Phil

I think the 18z GFS is going to be even blockier and colder than the 12z, at least over the US as a whole. Already a more amplified Eurasian ridge by 96hrs, PV weaker as well. The 80s are back, y'all.

The PV/NAM was perturbed significantly on numerous occasions that winter, it just wasn't destroyed. There's a difference between a perturbed PV/NAM and a SSW/PV breakdown. In a Niña convective background, generally a SSW/PV breakdown (aloft) isn't required unless it's a true unrelenting monster. An example of this would be 1988/89, where the SSW event that began in mid/late January dropped the dominos and I'm sure you know what followed that event..

There wasn't a SSW/PV breakdown event in 2013/14. Arguably, the PV was stronger than ideal that winter, which assisted in keeping that Hudson Bay vortex planted firmly through the majority of Nov-Mar.

An inch or two of slop isn't my idea of a "carrot". At least you're back-peddling now.

It was a joke. Did I say anything in regards to its validity? Use your head, man.

You should consider a career change from lawyering to comedy.

If this were a Niño winter, you'd be rooting for a SSW/thermal/wind reversal in the stratosphere to bring about an Arctic blast, since the background convective state in a Niño is unfavorable to begin with (so blowing up that background state of the Niño system would only help). In a Niña, you don't want that, but a highly perturbed PV/NAM is still ideal.

Thank you. Ideally, if I lived in the PNW, I'd want the PV highly perturbed, would root against a full SSW/PV destruction. A weak PV/NAM allows wave amplification to self-sustain more easily and amplify further. However, a massive SSW/thermal wind reversal would rapidly cool the equatorial tropopause and ignite the MJO/equatorward tropical convection, which risks destroying the weak niña background convective/walker cell state. We saw this happen in January 2013, and it lead to (or technically was a reflection of) a cascade of events that semipermanently altered the H/W ratio(s), low frequency NPAC/PDO state, etc.

I know it's kinda new-agey, but keep an open mind to the idea. I think there's something to it. I actually was implying that the degree and nature of the blocking is very much influenced by process in the upper levels, particularly wave dynamics that arise via interaction with the PV above 150mb.

Clown range GFS looks just a tad chilly over the US: http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/8CA56DDD-5644-4C62-AA2A-505EC7653A06_zps5guqbrce.jpg

At least we've had snow this winter. I didn't see a single flake until the middle of January last year. Hope to never repeat that again in my lifetime.

In the end, the strength of the PV/NAM will determine the degree of self-sustaining wavebreaking in the NPAC (as a backdoor conduit for heat/mass transfer), hence, the corresponding Arctic potential in the PNW hangs in the balance. If all goes right, and that's still a big if, we could be looking at an Arctic blast in January (directed into the western US) for the first time in many years. If the PV wins, however, the next Arctic dump will probably slide east again, following a broadening and flattening of the NPAC block. Don't want that to happen.

The poleward momentum transfer regime will impinge the surf zone on the vortex, particularly below 50mb, which will allow a further amplification of the next round of NPAC wavebreaking. Since strong anticyclonic wavebreaking precedes every Arctic blast in the PNW, the stronger and more amplified this regime can become, the better the long term prospects will be.

The PV is on roids currently, after strengthening rapidly over the last 10 days. However, it will be weakening overall going forward as poleward momentum transfer, subsequent wave breaking, and the corresponding bombardment via heat/mass fluxes increases into the stratosphere: http://www.atmos.albany.edu/student/hattard/realtime/u_65N_10hpa_gefs.png

GFS/GEFS based probabilistic forecast depicts a poleward propagation w/ jet retraction..what happens thereafter is in limbo but would prefer further retraction: http://www.atmos.albany.edu/facstaff/awinters/realtime/images/250hPaJet_verif_prob_8.gif

Nice site for analysis on the NPAC Jet/AAM transport: http://www.atmos.albany.edu/facstaff/awinters/realtime/D0_Verification_NPJPD.php

My thoughts are, rely more on the ensemble means, and ignore clown range operational runs. The upcoming pattern progression will be challenging for the modeling, and I anticipate a more classic Niña/EPO conduit to -NAM.

Lordy. Might want to consider moving..I'd have been outta there awhile ago.

Is the bolded actually true?

Frozen water falling from the sky is serious business. It really isn't something anyone should be joking about.

If that blocking verifies, I bet the US troughing is deeper.

I thought that was me?

Yuck, complete failure in the NPAC this run. Second breaker also ends up getting steamrolled.

First anticyclonic break over NEPAC/EPO area fails, but it's trying again further in clown range. Eventually it will succeed.