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Oct 29-30 snow threat


Typhoon Tip
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5 minutes ago, Ginx snewx said:

A familiar post. We shall see. That's cold

Not snow S of the Pike there during those times. Yeah, there's some decent accums in the high terrain of S VT, SW NH, and W MA, but 10:1 will be difficult to achieve in a RA>IP>SN scenario. I'm not saying no snow or no accums...just take the under on the 10:1 maps.

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5 hours ago, OceanStWx said:

Ensemble cluster analysis has really bifurcated today. Almost all of the slower solutions are now EPS based, while the faster/flatter ones are all GEFS or CMC based.

Not shocking ... 

Each camp playing into their respective, persistent biases.   The GFS stretched...The Euro may have been too deep... ( maybe in both cases!) ..but, your description does hearken -

Furthering complaint:  I've noticed a marked wind velocity surplus in the GFS operational model at middle latitudes everywhere in the World - I haven't bothered to analyze the GEFs members  individually, or the mean therefrom, to determine if this is member specific but... the oper. version consummately ablates(ed) ridges in the summer, quite figuratively ( if not physically so...) rasping the tops off them with these 'rest state' huge westerly geostrophic winds in a grinding action ( jesus) ...like, over the tops of ridge arcs where the NVA should - if anything - offset and show some slacking.   75 kts 500 mb wind flow at the bottom of troughs would be 70 kts at 500 mb over the curvi-linear plain ... uh, okay.

What makes that peculiar and perhaps 'insidiously' hidden, is that the flow is endemically faster than normal everywhere - like in actuality... In simple turn of phrase, it's a fast hemisphere, being modeled too fast -

So, it is as though that natively fast-ish flow is 'enabling' the GFS and making it look right for the wrong reason...at other times, I'm seeing it have to correct back west with S/W translation timing when passing from latter mid into temporal boundary between mid and short range ... I have also noted, during mid August through September, the GFS was consistently 6 to as much as 15 dm deeper with hypsometric trough axis/quasi-closed cores trundling through the flow over ~55 to 70 N through Canada, comparing to all other guidance.  It may be that integrating depth against the background subtropical canvas of summer giving rise to velocity - but this was also all true in winter last year.    

These are glaring biases that I really hope I get to see 'some' form of atonement as we near a release time for this Para- G/beta version. ...A model with a fast bias ... cloaked ( circumstantially ) by virtue of a hemisphere that really has been speeding up... 

And the global eddy really is mechanically faster - there's a reason commercial airline industry has been so frequently clocking historic, when not above average, ground-based velocity records when flying west to east over oceanic basins and over continental landmass.. everywhere.   There was one flight last winter or perhaps the previous ... ( I think 3 hrs and 50 min rings a bell but don't quote me ! ), between LGA and LHR over in London - some sonic speed relative velocity.  It's because they're up around 200mb level taking advantage of a gradient saturated hemisphere in the winters ...and I'm virtually convinced it is the expanding HC into the lower Ferrel latitudes ...causing height compression and anomalously high/balanced wind response. But, it's doing other things... 

For one, it's distorting the R-wave residences and making the entire systemic 'gears' around the hemisphere less capable of blocking - or blocking becomes more ephemeral when it does occur.  I think one of the reasons why we are seeing lower -NAO frequencies in the last 10 years, when the multi-decadal EPO/AO/NAO is/was supposed to be tipping negative, is because this velocity richness is impeding/distorting the 'fragile' nature of the NAO domain space... It's suppositional at this point - but may be intuitive in a purely conceptual wave-mechanical sense.

But, it is also causing storm behavior/morphologies that are subtle...at other times more gross.  There are more 'busted ravioli' type precipitation events ... blown up and smeared across the synoptic plate, where we have lows in multiple nodes along baro-c axis .. Also, often bigger temperature variances astride boundaries in transition seasons ... 80 next to 30 with no storm in a vicinity..because the flow over top is so screaming fast no S/W fan mechanically force jets to even initiate over frontal slopes keeping them stable...  But when they do, overrunning becomes favored over the Norwegian Model variation/classic.  And, then! When the latter does occur, interestingly we are seeing historically deep pressure cores ... it's like it takes more to overcome a canvas of velocity, but when it does, the other steeper gradients ignite bombs plumbing to category 3 hurricane likeness...  ( See NS/NF last year for example..), and they tend to be fast movers. It's like the sped-up flow is favoring less mid grade cyclones ... "in low"  ( haha)  of either overrunning or hideously violent bombs. 

