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Moving Through December - Changing Patterns and Changing Diapers


ChrisM

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Keep in mind the date...still early. Lots of time

Very true Dave, climo does not even favor sne until later this month and considering I just had the snowiest November ever down this way the angst is probably unwarranted. I am sure last season has a lot to do with it but I also love snow for the holidays. Things do look better the second half of the month, who cashes in is up in the air but looking at long range models and such you would have to favor the interior west which would make sense in most winters at this juncture of the winter season.

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Becoming more optimistic with time...I was already reasonably optimistic, but its nice to see the guidance trending toward a favorable pattern after a bit of waffling. I'm sure we will still see a few more shifts and plenty of weenie meltdowns...but I think the NAO possibility is becoming real. Its not in fantasy range anymore. What was nice about today's ensembles runs...there was agreement across all models...Canadian ensmebles, GEFS, Euro ensembles...at least WRT the NAO. GEFS and Canadian were faster to rebuild the cross polar flow in the N PAC...Euro does it, but slower and more methodical. (probably also more correct)

Thanks Will, patience is not always a snowlovers virtue.

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Pretty amazing. I knew you guys could do well in such patterns, but would have never guessed this highlights your top snowy months..is this just a december thing or applied to the whole winter?

December reacts much better here to a -PNA than other months....HM has had his own version of explaining it with wavelengths. December wavelengths are def a bit different than Jan/Feb.

But really any month with a -PNA and a solid -NAO produces well. December seems to be the most prolific with a -PNA and requires less cooperation from the Atlantic (see December 2007 and December 2008).

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December reacts much better here to a -PNA than other months....HM has had his own version of explaining it with wavelengths. December wavelengths are def a bit different than Jan/Feb.

But really any month with a -PNA and a solid -NAO produces well. December seems to be the most prolific with a -PNA and requires less cooperation from the Atlantic (see December 2007 and December 2008).

I know this is out of this area but its pretty remarkable how you guys cleaned up in those months. I looked at philly's snowfall records from dec 1970,07,08 and the snowiest december was 1.6 inches. Would be interesting to see what nyc did in those months considering they are further north.

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I know this is out of this area but its pretty remarkable how you guys cleaned up in those months. I looked at philly's snowfall records from dec 1970,07,08 and the snowiest december was 1.6 inches. Would be interesting to see what nyc did in those months considering they are further north.

NYC had 2.4" in 1970, 2.9" in 2007, and 6.0" in 2008. December 1970 and 2007 were freakishly similar in the snowfall department all through the northeast/New England.

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Weathergun made an astute observation in the NYC thread. The Euro and its ensembles are back with a more potent MJO signal in phases 1 and 2. That could explain the better model runs.

2n8spwi.jpg

Yeah that's a change too, although the MJO has not been the easiest to forecast which is partially responsible for the models trending lousy the first 10+ days of this month. Things do look like they are better looking on the models over the last day or so, but I'd like to see it continue. I really want that -NAO because the -PNA is totally governing things. If that Aleutian ridge builds, that will also help. Can't be that combo up here as Will showed.

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I know this is out of this area but its pretty remarkable how you guys cleaned up in those months. I looked at philly's snowfall records from dec 1970,07,08 and the snowiest december was 1.6 inches. Would be interesting to see what nyc did in those months considering they are further north.

NYC had 2.4" in 1970, 2.9" in 2007, and 6.0" in 2008. December 1970 and 2007 were freakishly similar in the snowfall department all through the northeast/New England.

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.

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Yeah that's a change too, although the MJO has not been the easiest to forecast which is partially responsible for the models trending lousy the first 10+ days of this month. Things do look like they are better looking on the models over the last day or so, but I'd like to see it continue. I really want that -NAO because the -PNA is totally governing things. If that Aleutian ridge builds, that will also help. Can't be that combo up here as Will showed.

Yeah, considering the one dominant signal (that would actually significantly affect the pattern) was the PNA, there were no other real signals to provide much better change. But now that we have wave breakers for the NAO combined with a better MJO being forecast, that could explain the better regime changes we have seen in the model data.

But yes, this is still quite fragile. The MJO has been tough to forecast, so if the models are wrong on that, they might be wrong on the NAO and more improved Pacific pattern. At least the phase 1 forecast is not too far out in lead time, and it is phase 1 that correlates to a -NAO.

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December reacts much better here to a -PNA than other months....HM has had his own version of explaining it with wavelengths. December wavelengths are def a bit different than Jan/Feb.

But really any month with a -PNA and a solid -NAO produces well. December seems to be the most prolific with a -PNA and requires less cooperation from the Atlantic (see December 2007 and December 2008).

Yeah I definitely knew that, but didnt realize just how well...Very Interesting how that historic aspect applies to december versus other months...I guess it makes sense having a strong temp gradient for frequent precip events, and being on the right side of said gradient..

Not sure what boston's snowiest january's and february's look like with the longer wavelengths than december, but id assume one of the 1994 months are in there...gradient pattern via.-EPO, -PNA, +NAO?

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The GEFS look wasn't that great until now either. It's definitely good to have multiple model suites agree. I think for a few days now we did mention that models were showing this.

You've said you were a visual person - perhaps you don't look at this product, then, because this has had a massive dip like this for a long while now.

That's what these products are good because they calculated via empirical orthogonal function which are very powerful characteristic derivatives.

The GEFs may not look this or that, but if if the orthogonals compute - it could also be that transgressor impulses are masking things.

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The GEFS look wasn't that great until now either. It's definitely good to have multiple model suites agree. I think or a few days now we did mention that models were showing this.

Plus the major change was having the NAO become more central or west based as opposed to east based. The different regions of the NAO might not have much of an effect on the numbers in those progs, but it makes a difference in our pattern. That's why I almost never look at those indice number forecasts and just look at the 500mb pattern.

But the agreement on a strong (at least originally) of an east based huge NAO block as far out as 180 hours on an ensemble mean is quite staggering: what a strong signal.

f180.gif

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You've said you were a visual person - perhaps you don't look at this product, then, because this has had a massive dip like this for a long while now.

That's what these products are good because they calculated via empirical orthogonal function which are very powerful characteristic derivatives.

The GEFs may not look this or that, but if if the orthogonals compute - it could also be that transgressor impulses are masking things.

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.

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Maybe Nate Silver can get the idiots in Washington to do something besides BS.

Right on track to a normal winter. What exactly is that? To me it's like the fall leaf change, gradually winter sets in N to S. A sustained period of solid winter conditions with some Arctic outbreaks, a cutter or 2 thaw then another solid winter period. As the dormancy of the leaf begins to end the process reverses. Thaws become more common the further S you are. Heard all about how we were due for a dead ratter last year, well we are due for a normal old fashioned winter.

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Yeah I definitely knew that, but didnt realize just how well...Very Interesting how that historic aspect applies to december versus other months...I guess it makes sense having a strong temp gradient for frequent precip events, and being on the right side of said gradient..

Not sure what boston's snowiest january's and february's look like with the longer wavelengths than december, but id assume one of the 1994 months are in there...gradient pattern via.-EPO, -PNA, +NAO?

Here are Boston's top 7 snowiest Januarys

71233120240339201030.png

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You've said you were a visual person - perhaps you don't look at this product, then, because this has had a massive dip like this for a long while now.

That's what these products are good because they calculated via empirical orthogonal function which are very powerful characteristic derivatives.

The GEFs may not look this or that, but if if the orthogonals compute - it could also be that transgressor impulses are masking things.

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?

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