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October 2020 Discussion


HoarfrostHubb
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2 hours ago, moneypitmike said:

What year was the big Halloween nor'easter?  93?

Halloween nor oh I think you mean the "perfect storm" - which I refuse to capitalize because of the cartoon provinciality in calling it that ... ? 

That was also Sandy ... btw -

Not that anyone asked or needs the lessen ... but all these fit into that ilk, really.  There are no true reduxes in nature; analogs are what they are but are never 100% 

Anytime the large scale circulation evacs a TC out of the deeper SW Atl Basin tropics/subtropics, pulling it up to where it is vulnerable to ... and exceptionally rarely succeeds, merging vorticity/physical fields into either a severing mid and upper level cold core low ..or trough capture in general, you are essentially dealing with similar ( to varying degrees) area of event spectrum... 

I've been posting about this the last couple days ... the autumn is the time of the year that this is likely to happen if at all, and amid the likeliness ... most of the time it is just in the models.  For one, hurricanes need to be present as an initial concern -duh.. But, particularly the mid to latter autumn, when we start to see trough incursions probing deeper in latitude over eastern N/A, do we pass through a touchy modeling period of time.  Every year we see this .. Usually - well, used to be ... the GGEM was the more guilty. Back 15 years ago, that model couldn't resist! Every cycle between ~ Oct 10 and Nov 21 seemed to wrapped up a D12 category 3 hurricane inside a rampart of baroclinic moating .. It was like the physics of that model had a duality at times.  But, you know... it was just taking a real phenomenon that can happen in nature, and assuming it was happening far more frequently than it ever does ( in the virtual realm of its performance ).   Out in the real world...return rate's prooobably like I don't 1::70 years for snow involvement?   Just spit ballin' .. I don't think we very frequently see full on fusion deals - certainly not 1804's ...my god.  

( so I guess in that sense, we are due?  :facepalm: ... unless Sandy counts.. )

But, anyway..  if the perfect cartoon ( it's almost like the era was still a bit green/bush-league to the notion of fusion phenomenon so that perfect jazz had more cache ) is the storm you're thinking of the capture of hurricane Grace into a cut-off low S of the Maritimes was October 28-30th of 1991 - 

otherwise, I don't believe I recall a 1993 nor'easter other than that other rogue event  that also got the notorious 'storm of the century' earlier that March. 

 

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27 minutes ago, CoastalWx said:

Getting back to Friday night and Saturday, that is a sweet spot at 700mb in VT. You have a big thermal gradient from west to east. If you want surprise snow, that will do it. 

The weenie snow maps seem extra weenish this time of year.  It’s like counting precip as snow with SFC of 37-40F and 925mb around 0C.  Many of the snow maps certainly don’t line up with what soundings would lead you to believe... seen a lot of snow maps shared on social this morning in ski country lol.

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1 minute ago, powderfreak said:

The weenie snow maps seem extra weenish this time of year.  It’s like counting precip as snow with SFC of 37-40F and 925mb around 0C.  Many of the snow maps certainly don’t line up with what soundings would lead you to believe... seen a lot of snow maps shared on social this morning in ski country lol.

Yeah I mean in your main area of Stowe at 700', you need everything to work out. But resort level, and especially above 2K...that might get interesting. Obviously lots of details to work out. One thing that might help....especially western slopes, is the NW CAA while upsloping at the same time.

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31 minutes ago, CoastalWx said:

Man the hammer drops in the Plains. That is classic Nina. 

Yeah...I'm seeing this as error prone in both direction - making it difficult to parse out a "correction vector" if you will ... heh

seriously, ..the Euro somewhat more than less subtly at time, carries on with a tendency to carve the flow back W too steeply at Ds 5 .. particularly D7 + ... It then ends during Ds 8-9-10 with either too much end-state meridional structure, or... has to pass through one that was too much so ...correcting back flat by 10 - either variation, I see the Euro do that all the f'n time. 

