September 2017 PNW Discussion Thread

[Phil]

True. Although almost every one of them is a terrible ENSO match.

 

One year that is a decent ENSO match, along with other factors, and had a significant heat event around this time of year (but a bit earlier) is 1996. That fall turned out to be fairly cool.

Wrong QBO, though, so we'll have a different NPAC state this year.

[Front Ranger]

Wrong QBO, though, so we'll have a different NPAC state this year.

 

It was -QBO like this year, just a lot further along with it.

[Front Ranger]

You mean the one around 8/23-8/24? That's going back a bit. 

 

Forest Grove hit 100 on 8/25. Yeah, like I said it was a bit earlier, I was just looking for events in late August/early September that were 95+ Portland area or 90+ for OLM.

[Phil]

It was -QBO like this year, just a lot further along with it.

We were already transitioning westerly at 30mb. Remember that the shear stress is more tied into the timing of the cycle than the U-wind integral.

[Front Ranger]

We were already transitioning westerly at 30mb. Remember that the shear stress is more tied into the timing of the cycle than the U-wind integral.

 

That didn't start until October though, right?

[Phil]

That didn't start until October though, right?

Fall/winter 1996 was transitioning to westerly @ 30mb and easterly @ 50mb, while this year it's transitioning into an easterly state @ 30mb and westerly @ 50mb.

 

So, believe it or not, the shear progression is completely opppsite despite a similar overall QBO sign.

[Phil]

For reference:

 

http://www.geo.fu-berlin.de/met/ag/strat/produkte/qbo/qbo_wind_pdf.pdf

[Kayla]

12z ECMWF says the torching and dryness continues for the west with a lot of flat ridging in the extended. Could really use a region wide deep and wet trough at this point to put out some of these wildfires.

[Phil]

So, I personally think the better QBO/ENSO analogs for boreal autumn/winter include 1956/57, 1967/68, 1981/82, 1989/90, 1995/96, 2000/01, 2003/04, 2005/06, and 2007/08.

[wx_statman]

Forest Grove hit 100 on 8/25. Yeah, like I said it was a bit earlier, I was just looking for events in late August/early September that were 95+ Portland area or 90+ for OLM.

 

That was on 8/24, you're seeing the 24 hour lag in COOP reporting. PDX was down to 87 on the 25th. And the Forest Grove thermo was consistently overexposed in the 1980s-90s so it was probably more like 98. 

 

Ok, ok. I'm totally nitpicking. I get what you're saying. That was an impressive late season heat event regardless. Back to back 95+ at PDX with a low of 68. 

[Jesse]

12z ECMWF says the torching and dryness continues for the west with a lot of flat ridging in the extended. Could really use a region wide deep and wet trough at this point to put out some of these wildfires.

Euro looks lost in the long range. Still brings a weak trough through toward the end of next week. A definite improvement over the 00z.

[Deweydog]

Might rain Wednesday evening with flashing lights and sounds in the sky!

[Kayla]

Euro looks lost in the long range. Still brings a weak trough through toward the end of next week.

 

Yeah, maybe the tropics causing the confusion? No landfall at all for Irma on this run. Really can't imagine how we don't see a major pattern shift post the 15th at this point but I suppose stranger things have happened. 

[Jesse]

Might rain Wednesday evening with flashing lights and sounds in the sky!

 

Definitely looks like a chance of a convective soaking coming up, in spots . Although new fire starts from lightning have the potential to outbalance the benefit of any rainfall unless it ends up being abundant and widespread.

[Jesse]

EPS looking cooler overall from day 4 onward, compared to the operational 12z Euro.

[wx_statman]

Sky looks almost blue. Just a very thin layer of smoke/haze up above. 

[Dave]

Air quality in Eugene is currently "Hazardous".  Truly disgusting out.

 

http://www.lrapa.org/

 

http://i.imgur.com/4H0kwbe.jpg

[wx_statman]

EUG is sitting at 93 despite 0.5-0.75 mile visibility in smoke. Considering PDX is at 90 despite what's essentially clear skies, the EUG temperature is right where I would expect it given clear skies as well. 

 

Maybe smoke doesn't impact temps as much as I thought in the Willamette Valley? I've definitely seen smoke impact temps at MFR this summer. However, they're in a narrow valley where the smoke is more likely to form an inversion. 

 

I'm wondering why both Mark Nelsen and Cliff Mass made a big deal about smoke holding down temps during last month's heat wave. I'm pretty sure Cliff Mass said that smoke held back Puget Sound temps by something like 3 to 6 degrees. Doesn't add up. There must be other factors in play that accentuate or mitigate the impact of smoke on maximum temps, depending on the conditions that day as well as local topography. 

[wx_statman]

Ironically, although my Tujunga house is right on top of a big fire (the "La Tuna" fire), the smoke is much less thick here than in Eugene.