Anyway, this thing with the NAM solution at 00z actually is a singular example that exactly fits this above... If that solution comes back --> materializes ... you have a near historically deep NJ Model bombogen running out under LI ... And, historically deep anything after mid October with a marginal atmosphere is going to over-produce in the Z range of the sensible sounding... It's just a potent system overcoming a fast flow, and such that it operates closer to the upper complexion of power and expression and we get tarred and feathered for it... 

These are like hypertension ... silent killers :)  ... I know these observational trends are true et al, ...I am not entirely certain it is climate change related, but strongly suspect it is so... And, it's probably endemic to this part of the acceleration therein... If the HC continues to expand...the Ferrel circulation will start to break down - gradient slackens and we're warmer overall < 60 N ...  But, by then ...permafrost has lost it Methane and we're really in a world of shit... because the Oceans are probably no longer fixing C02 as proficiently ...and that's the ball-game.   It's easy to say that won't happen in our life-times ...but that feels like a cozy euphemism and/or bargaining/evasive tactic  ... particularly when the changes we are observing in the environment now, have outpaced the climate modeling from the 1990s by some 20 to 30 years! This fact should not put bricks in the foundation of people's confidences as to where this shit's going - but... this whole missive is now a 1,000 words more than you wanted to read if you've even gotten this far so - I appreciate your candor if you did.   lol 

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26 minutes ago, PhineasC said:

Whatever happened to the legendary north trend?

Still some time for it. Though this pattern has some things working against it too. Zeta makes landfall in about 36 hours....which means that in probably 24 hours, models will be able to handle it better. It should influence the downstream ridging/phasing potential. If it runs too far ahead of the bowling ball currently in the southwest, then it will likely produce a flatter solution, if it is closer, then we'll probably see a more amped solution.

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2 minutes ago, ORH_wxman said:

Still some time for it. Though this pattern has some things working against it too. Zeta makes landfall in about 36 hours....which means that in probably 24 hours, models will be able to handle it better. It should influence the downstream ridging/phasing potential. If it runs too far ahead of the bowling ball currently in the southwest, then it will likely produce a flatter solution, if it is closer, then we'll probably see a more amped solution.

Yeah, it seems like the models would have some trouble with how to tie a landfalling hurricane into this picture. Definitely adds a complex factor.

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21 hours ago, dryslot said:

Yeah, The tropical connection may play the wild card in all this in the end, Its a tricky situation, Being early on, Rooting for something more amped then modeled to track more NNE, A weaker scenario would shift this south and more suppressed.

Zeta will decide this systems fate, Over night runs were much weaker south as it gets shunted more south.

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Guys ...some people like reading - 

you're not one of them. Fine - don't read it.  

If Chris doesn't give a shit beyond the first sentence or two...that's okay too - but that's who it was addressed to. 

You're welcome to read that take on things if you like ... 

From a laptop/PC interface, it is not as long as you think - it's just that on a phone it 'looks' overwhelming -

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Just my opinion, but I don't think Zeta really does much -    

It's plausibly dumping a huge diabatic source into this thing, but... the real difference between ...say a 00z NAM vs a 00z GFS oper. event, appears to be subtle nuances in the timing/orientation of the N and S/ stream, as the latter begins to integrate in a phasing/.. proficiency therein.   

The NAM was superb in harmonizing...

The GFS was assonant - rotating southern stream positively sloped/and/or absorbing it in a velocity shearing mess.   Positive slope/absorption = less DPVA ...   These large synoptic wind stream variances would play out regardless of a wayward Zeta running up out ahead of it or not. 

Now... if the NAM solution comes back/or plays out... yes, having Zeta be absorbed into it ...or having its moisture infused ..etc., that would add to PWAT and other complex feedbacks ...but I suspect in order of importance, if one want to get a more upper tiered system ...do not do a GFS 500 mb evolution from 00z .. and that is independent of Zeta

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