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NNE Fall Thread


dryslot

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17 minutes ago, CoastalWx said:

Right, that's my point. It's the most ridiculous argument ever. That's fine in marginal rates, but given the issues of power outages and tree damages etc that the AFD was mentioning, warm ground is the least of the issues. Latent cooling is a powerful process. 

Yeah I've also seen plenty of times where at the snow level you don't get much ground accumulation but the trees can have 3" on them.

I see a lot of these events mostly because I've got 3000ft of verts for the snow line to end up somewhere in that zone.  

What Will said about visibility and rates is very true in these situations.

I'm expecting something like sloppy 34F 1sm -SN at 1,500ft that struggled mightily on the warm ground (maybe some treetop accums) while at 2000/2500ft it's ripping 1/4-1/2sm SN with much better flakes than the pouring white rain at 1500ft.  

The other one from Will is the constant rates...upslope can be very squally and or pulse in nature.  If it's constantly going from heavy to light that ground will eat it from the bottom up.  That's where you get the difference between 5.5" vs 8" if the ground was frozen in January.

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13 minutes ago, ORH_wxman said:

 

Probably the single most useful sentence to use as a baseline about warm ground is:

-Warm ground impeding accumulations is almost entirely rate-dependent

You can just pin that on the 10 commandments of forecasting right below "Thou shalt not forecast over 12" in a SWFE".

Yeah see when I read the warm ground comments I assume that's implied.  Of course CCB putting 0.2"/hr QPF snow will stick.  But the 0.05"/hr in the bucket can struggle mightily and the warm ground will make a difference.

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5 minutes ago, powderfreak said:

Yeah see when I read the warm ground comments I assume that's implied.  Of course CCB putting 0.2"/hr QPF snow will stick.  But the 0.05"/hr in the bucket can struggle mightily and the warm ground will make a difference.

I would also argue too that 34F light snow is inherently tough on accumulations. Even in mid winter. That's hard to accumulate. Warm ground makes it worse but you probably aren't piling up 6" of fluff on .3 of qpf at 34F. 

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Looks great Alex.   I think the brightness is good.  If you bring up the brightness then the sky will always look white.  Much sharper than the other cam.  Can you raise the view up just a bit so the top of the ridge is in view?   That would be nice to see especially if the snowline is someplace up there.

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7 minutes ago, ORH_wxman said:

I would also argue too that 34F light snow is inherently tough on accumulations. Even in mid winter. That's hard to accumulate. Warm ground makes it worse but you probably aren't piling up 6" of fluff on .3 of qpf at 34F. 

Ha funny you say that, I was thinking of a couple JSpin events where he had some real good ratios above freezing on the elevated snowboard.  I can picture his photos, I'm trying to remember the dates. 

We can go around in circles haha.  I do think the warm ground hurts in some circumstances and not in others.  It's a factor in accumulation forecasts depending on the set up.  I'm sure this weekend I can find some elevation band where frozen ground would've helped haha.

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9 minutes ago, wxeyeNH said:

Looks great Alex.   I think the brightness is good.  If you bring up the brightness then the sky will always look white.  Much sharper than the other cam.  Can you raise the view up just a bit so the top of the ridge is in view?   That would be nice to see especially if the snowline is someplace up there.

Done! Might need a few trees to come down to see the rigde well ;)

Snowstake will go in the round thing, front right. I made it with large numbers, should be easy to see. I won't be plowing this side in the winter (there's an entrance on the other side), so it will be pretty untouched (albeit exposed to wind). Would be cool to be able to see the other side on the cam - you can see the ski trails, but can't have it all!

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31 minutes ago, ORH_wxman said:

I would also argue too that 34F light snow is inherently tough on accumulations. Even in mid winter. That's hard to accumulate. Warm ground makes it worse but you probably aren't piling up 6" of fluff on .3 of qpf at 34F. 

That's what I mentioned earlier. Even in January that's tough. 

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13 minutes ago, powderfreak said:

Ha funny you say that, I was thinking of a couple JSpin events where he had some real good ratios above freezing on the elevated snowboard.  I can picture his photos, I'm trying to remember the dates. 

We can go around in circles haha.  I do think the warm ground hurts in some circumstances and not in others.  It's a factor in accumulation forecasts depending on the set up.  I'm sure this weekend I can find some elevation band where frozen ground would've helped haha.

That's tough to get good ratio above freezing. Maybe his thermo is slightly off. You can have good ratios as the snowflake production is occurring, but temps above freezing will affect ratios at the surface over a period of time. Unless you had a 10min squall and the time above freezing didn't have a huge effect yet.

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22 minutes ago, powderfreak said:

Ha funny you say that, I was thinking of a couple JSpin events where he had some real good ratios above freezing on the elevated snowboard.  I can picture his photos, I'm trying to remember the dates. 

We can go around in circles haha.  I do think the warm ground hurts in some circumstances and not in others.  It's a factor in accumulation forecasts depending on the set up.  I'm sure this weekend I can find some elevation band where frozen ground would've helped haha.

 

An elevated snowboard would def be immune to warm ground temps (and the white surface will especially help in a marginal event). I'm not arguing the warm ground has zero effect...it definitely does when the snow is light...I'm simply saying that when you add in variables like a 34F temp, you are adding hostile conditions for snow accumulations outside of the warm ground factor. Start adding in other variables too like partially melted flakes where you are straddling the snow level, and that will inhibit accumulations too even if you had a frozen ground.

