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May 2017 Observations and Model Discussion for the Pacific Northwest


stuffradio

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Really hoping Phil's cold and wet June pulls through. We need a break from this endless warmth.

I'm not worried at all about a cool June (not 100% sure about "wet", though). Think back to early February with the models' mishandling of the wavetrains ahead of an AAM downcycle, until the very last minute. Classic.

 

The AAM tendency will start dropping during the first week of June, and it will be solidly negative for awhile afterwards. This upstream removal of AAM is a nightmare for modeling over the NPAC (downstream), and this will be the case here as well.

 

At some point, over the next week, the modeling will catch onto the upstream AAM sink action and respond drastically in the NPAC with he building of an Aleutian anticyclone and downstream PNW/western US trough. It might be a single model cycle that catches it, or it might take a few days, but when they catch on it will happen fairly quickly.

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I'm not worried at all about a cool June (not 100% sure about "wet", though). Think back to early February with the models' mishandling of the wavetrains ahead of an AAM downcycle, until the very last minute. Classic.

 

The AAM tendency will start dropping during the first week of June, and it will be solidly negative for awhile afterwards. This upstream removal of AAM is a nightmare for modeling over the NPAC (downstream), and this will be the case here as well.

 

At some point, over the next week, the modeling will catch onto the upstream AAM sink action and respond drastically in the NPAC with he building of an Aleutian anticyclone and downstream PNW/western US trough. It might be a single model cycle that catches it, or it might take a few days, but when they catch on it will happen fairly quickly.

That is my general feeling as well. Glad we might sneak in a nice Memorial Day weekend at least.

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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That would be good too. I am cheering for dry... don't care as much how it gets there. That's just me.

 

You said you are hoping for a wet and cold June. As most people are... I am sure. :)

I am cheering for cool. I don't care as much how it gets there. That's just me. ;)

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I am cheering for cool. I don't care as much how it gets there. That's just me. ;)

Surprising. We have different opinions.

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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That is my general feeling as well. Glad we might sneak in a nice Memorial Day weekend at least.

Oh, yeah it will be ridgy through Memorial Day weekend. The potential modeling errors I'm talking about follow the reduction of the AAM tendency, sometime during the first week in June, maybe the next weekend after the Memorial Day holiday.

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Oh, yeah it will be ridgy through Memorial Day weekend. The potential modeling errors I'm talking about follow the reduction of the AAM tendency, sometime during the first week in June, maybe the next weekend after the Memorial Day holiday.

 

Yeah... based on our history we will be due again for a cooler and wetter period in June for sure.      Its almost never turned warm and dry in mid-May and just stayed that way.  

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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GOOD.

 

Just keep it going!    Find an example in the last 12 years where I have not capitalized both letters of "OK".   I have never typed it "Ok" in conversation in my life unless by accident.   Does not look right to me.  

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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Oh, yeah it will be ridgy through Memorial Day weekend. The potential modeling errors I'm talking about follow the reduction of the AAM tendency, sometime during the first week in June, maybe the next weekend after the Memorial Day holiday.

What are your thoughts on the IOD turning positive. Is this going to have an effect on your thoughts for summer.
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Just keep it going! Find an example in the last 12 years where I have not capitalized both letters of "OK". I have never typed it "Ok" in conversation in my life unless by accident. Does not look right to me.

It's a weird phrase. I think it might have something to do with Martin Van Buren's Presidential campaign in the 1830s, originally. No seriously.

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It's a weird phrase. I think it might have something to do with Martin Van Buren's Presidential campaign in the 1830s, originally. No seriously.

I think I read that before.

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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Some chances of convection mid-late week. Hopefully I can grab a couple storms before the end of May. I'll even accept the very low end types as long as I get some action!

Ashland, KY Weather

'23-'24 Winter

Snowfall - 5.50"
First freeze: 11/1 (32)
Minimum: 2 on 1/17

Measurable snows: 4
Max 1 day snow: 3" (1/19)

Thunders: 11
1/27, 1/28, 2/10, 2/22, 2/27, 2/28, 3/5, 3/6, 3/14, 3/15
3/26, 

-------------------------------------------------------
[Klamath Falls, OR 2010 to 2021]
https://imgur.com/SuGTijl

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Yeah... based on our history we will be due again for a cooler and wetter period in June for sure.      Its almost never turned warm and dry in mid-May and just stayed that way.  