Yet, as you guys joked last week ( and I agree frankly ..) you go to any verification scoring database and it's like all accolades and polish ... Maybe it is just something that it does over the box of 120 W - 70W by 40 N ...so inbetween the seams of it's testing domain ??? Just an idea  - 

Anyway, what the Euro is doing is dropping the hammer - perhaps - too mightily in keeping with that tendency.  So, we end up with a historic warm spell in the OV and NE regions.  There's some flirtation out there with a BD but frankly ... even though BDs are a fact of New England life and we should expect them ( regardless... ), that deep layer general circulation set really does not support a very convincing one... Otherwise, that's a recipe for the latest hottest October temper ever between Dayton OH to Boston somewheres...  It had this on a run ... yesterday - I think it was the 12z... So, it's been fiddling with this... But again, I need to really see this inside of D5 to bite because the Euro tends to have to go through said correction two-step - not always but we'll see. 

Thing is, ... you get to 79 on D6 in that with that warm front ..dry warm fropa too... But the atmosphere then starts caching kinetic charge ... and nights start elevating launch pads...such that by D3 of that stretch... you could be in the mid f'um 80s!   ... relative to that animation it has...  That's obviously a half bubble off the plumb line to go out and forecast that at this range, but, that's relative to this model run. The 2-meter depictions on that cycle definitely shirk the potential - it would be warmer D6.5 out to the end of that particular run. 

Meanwhile...the GFS ... it's bias is the other direction.. I mean, perhaps literally too - not just figuratively. It has a velocity surplus that is being missed by everyone, because the flow everywhere is also ... in a velocity surplus.  Really incredible as a separate bamboozling phenomenon... but I'm onto the damn thing.  SO, it ends up stretching the longitude of wave features so dramatically... it either ablates warm penetrations, or... gets so extreme beyond D6 that it flips into the next wave cog and the pattern rolls into the next configuration entirely... And that is almost like what is happening here when straight up comparing the D9 Euro to the GFS from 00z ... That synoptic variance would have almost a 25 F sensible difference/consequence for the NE on that run.  

We'll prolly end up somewhere in between ... which is banal and uninspired boring weather -

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5 minutes ago, powderfreak said:

The weenie snow maps seem extra weenish this time of year.  It’s like counting precip as snow with SFC of 37-40F and 925mb around 0C.  Many of the snow maps certainly don’t line up with what soundings would lead you to believe... seen a lot of snow maps shared on social this morning in ski country lol.

I like to wait until I can get the NAM 3K hourly soundings otherwise using a 6hr GFS sounding with accumulated precip that has already happened gives a false sense that it had been cold enough to support snow above a certain elevation. Plus, I'm not even exactly sure if my hPa math is right. I usually ballpark 900 at about 3250' and 850 at about 4500'. That being said, it looks like some snow above 3000' and MWN will get dumped upon.

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18 minutes ago, CoastalWx said:

Yeah I mean in your main area of Stowe at 700', you need everything to work out. But resort level, and especially above 2K...that might get interesting. Obviously lots of details to work out. One thing that might help....especially western slopes, is the NW CAA while upsloping at the same time.

Oh there’s no way it snows below 1500ft IMO, not a chance unless it’s like May 11th last year when it was ripping 0.20”/hr in the MVL bucket and after 4 hours of that type of rates it dynamically cooled to paste down low.

I like 3,000ft and higher right now for anything real fun. 925mb is very marginal throughout on all models.  Even in heaviest precip that layer is only barely touching 0C on Euro/GFS.  GGEM keeps it like +1C to +2C.

Need to see a well defined CCB develop for any chance at snow under 3kft.

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1 minute ago, WinterWolf said:

I notice you’re making trips to Pittsburg NH frequently.  Got a place up there?  Good sledding area in the winter for sure. 

No, lol. I mean he is going. I have never been there. I go to Winnipesaukee because my folks have a place there, although more like a cottage.

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13 minutes ago, ORH_wxman said:

Steadily trending east

Yeah the Euro and NAM bias of being slow and amped getting corrected quickly. 

Ride the GFS these days.  It’s been on that for days now.  Go East young man.  Crazy how good the GFS has been the past 4-6 weeks, have to toss the Euro these days.

GFS has gone wide right of the Cape past two runs.  Here’s 6z:

E0846800-561D-4723-B340-2AC1D073CD5F.thumb.png.34776b57f69d274e41086755ec4c3d0e.png

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Just now, dryslot said:

Looks like 1"+ for the whole region on rainfall with some seeing 2" outside of areas that may see some snow.

Yeah this system is another very wet one when you factor in the stalled boundary and frontogenic forcing along that, then the follow up coastal low.  Plenty of QPF.  The stalled boundary even looks like it might temporarily become a warm front going back the other way for a time in NNE ahead of the surface low.  

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