I always enjoy your input…

    • MasterNate says:

      I always enjoyed hearing your analysis on models every winter Rob. I hope you decide to stick around for awhile.

  16. 00z GFS is interesting at the end.

  17. Think Cold and SNOW! C’MON!!!!

  18. Zach says:

    It appears PDX is now officially at about 4.5″ for the month. I’d be really surprised if we don’t end up above average by the end.

  19. Roland Derksen says:

    Quite a beautiful sunset here a few minutes ago- the setting sun was shining on a patch of “mackerel sky” turning it pinkish-orange. i’m cherishing the moments of sun we get because, the weekend looks very wet.

  20. ron says:

    Two day total, so far is 4.1 inches in Nehalem. Thankfully, it looks like weโ€™re seeing the end of it.

  21. Andrew says:

    iโ€™m at 1.8 inches since midnight. over 3 for last 36 hours. Anyone know when Portland area last saw those types of totals. I know thatโ€™s not like crazy unusual but i donโ€™t recall something like this in at least last couple years.

  22. Anonymous says:

    It’s not even winter yet and I am already sick of this weather, the incessant rain and clouds are soul sucking… fingers crossed this is my last winter here.

  23. W7ENK says:

    Quick in-and-out here while taking a little break
    (staying dry in my car).

    1.40″ rainfall yesterday at my place in Milwaukie.
    1.15″ overnight (by 8am this morning)
    Looks on camera like it’s still coming down at a pretty good clip!

    Will update when I get back home later this afternoon.

  24. Joshua Lake Oswego says:

    Hi, Doug. Agreed about the last week. I am talking in general. I am an extremely avid radar watcher and weather station reviewer. Like I said, it is anecdotal, but it sure seems like we get less rain than the majority of the metro area. I am confident we get more than PDX airport though. That location consistently underperforms and itโ€™s our official station.

    • Doug in LO says:

      I should have read more carefully! Overall, Iโ€™d say that your observation is correct, and I often think the same, as in Hey, where is OUR big rain??? But overall, most of this month and much in October has been more decent than not. I have never figured out why the airport, our official station, is so consistently lower than everywhere else, even communities that are close to it.
      Loving this weather! Except that I am weary of indoor bike workouts and eager to at some point roll out on some dry roads.

      Doug

      • Joshua Lake Oswego says:

        Doug, if you want visualize what I’m talking about, check out Weather Underground or Ambient Weather stations around us today. We are at around 1.25” for the day and it’s hard to find any stations lower than that except as you get quite a bite SE of here.

        I understand that areas to the NW were favored by way of the orientation and movement of the AR, but that does not explain areas directly to our SW, NE, or even E being much wetter than we are. There are tons of stations over 2” for the day that are within a couple of miles of here. This is a very common occurrence.

        • Doug in LO says:

          Thanks for the info, Joshua. JIves with my past perceptions. I recall the bygone days when The Oregonian weather page posted precip #s every day for 20 or more stations in Greater PDX and just across the river in WA; we (LO) were invariably at the bottom of the rain food chain and I never understood why this occurred so consistently.

  25. Doug in LO says:

    I canโ€™t live much more than a half mile from where you live and the rain here the past few days (actually much of the week) has been intense and heavy and nearly nonstop. Oswego Creek is now a deep roaring river replete with whitewater.

  26. Anonymous says:

    Now I know why we always got skunked over in the Rock Creek area! Interesting map on the average precipitation. Although I’ve been getting skunked in South Metro also over the years ๐Ÿค”. I didn’t know I had such a large influence over the weather ๐Ÿ˜‚

    • Joshua Lake Oswego says:

      Yea, no chance that chart is correct for the far SW metro area. We are most definitely drier than what is indicated. Just a few miles north or east makes a big difference and is much wetter. For example, the Hillsdale area and downtown Lake Oswego area are both quite a bit wetter than me in extreme SW Lake Oswego. Admittedly, my evidence is anecdotal and unsupported.

      Meanwhile, I am very much enjoying this AR event. We have had much stronger ones, but itโ€™s great to finally get in on the action. Vancouver Island, the Puget Sound, and Northern California have all had their turn already this fall.

  27. Ken in Wood Village says:

    Thanks for the update Mark. It’s always good to see how things are progressing with this AR.

    Mark emailed me back about the so called “implementation.” He said it’s coming from the same IP address so I guess there is no implementation going on ๐Ÿค” I hope people will behave like adults on this blog. We are suppose to be talking about the weather, not being children ๐Ÿ™„๐Ÿ˜’

  28. Thanks for the update Mark!

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