Two Mdt to high impact events NYC subforum; wknd Jan 6-7 Incl OBS, and mid week Jan 9-10 (incl OBS). Total water equiv by 00z/11 general 2", possibly 6" includes snow-ice mainly interior. RVR flood potential increases Jan 10 and beyond. Damaging wind.

[North and West]

Cold and snow sells, warm and rain does not...think of the past 3-4 yrs-certain people have spent alot of time barking about great patterns etc and we've been mostly warm and snowless-last great pattern was back in Feb 2021

Exactly. Most of us want to hear cold and snow. Local media wants to peacock cold and snow. People want ice cream, not vegetables.


.

[MJO812]

Nam is slightly more amped than 6z but nothing earth shattering.

[RU848789]

1 hour ago, donsutherland1 said:

This page explains it and has some links to more detailed discussions:

https://home.pivotalweather.com/guides/snowfall

The Pivotal page is definitely well done, but they acknowledge that in marginal temp situations it's simply very difficult to translate the "snow that falls" to the "snow that accumulates."  Also, as I've discussed many times over the years, Kuchera is very simplistic (it simply takes the warmest temp in the air column and has a simple algorithm reducing ratios based on that temp only) and doesn't account for snow crystal shape impact on accumulated depth nor snowfall intensity, which can easily overcome melting in some situations. 

IMO, as someone with significant expertise in crystallization, heat transfer and phase change dynamics, the biggest "miss" in that page is not accounting for intensity, nor the fact that once there is some accumulation on a warmer-than-32F surface, the "new" surface is now snow/slush, which, by definition is then 32F, meaning subsequent accumulation of snowfall will no longer be significantly impacted by melting on that surface, plus air temps a few degrees above 32F will have a very small melting effect, since heat transfer via air to the snow is far less than from a solid (the ground) or liquid (e.g., wet ground/puddles), due to the huge density difference, primarily (air is far less dense, which is why the heat transfer coefficient is about 20X less from air than water, for example - that's why one can kep one's hand in a -10F freezer for minutes, but can't keep one's hand in a 32F cooler filled with ice/water for more than a few seconds).  

This is why we can see snow accumulate quite well at high intensity in April during the day with ground and air temps well above 32F - and we're not going to have ground or air temps that far above 32F in this case, plus we're not going to have any solar insolation issues for most of the storm, at night and even during the day, as the sun angle is still quite low, so we're not going to need high intensity to accumulate well (just moderate intensity most likely, although high would be better, of course).  I'm not saying we're going to see 10-15:1 snow to liquid ratios (which is what we'd likely get with good dendritic growth we're likely to see where the snow crystals are being formed, if that snow didn't encounter above 32F air in the column nor above 32F ground), but I am saying getting to 8-10: ratios shouldn't be that much of a stretch, as long as we have decent intensity.  

[Tatamy]

12z RGEM is in a totally different world as compared to the 12K NAM at the end of their runs in terms of precip type, extent, and temperatures.

[Allsnow]

Confluence stronger on the 12z icon this run 

[Tatamy]

16 minutes ago, RU848789 said:

The Pivotal page is definitely well done, but they acknowledge that in marginal temp situations it's simply very difficult to translate the "snow that falls" to the "snow that accumulates."  Also, as I've discussed many times over the years, Kuchera is very simplistic (it simply takes the warmest temp in the air column and has a simple algorithm reducing ratios based on that temp only) and doesn't account for snow crystal shape impact on accumulated depth nor snowfall intensity, which can easily overcome melting in some situations. 

IMO, as someone with significant expertise in crystallization, heat transfer and phase change dynamics, the biggest "miss" in that page is not accounting for intensity, nor the fact that once there is some accumulation on a warmer-than-32F surface, the "new" surface is now snow/slush, which, by definition is then 32F, meaning subsequent accumulation of snowfall will no longer be significantly impacted by melting on that surface, plus air temps a few degrees above 32F will have a very small melting effect, since heat transfer via air to the snow is far less than from a solid (the ground) or liquid (e.g., wet ground/puddles), due to the huge density difference, primarily (air is far less dense, which is why the heat transfer coefficient is about 20X less from air than water, for example - that's why one can kep one's hand in a -10F freezer for minutes, but can't keep one's hand in a 32F cooler filled with ice/water for more than a few seconds).  

