Pattern Discussion 12/15 and beyond

[toronto blizzard]

How did the euro ensembles look like after d10?

[OSUmetstud]

Depends which side of the pond is right ... GFS' cluster is polar opposite

Guess I'd put my money on the $-D variable system too, but I don't know if that really helps (Euro) for at least partially oceanic atmospheric coupled physics.

I'll go ahead a put my money on whichever solution makes for the worst weather relative to the collective voice's desire.

Those are analog/autoregression plots

This the GFS ensemble forecast.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/foregfs.shtml

[CT Rain]

12z Euro from yesterday shows that bulge of warmer temperatures in the stratosphere at 50mb sort of rounding the globe from Asia to North America by D10.

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/ec.php?alert=1&level=50&forecast=all&lng=eng#fig11

Higher up... at 10mb... no such anomaly but the huge vortex over Greenland begins to get the boot and moves northeast of Finland and north of Russia by D10.

Some movement of the features up there.

[Typhoon Tip]

12z Euro from yesterday shows that bulge of warmer temperatures in the stratosphere at 50mb sort of rounding the globe from Asia to North America by D10.

http://wekuw.met.fu-...l&lng=eng#fig11

Higher up... at 10mb... no such anomaly but the huge vortex over Greenland begins to get the boot and moves northeast of Finland and north of Russia by D10.

Some movement of the features up there.

What's interesting for me is that the 100mb thermal layout is much more impressive - considering that the tropopause is just beneath that pressure coordinate, that implies that the "squashing" action onto the PV is not really coming from much above that level.

A quick thought on that: It makes sense for me that it is not. If you look at the monitoring divisions on-going analysis of the 100mb through 1mb stratospheric depths, there's been pretty much 0 warm thermal anomalies in the realm that is measured and computed for (I am not sure if they are doing the whole 3-D domain above 70 N, or whether just the part that matters to N/A). When the exertion on the mixing depths of the PV domain comes from above the tropopause as a propagating warm anomaly (or cold), those have to do with sudden stratospheric perturbation events - denoted SSW's for warming. The point being ... we have not observed any SSWs at this time.

The question is really, what is driving/causing the 100 to 150mb level warm anomaly, because it is pervasive going out across the next 10 days and gets stronger out in time - here is the D7:

My current thinking is that suppression on the ambient mixing depths of the PV domain is likely coming from lower than stratospheric influence - i.e., there is a disconnect here, perhaps, where dissipating planetary wave events (WAA termination at high altitudes and latitudes) may actually be the cause for the near tropopause warm anomalies.

Be that as it may, I too am noticing this "lobe" of warmth in the above picture as having migrated slowly cyclonically around the axis of the pole. Moreover, the conterbalancing negative region that is subtended beneath the stratospheric PV component is very weak and not really compensating for the said warm regions elsewhere. Without that mass source/sink balance at this 100mb level, its got to come from somewhere, and that would mean downward exertion ensuing.

This is why in total I believe a -AO bias should persist now that we have gone negative. It may try to recover based on other influence creating oscillations, but already, the CPC nightly evaluations show a new nadir showing up beyond D10. We plummet to perhaps as much as minus 4 SD, then it recovers to -1 (still negative), but then the bulk of the members go right back down again.

[Typhoon Tip]

Those are analog/autoregression plots

This the GFS ensemble forecast.

http://www.cpc.ncep....O/foregfs.shtml

No you're right - I f that up. My bad... Thanks for clearing that up.

The current one that I saw this morning is actually very encouraging. The means is fairly tightly clustered as emerging abruptly amid Phase 1... That's gotta be a good sign.

I would also add that the Pac domain is more than likely not responding to that signal at the present time.

[CT Rain]

No you're right - I f that up. My bad... Thanks for clearing that up.

The current one that I saw this morning is actually very encouraging. The means is fairly tightly clustered as emerging abruptly amid Phase 1... That's gotta be a good sign.

I would also add that the Pac domain is more than likely not responding to that signal at the present time.

I feel like some of the stratosphere funkiness is going to overwhelm the MJO signal.

Thoughts from HM or others about the MJO signal and the stratosphere signal?

