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December Medium/ Long Range


Terpeast
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16 minutes ago, Terpeast said:

I noticed the GFS ensembles trended weaker with the SW energy and this is becoming a wave almost purely driven by the NS.

New run:

gfs-ens_z500_vort_us_38.thumb.png.53920ce3694ba9618a630647a78a520f.png

 

Old run from 3 days ago:

gfs-ens_z500_vort_us_52.thumb.png.6baf22ee4d4a8819ab351b4f65c73175.png

Is this a good or bad thing?  Tbh, I don't need a huge storm... a simple 2-4 would do for me

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6 minutes ago, yoda said:

Is this a good or bad thing?  Tbh, I don't need a huge storm... a simple 2-4 would do for me

Hard to say. Some members still show a dec 8 wave, at which time we have the cold air to support snow. But how strong it is, and whether it’s even going to play out or get swallowed up by stronger energy out west, is still TBD. Unfortunately it’s been trending the wrong way for several days now.

The stronger system could potentially be a Midwest low, with coastal redevelopment. Best to hope for with that system is we have enough cold air damming to keep up the potential for a front end thump before changeover. Not loving the ice storm scenario, though. 

 

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1 hour ago, high risk said:

       I appreciate what you're trying to say here, and you were very much on the right track in saying that a small error at the start can lead to a massive error downstream 10 days later.     But you can't design a model like the GFS with "bumpers".     You can absolutely mitigate extreme solutions with bias-corrected, calibrated products, but the actual model solutions are what the model integration leads to.

Thanks for the clarification. By "bumpers" I meant the literal way the physics are implemented in the model, such as removing/correcting for known biases based on analysis of prior versions of a model.

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45 minutes ago, RedSky said:

How much kitchen sink for Philly?

 

Now minus the kitchen sink actually I like this look better for the fact we have a cold high up north introducing the cold air damming situation which is what we need with a NNE wind the surface blocking the warming off the ocean all about placement and timing of course. 

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4 minutes ago, TSG said:

Thanks for the clarification. By "bumpers" I meant the literal way the physics are implemented in the model, such as removing/correcting for known biases based on analysis of prior versions of a model.

One of my weather textbooks talks about how sensitive long range modeling is to any perturbation in conditions.  I can't remember which model it was, but one they discuss how even running the model twice in a row with the exact same starting conditions produced wildly different results just due to a difference in rounding of decimal places at a single calculation between runs.  

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1 hour ago, IronTy said:

One of my weather textbooks talks about how sensitive long range modeling is to any perturbation in conditions.  I can't remember which model it was, but one they discuss how even running the model twice in a row with the exact same starting conditions produced wildly different results just due to a difference in rounding of decimal places at a single calculation between runs.  

This is also mentioned in the Northeast Snowstorms books by Kocin and Uccellini. Some of our biggest "surprise" winter events were not detected until we got inside D4.

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10 minutes ago, Kevin Reilly said:

As for some models an example of this was January 7th, 1996, up here in Philadelphia.

Actually that is not true

LC who was the TV met on I believe Chanel 17 sniffed this out a full week in advance 

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2 minutes ago, bigtenfan said:

Actually that is not true

LC who was the TV met on I believe Chanel 17 sniffed this out a full week in advance 

Yes, as I said some models or Mets... because one local met in Philly who went to Mexico on a trip was calling for 2-4" two days before the storm was coming.... Yes, some Mets Dave Roberts WPVI and others had this pegged a week out.  I suppose the met then calling for 2-4" wanted to be different then. 

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1 hour ago, Weather Will said:

With our December snow chances on life support, WB's JB sees a stratwarm later this month that will cause an arctic outbreak in mid January...

Thought the strat PV is staying strong for the foreseeable future. Got any new data on that? 

And a strat warm is no guarantee of a cold outbreak here. It could spill to the other side or to Europe. We better hope that EPO stays negative if we get a strat warm.

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3 hours ago, winter_warlock said:

Well I live outside the baltimore beltway but I remember the whole county getting a major ice storm in Feb of 2007

In most of FFCO that storm was a sleet fest. about 6 inches of it.  Took place most of 13 Feb and overnight into the morning of 14 Feb.  Will never forget it.  My family and I moved to Bangkok that morning.  IAD was closed but we still had to check out of our hotel in Tysons and take our chances.  Eventually IAD opened and our flight to Tokyo was the first international flight to depart, albeit 2 hours late, which meant we missed our connecting flight from NRT to BKK.  It was hell getting a taxi (van) to pick us up at the Intercon big enough to accommodate the three of us and our 8 bags. 

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26 minutes ago, brooklynwx99 said:

even when the jet retracts, the lingering AK ridging will keep Arctic air in Canada and in the western and central US. it’s definitely AN for a bit, but it’s no torch

IMG_0322.thumb.png.c10e11ddad88a39f6d6cab4748116ffb.pngIMG_0323.thumb.png.2fa499d3740198883cdb69100e9bf572.png

 I think that lil warm up will be short lived and cold comes back  later in december.. unless I'm reading data wrong lol my wife says I'm wrong alot so... lol

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