September 2017 PNW Discussion Thread

[Jesse]

Nope. It's -PNA/-NAO/western trough.

Funny. I was seeing 11-15 day maps showing an orange hot poker of ridging over the PNW for that range a few days ago.

[TT-SEA]

On the edge of the cloud shield here... clouds to the east and sun to the west.   

 

You can see the fire damage on the other side of the river now as the sun has come around.    Definitely spotty... not as bad as it could have been for sure.

[TT-SEA]

Funny. I was seeing 11-15 day maps showing an orange hot poker of ridging over the PNW for that range a few days ago.

 

It changed.  Could change again I suppose.   And of course its 3 days later so the 11-15 day period now is not exactly the same time frame.   

[Jesse]

It changed. Could change again I suppose. And of course its 3 days later so the 11-15 day period now is not exactly the same time frame.

We all know why you decide to talk about the 11-15 day range when you do. Sometimes you've got to reach a little farther to get your hands on that sweet sweet trollfruit.

[ShawniganLake]

Not in the 50's or something?

September snows at 500ft seem pretty unlikely. Even October 21st is really pushing the envelope.

[Deweydog]

Nice day despite the sunshine.

[stuffradio]

Accuweather knows all.

They wouldn't be called Accuweather if they were INAccurate, would they!? Inaccuweather doesn't have the same ring to it.

[Phil]

Funny. I was seeing 11-15 day maps showing an orange hot poker of ridging over the PNW for that range a few days ago.

Haha. Yeah, the ridge was always going to be an intraseasonal affair. Ensemble spread by d15 just made it look like a more stable regime than it really was/is.

 

Same could be said for the next round of troughing, too. Not much in the way of low frequency stability right now.

[wx_statman]

Yeah, simply put, westerly flow under the Eurasian trough is deflected by the Himalayan mountains (transfer of angular momentum from the atmosphere to the Earth's surface), which builds mass downstream over the NPAC/slows the NPAC jet.

 

This can also play on the tropical forcing through alterations to static stability, usually reinforcing the +Jesse index style convective state.

 

Even if the immediate response is a (temporary) western ridge, the mass imbalance will almost always lead to a discontinuous westward retrogression of the ridge offshore, and a return to western troughing.

 

It's interesting to think that without the Himalayas disrupting NHEM circulation, we might have never entered the Pleistocene ice age. We might still be in pseudo-PETM conditions, albeit probably a bit cooler due to other factors. 

[wx_statman]

What's the earliest snow for you that you can remember in your lifetime? That October 21 or whatever in 2012 is the earliest for me. I think there have been times with snow here in September, but not in my lifetime.

 

I think lower BC was close to snowfall in September 1972, with snowfall in the higher hills for sure. There was a double shot pattern with an impressive cold trough around the 22nd-23rd, followed by a shortwave riding down the BC coast in a classic Arctic outbreak pattern on the 26th. In western WA, Longmire (2,700') had a 38 degree maximum with 1.5" of snow on the 23rd; Darrington at just 550' had a high of 43 with 1.77" of rainfall that day. I bet the snowline was just above 1,000 feet in that area, which is obviously further south from you. In the second phase, Abbotsford had 0.29" of rain on the 26th, followed by a low of 29F on the 27th. SEA had an "Arctic" frontal passage on the afternoon of the 26th, with 45 degrees and north winds:

 

https://www.wunderground.com/history/airport/KSEA/1972/9/26/DailyHistory.html?req_city=&req_state=&req_statename=&reqdb.zip=&reqdb.magic=&reqdb.wmo=

[Phil]

Soooo...Mt. Agung suddenly looks ready to erupt. This is the monster 10,000ft stratovolcano that infamously erupted in 1963, killing 1100 people and sending SO^2 over 10km high.

 

If it erupts as it has in the past, this could change the weather and climate picture for years. The chilly summer of 1964 was one of the consequences of that eruption.

[Phil]

It's interesting to think that without the Himalayas disrupting NHEM circulation, we might have never entered the Pleistocene ice age. We might still be in pseudo-PETM conditions, albeit probably a bit cooler due to other factors.

Yeah, it's truly fascinating. A growing body of literature attributes the termination of the Miocene to the growth of the Himalayas deflecting planetary waves. The timing is almost too perfect tone coincidence.

 

FWIW, they're still rising quite rapidly, from a geologic perspective.

[wx_statman]

Not aware of anything in September other than hail counted as snow traces.

 

The cold spell of mid October 1881 probably produced some sleet in areas on the 14th. Portland had a 45/32 day and Olympia was 42/28 as a warm front overtook an arctic airmass. That would be the earliest frozen precip that I'm aware of in the lowlands. October 2009 was similar of course, with the eastern gorge getting overrunning snow on the 13th and sleet in the western areas.

 

October 6-8, 1949 was interesting as well. Battle Ground had a 51 degree high on the 7th, followed by 32 on the 8th. There was measurable rain on both days although the overnight hours were dry. Cedar Lake at 1,560' was 45/37 with a trace of snow on the 6th. Nice little precursor to the much more impressive airmass 10 days later. 

[wx_statman]

Yeah, it's truly fascinating. A growing body of literature attributes the termination of the Miocene to the growth of the Himalayas deflecting planetary waves. The timing is almost too perfect tone coincidence.

 

FWIW, they're still rising quite rapidly, from a geologic perspective.

 

Its very interesting indeed. I've also read before that the rise of the Himalayas over the past ~50 million years coincides too perfectly with the gradual cooling since that time.

[stuffradio]

Soooo...Mt. Agung suddenly looks ready to erupt. This is the monster 10,000ft stratovolcano that infamously erupted in 1963, killing 1100 people and sending SO^2 over 10km high.

 

If it erupts as it has in the past, this could change the weather and climate picture for years. The chilly summer of 1964 was one of the consequences of that eruption.

