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Moving Through December - Changing Patterns and Changing Diapers


ChrisM

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Maybe the raw NAO numbers are not the best because of the West East issue but there is no arguing AO numbers. Don

S has the right idea and numbers to back it up.

Even with the -AO, there is a lot to how the height fields are oriented as to whether or not we get pieces of cold, or straight up crying or momma winters.

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Agree, it is uncommon, and generally when the AO/NAO are strongly negative, the pattern's not bad for us. Either way, the NPAC does not look to be anywhere near bad as that year. As long as we can keep some ridging poking up toward AK, the Pacific jet should be kept at bay.

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Agree, it is uncommon, and generally when the AO/NAO are strongly negative, the pattern's not bad for us. Either way, the NPAC does not look to be anywhere near bad as that year. As long as we can keep some ridging poking up toward AK, the Pacific jet should be kept at bay.

Looking forward to it.
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Feb 1969 had a +EPO but was a cold and obscenely snowy month (2nd snowiest Feb on record for BOS)...sometimes you get lucky. The monstrous west based NAO block was enough to offset it...there are exceptions to every general rule.

7123312024033921258.png

That's a great map. Besides the nao being beautiful the epo was much less ugly than the 1953 case.

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That's a great map. Besides the nao being beautiful the epo was much less ugly than the 1953 case.

Yeah the EPO is the worst when the vortex is very concentrated up in the region...it was more anomalous south of the EPO region in Feb 1969....but the NAO definitely prevented an east coast torch that month.

Here's a composite on the warmest CONUS winters in the past 50 years....the convergence of the where the lowest anomalies on the map is pretty obvious

71233120240339211243.png

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And we were pretty much right in the middle of NYC and PHL here in CNJ. 3.5" was my top value for December 2008. The southern periphery of the above avg snows was NNJ/NYC.

Although snowfall here was not terribly more than in NYC, the increase to the north and east for those years still shows (well not so much in 2007) at Upton with 6.4" in 1970, 3.0 in 2007, and 10.9" in 2008.

IMBY, we had 4.0" in 12/2007 and 12.4" in 12/2008. I am about 17 miles from the OKX office.

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Well I look at those too. Doug (Dsnowx) laid it out. The NAO domain definitely had a height configuration that supports low values, but recently the block has built west. The more east based prog was still not really helping us. That's all I meant.

You're absolutely correct! The "west based" aspect of the NAO is critical when the Pac isn't behaving - seems the Pac not behaving has plagued a few years now, as an interesting angle on this. You're also [implicitly] correct that the calculations don't qualify west or east based; THAT requires your visual nature.

I start from the calculations and work toward the visual, in that order.

The PNA really completely F us here. The East Pac ridge is flexing too far west for the Dec 11 scenario, but in our defense, we did put the if if if the PNA rise was legit. It's a huge domain, so much so that it is harder to work with. That said, the calculations for the domain relaxed abruptly, and that is likely a reflection of said ridge being less coming over land.

Good stuff - but folks' just want snow, I know -

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You're absolutely correct! The "west based" aspect of the NAO is critical when the Pac isn't behaving - seems the Pac not behaving has plagued a few years now, as an interesting angle on this. You're also [implicitly] correct that the calculations don't qualify west or east based; THAT requires your visual nature.

I start from the calculations and work toward the visual, in that order.

The PNA really completely F us here. The East Pac ridge is flexing too far west for the Dec 11 scenario, but in our defense, we did put the if if if the PNA rise was legit. It's a huge domain, so much so that it is harder to work with. That said, the calculations for the domain relaxed abruptly, and that is likely a reflection of said ridge being less coming over land.

Good stuff - but folks' just want snow, I know -

GEFS mean had a NAO value of like a -1 or so just a day or two ago. The -NAO tanking like that is a new thing that wasn't being shown previously.

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Do you ever feel as if people just nod their head "yeah" when talking to them, but they don't really seem to get it?

Yes, unfortunately ... but Scott knows/knew what I mean.

fyi- I assume you are referring to the empirical orthogonality stuff; all that means is "how" they calculated teleconnectors.

Folks seem more so to not understand what "teleconnector" means, and how it is important. The simple science is, take the diagonal values of a given matrix and derive a polynomial expression (algebra), then calculate the roots - whether by quadratic method, completing the square: solve for the roots. If they are negative, -NAO, positive, +NAO. The 2nd part of the teleconnection definition is, statistical character of one domain correlates to characteristic of different domain. "Negative NAO correlates to negative geopotential (heights) from the OV to MA.

It gets complicated when considering this west or east based business, because east correlates less to that correlation; where west based correlates strongly.

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GEFS mean had a NAO value of like a -1 or so just a day or two ago. The -NAO tanking like that is a new thing that wasn't being shown previously.

Wait, haha - by GEFs are we talking about the same thing? The thread I started about the failing PNA signal - word - has NAO from CPC where more members were lower than -1, and that was actually true before that and since.

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Wait, haha - by GEFs are we talking about the same thing? The thread I started about the failing PNA signal - word - has NAO from CPC where more members were lower than -1, and that was actually true before that and since.

You posted a single image of the GEFS in that thread (5 days ago?). I look at the CPC indices everyday, and they have not been nearly this good on the -NAO until today.

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GFS showing alot of potential again after the 15th.

If we were all dry mild boring weather enthusiasts we probably would have noted long ago the tendency or these patterns to break down more slowly than modeled. Because to some degree we are all like Kevin we look at it as "how many days before it snow" and jmho always seem to rush the change. When the consensus was the 10th I liked the 18-20th and still feel that way. We will be into solid winter weather by Xmas which beats cold 12/6 and bikinis on Xmas.

I don't think we go straight to winter warlock weeks on end cold. I think the winter is going to flip back and forth which is fine. Some of our most epic storms come in these types of winters.

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You posted a single image of the GEFS in that thread (5 days ago?). I look at the CPC indices everyday, and they have not been nearly this good on the -NAO until today.

Well then we agree to disagree - I look daily; in fact, I don't look at a model depiction until I assess the teleconnectors. Not sure what you have been seeing, but the NAO may have varied some days higher or lower, but the general them of a dip for a temporal sector has been highly well advertised. And if you'er saying "a single" image - that does not diminish the significance of it, if you mean 'pulling a singe result' to make a point. I wouldn't have made it, if I did not take note of multi-cycle signal.

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