Overunning Mixed Event 12/18-12/19/21

[Greg]

In all honesty and kidding aside with these clown maps, I really don't know how much is really sleet vs snow in those maps that I posted and of course the 12K and 3K Nam is included in that.

[weatherwiz]

8 minutes ago, 40/70 Benchmark said:

Taking a closer look at this...that warm layer in the mid levels moves in around 00z Sunday (7pm Saturday), at which point I have like 1-2" of snow....then the rest of the snow looks to come on the back end early Sunday AM, which is suspect to me.

Not to mention this is all assuming 10:1 ratios.

I think Kevin maybe right with the 1-3" up here.

 

I wouldn't be too terribly surprised to see some back end snow. Latest NAM pushes those llvl circulations right through the region and may get cold enough on the backside. Maybe gives someone an inch or so. But yeah not sure how sold I am on this though. 

6 minutes ago, OceanStWx said:

It's going to be a weird one. If we're getting dendrites it's not likely to be from the layer around 500 mb, but maybe in the low level WAA that runs into the -8C air that contains some salt nuclei. I'd probably keep my meaty zone in the 8:1 to 10:1 range. 

That's what I was debating too...if that WAA running into that air could compensate some. We have seen that happen before and great point about the salt nuclei.  I'm wagering predominately snow ratios around 8:1 with 10:1 probably on the northern extent of the goods but that should be a very narrow area.

[40/70 Benchmark]

3 minutes ago, Greg said:

In all honesty and kidding aside with these clown maps, I really don't know how much is really sleet vs snow in those maps that I posted and of course the 12K and 3K Nam is included in that.

Look at the sounding I posted from coolwx.com.

Notice how that greater than 0c bubble of air shows up in the mid levels at 00z Sunday? Snow before that point is legit, any after that is the model's delusion.

[40/70 Benchmark]

1 minute ago, weatherwiz said:

I wouldn't be too terribly surprised to see some back end snow. Latest NAM pushes those llvl circulations right through the region and may get cold enough on the backside. Maybe gives someone an inch or so. But yeah not sure how sold I am on this though. 

That's what I was debating too...if that WAA running into that air could compensate some. We have seen that happen before and great point about the salt nuclei.  I'm wagering predominately snow ratios around 8:1 with 10:1 probably on the northern extent of the goods but that should be a very narrow area.

Doesn't really matter...1-3" would cover it.

[dryslot]

Just one stop shop.

[mahk_webstah]

5" or more is win on this one.

And you won't here me say that much.

[dendrite]

10 minutes ago, Greg said:

In all honesty and kidding aside with these clown maps, I really don't know how much is really sleet vs snow in those maps I posted and of course the 12K and 3K Nam is included in that.

[dryslot]

We need a clown emoji.

[Snowcrazed71]

This is and has been a northern Massachusetts through the green and white mountains, as well as northern northern Nee York and Western Marine type of storm. Yeah, I'll get a little mix snow and some sleet ( and rain ) just to get that wintry feel in the air. Anxiously and patiently waiting for that first big snowfall for the tri-state area

[dendrite]

Just now, dryslot said:

We need a clown emoji.

[dryslot]

3 minutes ago, dendrite said:

Never noticed it.

[Torch Tiger]

 it looks like maybe 1-3" here, which is better than the last "event".  Pretty ugly stuff to close December, was hoping for a legit snow event but the pattern never really supported it

[weatherwiz]

One thing that seems odd too is it almost looks like there are some embedded areas of subsidence involved from like maybe MA/VT/NH border on south...or certainly MA Pike on south. I guess this kinda makes sense though when you dig into some forecast soundings and look at VV's (it's even a bit apparent at 850mb). It's also a bit weird b/c it actually appears the BEST lift occurs just ahead of the main precipitation shield. But during the precip lift everywhere is pretty pathetic. 

Either subsidence or some dry air intrusions sneaking into the lower-levels where the flow has a more NNE component. 

Lots of weird little things going on 

 

[SJonesWX]

19 minutes ago, weatherwiz said:

I wouldn't be too terribly surprised to see some back end snow. Latest NAM pushes those llvl circulations right through the region and may get cold enough on the backside. Maybe gives someone an inch or so. But yeah not sure how sold I am on this though. 

That's what I was debating too...if that WAA running into that air could compensate some. We have seen that happen before and great point about the salt nuclei.  I'm wagering predominately snow ratios around 8:1 with 10:1 probably on the northern extent of the goods but that should be a very narrow area.

isn't backside/back end snow one of the fraud 5? it rarely works out

[dryslot]

1 minute ago, Torch Tiger said:

 it looks like maybe 1-3" here, which is better than the last "event".  Pretty ugly stuff to close December, was hoping for a legit snow event but the pattern never really supported it

[SJonesWX]

2 minutes ago, Torch Tiger said:

 it looks like maybe 1-3" here, which is better than the last "event".  Pretty ugly stuff to close December, was hoping for a legit snow event but the pattern never really supported it

December ends this weekend? thanks for the heads up, i don't want to miss any NYE parties.

