September 2024 PNW Weather Discussion

[TacomaWx]

Weather coming up looks like a snooze fest but atleast it’s pleasant and not smoky. 

[TacomaWx]

68/48 here today. Almost astrological fall! 

[CloudJunkie]

5 minutes ago, TacomaWx said:

Weather coming up looks like a snooze fest but atleast it’s pleasant and not smoky. 

If the weather is boring then at least it should make for some nice unspoiled fall foliage.

[The Blob]

[Cold Snap]

Was a pretty nice sunset.

[Port Angeles Foothiller]

Sunset alert!

[Port Angeles Foothiller]

57 minutes ago, snow_wizard said:

The ECMWF has barely been showing the storm at all though.

The EURO has been dogsh*t on tropical storms all year. I don’t know why, but it has not performed well this year.

[StormchaserChuck1]

re sunsets: end of the world lol

We started seeing beautiful sunsets in 2021-2022, a big step above post-1998. Here I made a graph

[High Desert Mat?]

1 hour ago, snow_wizard said:

Good chance with a big ridge in October.  Some fog sounds really nice this year.

That wouldn’t be good. We need a wet October. 

[Phil]

1 hour ago, StormchaserChuck1 said:

PDO looks to be under -3. Seattle and Portland hold a >0.5 correlation with the Winter PDO, making it a >3/4, or 75% chance you have below normal temps, all other things being neutral. 

The only October that looks more extreme than this current PDO was 1955. 

The correlation w/rt PDO is a result of ENSO, though. Because the PDO is a low frequency echo of ENSO-forced atmospheric circulation tendencies.

[Phil]

The extended EPS has been unwavering with the dry CONUS theme over the next 6+ weeks.

[StormchaserChuck1]

11 minutes ago, Phil said:

The correlation w/rt PDO is a result of ENSO, though. Because the PDO is a low frequency echo of ENSO-forced atmospheric circulation tendencies.

ENSO might not be as connected as you think. 

If you focus on the coldest normal equilateral region in the Pacific Ocean, which perfectly fits Strongest Nino's.. minus that signal, and you can see there is a weak PDO correlation. More west-based events have a higher PDO correlation because of the Hadley Cell/mid latitude Cell feedback at that longitude. But the "pure" Nina/Nino's, which are based on the coolest equilateral SST region, actually only have about a 0.30-0.40 PDO correlation. 

[Slushy Inch]

Hype!

[StormchaserChuck1]

^ pretty rare for them to go below average anywhere for a 3-month period. Especially since this was the warmest Dec-Aug on record for the CONUS. 

[Phishy Wx]

WARM DRY FALL

[snow_wizard]

33 minutes ago, Slushy Inch said:

Hype!

The shape of that below normal anomaly field is a big deal.  That look is more favorable for snow in WA because it suggests a good battle line between cold air and Pacific moisture tracking just south of the cold air.  Situations where the cold anoms penetrate well south are often not as favorable for snow.

[snow_wizard]

22 minutes ago, Phishy Wx said:

WARM DRY FALL

GOT IT!

Not the case here right now, but ok.

[Front Ranger]

47 minutes ago, Phil said:

The correlation w/rt PDO is a result of ENSO, though. Because the PDO is a low frequency echo of ENSO-forced atmospheric circulation tendencies.

 

37 minutes ago, StormchaserChuck1 said:

ENSO might not be as connected as you think. 

If you focus on the coldest normal equilateral region in the Pacific Ocean, which perfectly fits Strongest Nino's.. minus that signal, and you can see there is a weak PDO correlation. More west-based events have a higher PDO correlation because of the Hadley Cell/mid latitude Cell feedback at that longitude. But the "pure" Nina/Nino's, which are based on the coolest equilateral SST region, actually only have about a 0.30-0.40 PDO correlation. 

Yeah, there's obviously a relationship between ENSO and PDO, yet they also have some separate characteristics.

We are in one of the deepest -PDO periods on record, yet we're coming out of a major Nino and just entering a very weak Nina.

[Front Ranger]

2 minutes ago, snow_wizard said:

The shape of that below normal anomaly field is a big deal.  That look is more favorable for snow in WA because it suggests a good battle line between cold air and Pacific moisture tracking just south of the cold air.  Situations where the cold anoms penetrate well south are often not as favorable for snow.

TWL does NOT approve of this post.

[Snownerd3000]

7 hours ago, Sunriver Snow Zone said:

Mark my words, December 2008 redux but better followed by Jan 1950 redux but better followed by February 2019 redux but better.

 

Dec 2008 was so nice

Day After Tomorrow cometh 

[StormchaserChuck1]

6 minutes ago, Front Ranger said:

 

Yeah, there's obviously a relationship between ENSO and PDO, yet they also have some separate characteristics.

We are in one of the deepest -PDO periods on record, yet we're coming out of a major Nino and just entering a very weak Nina.

