December 2016 Observations and Model Discussion for the Pacific Northwest

[MossMan]

Heavy snow and 31 degrees...couldn't ask for anything more from a "non event"!!

[BLI snowman]

That is why I was asking about the a possible low over PDX... precip should back around that low as it moves NE.   If there really is a center of low pressure there.

 

Low is a bit north of Hoquiam, they have SSE winds now.

[Phil]

Nice site for analysis on the NPAC Jet/AAM transport:

 

http://www.atmos.albany.edu/facstaff/awinters/realtime/D0_Verification_NPJPD.php

[Brennan]

Still dumping here in Bellingham. Hope it continues after dark so we can get these roads covered. I have no idea what's going to happen... enjoying it from the windows at work!

[Phil]

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

[Bham_Guy]

Still dumping here in Bellingham. Hope it continues after dark so we can get these roads covered. I have no idea what's going to happen... enjoying it from the windows at work!

 

I'm surprised how well downtown Bellingham is doing - more than Ferndale in fact.

[Phil]

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

[crf450ish]

[luminen]

35F degree rain here. 

[Phil]

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.

[Phil]

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.

[Phil]

More snow here than in Philly this season.

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.

[Phil]

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

[Front Ranger]

All of Tim's fretting this morning clearly paid off.

[Deweydog]

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.

Wait, wait, WAIT! Hold the f*cking phone!

 

Are you saying there's a connection between strong blocking and very cold weather in the PNW???

[The Swamp]

All this moisture and just four or five degrees too D**n warm. Arrrrgghh!

[Heavy Snow]

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

Great analysis. Ideally would we want the PV zonal winds to be under 30 m/s?

[MossMan]

An amazing day! Dumping snow big time...A Christmas miracle!!!

[Phil]

Wait, wait, WAIT! Hold the f*cking phone!

Are you saying there's a connection between strong blocking and very cold weather in the PNW???

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.

[Deweydog]

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.

So many millibars to worry about as we get to the start of PNW teeth-gnashing season (generally during the week between Xmas and New Year's).

[Phil]

Great analysis. Ideally would we want the PV zonal winds to be under 30 m/s?

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.

[Front Ranger]

Sun angle for the day has peaked!

[Phil]

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.

[SilverFallsAndrew]

The big question is if winter is now over as we exit our only winter month of December. The Faux winter months of March and April are still on the horizon though. 

[Front Ranger]

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.

 

 

Clown range GFS looks just a tad chilly over the US:

 

This is confusing.

[Phil]

So many millibars to worry about as we get to the start of PNW teeth-gnashing season (generally during the week between Xmas and New Year's).

You should consider a career change from lawyering to comedy.

[FroYoBro]

I am glad some people up in Washington are getting snow. I think we all agree that we want Snow Wizard to finally get some so he doesn't have a mental breakdown. 

[Phil]

This is confusing.

It was a joke.

 

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

[SilverFallsAndrew]

This system has been fair less juicy than I was anticipating. Just cloudy here in Salem the past 10 hours with no rain. 

[FroYoBro]

This system has been fair less juicy than I was anticipating. Just cloudy here in Sale the past 4-5 hours with no rain. 

 

Look at the radar near Seattle. It is pretty juicy, just not down here. 

[The Swamp]

I am glad some people up in Washington are getting snow. I think we all agree that we want Snow Wizard to finally get some so he doesn't have a mental breakdown.

Could start a Go Fund Me and raise money to have a truck load dumped in his yard.

[BLI snowman]

This system has been fair less juicy than I was anticipating. Just cloudy here in Salem the past 10 hours with no rain. 

 

The conditions you were supposed to get are occurring in Olympia. Everything shifted north at least 100 miles from the past few days' predictions. 

[SilverFallsAndrew]

Look at the radar near Seattle. It is pretty juicy, just not down here. 

 

Yes, I guess you are right. I guess all the rain we were supposed to get went 250 miles north...This system basically did what Jesse was afraid last Wednesday's would do. Thankfully the system with the most potential did what we wanted it to do. 

[Front Ranger]

It was a joke.

 

Did I say anything in regards to its validity? At least try to think critically?

 

Starting to see some heavy carrot accumulations north of Seattle!

 

Also a joke.

[BLI snowman]

Looks like at least a couple inches now in south Bellingham.

[MossMan]

Nothing better than just sitting and looking out the window with Christmas music playing on a day like this!

[SilverFallsAndrew]

So is this event in Washington largely precip intensity dependent right now or elevation dependent, or a little of both? Because I notice most observations in NW WA are either rain or in the 34-37 range. With a few exceptions like BLI and Everett at 33. 

[Phil]

Starting to see some heavy carrot accumulations north of Seattle!

 

Also a joke.

An inch or two of slop isn't my idea of a "carrot".

 

At least you're back-peddling now.

[SilverFallsAndrew]

Nothing better than just sitting and looking out the window with Christmas music playing on a day like this!

 

What is your elevation? 

[Bham_Guy]

Looks like at least a couple inches now in south Bellingham.

 

Could be with a bit of elevation. My buddy is reporting 2-3 inches at about 400' near Lake Whatcom.