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NYC/Tri-State Area: Stumbling into January Disco


earthlight

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In the longer range, the GFS Operational really kills the AO. In fact, it brings it to near record-low levels. However, if you use the bias-adjusted progs you can see that solution is not totally supported. That being said, it looks like we are starting to gain some big time support for the AO dropping below -1 to -2 near Day 10 and beyond.

gfs_ext_ao_bias.png

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In the longer range, the GFS Operational really kills the AO. In fact, it brings it to near record-low levels. However, if you use the bias-adjusted progs you can see that solution is not totally supported. That being said, it looks like we are starting to gain some big time support for the AO dropping below -1 to -2 near Day 10 and beyond.

John, having the ao go negative decently can help save us from the pacific not cooperating, and at least help not go completely into the crapper again, right?

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John, having the ao go negative decently can help save us from the pacific not cooperating, and at least help not go completely into the crapper again, right?

It can make things a little easier for us, definitely. The Pacific doesn't look bad at all in the long range -- I guess you can argue that it's not "cooperating" because in an ideal situation, we'd want a big PNA ridge etc. But having the -PNA and the ridge near the Aleutians extending towards the Pole is not a terrible look for us.

What comes into play if we get that type of setup, is the Atlantic side. It becomes important for us to see some semblance of high latitude ridging in the North Atlantic extending towards Greenland. Having that in place can help us tremendously if we do in fact get a -PNA type pattern with a N-S gradient of arctic air to the east of that.

What likely would transpire is an active pattern out west with plenty of shortwaves moving east across the CONUS. As you can imagine there would be a sharp gradient across the Northern 1/3 of the CONUS with the new availability of arctic air. However, without any blocking (or in the worst case, a +NAO), we could very easily be on the wrong side of the gradient as the storms move east. So that would be the main thing I would look for through the long range, if you're looking for a snowy pattern.

I think it's already set in stone that we are heading towards a generally colder pattern, with the re-adjustments in the Pacific and the forecast dip of the AO. But exactly how snowy it ends up, even through February, will likely be determined by the cooperation on both the Pacific and the Atlantic side...not just one of the two.

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It can make things a little easier for us, definitely. The Pacific doesn't look bad at all in the long range -- I guess you can argue that it's not "cooperating" because in an ideal situation, we'd want a big PNA ridge etc. But having the -PNA and the ridge near the Aleutians extending towards the Pole is not a terrible look for us.

What comes into play if we get that type of setup, is the Atlantic side. It becomes important for us to see some semblance of high latitude ridging in the North Atlantic extending towards Greenland. Having that in place can help us tremendously if we do in fact get a -PNA type pattern with a N-S gradient of arctic air to the east of that.

What likely would transpire is an active pattern out west with plenty of shortwaves moving east across the CONUS. As you can imagine there would be a sharp gradient across the Northern 1/3 of the CONUS with the new availability of arctic air. However, without any blocking (or in the worst case, a +NAO), we could very easily be on the wrong side of the gradient as the storms move east. So that would be the main thing I would look for through the long range, if you're looking for a snowy pattern.

I think it's already set in stone that we are heading towards a generally colder pattern, with the re-adjustments in the Pacific and the forecast dip of the AO. But exactly how snowy it ends up, even through February, will likely be determined by the cooperation on both the Pacific and the Atlantic side...not just one of the two.

Nice, thanks. Over the years ive learned a lot about the different indices and such, but im still trying to learn how they all interact with each other, and how their strength affects our weather.

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The whole pattern change window is starting to slowly close by the way. Obviously a pattern change can happen multiple times a year but obviously in this winter the term pattern change means the chance for snow and that window is closing slowly. It's January 8, any change may happen January 15-20 and there is no guarantee. Once we enter February, the chance for snow is going to play against climatology, especially after mid February so it's only a matter of time.

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Thank you, we're all quite aware of the stakes. You do realize it snowed in October this year right? We average plenty of snow from mid February on and can get plenty of snow in March

The whole pattern change window is starting to slowly close by the way. Obviously a pattern change can happen multiple times a year but obviously in this winter the term pattern change means the chance for snow and that window is closing slowly. It's January 8, any change may happen January 15-20 and there is no guarantee. Once we enter February, the chance for snow is going to play against climatology, especially after mid February so it's only a matter of time.

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Thank you, we're all quite aware of the stakes. You do realize it snowed in October this year right? We average plenty of snow from mid February on and can get plenty of snow in March

nothing is working against snow in February, some of our best storms have come or formed in this month.

Its the snowiest winter month by far.

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The whole pattern change window is starting to slowly close by the way. Obviously a pattern change can happen multiple times a year but obviously in this winter the term pattern change means the chance for snow and that window is closing slowly. It's January 8, any change may happen January 15-20 and there is no guarantee. Once we enter February, the chance for snow is going to play against climatology, especially after mid February so it's only a matter of time.

The pattern is changing right now as john as said but that doesnt necassarily mean its going to snow around here does it?

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The whole pattern change window is starting to slowly close by the way. Obviously a pattern change can happen multiple times a year but obviously in this winter the term pattern change means the chance for snow and that window is closing slowly. It's January 8, any change may happen January 15-20 and there is no guarantee. Once we enter February, the chance for snow is going to play against climatology, especially after mid February so it's only a matter of time.

Disagree about the chances for snow diminishing in Feb. If a favorable pattern were to emerge during the timetable you suggested, i think the chances for building a lasting snowpack are diminshed are compared to last year, but snow events in a favorable pattern in Feb are not against climo around here. After two months of waiting, at least some parts of the country are going to see big changes.

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It seems like the pattern will change to seasonal or even slightly below which give most of us especially from philly north and maybe dc to get snow.

With the NAEFS temperature anomaly forecast, that prediction might have to be called into doubt.

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I believe the NAEFS will adjust if the data keeps supporting change.

Relative to the means, the third week of the month should be colder than last week and this coming week.

Any bump up in the PNA would allow a piece of colder air building up in Canada to come south. The details

of any such amplification will have to wait until we get much closer.

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