May 2017 Observations and Model Discussion for the Pacific Northwest

[Phil]

Verbatim, the 12z Euro would put your cool June call in jeopardy with a fairly warm first 1/3.

It looks like an outlier to its own ensemble mean, as well as the GFS/CMC and their corresponding ensemble means.

 

I'm not worried about a warm June in the PNW, unless a brief heatwave lasting 3-4 days is somehow enough to outweigh the slew of cool days that should dominate the month.

[Jesse]

Nice and refreshing today.

[SilverFallsAndrew]

55/51 today with 0.09" of rain.

[Phil]

Some of the 12z EPS members (maybe eight) drop 850mb temperatures to between 0C and -2C during the middle of week two over most of WA/BC. That would be pretty nuts for mid-June, looking at ESRL reananalyses for upper level temperatures back to 1946.

[Phil]

Another anecdotal quirk favoring a cool summer in the west is actually the deep troughing that's dominated the eastern US since the beginning of May. It's a classic response to IPWP subsidence and/or an EHEM forced waveguide (see 1980, 1983, 1988, 1993, 1995, etc). That relationship reverses around the summer solstice, and often acts to constructively feed back on the EAMT precursors hence reinforced the -PNA/NPAC anticyclone, especially under a background -NAO

 

Personally speaking, I can attest to this relationship. We east coast weenies always dread the combo of a mild winter followed by a cool/wet May, because it almost always leads to a blast furnace pattern in July/August, which will usually feature troughing in the western states. I can't recall this relationship ever failing under a regime of EHEM forcing/Pacific subsidence.

[weatherfan2012]

Another anecdotal quirk favoring a cool summer in the west is actually the deep troughing that's dominated the eastern US since the beginning of May. It's a classic response to IPWP subsidence and/or an EHEM forced waveguide (see 1980, 1983, 1988, 1993, 1995, etc). That relationship reverses around the summer solstice, and often acts to constructively feed back on the EAMT precursors hence reinforced the -PNA/NPAC anticyclone, especially under a background -NAO

Personally speaking, I can attest to this relationship. We east coast weenies always dread the combo of a mild winter followed by a cool/wet May, because it almost always leads to a blast furnace pattern in July/August, which will usually feature troughing in the western states. I can't recall this relationship ever failing under a regime of EHEM forcing/Pacific subsidence.

blow torch in july and August is something we hardly ever fail around here.especially as of late.

[Phil]

blow torch in july and August is something we hardly ever fail around here.especially as of late.

There's a reason I leave town every August, lol. This year I'm gone from 7/23 until sometime in late August or early September, so I'm not fretting.

[Phil]

00z GFS is quite troughy, but it could be handling the frictional torque response incorrectly after 204hrs. Overall, it just delays the progression a bit, and shortens the period of ridging by a few days.

[ShawniganLake]

00z GFS is quite troughy, but it could be handling the frictional torque response incorrectly after 204hrs. Overall, it just delays the progression a bit, and shortens the period of ridging by a few days.

Looks like a pretty seasonable first half of June on that run. Wouldn't amount to much in the way of negative departures.

[Phil]

Looks like a pretty seasonable first half of June on that run. Wouldn't amount to much in the way of negative departures.

There's some back/forth as the pattern transitions, but the dominant ridge sets up offshore in the long run, which places the antecedent trough axis along the west coast.

 

http://www.tropicaltidbits.com/analysis/models/?model=gfs&region=nhem&pkg=T850a&runtime=2017053100&fh=288&xpos=0&ypos=69

[Timmy Supercell]

Raining moderately to heavily in Klamath Falls, in late May. That is not too common. 

 

It is noisy enough outside with the window open that it woke me up.

[Phil]

Check out this reversal in the tropics:

 

http://www.tropicaltidbits.com/analysis/models/?model=gfs&region=global&pkg=chi200&runtime=2017053106&fh=18&xpos=0&ypos=339

[Jesse]

The first 7-10 days of June are looking pretty warm on most models.

[Jesse]

I haven't really run the numbers, but I'm guessing most places in OR/WA will avoid a top 10 warm May. Even in the I-5 corridor, where the greatest warm anomalies were concentrated.

[TT-SEA]

The first 7-10 days of June are looking pretty warm on most models.

 

12Z ECMWF is fairly variable.   The weekend is interesting with basically no rain shown but quite cool.    

 

No sign at day 10 of a large western trough either.    Basically an alternating pattern of ridges and troughs... which is probably quite seasonal for the first half of June.  

[Jesse]

12Z ECMWF is fairly variable. The weekend is interesting with basically no rain shown but quite cool.

 

No sign at day 10 of a large western trough either. Basically an alternating pattern of ridges and troughs... which is probably quite seasonal for the first half of June.

Probably average to slightly warmer than average at face value. Definitely doesn't look like non-stop troughing.

[TT-SEA]

Probably average to slightly warmer than average at face value. Definitely doesn't look like non-stop troughing.

 

I would not call this "pretty warm" for early June...

 

[Jesse]

I would not call this "pretty warm" for early June...

 

 

Role reversal!

 

Those temps look underdone. We will see I guess.

 

I said slightly warmer than average, for the record. We'll see what things look like on 6/10. The models will probably change dramatically again anyway.

[TT-SEA]

The first 7-10 days of June are looking pretty warm on most models.

 

You also said "pretty warm".   I disagree.   Time will tell.  

