April Weather in the Pacific Northwest

[Jesse]

That’s why it’s called flatironing. It’s a skill few have.

 

Yep. That's why this is the most I'm even going to chime in.

[Front Ranger]

That’s why it’s called flatironing. It’s a skill few have.

 

This is a fallacy. I'm not the one twisting things.

 

- I never said January as a month wasn't a torch

- I never said late January had "very negative" -PNA as you tried to say I did

[Front Ranger]

Not really, the steeper climb didn't kick in until mid-February - the big pattern change to a colder/more Nina like pattern.

 

Mountain snow in January isn't necessarily indicative of a cool pattern. It isn't that hard to do even if the lowlands are well above average. January 2006 (another top tier warm January) is a good example of this as well.

 

The climb from mid January to the beginning of February was steeper and more sustained than any other period this winter/spring, except the second half of February. That is fact.

[Front Ranger]

Yep. That's why this is the most I'm even going to chime in.

 

I just pointed out two examples where you and Phil twisted what I said. Where have I been dishonest or twisted anything in this discussion?

 

Oh, that's right...this is where you copout because you have no facts to back what you say. 

[Phil]

It was a top warm January for many stations in the PNW. Second warmest on record at PDX. The first ten days of February were also a total torch.

Shhh. That part doesn’t count. We must completely erase the 1/30 - 2/11 +PNA stretch from the history books, because it doesn’t fit niña climo.

 

Oh, but the -PNA after 2/15? Totally niña climo, man. Even though niña forcing was absent..I mean, what else could it possibly be? #logic

[Phil]

This is a fallacy. I'm not the one twisting things.

 

- I never said January as a month wasn't a torch

- I never said late January had "very negative" -PNA as you tried to say I did

I’m pretty sure you changed your quote. Hopefully Fred can track edits.

 

And the PNA was dormant during the second half of January. It stayed at less than half a sigma for 13 days, which requires the EOF to not be matched. That’s actually extraordinary to see.

[Phil]

Amazing. Trying to spin an unvarying 0.4 sigma EOF departure into a signal.

 

Just when I thought I’d seen it all.

[Front Ranger]

Shhh. That part doesn’t count. We must completely erase the 1/30 - 2/11 +PNA stretch from the history books, because it doesn’t fit niña climo.

 

Oh, but the -PNA after 2/15? Totally niña climo, man. Even though niña forcing was absent..I mean, what else could it possibly be? #logic

 

It was actually 2/2 - 2/10. I know, stupid accuracy.

 

And I never said that didn't happen. Again...you're twisting my words. Why do you feel the need to do that in this discussion?

 

The -PNA period was 1/18 to 2/1. It followed a very dominant +PNA stretch from late November to mid January. The weak +PNA stretch from 2/2 - 2/10 was nothing close the previous +PNA period, and was in fact weaker and shorter-lived than the -PNA stretch from 1/18 to 2/1.

[Front Ranger]

I’m pretty sure you changed your quote. Hopefully Fred can track edits.

 

Yes, he can. And no, I didn't. The post where you quoted me even shows "negative" not "very negative".

 

Despite the baseless and hypocritical accusations you and Jesse like to throw out there, I don't do s**t like that. 

[Phil]

The original fallacy was alluding to “niña climo” as a causative mechanism for the mid-February pattern change.

 

There is absolutely nothing about La Niña (alone) that favors warm Januaries and cold Februaries in the PNW. There are other variations in boundary conditions than can modulate wavetrain seasonality uniquely based on ENSO, but these are temporary, usually lasting a few decades at most. It’s not necessarily a component of the ENSO system itself. It doesn’t have to arise from it either.

[Front Ranger]

The original fallacy was alluding to “niña climo” as a causative mechanism for the mid-February pattern change.

 

There is absolutely nothing about La Niña (alone) that favors warm Januaries and cold Februaries in the PNW. There are other variations in boundary conditions than can modulate wavetrain seasonality uniquely based on ENSO, but these are temporary, usually lasting a few decades at most. It’s not always part of ENSO itself.

