Good News…Rain Is On The Way!

9pm Sunday…

What a nice early fall weekend; partly cloudy (& dry) sky plus comfortable temperatures. I drove through a couple spots of drizzle midday on the way to work, but it was not measurable. Yesterday we were a few notches above average; today a few below.

The next two days will be similar with more sunshine than cloud cover. Wednesday a weak/dying cold front moves overhead. The main result will be cloudier skies (like today) PLUS spots of morning drizzle or a shower. Thursday should be uneventful as well. So other than a shower/drizzle chance Wednesday morning, not much happens through Thursday and your life will be un-affected by any real weather. Then on Friday things change…rain arrives (yes, real rain) and we may have 4 wet days on tap.

HIGHLIGHTS

  • The endless dry days we’ve seen for 3 months (since mid-June) come to an end this coming weekend
  • Expect whatever you have outside to get soaked Friday through NEXT Monday…around 1.00″ rain in the lowlands
  • This won’t help the drought much, but at least the top layer of soil will finally moisten up
  • All Cascade wildfires will see chilly temps, high humidity, and a good soaking.
  • After next weekend, Fire Season 2021 will be on life-support over/west of the Cascades; we are going to avoid a long episode of smoke and huge fires west of the Cascades this year. A good ending considering how bad things were looking by late June (drought + driest spring + extreme heat). A lack of lightning for most of August plus a cooldown late that month was a game changer.

The reason for a cooler/wet forecast next weekend?

Our first strong upper-level trough of the season. That means a significant dip in the strengthening early fall jet stream. Cool air pushing farther south than it has the past few months, spinning up several disturbances on the boundary with the warmer air. You can see the relatively flat flow now…no hot ridge of high pressure nearby

But check out next weekend. Our typical wet/cool weather pattern in both spring and fall

How confident am I that this is a real pattern change? Just one example…ALL of the 12z ECMWF 24 hour precipitation ensemble members produce some sort of significant rain Friday-Monday. That’s unusually high confidence. If only half of them were showing this I’d be a bit more skeptical. Also notice about half of these members bring in more rain as we head toward the end of September

Ensemble forecast temps also show we are headed into cooler weather

How much rain? The operational high resolution runs of the GEM, ECMWF, & GFS produce anywhere from 0.70″ to 1.20″ during this time in the western valleys (Portland, Vancouver, Salem). In this case it’s better to use the averages from the ensembles…which are in good agreement… Somewhere around 1.00″ or so in the lowlands of NW Oregon and SW Washington. Not a drought-buster, but enough to moisten things up quite a bit

You’ll notice in the comments above I’m quite optimistic about putting this fire season partially to rest. That’s because those ensembles also push 2-3″ rainfall into the Cascades, right over those 5 fires burning from north of Detroit down to east of Grants Pass. That’s enough to eliminate most smoke from those fires. That’s why I’m feeling good about that last few weeks of this fire season. Last year just under 2 million acres burned on the Oregon and Washington landscape. About a million of that was in the one week after Labor Day (easterly windstorm leading to mega-fires). So far we’re at about 1.4 million this year. We will likely end up with less acreage burned this year, even with a hotter summer and much drier spring conditions. By the way, last year on this date we were in the middle of that incredible 8-11 day stretch (depending on location) that featured the worst air quality we had ever seen in NW Oregon and SW Washington. Here are the numbers that we will be avoiding this year

That’s it for now, I just wanted to give a heads up about the wet weather arriving later in the week. I’ll plan on another blog post midweek with an update. Chief Meteorologist Mark Nelsen

42 Responses to Good News…Rain Is On The Way!

  1. tim says:

    A November storm in September? i’ll take it, just hope it’s not the other way around come November. 2013 was like that, boring.

  2. Zach says:

    The NWS pointed out that NBM gives a 91% chance PDX sees over 1″ and 54% chance we exceed 2″. So basically a bust would be anything less than 1″ of rain by Sunday evening.

  3. Anonymous says:

    I see mentions of “the last 80+ degree day”, but the GFS has been showing 80+ at the tail end of the month since at least yesterday.
    Don’t celebrate too soon.

    • Jake says:

      Agreed and morning every1. If the jet stream goes North after this event (Northern BC)?

      Even if it stays strong we could be back into late Summer weather. Plenty of window still for 90F+ and certainly 80F+.

      My only view here is this system soaks the ground enough so our trees gasp a sigh a relief. Worst. Summer. Ever. Period.

  4. Weatherdan says:

    CPC is forecasting cooler and wetter for N,D,J,F 2021-2022. They are also forecasting September to be warmer and drier than normal. So methinks 2 or 3 wet cool days then back to warm and dry for the rest of the month. Which is only 11 days. Peace.

  5. Jake says:

    Logistical question for all of you here. What do shipping container ships do with such a storm arises in the Pacific?

    I mean it basically is so big it IS the jet stream and spans from Japan to here almost.

    What if a company wants to boat pineapples from Hawaiian farm to say Anchorage, Alaska?

  6. Opie says:

    I’ve never been so excited for rain!

  7. Ken in Wood Village says:

    Looks like this is the last day of 80+ for awhile. We should see some drizzle tonight into tomorrow. With all the clouds, we will be much cooler tomorrow. I’ll be looking forward to cooler weather 🙂

    Models are in good agreement for the upcoming storm. It looks like we will have a good chance of having over an inch of rain. With the cooler temps, there is also a good chance of thunderstorms this weekend. Since we haven’t really had any thunderstorms this summer, it will be a nice change of pace.

    Models seems to want to clear us out by Tuesday but I’ve been seeing them waver a little so I’m holding off on what will happen next week until this weekend.

