April Weather in the Pacific Northwest

[SilverFallsAndrew]

Hart mtn refuge is a bit higher up than your realize Tmmy Supercell. About 5500’

[Jesse]

[Jesse]

Just got a look at the 12z Euro. So nice to see general troughing stick over the NW the whole ten days of a run.

[Deweydog]

I’m sure you’d enjoy that.

It's like beating and withholding food from your children. It hurts me more than it hurts you.

[Phil]

Just so it’s clear, the SSW began on February 4th, and the SPV was demolished by February 14th. The recovery cycle began around March 2nd (though obviously it never fully recovered).

 

The Barotropic —> Baroclinic transition of the SPV occurred even earlier, starting around January 25th as the MJO entered the WPAC. By the time the SSW/U-wind reversal was in full swing (February 8th), the MJO was being amplified in Phase-8 by the BDC response/equatorward wavetrains. The TPV lost its connection to the stratosphere, and it was hence unchained, free drift off the pole and rot in southern Canada.

 

This process is what produced the large downwelling OKW which is working to terminate the La Niña, and it’s why many are calling for an El Niño.

[Jesse]

It's like beating and withholding food from your children. It hurts me more than it hurts you.

Maybe start giving them that extra Saturday Chik-Fil-A order rather than letting it deteriorate in the fridge.

[Deweydog]

Maybe start giving them that extra Saturday Chik-Fil-A order rather than letting it deteriorate in the fridge.

It doesn't need refrigeration, unlike Jimmy Carter (aka Hitler).

[Jesse]

Some good news. Snow depth and SWE are at a new high for the season at the Mount Hood snotel site today.

 

47.7” of SWE and a 126” depth.

[Phil]

Just so it’s clear, the SSW began on February 4th, and the SPV was demolished by February 14th. The recovery cycle began around March 2nd (though obviously it never fully recovered).

 

The Barotropic —> Baroclinic transition of the SPV occurred even earlier, starting around January 25th as the MJO entered the WPAC. By the time the SSW/U-wind reversal was in full swing (February 8th), the MJO was being amplified in Phase-8 by the BDC response/equatorward wavetrains. The TPV lost its connection to the stratosphere/SPV, and it was hence unchained, free drift off the pole and rot in southern Canada.

 

This process is what produced the large downwelling OKW which is working to terminate the La Niña, and it’s why many are calling for an El Niño.

The bolded is when you guys were able to cash in, as the upper sigma NAM reversal/AAM propagation produced the Aleutian High/-PNA response while the TPV (and all its frigid, O^3-depleted air) was nearby.

[Front Ranger]

Imagine the kind of explosive thunderstorms in that weather!

 

I admire the fact that you live up to your name, unlike many posters here. For instance, you rarely hear Deweydog talk about dew or dogs. Mossman almost never discusses moss. I don't think I've heard Black Hole once bring up black holes.

[Frontal Snowsquall]

I admire the fact that you live up to your name, unlike many posters here. For instance, you rarely hear Deweydog talk about dew or dogs. Mossman almost never discusses moss. I don't think I've heard Black Hole once bring up black holes.

I was always curious, when you went by Flatiron was it because you loved flat iron steaks?

[Front Ranger]

Huh? The SSW occurred when the PNA was increasing and the MJO was moving into phase-8.

 

And there is no single cause for the recent February tendencies, just as there is no single cause for the January tendencies. Each winter is unique..you donhave seasonal factors that can modestly (and temporarily!) tilt the odds in particular directions given particular low frequency boundary conditions, but largely what you have here is pure coincidence/resonant overlap.

 

The PNA index was negative from mid January into early February, after a lengthy period dominated by +PNA (late November through mid January). Though it never really turned cold until later in February, the typical -ENSO shift towards -PNA and increased troughing in the West began in late January.

 

[MossMan]

[stuffradio]

I admire the fact that you live up to your name, unlike many posters here. For instance, you rarely hear Deweydog talk about dew or dogs. Mossman almost never discusses moss. I don't think I've heard Black Hole once bring up black holes.

You do hear me talk about stuff every day though.

[Front Ranger]

I was always curious, when you went by Flatiron was it because you loved flat iron steaks?

 

Nope.    The rock formations just west of Boulder are called the Flatirons. That's what you see in my profile pic.

[Front Ranger]

I changed to MossMan when Tim talked a lot about moss being all over west of the cascades and most people not taking enough pride in their properties to remove it from their roofs, etc. I agreed with him and suddenly both of us got hammered by other forum members and there was a big to do about it.

 

Yeah, wasn't that circa 2008 or so? I don't remember what your name was before...I joined mid 2007.

[Deweydog]

Yeah, wasn't that circa 2008 or so? I don't remember what your name was before...I joined mid 2007.

I think it was Flatiron.

[Front Ranger]

Some good news. Snow depth and SWE are at a new high for the season at the Mount Hood snotel site today.

 

47.7” of SWE and a 126” depth.

 

When does Mt. Hood peak on average? My somewhat uneducated guess would be late March.

[SilverFallsAndrew]

Yeah, wasn't that circa 2008 or so? I don't remember what your name was before...I joined mid 2007.

 

I remember that, I seem to recall him mentioning it more recently too, but not since 2011-12ish...

 

The hot summers have probably been killing the moss on most roofs. 

