Last Weekend of September: Looks Great!

7pm Friday…

Today was a cool & cloudy day, but at least our rain forecast was on the wet side.  In the end it rained very little with just light sprinkles/showers at times.

plot_rain_orwa_autoplot It wasn’t exactly a “windstorm”, but we did see the strongest gust in about 6 weeks here in Portland.  We saw a gust to 27 mph.  Coastal gusts were in the 30-50 mph range…a sign of the wind season to come!

The day started with one of those fantastic Mt. Hood shadows that extends UP onto the clouds.


I love that view! It comes from the sun below the horizon shining up through mainly clear skies east of the Cascades.  That first sunlight hits the top of the mountain only, projecting a shadow up on to the increasing high cloud cover spreading in west of the Cascades.  This pic was from Clifford Paguio (you probably figured that out already).

By the way, I was a bit lax this week in posting, partly because the weather was slow early in the week but also because we’ve been busy training a new employee Marja Martinez.  She comes to us from the Telemundo station in Houston.

Looking ahead, a strong upper-level ridge develops directly over the Pacific Northwest over the next 48 hours with 500mb heights up over 590 dm.  That’s a mid-summer quality ridge!  850mb temps soar from +5 tomorrow morning to +20 by Sunday afternoon!  We get about 3 millibars of easterly flow over the Cascades and through the Gorge Sunday afternoon through Monday morning.  Definitely not strong offshore flow, but with such a warm atmosphere overhead that should push our high temperatures into the 85-90 degree range both days.  Those will not be record-setting days since we’ve been as warm as 92-95 during this period.  I checked that 2003 record (95 on the 27th) and found it was +24 at 850mb over Salem with a good easterly flow.

Beyond Monday, we go back to onshore flow quickly and temps return to a more typical 68-75 degree range for the last few days of the month.  The GEFS ensembles and ECMWF both show a cool pattern for later next week and into the early part of October.  Check out those temps dropping off a cliff in the ECMWF 850mb ensemble chart as a cool upper-level trough comes out of Alaska and down over the Pacific Northwest the first few days of October!


Then the 16 day GEFS ensemble forecast temps for the surface here in Portland:


I’m pretty sure we’re done with the 80 degree weather after Monday!

Enjoy the last weekend of September…

Chief Meteorologist Mark Nelsen


26 Responses to Last Weekend of September: Looks Great!

  1. Joshua Downtown PDX says:

    I think it’a an appropriate time to predict the next 80 degree day at PDX. I’m going with May 25th, 2017.

  2. JohnD says:

    One of those anomalous (but not unprecedented), utterly gorgeous late September days today. At one point I was thinking that it might make 90′. Looks like it will fall short though. One of those days you wish you could bottle and bring out at some point later on after the incessant 40’s, grey and drizzly rain days ensue in a few weeks.

  3. SortingHat says:

    I hope this isn’t another JUST 10 DAYS AWAY winter where the runs always make it vanish as it comes into day 8 range.

  4. Tyler Mode in Battle Ground says:

    Weather geek alert! Brookings on the southern Oregon coast hit 100 degrees today and it is still 91 there at 9 PM.

    It’s the same weather pattern that will have us so warm tomorrow (85-90)

  5. Scooter says:

    I bet we will have another 80 + degree day or two in October, we always do. I don’t quite understand all of the weather experts putting such a cold bias on the weather so early in the season. I find Octobers to be the most beautiful time of the year in the NW.

  6. Erika Araiza says:

    Enough with the 85-90 temperatures already! Summer is over, I’m tired of this heat! Im more looking for days just like Friday which has been the best day of the month so far

  7. runrain says:

    Had the unique opportunity to do a 6K run on the 9,800 foot north runway at PDX. Down and back with an F-15 at each end to mark the length. Good running weather too with the low clouds and very light wind.

  8. Josh "The Snowman" from Gladstone, OR says:

    I’m thinking at least 8-12″ of snow for downtown pdx this year. Easily due for that. Foothills will get blasted most likely i.e; above 1000′. Pattern is setting up me thinks.

  9. Paul D says:

    Thick fog in Hillsboro this morning!

  10. I measured 0.36 inches yesterday, but much of that was in the form of drizzle. It was cool yesterday afternoon with temperatures in the low 50’s. Looking forward to drier, sunnier weather, now that I have over 3 inches of precipt. for the month.

    • I’m not surprised Vancouver got that much. I was in Boston Bar over the weekend and even there it was on the damp side on Friday afternoon (though still just a few hundredths by my estimate). Was a surprise as that area is typically warmer and drier than Seattle (at least in the warmer part of the year). Apparently the bulk of that system’s energy was in Canada.

  11. Jason Hougak says:

    Looking forward to hunting season coming up next week

  12. Paul D says:

    Looking forward to Tuesday and beyond!

  13. High Desert Mat says:

    Thanks for the post Mark. Informative as always and after Monday I’m sure that fall is upon us. There’s always next summer. I have a feeling with us going into a weak La Niña and a +QBO, we could all be in for a more exciting winter than the last few, granted ’13-’14 was record breaking for parts and had two major Arctic outbreaks. Sure seems people forget that easily. Eugene at -10. Wow. Redmond hit -28. Maybe it was because pdx didn’t have the snow the south valley did but they sure got their fair share. People, it was two years ago. It’s just easily forgotten since we’ve had so many record record warm months. We shall see what’s in store this winter but I think we will begin a more regular pattern with less records broken.

    • Boydo3 N. Albany says:

      I hope you’re right Mat. Looks like the mtns might see their first dusting of snow the first week of Oct….maybe..

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