 

I'm defying a mandatory evacuation order which I believe is mostly precautionary due to forecast thunderstorms which could cause erratic winds to fan the flames in new directions.  I'm watching the sky and the radar -- if I see flames outside or a big red blob coming my way on radar, I'm outta here.

 

Stay safe down there!

[Deweydog]

Gonna be a close shave for a 95 at PeedeeX.

[Front Ranger]

EUG is sitting at 93 despite 0.5-0.75 mile visibility in smoke. Considering PDX is at 90 despite what's essentially clear skies, the EUG temperature is right where I would expect it given clear skies as well. 

 

Maybe smoke doesn't impact temps as much as I thought in the Willamette Valley? I've definitely seen smoke impact temps at MFR this summer. However, they're in a narrow valley where the smoke is more likely to form an inversion. 

 

I'm wondering why both Mark Nelsen and Cliff Mass made a big deal about smoke holding down temps during last month's heat wave. I'm pretty sure Cliff Mass said that smoke held back Puget Sound temps by something like 3 to 6 degrees. Doesn't add up. There must be other factors in play that accentuate or mitigate the impact of smoke on maximum temps, depending on the conditions that day as well as local topography. 

 

I think it really just depends on the amount of sunlight being blocked, no different than clouds or anything else. A microscale inversion could certainly enhance that, but I don't think that explains the widespread lower high temps that we've seen with really smoky days this summer compared to what would be expected with those air masses.

 

BLI especially, and other places in the Puget Sound region and Fraser Valley clearly had temps heavily affected by smoke last month.

 

Examples...

 

- BLI with a high of 68 on 8/5

- SEA with 82 on both 8/5 and 8/6

- OLM with 91 on 8/4

 

All of those highs are at least 4-5 degrees cooler than what one would have expected from that air mass. And they're very different micro-climates. BLI on 8/5 was probably at least 10 degrees cooler than they should have been.

 

And I'm not sure what's going on today, but EUG's high of just 91 yesterday (with smoke) seemed awfully low for the 850s. They did start three degrees warmer today.

[Phil]

Just posted my rough ideas for winter in the 17/18 thread. The progression in the tropics is now following some of the more modern -QBO/-ENSO/+AMO years, which is predominantly your typical zonal-ish, cold west/warm east pattern under +EPO.

 

The +IOD/+SIOD and warm tropical Atlantic does favor a classic wave-1 (MJO-like) signature in the tropics, which is good because the -QBO also favors a more active MJO given a cooler/raised tropical tropopause/more unstable tropical domain overall. So in my opinion, the -QBO analogs are definitely the way to go this winter.

 

One possible wrench this year, however, is that the NPAC/NAM progression will be less constrained by ENSO. We now have a healthier BDC/increased poleward O^3 flux when compared with similar years a decade ago, thanks to a combination of the long term recovery from anthropogenic CFC effects, and a weaker solar maximum compared to cycle 23

 

So there's a chance we completely blow up the PV/NAM around the Holidays (or whenever the winter waveguide conduits mature and the tropical forcing allows), and take a different path than 2007/08 et al during the second half of winter.

 

Going to be an interstate one either way, in my opinion.

[Jesse]

Gonna be a close shave for a 95 at PeedeeX.

High of 94 as of 4:53pm. But lately they always seem to tack on a degree or two after 5pm.

[BLI snowman]

EUG is sitting at 93 despite 0.5-0.75 mile visibility in smoke. Considering PDX is at 90 despite what's essentially clear skies, the EUG temperature is right where I would expect it given clear skies as well.

 

Maybe smoke doesn't impact temps as much as I thought in the Willamette Valley? I've definitely seen smoke impact temps at MFR this summer. However, they're in a narrow valley where the smoke is more likely to form an inversion.

 

I'm wondering why both Mark Nelsen and Cliff Mass made a big deal about smoke holding down temps during last month's heat wave. I'm pretty sure Cliff Mass said that smoke held back Puget Sound temps by something like 3 to 6 degrees. Doesn't add up. There must be other factors in play that accentuate or mitigate the impact of smoke on maximum temps, depending on the conditions that day as well as local topography.

Yesterday seemed to underachieve down there though.

[wx_statman]

I think it really just depends on the amount of sunlight being blocked, no different than clouds or anything else. A microscale inversion could certainly enhance that, but I don't think that explains the widespread lower high temps that we've seen with really smoky days this summer compared to what would be expected with those air masses.

 

BLI especially, and other places in the Puget Sound region and Fraser Valley clearly had temps heavily affected by smoke last month.

 

Examples...

 

- BLI with a high of 68 on 8/5

- SEA with 82 on both 8/5 and 8/6

- OLM with 91 on 8/4

 

All of those highs are at least 4-5 degrees cooler than what one would have expected from that air mass. And they're very different micro-climates. BLI on 8/5 was probably at least 10 degrees cooler than they should have been.

 

And I'm not sure what's going on today, but EUG's high of just 91 yesterday (with smoke) seemed awfully low for the 850s. They did start three degrees warmer today.