[Jesse]

You also said "pretty warm". I disagree. Time will tell.

Pretty warm compared to what has been screamed from the rooftops the last four weeks. In relation to average...near or slightly above.

[TT-SEA]

Pretty warm compared to what has been screamed from the rooftops the last four weeks. In relation to average...near or slightly above.

Ahhh... then I agree.

[BLI snowman]

Role reversal!

 

Those temps look underdone. We will see I guess.

 

I said slightly warmer than average, for the record. We'll see what things look like on 6/10. The models will probably change dramatically again anyway.

 

We'll be hard pressed to get much above 80 any time soon. 

[Jesse]

We'll be hard pressed to get much above 80 any time soon.

Sure. But the average high is still around 70.

 

I also don't see anything colder than yesterday's marine layer miracle happening over the next 10.

[stuffradio]

I haven't really run the numbers, but I'm guessing most places in OR/WA will avoid a top 10 warm May. Even in the I-5 corridor, where the greatest warm anomalies were concentrated.

It will probably be pretty average up here.

[Phil]

The first 7-10 days of June are looking pretty warm on most models.

Except for the 12z GFS, which does weird stuff over Siberia, the modeling is pretty troughy overall @ 500mb for the first half of June, and we're priming the system for even deeper troughing for the second half of the month.

 

At 2m, daytime highs are average cooler than normal on the ensemble means, while overnight lows average warmer than normal, so maybe some marine cloudiness around under W/SW flow or something?

[BLI snowman]

Sure. But the average high is still around 70.

 

I also don't see anything colder than yesterday's marine layer miracle happening over the next 10.

 

Yeah, average as it gets the next two weeks. Not much rain in the cards either, which is now a biggie for achieving any noteworthy cold anomalies.

[Phil]

Role reversal!

 

Those temps look underdone. We will see I guess.

 

I said slightly warmer than average, for the record. We'll see what things look like on 6/10. The models will probably change dramatically again anyway.

Translation: F**k that 12z GFS and its wandering ULLs!

[TT-SEA]

Here is the 12Z EPS for 2 weeks from today... which is basically the middle of June.  There are some ridgy and troughy periods before that time... but it does not show a deep western trough in this time frame.  

 

[Phil]

Here is the 12Z EPS for 2 weeks from today... which is basically the middle of June. There are some ridgy and troughy periods before that time... but it does not show a deep western trough in this time frame.

 

It makes no sense to cherrypick a single day on an ensemble mean two weeks out.

 

Here's the five-day mean for that week-two period.

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/F59C31F1-38AF-484E-86D9-D12431342C9E_zps7wapd495.png

[TT-SEA]

Nice try. Here's the five day mean for that week two period:

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/F59C31F1-38AF-484E-86D9-D12431342C9E_zps7wapd495.png

 

 

Nice try?   I am just pointing out what it looks like at the end of the run.   You are picking up one of the alternating troughs in the 5-day mean. 

 

Even the 5-day mean is just weakly troughy here.   

[TT-SEA]

Here is the mean for day 10-15.   Looks like a strong GOA trough... not a GOA ridge with a trough over the western US.  

 

[Phil]

Nice try? I am just pointing out what it looks like at the end of the run.

 

Even the 5-day mean is just weakly troughy here.

Not trying to be rude, but cherrypicking a single day on an ensemble mean two weeks in advance is like hyping an hr300 lowland snowstorm on the GFS.

[TT-SEA]

Not trying to be rude, but cherrypicking a single day on an ensemble mean two weeks in advance is like hyping an hr300 lowland snowstorm on the GFS.

Fair enough. Was expecting to see a stronger signal at that time though.

[Phil]

Here is the mean for day 10-15. Looks like a strong GOA trough... not a GOA ridge with a trough over the western US.

 

Yeah, the GOA trough looks more like the extended jet analogs than the real -PNA analogs. Interesting 850mb temperature signal too. Cold at the pole for obvious reasons, but also cool in the PNW and the SE US with that big ULL trapped there.

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/0D3CA09A-4718-45C7-8B9F-CABBAC66D065_zpsf6a8dqmq.png

[TT-SEA]

2006 has been showing up quite often on the top of the analog list lately... any merit with that for this summer?

 

I only mention it because it was another weak Nina to weak/moderate Nino transition year.

[TT-SEA]

Beautiful day... partly to mostly sunny and pleasant.   

[TT-SEA]

Definitely warmed up in the Indian Ocean over the last few weeks.   I remember a cold IO being part of the forecast for this warm season.   

 

http://www.tropicaltidbits.com/analysis/ocean/cdas-sflux_ssta_global_1.png

[James Jones]

Looks like an incredibly typical early June pattern coming up.

[ShawniganLake]

2006 has been showing up quite often on the top of the analog list lately... any merit with that for this summer?

 

I only mention it because it was another weak Nina to weak/moderate Nino transition year.

Models have been waffling on the idea of a Nino. The 2006 analog is probably an okay one though.

[TT-SEA]

Models have been waffling on the idea of a Nino. The 2006 analog is probably an okay one though.

 

For sure... the models seem to be set on neutral now.

 

http://www.bom.gov.au/climate/enso/wrap-up/archive/20170523.poama_nino34.png

 

 

This is leaning a little bit more towards Nino but not strongly...

 

http://iri.columbia.edu/our-expertise/climate/forecasts/enso/current/?enso-iri_plume