[WeatherX]

This is one of the largest shifts I've seen in the Euro Op on the 12 hour height change maps. Perhaps the renewed MJO signal would account for this? I don't know. Nice height rises in the "sweet" spots. Patience is required...PAC still doesn't look that great, but the PAC can suck it.

[Heisy]

EURO still shows low anomalies over Alaska area, we just can't get rid of the SE Ridge...Damnit.

[CoastalWx]

Just enough blocking to force the low souh after

Next weekend on the GEFS. Give it time folks.

[Typhoon Tip]

Just enough blocking to force the low souh after

Next weekend on the GEFS. Give it time folks.

One thing I am noticing is that the AO seems to be verifying with more success via the ensemble means/ EOFs, whereas the NAO counterpart keeps getting pushed back in time - so to speak. As of last night the NAO is still slightly negative and forecast (still) to fall, but not quite with the same panache as the previous signal. This has recurred a few times in the past month.

The operational GFS seems to also be performing this, now not looking very -NAO west based on this run over all, compared to a couple/few days back.

I really think that what is going to be necessary in the "give it time folks" is that we are in wait or something to disrupt the incredible month long static nature of the PNA. Take a look below at the PNA, and take note of how it has been unaltered since the First of November for all intents and purposes - the previous 3 months worth showed much more dynamic behavior in altering between -1 and + (~) SD. It's flat-lined and unmoving character set in just post Sandy - not that there is any correlation there (don't see how there could be...)

The PNA is really a very vast domain, and the overall can be negative while just the CONUS aspect of its domain looking more +PNAP in nature; unfortunately for more winter like pattern, that is not the case this time. The general flow appears to be hugely stable, and unwavering and desperately in need of a perturbation significant enough to alter this toward a new paradigm. The flow appears to be quite consistent with a -.5 PNA, and that features more than less a zonal flow that is tending to tip systems toward a GL/Upper OV track.

I discussed this with Will in the other thread, and that having a negative NAO tends to limit GL cyclone tracks there - we all know this. But having the -NAO duping us by not showing up on schedule well ... you're screwed if you seek winter weather.

I don't really see given that that Pac and N/A flow appears to be stably locked in a -.5 PNA construct how we are going to do it beyond some anomaly relative to. The NAO needs to put up or shut up in this circulation scenario; or, alter the Pacific.

Hopefully this abrupt emergence into Phase 1 wave space will register some of that necessary perturbation - What's funny, ...if perhaps a smack in the face, is that last night run shows that no sooner does it emerge (GFS) does the wave terminating into Phase 3 with extreme rapidity.

[Eduardo]

May be a silly question, but I'm guessing that the recurvature of Typhoon Bopha out in the WPac won't be doing anything to dislodge this horrendous Pacific pattern? Thoughts anyone?

[leo1000]

Ya wouldn't the recurvature of typhoon bopha in the WPac & the MJO heading to phase 1 & a negative NAO and AO with blocking be enough to stop any pacific flow coming up?.

[Typhoon Tip]

Ya wouldn't the recurvature of typhoon bopha in the WPac & the MJO heading to phase 1 & a negative NAO and AO with blocking be enough to stop any pacific flow coming up?.

Not seeing much evidence that Bopha recurved - it moved into an unusually deep latitude, around 14 or 17 N, by -120 W, then decayed in place - actually its remnant circulation at llvs is drifting S it appears.

Although, there is a bit of a subtropical jet emerging in that vicinity that has stripped a good deal of latent heat off the dying system - that could assist, but not likely, because the study argues for latent heat flux that ends up in the NW Pac.

[CoastalWx]

Some signs that that day 8-10 deal may be a two part messy storm especially interior and NNE. That may also promote -NAO after. I still think people should give this a chance. We seem to

be locking into a stormier pattern for sure. The colder air may come in successive stages in these double storms after day 8-10. Still a shot it could come se, especially the possible follow up wave.

[Typhoon Tip]

Some signs that that day 8-10 deal may be a two part messy storm especially interior and NNE. That may also promote -NAO after. I still think people should give this a chance. We seem to

be locking into a stormier pattern for sure. The colder air may come in successive stages in these double storms after day 8-10. Still a shot it could come se, especially the possible follow up wave.

Again, as I was discussing earlier: the NAO is being pushed off ... I'd like to see this NAO actually take place.