We'll have to keep an eye on this for sure. It would (or could) put a wrinkle in all the climate models projections, if even just a couple years. Who knows what else it could also alter, but we have more instruments now than ever to measure and track such things.

[Phil]

Its very interesting indeed. I've also read before that the rise of the Himalayas over the past ~50 million years coincides too perfectly with the gradual cooling since that time.

Interesting stuff. I've heard that there's growing evidence of an ancestral mountain range that existed there before the current period of mountain building began and further developed the Himalayas: http://www.nature.com/news/1998/030929/full/news030929-6.html

 

Maybe the question is, at what point did they grow tall enough to produce the monsoonal cell and adequately alter the wavetrain/heat pumps? As far as I know, there's no consensus on this.

[Jesse]

October 6-8, 1949 was interesting as well. Battle Ground had a 51 degree high on the 7th, followed by 32 on the 8th. There was measurable rain on both days although the overnight hours were dry. Cedar Lake at 1,560' was 45/37 with a trace of snow on the 6th. Nice little precursor to the much more impressive airmass 10 days later. 

 

I'm assuming you mean a 32 degree low?

[Phil]

I'm getting nervous about the Caribbean in October. Those waters are the warmest on planet Earth right now, and upper level conditions are going to markedly improve once the -PNA starts in early/mid October.

 

Powder keg.

[wx_statman]

I'm assuming you mean a 32 degree low?

 

It would stand to reason.

[wx_statman]

I'm getting nervous about the Caribbean in October. Those waters are the warmest on planet Earth right now, and upper level conditions are going to markedly improve once the -PNA starts in early/mid October.

 

Powder keg.

 

Mitch and Wilma come to mind. Cat 5 monsters in -ENSO Octobers.

[Jesse]

It would stand to reason.

I thought maybe you had mistyped and meant a 42 degree high the next day or something. Thanks for clarifying.

[Farmboy]

18z GFS looked promising for some cooler weather for the first week of October...

[Jesse]

18z GFS looked promising for some cooler weather for the first week of October...

Are you going to do a corn maze this year?

[Jesse]

18z ensemble just flipped really cold in the long range.

[Farmboy]

Are you going to do a corn maze this year?

Corn mazes are for idiots.

[wx_statman]

I thought maybe you had mistyped and meant a 42 degree high the next day or something. Thanks for clarifying.

 

The day I make a mistake like that, will be the day I start going senile. I'm a numbers guy. 

[Jesse]

Corn mazes are for idiots.

:'(

[Front Ranger]

Corn mazes are for idiots.

 

Strong take!

[Jesse]

The day I make a mistake like that, will be the day I start going senile. I'm a numbers guy.

If you read the post you can see how it was a little unclear. And it doesn't take senility to accidentally type the wrong number.

[Phil]

Another round of harmonic tremors are rocking Mt. Agung. It might be ready to blow.

 

https://www.google.com/amp/s/amp.smh.com.au/world/bali-volcano-australians-warned-to-check-travel-plans-as-240000-residents-evacuate-20170922-gynb00.html

[Phil]

Hopefully, if it blows, it's not a larger eruption. Would be yet another socioeconomic headache amongst many others ongoing, not to mention terrible timing with the Niña/solar minimum coming on.

[wx_statman]

If you read the post you can see how it was a little unclear. And it doesn't take senility to accidentally type the wrong number.

 

Nah, it was only unclear if you completely remove everything you know about the local climate.

[Phil]

Emeritus Professor Richard John Arculus from the Australian National University wrote that although infrequent, eruptions of Mount Agung have been among the largest of the past 100 years of global volcanic activity.

 

"Mount Agung is one of many similar volcanoes in Indonesia and the ring of fire surrounding the Pacific and eastern Indian oceans," he wrote in upi.com.

 

"But during its sporadic eruptions, Agung has been one of the most prominent injectors of volcanic ash and sulphur dioxide into the atmosphere."

 

Professor Arculus said the ability to predict eruptions had improved dramatically and it was hoped the high death toll of 1963 would not occur again.

 

The 1963 eruption was also preceded by earthquakes. Lava and small explosions of volcanic ash began in February leading to a major explosion on March 17.

 

There was an eruption of similar intensity in 1843 and several in the 16th to 18th centuries.

[Jesse]

Nah, it was only unclear if you completely remove everything you know about the local climate.

Having a bad day? It was an innocent question. I wasn't trying to poke holes in your post....it had some great info.

[Front Ranger]

Hopefully, if it blows, it's not a larger eruption. Would be yet another socioeconomic headache amongst many others ongoing, not to mention terrible timing with the Niña/solar minimum coming on.

 

One more major disaster to add to the "world is ending" hype.

[Farmboy]

18z ensemble just flipped really cold in the long range.

Exciting.  Anxiously awaiting next set of models....

[wx_statman]

Having a bad day? It was an innocent question. I wasn't trying to poke holes in your post....it had some great info.

 

Why do you have to make it personal? My day is going fine since you're wondering. 

[Jesse]

Why do you have to make it personal? My day is going fine since you're wondering.

Sort of seemed like you were. But I'm fine to move on.

 

Today was day 6 in the 60s at PDX. I wonder when that last happened this early.

[wx_statman]

Sort of seemed like you were. But I'm fine to move on.

 

Today was day 6 in the 60s at PDX. I wonder when that last happened this early.

 

That's a weird and unnecessary thing to say. 

[Jesse]

That's a weird and unnecessary thing to say. 

 

Sorry then. I really don't want any beef with you. I misunderstood the post. You were talking about other places going from highs in the low 50s to low 40s the next day and I thought maybe that's what you meant. It was an interesting event I hadn't heard about before, so I was trying to make sure I understood what you were saying.