I wish I knew more about the physics of smoke particles and their interaction with incoming and outgoing radiation. Because right now I can't make heads or tails of it.

[wx_statman]

Yesterday seemed to underachieve down there though.

It certainly did.

[weatherfan2012]

Just posted my rough ideas for winter in the 17/18 thread. The progression in the tropics is now following some of the more modern -QBO/-ENSO/+AMO years, which is predominantly your typical zonal-ish, cold west/warm east pattern under +EPO.

The +IOD/+SIOD and warm tropical Atlantic does favor a classic wave-1 (MJO-like) signature in the tropics, which is good because the -QBO also favors a more active MJO given a cooler/raised tropical tropopause/more unstable tropical domain overall. So in my opinion, the -QBO analogs are definitely the way to go this winter.

One possible wrench this year, however, is that the NPAC/NAM progression will be less constrained by ENSO. We now have a healthier BDC/increased poleward O^3 flux when compared with similar years a decade ago, thanks to a combination of the long term recovery from anthropogenic CFC effects, and a weaker solar maximum compared to cycle 23

So there's a chance we completely blow up the PV/NAM around the Holidays (or whenever the winter waveguide conduits mature and the tropical forcing allows), and take a different path than 2007/08 et al during the second half of winter.

Going to be an interstate one either way, in my opinion.

also will be interesting to see how the next two solar cycles behave as well and if cycles 25 and 26 end up as being very deep low cycles this will determined reather we will be going towards cooling that potentially could be quite deep global wise or if it's something more aken to the 60s 70s certainly questions that have to be watched over the next few decades should be a very interesting time in this modern age of record keeping.

[Deweydog]

High of 94 as of 4:53pm. But lately they always seem to tack on a degree or two after 5pm.

Looks like they maded it.

[wx_statman]

Well, apparently PDX hit 98 earlier. Daily climate report shows a maximum of 98 occurred at 4:09 pm - weird that it didn't show up on the 4:53 ASOS update.

 

Regardless...98 degrees on a NW wind in September. Epic.

It finally clicked as to what's going on. The daily climate report shows standard times. So the maximum yesterday was at 5:09 and not 4:09, today at 5:17 and not 4:17. Keeping me on my toes...

 

Ppl feel free to correct me when I make posts where I clearly don't know what I'm talking about.

[wx_statman]

Looks like they maded it.

Surprised me, although we did start at 26C this morning.

[Jesse]

It finally clicked as to what's going on. The daily climate report shows standard times. So the maximum yesterday was at 5:09 and not 4:09, today at 5:17 and not 4:17. Keeping me on my toes...

 

Ppl feel free to correct me when I make posts where I clearly don't know what I'm talking about.

That's thrown me off before too. I was going to mention something when I saw your post yesterday, but we were on the road and I forgot.

[Jesse]

Surprised me, although we did start at 26C this morning.

Consecutive 95+ record for September should be in the bag then.

[wx_statman]

Consecutive 95+ record for September should be in the bag then.

Yeah, should double it.

[Kayla]

Yeah, should double it.

 

Looks to also be an outside chance at three consecutive record breaking days... Any idea when that last happened??

[James Jones]

Monthly record warm minimum possible tonight?

[Kayla]

FWIW, 00Z GFS is going with 104 tomorrow and 104 on Tuesday at PDX.

[wx_statman]

Looks to also be an outside chance at three consecutive record breaking days... Any idea when that last happened??

 

Tuesday will be a tough nut to crack, although the 0Z GFS keeps insisting on 27.3C and offshore flow.

 

At any rate, we've been on a tear lately. We had three separate stretches last year alone:

 

April 17-19 (81-87-89)

August 18-20 (99-100-100)

November 8-10 (68-66-68)

 

We almost did again from August 1-3 this year. The 97 on 8/1 came up a degree short. 

[Front Ranger]

Monthly record warm minimum possible tonight?

 

It's funny, none of the most comparable heat waves to this event (1944, 1987, 1988) had record warm mins.

 

NWS is going with lows of 66, 68, and 66 for the next three nights, which would all beat the monthly record of 64. Seems very doable for PDX, significantly less likely for less UHI-influenced places like EUG and OLM.

[Jesse]

Looks to also be an outside chance at three consecutive record breaking days... Any idea when that last happened??

Probably relatively recently. It's not like we've been starved for record warmth lately or anything.

[Kayla]

Tuesday will be a tough nut to crack, although the 0Z GFS keeps insisting on 27.3C and offshore flow.

 

At any rate, we've been on a tear lately. We had three separate stretches last year alone:

 

April 17-19 (81-87-89)

August 18-20 (99-100-100)

November 8-10 (68-66-68)

 

We almost did again from August 1-3 this year. The 97 on 8/1 came up a degree short. 

 

Wow, I knew PDX has been on a tear lately but didn't know it was that bad!

 

Looks like it would be a first for September in any year though if I'm not mistaken.