[OceanStWx]

2 minutes ago, weatherwiz said:

One thing that seems odd too is it almost looks like there are some embedded areas of subsidence involved from like maybe MA/VT/NH border on south...or certainly MA Pike on south. I guess this kinda makes sense though when you dig into some forecast soundings and look at VV's (it's even a bit apparent at 850mb). It's also a bit weird b/c it actually appears the BEST lift occurs just ahead of the main precipitation shield. But during the precip lift everywhere is pretty pathetic. 

Either subsidence or some dry air intrusions sneaking into the lower-levels where the flow has a more NNE component. 

Lots of weird little things going on 

Check some cross sections. I'm not sure it's subsidence so much as it is vertical velocity not occurring or maxing out at 700 mb. There's a lot of low level lift and upper level lift. 

[weatherwiz]

7 minutes ago, SJonesWX said:

isn't backside/back end snow one of the fraud 5? it rarely works out

I guess it depends on what expectations one has on backside snows. If someone is probably hoping for several-inches that may not work out but getting some snow showers or some light snow (enough to drop a coating to an inch or two) isn't that unrealistic. 

4 minutes ago, OceanStWx said:

Check some cross sections. I'm not sure it's subsidence so much as it is vertical velocity not occurring or maxing out at 700 mb. There's a lot of low level lift and upper level lift. 

Gotcha...makes much more sense. 

[dryslot]

12z GFS was a tic or so warmer then 06z, But pretty much held serve overall.

[wxsniss]

12z RGEM isn't budging much, still the coldest

On its own here

 

[ORH_wxman]

1 minute ago, wxsniss said:

12z RGEM isn't budging much, still the coldest

On its own here

 

Yeah I'm selling advisory snow here....I'd prob go C-2" for pike region. I'd consider 2" a pretty solid win for this event.

[dendrite]

3k NAM gets a little lift into the DGZ on the front edge up here, but it won't really matter when the eventual baking soda compacts it down anyway. There could still be some dry air below that at the start as well to eat up any above average snow growth. H55 is way up there when trying to get any precip down to the sfc on the front end with low level CAA. GFS is still fairly moist...0.70-0.90". No surprises here...sticking with 5-8".

[Greg]

12Z CMC looks decent here. Colder solution than the GFS.

[wxsniss]

11 minutes ago, ORH_wxman said:

Yeah I'm selling advisory snow here....I'd prob go C-2" for pike region. I'd consider 2" a pretty solid win for this event.

Agree

Antecedent mass is junk, there's no robust confluence to anticipate trends the other way, ratios will be crap with DGZ much higher than best lift, meager QPF, and boundary layer will be working against us in the coastal plain.

Box will probably shave map an inch or so across the board in afternoon update

[ORH_wxman]

3 minutes ago, wxsniss said:

Agree

Antecedent mass is junk, there's no robust confluence to anticipate trends the other way, ratios will be crap with DGZ much higher than best lift, meager QPF, and boundary layer will be working against us in the coastal plain.

Box will probably shave map an inch or so across the board in afternoon update

Yeah the higher end SWFEs usually have a nice high north of Maine that is holding in an already advected-in cold antecedent airmass. In this one, the cold is kind of leaking in at the same time the event tries to start and you don't quite have that really good ML fronto that causes the storm to come in like a wall.

There is definitely some good confluence, but it is not oriented great for the classic warning event SWFE and in this case, prob not even advisory until you are north of Rt 2.

[Great Snow 1717]

4 minutes ago, wxsniss said:

Agree

Antecedent mass is junk, there's no robust confluence to anticipate trends the other way, ratios will be crap with DGZ much higher than best lift, meager QPF, and boundary layer will be working against us in the coastal plain.

Box will probably shave map an inch or so across the board in afternoon update

Outside of what you mentioned is there anything else about the "storm" that you do not like? lol

A December to Remember!! 

[40/70 Benchmark]

27 minutes ago, dendrite said:

3k NAM gets a little lift into the DGZ on the front edge up here, but it won't really matter when the eventual baking soda compacts it down anyway. There could still be some dry air below that at the start as well to eat up any above average snow growth. H55 is way up there when trying to get any precip down to the sfc on the front end with low level CAA. GFS is still fairly moist...0.70-0.90". No surprises here...sticking with 5-8".

Yea, I looked at KCON....little better than down here with lift closer to SGZ, but still not very good.

[OceanStWx]

13 minutes ago, wxsniss said:

Agree

Antecedent mass is junk, there's no robust confluence to anticipate trends the other way, ratios will be crap with DGZ much higher than best lift, meager QPF, and boundary layer will be working against us in the coastal plain.

Box will probably shave map an inch or so across the board in afternoon update

[Great Snow 1717]

11 minutes ago, OceanStWx said:

Watching the play might be a lot better than watching the winter of 21-22 play out...

[SnowGiant611]

This looks like slight bust potential in the Capital region of NH.  Consider:

 

1. Air/ground temps:  These have been higher than expected this week, including > 50 degrees today.  Low temps are only forecast to drop to 32 or so tonight, so this is a factor.

2. Dry air at storm onset : because the temps have been so high this week, we'd need a really good front-end thump to cool the lower levels and promote rapid sticking/accumulations on non-grassy surfaces.  I see a good virga event for the first few hours due to the column needing to saturate based on the cold air draining from Canada.  

3. Climo - need a stronger low in order pull more cold air down from Canada in a more aggressive fashion.

This looks like 3-5", but not as much accumulation on non-grassy surfaces.