 

2015, 2014, 2009, 2003, 1995, 1992, 1986, 1970, 1958, 1951...others I'm sure I'm forgetting. Mediterranean summer can definitely set in during May and stay until September. Has many times.

 

But obviously all of June won't be like today, no matter what.

A forum for the end of the world.

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What are your thoughts on the IOD turning positive. Is this going to have an effect on your thoughts for summer.

Yeah, it will, because it interferes destructively with the convection over the Indo/120E domain, which favors +ENSO in the long run unless it's overpowered (and the circulation over the next few weeks will try and weaken the +IOD). The recent tendency for a midsummer IOD drop is something that can't be ignored.

 

However, this year, much like in 1993/1983 et al, the +IOD signature has easily coexisted with subsidence over the western IPWP, including the dateline/WPAC, which has greatly reduced the forcing from diabatic heat release within the PNA entrance domain, so we'll have to watch for that since it has been manifesting persistently as an extreme west-based Niña forcing (or extreme east-based Niño forcing) on the extratropical wavetrains (for the most part).

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2015, 2014, 2009, 2003, 1995, 1992, 1986, 1970, 1958, 1951...others I'm sure I'm forgetting. Mediterranean summer can definitely set in during May and stay until September. Has many times.

 

Ahem... there was a mid June gloom in 2009. 

Ashland, KY Weather

'23-'24 Winter

Snowfall - 5.50"
First freeze: 11/1 (32)
Minimum: 2 on 1/17

Measurable snows: 4
Max 1 day snow: 3" (1/19)

Thunders: 11
1/27, 1/28, 2/10, 2/22, 2/27, 2/28, 3/5, 3/6, 3/14, 3/15
3/26, 

-------------------------------------------------------
[Klamath Falls, OR 2010 to 2021]
https://imgur.com/SuGTijl

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Yeah... based on our history we will be due again for a cooler and wetter period in June for sure. Its almost never turned warm and dry in mid-May and just stayed that way.

Thing is, these next few weeks are sort of an abomination in the grand scheme of things. The first anticyclone (this week) is kind of rogue in that the AAM maximum was/is timed perfectly to throw it up when the tropical forcing favors the Aleutian ridging. Them, when the Aleutian ridge builds and starts to cycle out the western ridge, the tropics move into an intraseasonal +PNA state with the relatively brief WPAC connection, so a trough/jet-max evolves over the Aleutians which rebuilds the western ridge again.

 

Then the response to the EAMT backcycle occurs in early June while the forcing is leaving the dateline/WPAC which enhances the IO/ISM wave, which will dig a trough into the NW-Pacific and throw the ridge offshore into the GOA, and eventually back towards the Aleutians.

 

So, a very complicated situation to model accurately, and possibly just as tough to analog for.

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2015, 2014, 2009, 2003, 1995, 1992, 1986, 1970, 1958, 1951...others I'm sure I'm forgetting. Mediterranean summer can definitely set in during May and stay until September. Has many times.

 

But obviously all of June won't be like today, no matter what.

Again, only two of those years are remotely close to the 2017 system state. That said, I've never really understood your methodology for selecting analogs, so I can't exactly offer judgement until I know your thought process.

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It wasn't a list of analogs. That isn't the point.

I'm referring to the years you mentioned a few days ago, many of which you just listed above. It looks like you're favoring a Niño/+PNA style summer pattern, which I think will be almost impossible to obtain until (at earliest) sometime in August . It has never happened without dateline/Pacific forcing.

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2015, 2014, 2009, 2003, 1995, 1992, 1986, 1970, 1958, 1951...others I'm sure I'm forgetting. Mediterranean summer can definitely set in during May and stay until September. Has many times.

 

But obviously all of June won't be like today, no matter what.

 

Right... my point is not about the statistical end result of June but rather that a cooler/wetter period is pretty likely.    

 

June of 2016 for example was warmer than normal but there was a 2-week stretch of cooler/wetter weather in the middle of it.   

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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It was a warm and dry month overall for the PNW, especially further north.