Also, the character of the flow from the Pacific into N/A is the lions share of winter's abandonment. That needs to change - it's the majority of the problem. I really almost care less about the NAO,when there are negative anomalies pervasive in west-central Canada and the NW Territories - Pac is hell bent on blocking that from coming south with this zonal thing.

Pac flow has to change. That's the key.

[CoastalWx]

Boy I would take the 18z GEFS in a heart beat. It's gonna be funny if we all have >150% of December snowfall by 12/31. Lots of posts will look quite weenie-ish.

[CT Rain]

For another set of runs both the GEFS and Euro Ensemble generate a stout MJO wave. Here's the GEFS OLR anomalies over the next 15 days.

You can see the convection firing over the western Indian Ocean/Africa next 5 days and then beginning to move east through the Indian Ocean to Sri Lanka by D11-D15. For the 5th straight day (Maybe 4 for GEFS and 5 for Euro Ens) the dynamical globals have shown this occurring. Here are the GEFS and Euro Ens Wheeler diagrams showing the wave propagation.

So what does that mean for us? At least for the next 1-5 days the MJO signal is nonexistent and you can see the forecast 500mb anomalies across the Northern Hemisphere per the Euro Ens. Not a great pattern with an east based NAO... strong Pac jet that's active from Alaska through the Pacific Northwest.

The east-based NAO is not enough to suppress the storm track so we're left with tomorrow's cutter and the continent has been flooded with mild Pacific air. Even with below normal 500mb heights across a large portion of the country the 850mb temperatures anomalies are marginal at best.

Not a great pattern for us. What will be interesting though is to see how the renewed MJO wave can help shake up the pattern a bit. Here's the December composite for phase 1 and phase 2 from Alan's site.

Both phase 1 and phase 2 correlate to below normal 500mb heights over the Aleutians and a pumped up +PNA ridge in the east coast. Not surprisingly, east coast troughing is favored.

For temperatures, the NDJ phase 1 composite does favor below normal temperatures across the northern tier but notice that the statistical significance is sort of meh outside of the northern Plains (lower percentages of significance indicate higher statistical significance). Phase 2 begins to show the torch moving east.

Moving forward here's the 6-10 day and 11-15 day GEFS 500mb height anomalies. The Pacific and west coast doesn't show anything like what you'd expect from the given MJO composites. Will tropical forcing mute the Aleutian ridge/west coast trough signal (the Bering Strait ridging has vanished)? Will the above normal heights over Labrador/Greenland has shown in both the GEFS and MJO composites remain?

Regardless of what happens there's not much of a signal for cold. We can hope enough anomalous ridging to our north can suppress the storm track some but with a pretty lame cold source it may prove difficult to get snow in the coastal plain.

As has been mentioned it doesn't look like much of a "gradient" pattern either. We will have to watch for some transient ridging to our northeast to help us out - that's why I'm still interested in this pattern I could also see 1 to 2 wintry threats with some luck (first may be next weekend).

For the cold and snow depth fetish people, unfortunately, I do expect the rest of the month to average above normal temperature wise.

One word of caution as well. If the MJO remains stout and starts rounding the circle post Christmas and especially post-New Years we're going to enter into some really toasty phases. May have a period of furnace weather to deal with.

[CoastalWx]

It is a shame the Aleutian ridge is Kid N Play flat topped otherwise we would have a further east cold dump, but the PNA is super negative at this time. It does look like ridging will try to develop northeast of us like Ryan said. That would favor interior northeast and NNE I think through day 10 or so. There is still the chance the GEFS can happen so not all hope is lost.

[CT Rain]

It is a shame the Aleutian ridge is Kid N Play flat topped otherwise we would have a further east cold dump, but the PNA is super negative at this time. It does look like ridging will try to develop northeast of us like Ryan said. That would favor interior northeast and NNE I think through day 10 or so. There is still the chance the GEFS can happen so not all hope is lost.

I think we could squeeze out a snowstorm though. Pattern is definitely not cold but it's definitely not making me tie the noose tonight. I would much rather be in VT or NH though.

One thing that's sort of funny is that our "gradient" pattern has sort of gone to hell. With any luck and the teleconnection for some Davis Strait ridging/east coast troughing maybe we can get a decent coastal.