The El Nino last Winter matched the El Nino/-PDO blend over N. America just about perfectly.  I always think SSTs are secondary, but according to some sources, there are anomalies up to +15F in that PDO region! Put hot bath water in a room, and you'll raise the temperature 0.1-0.2 degrees.  It's also a matter of consistency forecasting, since we don't always know everything, and similar global factors occurring are more likely to repeat: they can be reflected in SSTA's. I also think there is a subsurface variable at play, sometimes identified as sea-level height anomalies.  

[snow_wizard]

51 minutes ago, Phil said:

The extended EPS has been unwavering with the dry CONUS theme over the next 6+ weeks.

If this verifies WA and OR will be in moderate drought soon.  Some places already are in fact.

[snow_wizard]

5 minutes ago, Front Ranger said:

 

Yeah, there's obviously a relationship between ENSO and PDO, yet they also have some separate characteristics.

We are in one of the deepest -PDO periods on record, yet we're coming out of a major Nino and just entering a very weak Nina.

Not so sure this Nina is going to be very weak.  Some datasets already show the Nina pretty well established.  MEI is pretty Ninaish too.

No doubt it is interesting the PDO was so negative during the recent Nino.

[StormchaserChuck1]

Subsurface on the TAO/Triton maps are dropping again.. approaching -4c in the central region about -150m. It was waning for a while, but now it's back at borderline Weak/Moderate Nina range.  The subsurface has been correlating with the PNA strongly since mid February. 

[snow_wizard]

7 minutes ago, Front Ranger said:

TWL does NOT approve of this post.

I really hope he scores this winter.

[Front Ranger]

6 minutes ago, snow_wizard said:

Not so sure this Nina is going to be very weak.  Some datasets already show the Nina pretty well established.  MEI is pretty Ninaish too.

No doubt it is interesting the PDO was so negative during the recent Nino.

I just meant so far it's pretty weak. At least by traditional standards. 

[snow_wizard]

Solar activity has dropped way off.  Hopefully the recent crescendo was the peak of the cycle.

[snow_wizard]

5 minutes ago, Front Ranger said:

I just meant so far it's pretty weak. At least by traditional standards. 

Tropical Tidbits has it at -1.057 now.  Probably suspect, but it has dropped a lot in just the last two weeks.  Even if their dataset is off the rate of change should be accurate.

[TT-SEA]

3 minutes ago, snow_wizard said:

Tropical Tidbits has it at -1.057 now.  Probably suspect, but it has dropped a lot in just the last two weeks.  Even if their dataset is off the rate of change should be accurate.

It is much weaker at this point than the 2022 Nina. 

 

[Front Ranger]

2 minutes ago, snow_wizard said:

Tropical Tidbits has it at -1.057 now.  Probably suspect, but it has dropped a lot in just the last two weeks.  Even if their dataset is off the rate of change should be accurate.

Ok. Well the main point of the post was not the exact strength of the current -ENSO, but rather how deep the -PDO period has been to this point compared to the corresponding ENSO.

[GHweatherChris]

2 hours ago, StormchaserChuck1 said:

PDO looks to be under -3. Seattle and Portland hold a >0.5 correlation with the Winter PDO, making it a >3/4, or 75% chance you have below normal temps, all other things being neutral. 

The only October that looks more extreme than this current PDO was 1955. 

PDO is a result not a driver.

[snow_wizard]

Looking like tomorrow night is going to have a nice nip in the air.  Probably some upper 30s in some places.

[snow_wizard]

1 minute ago, GHweatherChris said:

PDO is a result not a driver.

Prove it.

[StormchaserChuck1]

2 minutes ago, GHweatherChris said:

PDO is a result not a driver.

Heavy ENSO forcing since 1998? 

[snow_wizard]

Just now, StormchaserChuck1 said:

Heavy ENSO forcing since 1998? 

Mighty impressive!

[StormchaserChuck1]

1 minute ago, snow_wizard said:

Prove it.

The H5 pattern has certainly had more ridges there this year than would be normal otherwise, ENSO, etc, all.  I think the CPC is using PDO for their forecast. I could see that last year too. 

[StormchaserChuck1]

Just now, snow_wizard said:

Mighty impressive!

Yeah, that's 306 consecutive months to the present. Definitely a variable!

[SilverFallsAndrew]

7 hours ago, snow_wizard said:

There were some obvious screw zones even with that.

Oh yeah, I was in SIlverton then, you can see Salem across to Silverton was the only area south of PDX where the snow cover extended all the way from the Coast range to the Cascades. North of Salem, and south of Albany places east of I-5 were generally pretty screwed. Eugene at the very south end of the Willamette Valley got hit pretty hard too. Things were tough north of the Columbia too, but they did alright later on. 

[Front Ranger]

42 minutes ago, GHweatherChris said:

PDO is a result not a driver.

Can still be a predictive correlation, though.

[snow_wizard]

2 minutes ago, Front Ranger said:

Can still be a predictive correlation, though.

I think a negative PDO suggests a persistent positive height anomaly over the GOA and or NE Pacific, which of course is favorable for cold in the NW.