[Jesse]

When does Mt. Hood peak on average? My somewhat uneducated guess would be late March.

Last week of April/very early May.

[SilverFallsAndrew]

When does Mt. Hood peak on average? My somewhat uneducated guess would be late March.

 

I have always heard April 1, but that may be approximate. 

[Deweydog]

When does Mt. Hood peak on average? My somewhat uneducated guess would be late March.

Labor Day Weekend.

[Frontal Snowsquall]

Nope. The rock formations just west of Boulder are called the Flatirons. That's what you see in my profile pic.

Oh okay. Makes sense, I didn't know those rock formations are called that.

[Phil]

I’m tired of educating you on this, man.

 

The PNA index was negative from mid January into early February, after a lengthy period dominated by +PNA (late November through mid January).

The PNA was not “very negative” from mid-January into early February. It was neutral (~ -0.45 sigma) for a few weeks in January despite the phase 5/6 MJO and Niña background state.

 

And the PNW blowtorched at the time, under the influence of a strong baratropic PV/+NAM and +PNA returning in early February.

 

 

Here is the week leading up to the SSW from Jan 29th to Feb 5th. This is clearly a modest +PNA, along with a +NAM going baroclinic alomg with a developing western ridge.

 

 

 

Though it never really turned cold until later in February, the typical -ENSO shift towards -PNA and increased troughing in the West began in late January.

You’re missing the trees through the forest, dude.

 

- Before the MJO reached the WHEM/phase-8, it propagated through the Indo-Pacific/phase-6 during mid/late January, which still failed to tank the PNA and bring Arctic air into the PNW.

 

- After the SSW, despite Niño forcing/phase-8 MJO, the system state flipped, AAM transport and all. The Niña cell wasn’t operating efficiently at this time..the dominant driver was the equatorward wavetrain forced by the stratosphere. Convection in the tropics was more reminiscent of an El Niño.

[MossMan]

Yeah, wasn't that circa 2008 or so? I don't remember what your name was before...I joined mid 2007.

It was R-Dub. A nickname from a co-worker back in the day.

[Phil]

[Jesse]

For those interested, a comparison chart for the Mount Hood snotel (5,400’):

 

 

Peak SWE is later at this site than others in the mid-elevations of the Cascades thanks to its altitude.

[Front Ranger]

Last week of April/very early May.

 

Wow, that's surprising, even at 5400'.

[Front Ranger]

The PNA was not “very negative” from mid-January into early February. It was neutral (~ -0.45 sigma) for a few weeks in January despite the phase 5/6 MJO and Niña background state.

 

And the PNW blowtorched at the time, under the influence of a strong baratropic PV/+NAM and +PNA returning in early February.

 

I didn't say it was "very negative".  I just said it was negative, which it was indeed from mid January through early February. 

 

The PNW did not blowtorch during this period, unlike most the country, as is often the case with west-based -PNA. The blocking was simply too far west for real cold.

 

[Front Ranger]

For those interested, a comparison chart for the Mount Hood snotel (5,400’):

 

417CE716-5A71-4EEF-8057-BC635549D137.png

 

Peak SWE is later at this site than others in the mid-elevations of the Cascades thanks to its altitude.

 

Basically steady/flat from early April to early May. Kinda interesting how there are two peaks.

[El Nina]

So you want to legalize cocaine too???

If we did then it could actually be controlled and taxed... just sayin.

[Jesse]

Basically steady/flat from early April to early May. Kinda interesting how there are two peaks.

The IRS usually confiscates some snow around 4/15.

[Phil]

I didn't say it was "very negative". I just said it was negative, which it was indeed from mid January through early February.

 

The PNW did not blowtorch during this period, unlike most the country, as is often the case with west-based -PNA. The blocking was simply too far west for real cold.

 

compday.a59p_VpoxF.gif

Let me fix your cherrypicking.

 

Here are the 3 weeks before the SSW, including the Maritime/Phase-6 MJO wave.

 

January 15 - Feb 5:

 

 

Here are the 3 weeks following the SSW, including the WHEM/Phase-8 MJO.

 

Feb 5 - Feb 28:

 

 

There was no niña forcing after mid-January. In fact, the strongest MJO wave in recorded history was charging across the Pacific/WHEM. The tropics were in a niño regime for awhile there.

[Front Ranger]

 

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.

[Jesse]

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.

[Jesse]

One would be hard pressed to spin this as anything but a regional torch:

 

[Front Ranger]

The graph posted by Jesse earlier illustrates the effects of the -PNA pretty well. You can see the steeper climb in snow depth the second half of January as the -PNA/troughing kicked in, after a very lackluster late November through mid January. Then a sharper climb starting in mid February as the deeper -PNA emerged.

 

[Front Ranger]

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.

 

The -PNA period was 1/18 - 2/1. That period was not a torch.

 

Obviously January torched as a whole thanks to an ungodly warm first half of the month. Which also happened to be +PNA.

[Phil]

One would be hard pressed to spin this as anything but a torch:

 

1481AAA6-0F34-4C1E-8E19-AD89303BC22C.png

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

[Jesse]

The graph posted by Jesse earlier illustrates the effects of the -PNA pretty well. You can see the steeper climb in snow depth the second half of January as the -PNA/troughing kicked in, after a very lackluster late November through mid January. Then a sharper climb starting in mid February as the deeper -PNA emerged.

 

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