 

This is yet another example of you twisting my words. I never said Nina climo was a causative mechanism. I already made that clear.

[Phil]

It was actually 2/2 - 2/10. I know, stupid accuracy.

It depends which leading empirical orthogonal function you use to define the PNA, actually.

 

I know, stupid stupid accuracy.

 

The -PNA period was 1/18 to 2/1. It followed a very dominant +PNA stretch from late November to mid January. The weak +PNA stretch from 2/2 - 2/10 was nothing close the previous +PNA period, and was in fact weaker and shorter-lived than the -PNA stretch from 1/18 to 2/1.

It wasn’t a -PNA period. Lol.

 

There was zero PNA signal whatsoever during that period..it ran an 0.395 sigma departure on the negative side. It’s almost impossible to get closer to zero.

[BLI snowman]

 

I didn't cherry pick anything, Phil. I showed the period that was actually -PNA. It was not a blowtorch for the PNW.

 

Yes, it's been colder since then.

 

 

That January 19 to February 2 stretch averaged 2-4F above normal around the region. That being a blowtorch or not comes down to semantics, but it was definitely warm and not at all cold.

[Phil]

That January 19 to February 2 stretch averaged 2-4F above normal around the region. That being a blowtorch or not comes down to semantics, bu it was definitely warm and not at all cold.

But..there was an 0.39 sigma faux -PNA and niña climo forcing was kicking in too. That can’t be possible.

 

Definitely some fake anomalies in play.

[Front Ranger]

That January 19 to February 2 stretch averaged 2-4F above normal around the region. That being a blowtorch or not comes down to semantics, but it was definitely warm and not at all cold.

 

Got a map or anything that shows this? Because according to HPRCC, most of western WA didn't even finish above +3 for all of January.

 

[Front Ranger]

It wasn’t a -PNA period. Lol.

 

There was zero PNA signal whatsoever during that period..it ran an 0.395 sigma departure on the negative side. It’s almost impossible to get closer to zero.

 

And what was the sigma departure for your vaunted early February +PNA? Because the official stats I'm looking at from the CPC show that was a weaker signal.

 

ftp://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.pna.index.b500101.current.ascii

[Phil]

This is yet another example of you twisting my words. I never said Nina climo was a causative mechanism. I already made that clear.

That’s exactly what you’re implying.

 

This is your initial quote:

 

It's possible man, but it's also hard to ignore that it fit -ENSO climo pretty neatly. Regardless of shorter term forcings going on this time, -ENSO Feb/Mar ends up cooler than normal for the PNW about 70% of the time.

 

Not that the SSW didn't play a role in the pattern forcing, but it probably wasn't the only or even primary factor in Feb/Mar being cool in the PNW with good mountain snows in WA.

How else am I supposed to interpret this?

[Front Ranger]

That’s exactly what you’re implying.

 

This is your initial quote:

 

 

Saying it fit -ENSO climo is not implying that "climo" is the cause.

 

I already addressed this, there's no reason to rehash it.

[Phil]

Saying it fit -ENSO climo is not implying that "climo" is the cause.

 

I already addressed this, there's no reason to rehash it.

Then why bring up “-ENSO climo” to argue something else (besides the SSW/U-wind reversal) caused the February pattern flip?

 

If it wasn’t the SSW, and if it wasn’t -ENSO climo, then what was it?

[Front Ranger]

Whether you look at 500mb heights, 850 temps, or 925 temps, this is clearly west-based -PNA and not a "blowtorch" pattern for the PNW. Inland areas and beyond, yes.

 

 

 

[BLI snowman]

Got a map or anything that shows this? Because according to HPRCC, most of western WA didn't even finish above +3 for all of January.

 

Jan18TDeptWRCC-NW.png

 

Here are the departures during that stretch, 1/19 to 2/2

 

BLI: +4.5

SEA: +1.7 (third runway!!!)

OLM: +3.3

PDX: +4.5

SLE: +4.7

EUG: +3.9

 

I'm not really sure what you're trying to argue here when the numbers are so clear cut. That was a very mild stretch of our winter. 

