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Big Snow threat, what will it do, part II


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I understand the whole feedback thing, but it can be real too. Unless you are a meteorological God who can see everything..it's kind of early to trash a set of guidance based on previous performance.

And unless you've got true blue indications of feedback....IMHO it's an overused term. Not only is it less likely to happen than in previous model incarnations I think when it does show up the effects are less severe on the overall model outcome. Sometimes we do just have "nearly" ideal solutions that just don't roll together into a blockbuster low.

I'm just surprised at the wording used on the 11p news based on today's guidance.

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The fact you fell for the Euro über bomb last night is well, rather unsettling, cripes even Kevin downplayed it.

Who ever said that I bought that EURO from last night?

You're either suffering from a reading comprehension impairment, or simply ignored the several posts I made regarding the likelihood that the EURO will back down somewhat.

That being said, I was hopeful that this would not devolve into a 6-8" cj, yes.....guilty as charged. Sue me.

Expecting 20"?

Negative.

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A quick question. There's a lot of discussion about directional trending in the time series of model outputs. What is the historical context here? Have successive model runs shown serial correlation in the way that has been suggested, historically? I'm just curious from a modeling perspective...if it's true that models have demonstrated serially correlated evolutions instead of random errors, why haven't the models been altered to presumably converge on the actual solution?

Sorry for the aside...just the musings of a non-met quant.

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And unless you've got true blue indications of feedback....IMHO it's an overused term. Not only is it less likely to happen than in previous model incarnations I think when it does show up the effects are less severe on the overall model outcome. Sometimes we do just have "nearly" ideal solutions that just don't roll together into a blockbuster low.

I'm just surprised at the wording used on the 11p news based on today's guidance.

 

And to me...I couldn't care what people call it since we are still in the timeframe where things shift around. Your best thing to do is take a collective look at all the guidance and make an educated guess as to what might happen. The GFS and Ukie I believe were way SE with the Feb blizzard last year only to come back so it can happen. However, the storm doesn't really form until 3 days from now and things can happen. We will see what the EC does. I won't be up.

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And to me...I couldn't care what people call it since we are still in the timeframe where things shift around. Your best thing to do is take a collective look at all the guidance and make an educated guess as to what might happen. The GFS and Ukie I believe were way SE with the Feb blizzard last year only to come back so it can happen. However, the storm doesn't really form until 3 days from now and things can happen. We will see what the EC does. I won't be up.

hmmmm

 

:whistle:

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Well hopefully the euro isn't caving too hard. The GFS op looked good and I would think it's similar or a bit better as far as the 00z euro op goes. The ukie and GEM have sh*t on themselves before in this range. I trust the GFS and Euro a lot more.

At this point I'm not thinking a big deal snow-wise is in the cards up this way. But what is pretty rare is going to be the combination of falling snow, wind, and cold. I'll probably struggle to get above 3 or 4 degrees Thurs with increasing wind and snow.

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And to me...I couldn't care what people call it since we are still in the timeframe where things shift around. Your best thing to do is take a collective look at all the guidance and make an educated guess as to what might happen. The GFS and Ukie I believe were way SE with the Feb blizzard last year only to come back so it can happen. However, the storm doesn't really form until 3 days from now and things can happen. We will see what the EC does. I won't be up.

Scott all I'm saying is just a week or two ago there was talk here and even in some AFDs and other outlets of feedback issues as it related to a weak front system stealing the show as that monster s/w dug down later. Turns out as we got closer that weak surface reflection was the real deal. More times than not in recent years that seems to be the case.

Pure feedback seems to be less of an occurrence than pure error at init. I haven't seen much on this one but if the euro ens were se of the op and all else is down in that area I would expect that's where tonight's op goes.

Good system we have no reason to complain.

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Scott all I'm saying is just a week or two ago there was talk here and even in some AFDs and other outlets of feedback issues as it related to a weak front system stealing the show as that monster s/w dug down later. Turns out as we got closer that weak surface reflection was the real deal. More times than not in recent years that seems to be the case.

Pure feedback seems to be less of an occurrence than pure error at init. I haven't seen much on this one but if the euro ens were se of the op and all else is down in that area I would expect that's where tonight's op goes.

Good system we have no reason to complain.

I don't disagree at all. I just think that we need to be careful assuming something is convective feedback. I think as mets we have a knack of knowing if it is or not, but we know the phenomenon exists too. In general when you parameterize convection so a model doesn't implode on itself, you do run the risk of false feedback. Luckily we are getting better at that.
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At this point I'm not thinking a big deal snow-wise is in the cards up this way. But what is pretty rare is going to be the combination of falling snow, wind, and cold. I'll probably struggle to get above 3 or 4 degrees Thurs with increasing wind and snow.

Every model has frigid temps. Pretty dam cool to see. I think each model has near 0F temps at ORH as snow is falling lol. Fairbanks comes to New England.

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Down time before the king....I was watching the GFS come out and it looked like it totally wanted to close at H5 and then it scooty scoot scooted out of here with that annoying L off NC and a burst of precip - feedback? - not sure i buy that...but I'm admittedly inexperienced here....gonna burn the oil to the king....

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Mesoscale models, like the Nam, are more prone to it, I think.

No what the NAM does is allow for convection to run wild because it's what we call non-hydrostatic. It's not the same parameterization like the gfs has. It's trying to mimic real life, but the problem with that is in real life we have checks and balances as to why the atmosphere isn't turned upside down. Sometimes the NAM doesn't fully get that.

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Will thought it was near -2 in January 2004 in a weak clipper with snow, but yes it's unheard of. It realistically might be single digits, but that is Sam cold.

 

 

I only recall the Jan '04 clipper being below zero...but it was a clipper. The larger SWFE in January 1999 started off as like 3F and snow I remember. And I also now recall around 5F and snow in January 1994 during one of those storms...but it didn't last long...usually on the front end.

 

I cannot recall near zero temps in the cold conveyor belt of a system around here. I'm sure its happened at some point, but it has to be extremely rare.

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Every model has frigid temps. Pretty dam cool to see. I think each model has near 0F temps at ORH as snow is falling lol. Fairbanks comes to New England.

So hard to keep daytime temps below zero these days. Last time I saw it personally was probably 1999 or 2000 up at Lyndon State. Would be interesting if I could pull it off. Getting frigid temps (day or night) through advection has been a tough task.

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No what the NAM does is allow for convection to run wild because it's what we call non-hydrostatic. It's not the same parameterization like the gfs has. It's trying to mimic real life, but the problem with that is in real life we have checks and balances as to why the atmosphere isn't turned upside down. Sometimes the NAM doesn't fully get that.

Dumb question.

 

What is the diff between that and convective feedback??

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