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Major Nor'easter snow storm (possible top 20) Noon Wednesday-Noon Thursday Dec 16-17, 2020


wdrag
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2 minutes ago, NJwx85 said:

You literally cherry picked the warmest panel. It's a little dicey 00-04z but the warm layer gets pushed back.

Sincere thanks to both of you. If it wasn’t for the “nose” description I might have never figured out how to read this thing. My own nose looking like that sorta helped. As always ....

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11 minutes ago, weatherpruf said:

You should have seen the Jan 87 storm. It was evil. Not the biggest storm, but so intense i could not see beyond the tail lights in front of me for two hours. Had no idea where I was even going.And that was mid-day.

The night only 334 fans showed up to a New Jersey Devils game at the old Brendan Byrne Arena.  Think it took until about 9 PM for enough Devils to show up so they could start the game. 

New here.  Looking forward to following the storm and the upcoming winter with all of you.

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It's fascinating really: we have we have the Euro/GFS (snowy) vs. CMC/UK (snow/sleet) on the globals and HRRR (snowy) vs. NAM (snow/sleet) on the mesoscale models - almost 50/50 to me. Anyway, 18Z HRRR ftw!  Or 18Z NAM for the...sleet, I guess (still way better than rain) - posted both the Pivotal/Tidbits maps so people could see the difference (sleet counted as snow by TT, which is ok if one uses both, as per below).  

Also, I've posted about sleet in models and sleet impact in depth before, but worth a repost, IMO (this is from last night, elsewhere, but applies still).  Briefly, Pivotal only reports pure snow and TT reports snow + sleet, but all counted as snow.  One can't figure out how much of the TT frozen equivalent is snow vs. sleet directly, but you can if you compare the Pivotal and TT maps, as long as you use the 10:1, snow:liquid outputs.  Pick a spot like Philly, which shows 4.4" of snow on Pivotal and 13.4" of "snow" on TT.  Since both are reporting the amount as 10:1 that means the Pivotal LE is 0.44", while the TT LE is 1.34".  If you then subtract out the snow from Pivotal from the TT total, that means that 0.90" of that LE is sleet and if one assumes that the sleet has a snow:liquid ratio of 3:1, then that is 2.70" of sleet by depth. 

In theory, that that 4.4" of 10:1 snow and the 2.70" of 3:1 sleet would equal 7.1" on the ground, but often sleet falling on top of snow will compact the far less dense snow underneath it (I measured that effect in the linked post) by 25-50%, so one might get a snow/sleet depth of 5-6" and not 7.1".  The opposite is not true, i.e., snow falling on top of sleet will not change the depth of the sleet, so you'd see 7.1" on the ground for this case.  

Given my long history in emergency preparedness, including being in charge of snow removal crews for the site where I worked for 30+ years (5000 person site in Rahway - Merck), that's why I like the TT maps better from that perspective, since frozen mass and not depth is far more important with regard to plowing/shoveling/snow removal, as well as with regard to impacts on the road, meaning 1.34" of frozen LE mass is just as impactful whether it's 13.4" of 10:1 snow or 4.5" of 3:1 sleet or anything in-between.  The one exception to this is visibility, as sleet barely affects visibility. 

That's why, to me, the Pivotal map of 4.4" does not tell me at all what the impact really is going to be, while the 13.4" of "snow" (which is really a snow/sleet mix) from TT tells me what the impact will be.  I get the aesthetics part of it, but from a meteorology perspective, since so much is based on preparing the public for impacts, I've always been surprised and disappointed that mets don't report total frozen mass at least alongside frozen depth.  Maybe more than folks bargained for, lol, but hope it's useful. 

 

sn10_acc.us_ma.png

 

sn10_acc.us_ma.png

 

namconus_asnow_neus_10.png

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1 hour ago, liwxfan said:

Fellow north shore Suffolk peeps out there..how you feeling? This should be pretty interesting for us..excited to see how it unfolds here in Miller place

Port Jeff Station here...feeling pretty good about where we are. Looking forward to the snow pounding down for a few hours. Think the damage will be done before any changeover, if that happens.

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1 minute ago, wdrag said:

Can everyone live with this??? I think it's realistic, with another 1-4" coming I80 LI after 5AM and 3-6" coming after 5A n of I80 in far nw NJ/ne PA and se NYS CT. 

 

We'll see if this comes down a bit in future cycles?

Screen_Shot_2020-12-16_at_3_26.58_PM.png

no, shift those purples se.

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Just now, wdrag said:

Can everyone live with this??? I think it's realistic, with another 1-4" coming I80 LI after 5AM and 3-6" coming after 5A n of I80 in far nw NJ/ne PA and se NYS CT. 

 

We'll see if this comes down a bit in future cycles?

Screen_Shot_2020-12-16_at_3_26.58_PM.png

If that pans out, I guess MMU does all right. (If I could call my 9 year self back in 1991, and let him know that I know some people - like myself - who are a bit meh on a potential 12" to 18" storm because some sleet might mix in and it's not as great as the several 20"+ storms we've had over the past 25 years, he would look at me like I had three heads, and wonder how I'm calling him.)

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