[OSUmetstud]

Horrible. lol

Seriously, nice write up, Ryan.

From the North American anomalies for phase 2, it still looks like a pretty cold signal for December. Perhaps the warming signal is more for Phase 2 in January and February?

I wonder if we can really pop a PNA given the MJO, it seems so elusive this year.

[CT Rain]

Horrible. lol

Seriously, nice write up, Ryan.

From the North American anomalies for phase 2, it still looks like a pretty cold signal for December. Perhaps the warming signal is more for Phase 2 in January and February?

I wonder if we can really pop a PNA given the MJO, it seems so elusive this year.

Yeah I think the MJO composites are only of "some" use since the Pacific is doing its own thing. Maybe the MJO is modulating it some so instead of a monster Bering Strait ridge (which would be nice) we're left with a flatter ridge etc in N Pac.

Sort of a weird pattern though with that big trough on the west coast... but no real gradient pattern with lower than normal heights over the SE and above normal heights over Quebec lol.

[CoastalWx]

I think we could squeeze out a snowstorm though. Pattern is definitely not cold but it's definitely not making me tie the noose tonight. I would much rather be in VT or NH though.

One thing that's sort of funny is that our "gradient" pattern has sort of gone to hell. With any luck and the teleconnection for some Davis Strait ridging/east coast troughing maybe we can get a decent coastal.

Yeah it definitely has that marginal snow look too, agreed. I haven't looked at much except some ensemble stuff but agree with what you said. It will be nice I actually have laptop access tomorrow when I go home lol.

[40/70 Benchmark]

Well, looks as though we punt December.....oh well.

It happens even in good seasons.

[HM]

I still think that the models are keying in on a Kelvin Wave and mistaking it for the MJO because of the broad 200mb easterlies. There is one in the 100-120E sector and another about to enter the IO. While Roundy's plots are certainly eye opening as we get to the New Year, I think the tropical forcing will keep things pretty ugly for the rest of the month.

Then again, if an internal KW within the general Walker uplift cell can act like a MJO wave...then what's the point to my post?

[HM]

The potential for a PNA spike will exist if Roundy's plots are correct in the second week of January.

[CoastalWx]

Well, looks as though we punt December.....oh well.

It happens even in good seasons.

I honestly don't think we'll escape empty handed.

[HM]

I honestly don't think we'll escape empty handed.

Yeah you can't punt if you're in New England with this pattern. Of course we've seen better patterns but this one can still produce with the 6z GFS showing you how it's done on 12/16-17.

[CoastalWx]

Yeah you can't punt if you're in New England with this pattern. Of course we've seen better patterns but this one can still produce with the 6z GFS showing you how it's done on 12/16-17.

Glad you agree and it wasn't me just ring overtired and seeing things lol. Like you, I am referring to region wide and it may be difficult for people like me on the coast, but I think this can produce for the interior, and even here if we can get a good high in place. Personally, I'm just glad to see coastal storms modeled.

[HM]

I still think that the models are keying in on a Kelvin Wave and mistaking it for the MJO because of the broad 200mb easterlies. There is one in the 100-120E sector and another about to enter the IO. While Roundy's plots are certainly eye opening as we get to the New Year, I think the tropical forcing will keep things pretty ugly for the rest of the month.

Then again, if an internal KW within the general Walker uplift cell can act like a MJO wave...then what's the point to my post?

For the entire equatorial region, there really is 1 sink and 1 source for the Walker Cell. There has also been a strengthening 850mb easterly anomaly over Indonesia, where the collapsed warm pool has spread out the potential stagnant forcing of ENSO. Between these two basic things of 1 divergence to 1 convergence wave and the easterly winds over Indonesia-west. Pac now, the models are free to propagate the CHI wave coming through 0-60E. This is the same CHI wave that came by in mid-November.

So is the MJO prediction far-fetched? No... I'm just telling you what they are keying in on. As usually the case in the barotropic atmosphere, when you strengthen the u winds in one place, a restoring u wind with similar magnitude occurs elsewhere. The westerly u-winds have intensified in the Atlantic behind / along the departing CHI wave.

[HM]

The 30mb temperatures are blazing over Indonesia and tropical western Pacific. WTF

http://www.cpc.ncep.noaa.gov/products/intraseasonal/temp30anim.gif