[TT-SEA]

Here are the departures during that stretch, 1/19 to 2/2

 

BLI: +4.5

SEA: +1.7

OLM: +3.3

PDX: +4.5

SLE: +4.7

EUG: +3.9

 

I'm not really sure what you're trying to argue here when the numbers are so clear cut. That was a very mild stretch of our winter. 

 

 

What is SEA always running so much colder?  

[Front Ranger]

Then why bring up “-ENSO climo” to argue something else (besides the SSW/U-wind reversal) caused the February pattern flip?

 

If it wasn’t the SSW, and if it wasn’t -ENSO climo, then what was it?

 

Why do you think -ENSO forcing tends to show up most clearly in the second half of winter? It's quite consistent, just as +ENSO forcing shows up strongest the second half of winter.

 

I've never said the SSW didn't play a role in how the February pattern developed...I think it certainly did. But we had already seen a move towards more -PNA before that - that was my point. And it's very typical of Ninas to see forcing kick in more starting around mid/late January.

 

Of course, every winter is different.

[Phil]

Whether you look at 500mb heights, 850 temps, or 925 temps, this is clearly west-based -PNA and not a "blowtorch" pattern for the PNW. Inland areas and beyond, yes.

 

compday.CM4v3Wr0NM.gif

 

compday.Mo5PhPauxR.gif

 

compday.EySd6TTEvv.gif

1) There’s no such thing as a “west-based -PNA”. There is only the PNA index, as it is calculated.

 

2) That is a neutral PNA/+EPO cell, in response to the Maritime Continent MJO wave. The fact it failed to tank the PNA, despite the Niña, is quite revealing since tropical forcing flipped niño-esque thereafter.

 

3) The second half of February had a WHEM/Phase-8 MJO wave ongoing with equatorward waves..niño forcing on the intraseasonal scale. No way to explain the -AAM transfer and -PNA other than the SSW/NAM reversal.

[bainbridgekid]

You do hear me talk about stuff every day though.

But not on the radio.

 

Liar.

[Front Ranger]

Here are the departures during that stretch, 1/19 to 2/2

 

BLI: +4.5

SEA: +1.7 (third runway!!!)

OLM: +3.3

PDX: +4.5

SLE: +4.7

EUG: +3.9

 

I'm not really sure what you're trying to argue here when the numbers are so clear cut. That was a very mild stretch of our winter. 

 

It was actually 1/18 to 2/1. 2/2 was of course a huge blowtorch day.

 

The surface numbers don't reflect it as well, but that period was cooler aloft (as the 850 and 925 temps show), which also led to increased snowfall in the mountains. As usually happens with -PNA. Which is where this convo started...someone pointed out snow pack in western WA, and Phil responded by saying the SSW saved the winter. But for the mountains, the recovery had started before then, as the Mt. Hood snotel graph shows.

[SilverFallsAndrew]

0.87” of precip today. 45/34

 

It fell as snow until about 10am, just a slushy dusting at times though as it never fell below 34.

[Front Ranger]

1) There’s no such thing as a “west-based -PNA”. There is only the PNA index, as it is calculated.

 

2) That is a neutral PNA/+EPO cell, in response to the Maritime Continent MJO wave. The fact it failed to tank the PNA, despite the Niña, is quite revealing since tropical forcing flipped niño-esque thereafter.

 

3) The second half of February had a WHEM/Phase-8 MJO wave ongoing with equatorward waves..niño forcing on the intraseasonal scale. No way to explain the -AAM transfer and -PNA other than the SSW/NAM reversal.

 

1.  But you agree there is such thing as west-based -NAO, etc? You yourself have argued on many occasions that an index is more than just a number, and not every +/- NAO is created equal.

 

2. -PNA still happened. That is fact. It wasn't strong, but it was there, according to the index.

 

3. There is never only one factor. The exact timing of the tropics to the North American pattern was out of sync plenty of times this winter, and that's not a first.

[Front Ranger]

What is SEA always running so much colder?  

