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Moving Through December - Changing Patterns and Changing Diapers


ChrisM

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Well Will is right. There are several posts in the other thread from myself and others stating that it was around 12/10 when we would start to see changes in the pattern to allow more cold into the CONUS and thus begin the transition. I know I specifically said that is does not mean an abrupt change to cold and snow here locally on that date. I even said it may take several days after that, but none of us could possibly say exactly when. I don't think anything has changed regarding that time. I can't help it, if people think it means the onslaught of 3' snowpack..it simply means a change to a pattern that allows for more wintry chances.

Perhaps your damaging ice storm trends colder next week.

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Down in the Mid Atlantic, I wouldn't rule out a virtual December punt altogether.

The NA mountain torque spike is happening now...the wave 2 is happening now... the MJO pulse through the IO is happening now... the low sun is happening now...

All of these things can only change for the worse the deeper we move into December right?

I have no idea..lol. I agree about the MA, but I'm still interesting up here because it's pretty close to a decent pattern here in the longer range. I'm still curious to your last post....why do you think these perturbations to the vortex, screwed the -NAO? Because it pushed the vortex towards Greenland? At the same time, I thought maybe it helped with an Aleutian ridge.

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I check in on this board once a day at lunch and it has become comical how every 24 hours the outlook for the next month, and the attitudes on this board can swing from one end of the spectrum to the other. Gotta start archiving these fluctuations. December Torch - Muted Torch - First Half December Punt - Entire Month Punt - Sneaky cold - seasonable temps - December Torch...That is the summary of the last week or so...I think that is were we stand today...see you at lunch tomorrow. Same time... same place...completely different forecasts!

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Too much model thinking skin deep around here - the runs don't show it, must be time to flame December.

Okay - good luck with that.

Yeah...relying on the LR modeling right now is pretty ugly...they have been changing so much from run to run...literally run to run...one run of ensembles looks great and then the next run can look pretty bad.

The lack of a dominant factor driving the pattern is likely the reason for such model uncertainty. The AO being ultra negative will help us I think though. How that actually manifests itself...I couldn't say. My best educated guess is the cold air from western Canada bleeds ESE as it very often does with -AO but lack of good -NAO.

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Down in the Mid Atlantic, I wouldn't rule out a virtual December punt altogether.

The NA mountain torque spike is happening now...the wave 2 is happening now... the MJO pulse through the IO is happening now... the low sun is happening now...

All of these things can only change for the worse the deeper we move into December right?

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I have no idea..lol. I agree about the MA, but I'm still interesting up here because it's pretty close to a decent pattern here in the longer range. I'm still curious to your last post....why do you think these perturbations to the vortex, screwed the -NAO? Because it pushed the vortex towards Greenland? At the same time, I thought maybe it helped with an Aleutian ridge.

This is what happened...

Upward flux originally occurred in eastern Europe/western Siberia which is classic wave 2 origin. Despite the warm, -EPO/WPO pattern in the northern Pacific, the stratospheric air here was cold and so was the vortex. Since we knew the troposphere / stratosphere were not jiving yet, the warm anomalies were safe and the forcing from the troposphere/ocean would sustain them, despite the cold stratosphere aloft. The upward flux from eastern Europe in combination with the -QBO and lower solar periods allowed for the amplification to upwell, forcing a squeeze play from North America into eastern Siberia.

Now that tropospheric cold has carved out over Siberia, the stratosphere is beginning to warm here from the upwelling flux and is combining with the tropospheric -WPO wave anomaly to form a huge wave 1. This is NOT a classic wave 1 where an Aleutian Low is responsible but it doesn't matter since we have the wave 1 coming (the low is displaced from usual location). Because the strato-vortex itself was so cold and strong and the wave 2 was only predicted to be modest, we knew the vortex would stay in tact. It's positioning would send it back to the North Atlantic because of the warmings from Asia, keeping it from moving there.

This whole thing happened quickly and will force the PV back to Greenland. This is why I'm warning of models with west based -NAO patterns etc. I don't think this will happen until that PV is destroyed/out of there.

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Just throwing this out there... What storm was it that at D9 was a GL stem winder S gale for us, then, it was a coastal blizzard, and what happened.... flat wave with paltry overrunning.

Guys - relax! you're acting like a heroine addict that's paranoid about their next fix - haha.

I know what mean though - it would be nice for entertainment's sake if you had some eye candy. Agreed. But you just gotta be stronger and more insightful than that, and you can derive almost the same value. What I mean is, the NAO is also diving, and there is a H. A. signal from that, too, not just the PNA rise - albeit not quite as impressively as 2 night ago at CPC. That's fine, as Will pointed out, the ensemble means have been a bit flippy floppy as of late, and that could effect the PNA calculation.

To me I'm still thinking an icing scenario could be on the table to enter...

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I check in on this board once a day at lunch and it has become comical how every 24 hours the outlook for the next month, and the attitudes on this board can swing from one end of the spectrum to the other. Gotta start archiving these fluctuations. December Torch - Muted Torch - First Half December Punt - Entire Month Punt - Sneaky cold - seasonable temps - December Torch...That is the summary of the last week or so...I think that is were we stand today...see you at lunch tomorrow. Same time... same place...completely different forecasts!

But that's the thing, I think most forecasts haven't changed. You have to weed through all the emotional weenie posts, which I think cause more confusion and result in some of these statements and accusations of flip-flopping.

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fat lady

For the Mid Atlantic, I think we have to wait for something appreciable; however, you can always get sneaky changeover setups with patterns like these with proper high positioning.

My negative tone shouldn't discourage you northern folk who can do well in La Niña patterns.

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It's really ashame the wave 2 to wave 1 configuration in the stratosphere went down and is going down like it is because I think it is the thing that ultimately ruined the NAO. Of course, the month just started so we have a long way to go.

Isotherm, I meant "ineffective NAO" as in the charts may register negative and there may be a thumb ridge into the E / E-C regions but it does very little to combat the SE ridge / RNA pattern outside of maybe the Upper Midwest-New England corridor.

I seem to recall last year at some point the NAO registered negative, but that was because everywhere downstream of the Alaskan vortex, from california to greenland, had above normal heights. What a winter.

The end of the 12z gfs ensembles have a healthy -NAO developing, but I agree with the skepticism given the predicted vortex state/position at that point. It is curious to me that the gfs suite would even develop this -NAO block in the long range despite really stregnthening the vortex in that vicinity. I mean, it has your "tornado" up there big time by days 10-15. Closer inspection of the height departures though shows the "tornado" swinging towards the Asian side of the pole and a +height anomaly developing from 50mb to 10mb in Greenland over that time frame... This is of course in fantasy land, but had support from the ensembles...not sure what to make of that

I see a few people here are hopeful that the cold will settle into the east by the latter stages of Dec, I'm not sure though. I would think the trend will be towards a relaxation of the -AO (not that its helping us now anyway) /a trend towards positive with the strat gathering itself after these waves. The -PDO and pacific pattern that appears to be very assertive early on this winter would probably leave the east really torching without any AO help?

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