    The website I normally use to look at the satellite picture is not updating so I went to NWS and found a good picture of the upcoming storm.

    https://tinyurl.com/zb3u4n8k

    If you look closely at the satellite, you can see multiple Low’s. So which one is the Low that is going to hit the PNW…LMAO!!

  8. Weatherdan says:

    83 so far today. This is the 99th day at or above 80 this Summer. Still not a record though. That was set in 2015 with 103 days. Still time to exceed it. Peace.

  9. Roland Derksen says:

    The rain is here now- not heavy , but it will likely last all day. The rain I’m more intrested in actually, is the stuff coming Friday and Saturday. Could see a substantial amount- we often get at least one soaker in September.

    • Roland Derksen says:

      Looks like we could almost get 2 inches for Friday- that’s a large amount. Kind of reminds me of the 23rd last September.

  10. Zach says:

    Wild. The low is likely going to be further north than what is typically “ideal” for OR, but this system is so wet we still get soaked in the valley.

  11. W7ENK says:

    Laying in bed this evening, trying to fall asleep… actually, I may have… but I just woke up?

    Either way, I just had an epiphany! Maybe it’s prophetic? Maybe not, but hear me out…

    We hit 116 degrees in June.

    I think we drop to (or below) 16 degrees in December, and Portland joins the club of locations with an annual temperature spread of 100 degrees.

    Savvy?

    • Andy says:

      I agree with the extreme weather going on around our planet with record snow and cold in Greenland from hurricane Larry and above average ice and snow for Antarctic this winter running above average. Remember just because we were hot and dry here… other regions had the opposite conditions especially Texas and my Sister that lives near Quito Ecuador they experienced colder weather this year…it shows the weather will do what it wants.

  12. Ken in Wood Village says:

    I’m going to make this short. Models are in good agreement with having a good moist storm coming either Thursday afternoon or Thursday night (depending which model your looking at).

    I looked at the storm East of Japan. It’s amazing how fast this storm has grown. If you like to see what it looks like, I made a shorten link to the Satellite picture.

    https://tinyurl.com/yv4kvxb3

    I see something else but I’m holding off to see how it trends in the next couple of days 🙂

    • Ken in Wood Village says:

      I just noticed something on that satellite picture. It almost looks like that storm is pulling moisture in from that TS! It’s interesting to see 🙂

    • Jake says:

      GFS now wants to more than double (close to triple) the 1in forecast with this. I think euro / gfs are having a hard time grasping the tropical storm attributes feeding this thing. Clearly a massive system. More of a wall of rain then a low pressure lol

      • Joshua Lake Oswego says:

        PDX’s rain was cut in half on the 00z GFS.

        • Jake says:

          So ready for a Fall storm either way. I think with the tropical attributes it will verify to the wetter side (around 2in is my guess into Sunday night). I could be wrong but we shall see

        • Joshua Lake Oswego says:

          Yea, we’re likely getting a soaking either way. I genuinely don’t remember what rain is like.

  13. tim says:

    Have fun pdx this is clearly a oregon storm seattle will have to pay for rain at this point.

    • tim says:

      Strange days indeed pdx gets more rain then seattle.

      • Anonymous says:

        Where are you seeing this? 12z Euro shows Seattle getting as much as Portland, if not more. 18z GFS also shows similar amounts.

        • W7ENK says:

          Tim likes to make things up to play the “whoa is me” factor.

          It’s actually quite annoying.

          And he’s not the only one here who does it. In fact, I’ll admit, when it comes to both snow and thunderstorms, I’ve been guilty of it in the past.

          They’re young. They’ll eventually learn.

        • tim says:

          Yeah you got me there w7 I shouldn’t complain were all gonna get rain some more then others so what it’s life.

      • Joshua Lake Oswego says:

        Boy do you have mud on your face after the 00z runs, Tim. Especially the Euro.

  14. W7ENK says:

    lol

    “RAIN ADVISORY”
    NATIONAL WEATHER SERVICE PORTLAND, OR
    1158 AM PDT MON SEP 13 2021

    https://inws.ncep.noaa.gov/a/a.php?i=62044657

    • Jake says:

      This may make a mess with all the oil buildup on the roads /

      freeways.

      GFS is calling for an inch even in areas like the Blue Mountains.

      Could be a soaker, that none locals will go for a slip-n-slide

      party, unknowingly lol!

  15. Paul D says:

    Mark’s mid-week update will slash those rain amounts in half and then we’ll end up getting nothing as it moves north of us.

  16. Zach says:

    Another killer 12z run from the GFS. If it hangs on for 2 more days I might actually start getting excited.

    • Zach says:

      This storm seems to be powerful enough that we don’t even need optimal low trajectory in order to get soaked in the W. valley.

    • Zach says:

      The 12z Euro is better than the 00z last night, but still a tad further north than gfs. Needs to drop a couple hundred miles south.

  17. W7ENK says:

    Thanks Mark. Bring on the RAIN!!!

  18. Anonymous says:

    Woohoo, bring on the rain and cooler temps!

  19. Joshua Lake Oswego says:

    Thanks, Mark. I hope you’re right. Not loving the slight northward and weakening trend on the 00z GFS. Still a nice soaking from Eugene to Bellingham, but becoming a bit more marginal. I can’t help but be pessimistic.

  20. JohnD says:

    Thanks Mark—as always. Something to get excited about—weather wise! And totally, of course, so needed for the environment! Just wish I didn’t have seats booked in an uncovered section for the Seahawks game in Seattle next Sunday! Raincoats work!😊

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