 

The running warmer is mainly a warm season thing. For obvious reasons we've discussed.

[Phil]

Why do you think -ENSO forcing tends to show up most clearly in the second half of winter? It's quite consistent, just as +ENSO forcing shows up strongest the second half of winter.

Wait, what? How do you figure this?

 

There was no niña forcing in February, FWIW. The tropical forcing was actually niño-esque.

 

I've never said the SSW didn't play a role in how the February pattern developed...I think it certainly did. But we had already seen a move towards more -PNA before that - that was my point. And it's very typical of Ninas to see forcing kick in more starting around mid/late January.

Here’s the issue. This “move to -PNA” that you keep referencing was simply the reflection of the MJO wave crossing the maritime continent, not some low frequency niña cell. And it didn’t even force a real -PNA.

 

That last little factoid tells me everything I need to know.

 

It wasn’t until the SSW/NAM flip that AAM propagation out of the subtropics triggered the NPAC shift..and this was during one of the strongest phase-7/8/1 MJO waves on record. So..niña forcing? Not quite.

[BLI snowman]

It was actually 1/18 to 2/1. 2/2 was of course a huge blowtorch day.

 

The surface numbers don't reflect it as well, but that period was cooler aloft (as the 850 and 925 temps show), which also led to increased snowfall in the mountains. As usually happens with -PNA. Which is where this convo started...someone pointed out snow pack in western WA, and Phil responded by saying the SSW saved the winter. But for the mountains, the recovery had started before then, as the Mt. Hood snotel graph shows.

 

The 18th was pretty mild, too.

 

It was a more consolidated pattern than early January. Still not all that close to a good pattern for cold, as evidenced by the very mild temperatures.

[wx_statman]

Looking at some of the cold numbers from last weekend in the Midwest - apparently Stambaugh, Michigan hit -24 on Sunday (4/8). Incredible reading. Previous monthly record was -12 on 4/1/1924 and 4/5/1972. Very likely the latest in the season that a reading so cold has ever been recorded in the upper Midwest. Amasa, also in Michigan, hit -15. 

 

St. Cloud, Minnesota also pulled off an impressive late season record by hitting 3 degrees on 4/8; they had never been colder than 7 so late in the season (records back to 1894). 

 

Also - the true extremes geeks here will find this interesting - in looking up last weekend's numbers, I discovered just how anomalous the cold shot of April 20-21, 2013 was in the upper Midwest. Embarrass, Minnesota hit -14 on both April 20th & 21st that year, which are very likely the coldest readings ever observed in the Midwest so late into spring. I looked up Embarrass because they hit -10 this past Sunday. I thought, late season record? Looked 'em up, and 2013 pulled off the feat 2 weeks later into April! Babbitt, MN hit -11 on 4/20/2013, just missing the April record despite occurring 3 weeks into the month. Their monthly record, and previous latest -10 reading, is -12 on 4/3/1954. 

[Front Ranger]

I think there's a pretty clear lag when it comes to large-scale Nina forcing, Phil. It's not just a week-by-week MJO thing.

 

What would have happened with the pattern if the SSW hadn't occurred? We'll never know. 

[TT-SEA]

Quick update because I am bored and not happy about yet another rainy weekend ahead...

 

Only 1 dry day in April so far in Snoqualmie Valley... maybe 2 more in sight right now and that is looking more shaky on the 12Z ECMWF at least.    This April is on pace to be just as ridiculously wet as last April.  

 

 

 

 

 

I actually looked more closely at the average number of dry days per month and added the actual number of dry days in 2018 in parenthesis:

 

Jan - 12   (4)

Feb - 12   (6)

March - 14  (10)

April - 16  (1 so far)

May - 19  (?)

June - 21  (?)

 

 

So... just a normal number of dry days would have given us 25 additional dry days so far in 2018.   That would have been really nice.   I am not saying that all days with rain are washouts.   I am only saying that 2018 has been unusually persistently wet here compared to our normal.  

 

This all points to a dry summer and fall to me.   That is just my feeling.   I had the same feeling last spring.   