 

Yes it was overall. Just that some of the afternoons that are rainy/cooler are almost entirely inevitable at some point in June. Years like 2015 are the huge exception.

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Ashland, KY Weather

'23-'24 Winter

Snowfall - 5.50"
First freeze: 11/1 (32)
Minimum: 2 on 1/17

Measurable snows: 4
Max 1 day snow: 3" (1/19)

Thunders: 11
1/27, 1/28, 2/10, 2/22, 2/27, 2/28, 3/5, 3/6, 3/14, 3/15
3/26, 

-------------------------------------------------------
[Klamath Falls, OR 2010 to 2021]
https://imgur.com/SuGTijl

Link to comment
Share on other sites

Thing is, these next few weeks are sort of an abomination in the grand scheme of things. The first anticyclone (this week) is kind of rogue in that the AAM maximum was/is timed perfectly to throw it up when the tropical forcing favors the Aleutian ridging. Them, when the Aleutian ridge builds and starts to cycle out the western ridge, the tropics move into an intraseasonal +PNA state with the relatively brief WPAC connection, so a trough/jet-max evolves over the Aleutians which rebuilds the western ridge again.

 

Then the response to the EAMT backcycle occurs in early June while the forcing is leaving the dateline/WPAC which enhances the IO/ISM wave, which will dig a trough into the NW-Pacific and throw the ridge offshore into the GOA, and eventually back towards the Aleutians.

 

So, a very complicated situation to model accurately, and possibly just as tough to analog for.

 

Sounds very complicated.    

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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Right... my point is not about the statistical end result of June but rather that a cooler/wetter period is pretty likely.    

 

June of 2016 for example was warmer than normal but there was a 2-week stretch of cooler/wetter weather in the middle of it.   

 

Well yeah, of course it won't stay sunny/warm non-stop going forward. Was that your point?  :)

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Well yeah, of course it won't stay sunny/warm non-stop going forward. Was that your point?  :)

 

My point is that the models will likely start to trend troughier/cooler/wetter like Phil was predicting.   I was just agreeing with him.   

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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Sounds very complicated.

Migraine inducing. :)

 

This is the type of intraseasonal episode that you can never forecast accurately at-range, unless you get lucky for one reason or another. Just a mere 36hr timing differential between the AAM spike and MJO/ISM event would have resulted in deep PNW troughing until May 27th, +/- a few days, and May would have wound up notably cooler than average regionwide. The entire monthly average here was flipped by a perfectly positioned anticyclonic wave event that dropped a bunch of stealthy dominoes.

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I'm referring to the years you mentioned a few days ago, many of which you just listed above. It looks like you're favoring a Niño/+PNA style summer pattern, which I think will be almost impossible to obtain until (at earliest) sometime in August . It has never happened without dateline/Pacific forcing.

 

I think this is a more difficult summer to forecast than normal. My number one analog is 1991, followed by 2014. 1986 seems like a decent analog as well. I wouldn't rule out a 1983-type summer, but I think that's less likely.

 

But the list of years above had nothing to do with my analogs, just examples of years where the general warm/dry summer pattern set in during May.

A forum for the end of the world.

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2015, 2014, 2009, 2003, 1995, 1992, 1986, 1970, 1958, 1951...others I'm sure I'm forgetting. Mediterranean summer can definitely set in during May and stay until September. Has many times.

 

But obviously all of June won't be like today, no matter what.

 

Some of those had prolonged cool periods interspersed, though. July 1986 and August 1995 were both very cool (by today's standards).

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Migraine inducing. :)

 

This is the type of intraseasonal episode that you can never forecast accurately at-range, unless you get lucky for one reason or another. Just a mere 36hr timing differential between the AAM spike and MJO/ISM event would have resulted in deep PNW troughing until May 27th, +/- a few days, and May would have wound up notably cooler than average regionwide.

 

Sometimes, fickle, thread-the-needle intraseasonal events have multi-week consequences.

 

I have noticed at times in the models that little events happening upstream can have a profound effect later on.    Or maybe I am imagining it that way.   :lol:

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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From where they are now? Yes, that's a given (in the next week or two).

 

Thanks!   Sorry for agreeing with Phil.   You jumped in to challenge me by default.   ;)

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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