 

I typically notice the warm ground the most in like a 28F light snow event in November...rates never get very high and it's almost like slush in that initial layer and it takes its toll. I end up with like an inch and think "I porbably would have had 2" in mid winter or even a little more".

 

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49 minutes ago, ORH_wxman said:

 

An elevated snowboard would def be immune to warm ground temps (and the white surface will especially help in a marginal event). I'm not arguing the warm ground has zero effect...it definitely does when the snow is light...I'm simply saying that when you add in variables like a 34F temp, you are adding hostile conditions for snow accumulations outside of the warm ground factor. Start adding in other variables too like partially melted flakes where you are straddling the snow level, and that will inhibit accumulations too even if you had a frozen ground.

 

I typically notice the warm ground the most in like a 28F light snow event in November...rates never get very high and it's almost like slush in that initial layer and it takes its toll. I end up with like an inch and think "I porbably would have had 2" in mid winter or even a little more".

 

Nicely stated Will. Agree. 

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42 minutes ago, wxeyeNH said:

Meanwhile an area of moderate rain is approaching Central NE.   I was expecting a few light showers this evening but not expecting this.  Maybe a nice little bonus?

.36" in the gauge so far from that batch that's heading your way..might end up between .4-.5" when its done.

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Might have to dust off the old snowboard to get my first T in the books, we'll see.

Also saw my first black bear since moving to VT, but didn't think I would be seeing the thing in my frickin' garage in broad daylight! My garage door was open yesterday and around 11am I opened the door from inside to go into the garage and he was about 10 ft away, going though something (I didn't have garbage cans in there) He took off right away and actually ran down the road and not into the woods which I though was strange. It wasn't very big, but still kind of startled me a bit. More freaked out that I could have been outside and walked into the garage and I would have been blocking his exit, not sure how he would have reacted.

 

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2 hours ago, powderfreak said:

Ha funny you say that, I was thinking of a couple JSpin events where he had some real good ratios above freezing on the elevated snowboard.  I can picture his photos, I'm trying to remember the dates. 

We can go around in circles haha.  I do think the warm ground hurts in some circumstances and not in others.  It's a factor in accumulation forecasts depending on the set up.  I'm sure this weekend I can find some elevation band where frozen ground would've helped haha.

Never had significant accum at my place with temps above 32, but 10/29/2000 saw 4.5" of 28-to-1 snow (0.16" LE) at temps right around that mark.   Packed nicely but the snowballs were too light, even when squeezed hard, to travel far.

If I see catpaws at my place next week, I'll call it a win (especially if they arrive following 1"+ rain.)  The reverse of CAD is downslope.

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1 hour ago, backedgeapproaching said:

Might have to dust off the old snowboard to get my first T in the books, we'll see.

Also saw my first black bear since moving to VT, but didn't think I would be seeing the thing in my frickin' garage in broad daylight! My garage door was open yesterday and around 11am I opened the door from inside to go into the garage and he was about 10 ft away, going though something (I didn't have garbage cans in there) He took off right away and actually ran down the road and not into the woods which I though was strange. It wasn't very big, but still kind of startled me a bit. More freaked out that I could have been outside and walked into the garage and I would have been blocking his exit, not sure how he would have reacted.

 

Sure it wasn't just a dirty hippy left over from the Rainbow Family Gathering this past summer?  That wasn't too far from you was it?

Rainbow.jpg

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6 hours ago, powderfreak said:

Yeah it's all rate dependent.  I also look at warm ground as maybe the difference between 6-8" and 3-5"...maybe you lose .1-.2" QPF allowance on getting that initial layer down.  I guess the thing with the warm ground is how that's been used in several big time events to justify NO accumulation over the past few years.  I look at it like it's going to snow but even steady 0.5-1"/hr would obviously benefit from cold ground.  But it won't make or break the event, just something to consider when nailing down accums.  I'm sure on Sunday I'll be able to find examples of where a colder ground surface would've helped at some elevation band.

Anyway, in my mind the snow threat is with upslope for here.  The deform will be too far northwest to me, taking a model blend.  But that backside wind dynamics, strong closed mid-level lows, and decent low level moisture will get a good response from the mountains at some point.  It'll matter more if it can get going for 6 hours or more like 12 hours in a steady state.  

That's where I come out on the discussion. You can cite many examples of when heavy snow fell at 34F and did damage. Sure.  The point I'm making is the one Scott makes here. When we talk about totals I think you have to knock a bit - 1-2" inches is about right for a storm like this - off the modeled totals due to the snow melting on warm wet ground.

 

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24 minutes ago, adk said:

That's where I come out on the discussion. You can cite many examples of when heavy snow fell at 34F and did damage. Sure.  The point I'm making is the one Scott makes here. When we talk about totals I think you have to knock a bit - 1-2" inches is about right for a storm like this - off the modeled totals due to the snow melting on warm wet ground.

 

Yeah that's all...not that it can't or won't accumulate.  But when you have a sloppy muddy mountain from 2" of rain and a summer of warmth, we've seen it pound for 8 hours and leave 3-4" on top of half a foot of mud.  If that ground is frozen in mid January that same 8-hour blitz brings 8-10".  

Both of us are definitely envisioning plenty of mountain events in the autumn like that.  But that may be different than suburban well drained and short cut lawns.  Mountain trails run wet as a default.  Colder and frozen ground certainly helps.

 

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