[BLI snowman]

Looking at some of the cold numbers from last weekend in the Midwest - apparently Stambaugh, Michigan hit -24 on Sunday (4/8). Incredible reading. Previous monthly record was -12 on 4/1/1924 and 4/5/1972. Very likely the latest in the season that a reading so cold has ever been recorded in the upper Midwest. Amasa, also in Michigan, hit -15. 

 

St. Cloud, Minnesota also pulled off an impressive late season record by hitting 3 degrees on 4/8; they had never been colder than 7 so late in the season (records back to 1894). 

 

Also - the true extremes geeks here will find this interesting - in looking up last weekend's numbers, I discovered just how anomalous the cold shot of April 20-21, 2013 was in the upper Midwest. Embarrass, Minnesota hit -14 on both April 20th & 21st that year, which are very likely the coldest readings ever observed in the Midwest so late into spring. I looked up Embarrass because they hit -10 this past Sunday. I thought, late season record? Looked 'em up, and 2013 pulled off the feat 2 weeks later into April! Babbitt, MN hit -11 on 4/20/2013, just missing the April record despite occurring 3 weeks into the month. Their monthly record, and previous latest -10 reading, is -12 on 4/3/1954. 

 

1924, 1972, and 2013 all had major December cold waves here.

 

I think we're set.

[Deweydog]

00z!

[Phil]

1. But you agree there is such thing as west-based -NAO, etc? You yourself have argued on many occasions that an index is more than just a number, and not every +/- NAO is created equal.

1) No, the phrase “east-based” NAO is simply an improper terminology for the Scandinavia-Eurasia index. On the other hand, the “west-based” NAO is what represents the real NAO index, as it’s calculated.

 

2. -PNA still happened. That is fact. It wasn't strong, but it was there, according to the index.

A -0.35 sigma AO value isn’t a -AO. It’s a neutral AO. You should know how to read patterns and teleconnections by now, dude. You never see a perfect zero value.

 

3. There is never only one factor. The exact timing of the tropics to the North American pattern was out of sync plenty of times this winter, and that's not a first.

Ah, you’re getting closer now. Why do you suspect the tropics and extratropics will sometimes fail to communicate with one another? And vice versa? It’s not random or coincidence.

[TT-SEA]

Looking at some of the cold numbers from last weekend in the Midwest - apparently Stambaugh, Michigan hit -24 on Sunday (4/8). Incredible reading. Previous monthly record was -12 on 4/1/1924 and 4/5/1972. Very likely the latest in the season that a reading so cold has ever been recorded in the upper Midwest. Amasa, also in Michigan, hit -15. 

 

St. Cloud, Minnesota also pulled off an impressive late season record by hitting 3 degrees on 4/8; they had never been colder than 7 so late in the season (records back to 1894). 

 

Also - the true extremes geeks here will find this interesting - in looking up last weekend's numbers, I discovered just how anomalous the cold shot of April 20-21, 2013 was in the upper Midwest. Embarrass, Minnesota hit -14 on both April 20th & 21st that year, which are very likely the coldest readings ever observed in the Midwest so late into spring. I looked up Embarrass because they hit -10 this past Sunday. I thought, late season record? Looked 'em up, and 2013 pulled off the feat 2 weeks later into April! Babbitt, MN hit -11 on 4/20/2013, just missing the April record despite occurring 3 weeks into the month. Their monthly record, and previous latest -10 reading, is -12 on 4/3/1954. 

 

 

I think they had a decent snowstorm in early May in 2013 as well.   I remember some pretty loud complaints one year in May on facebook... much like what it happening right now. 

[wx_statman]

1924, 1972, and 2013 all had major December cold waves here.

 

I think we're set.

 

Been since 2013. We're due!

[wx_statman]

I think they had a decent snowstorm in early May in 2013 as well.   I remember some pretty loud complaints one year in May on facebook... much like what it happening right now. 

 

Yeah, that was 2013. That's the storm that buried Rochester under 14+ inches. Facebook complaint-worthy for most people I would imagine, considering the calendar.