This is why we can see snow accumulate quite well at high to high intensity in April during the day with ground and air temps well above 32F - and we're not going to have ground or air temps that far above 32F in this case, plus we're not going to have any solar insolation issues for most of the storm, at night and even during the day, as the sun angle is still quite low.  I'm not saying we're going to see 10-15:1 snow to liquid ratios (which is what we'd likely get with good dendritic growth we're likely to see where the snow crystals are being formed, if that snow didn't encounter above 32F air in the column nor above 32F ground), but I am saying getting to 8-10: ratios shouldn't be that much of a stretch, as long as we have decent intensity.  

This is a really great piece and provides a much needed scientific perspective to the ongoing conversation here regarding snow to liquid ratios.

[LibertyBell]

31 minutes ago, RU848789 said:

The Pivotal page is definitely well done, but they acknowledge that in marginal temp situations it's simply very difficult to translate the "snow that falls" to the "snow that accumulates."  Also, as I've discussed many times over the years, Kuchera is very simplistic (it simply takes the warmest temp in the air column and has a simple algorithm reducing ratios based on that temp only) and doesn't account for snow crystal shape impact on accumulated depth nor snowfall intensity, which can easily overcome melting in some situations. 

IMO, as someone with significant expertise in crystallization, heat transfer and phase change dynamics, the biggest "miss" in that page is not accounting for intensity, nor the fact that once there is some accumulation on a warmer-than-32F surface, the "new" surface is now snow/slush, which, by definition is then 32F, meaning subsequent accumulation of snowfall will no longer be significantly impacted by melting on that surface, plus air temps a few degrees above 32F will have a very small melting effect, since heat transfer via air to the snow is far less than from a solid (the ground) or liquid (e.g., wet ground/puddles), due to the huge density difference, primarily (air is far less dense, which is why the heat transfer coefficient is about 20X less from air than water, for example - that's why one can kep one's hand in a -10F freezer for minutes, but can't keep one's hand in a 32F cooler filled with ice/water for more than a few seconds).  

This is why we can see snow accumulate quite well at high intensity in April during the day with ground and air temps well above 32F - and we're not going to have ground or air temps that far above 32F in this case, plus we're not going to have any solar insolation issues for most of the storm, at night and even during the day, as the sun angle is still quite low, so we're not going to need high intensity to accumulate well (just moderate intensity most likely, although high would be better, of course).  I'm not saying we're going to see 10-15:1 snow to liquid ratios (which is what we'd likely get with good dendritic growth we're likely to see where the snow crystals are being formed, if that snow didn't encounter above 32F air in the column nor above 32F ground), but I am saying getting to 8-10: ratios shouldn't be that much of a stretch, as long as we have decent intensity.  

I remember April 2003 and April 2018 quite clearly, in both cases we had snow all day in April, and the amounts were around 6" in each case.

 

[mikeysed]

2 minutes ago, LibertyBell said:

I remember April 2003 and April 2018 quite clearly, in both cases we had snow all day in April, and the amounts were around 6" in each case.

 

April 2018 was Yankees opening day. I am in southern morris county we got 8 inches. I couldn't believe how quickly it was sticking in daylight and how heavy the rates were. Game got postponed about 2 hours only before gates opened, I was already on my way into the City. Was ridiculous they waited as long as they did.

[RU848789]

26 minutes ago, Tatamy said:

This is a really great piece and provides a much needed scientific perspective to the ongoing conversation here regarding snow to liquid ratios.

Thanks, that's very nice of you to say.  

[Allsnow]

This won’t be a weak sauce 06z gfs run at 12z 

[Allsnow]

[vegan_edible]

gfs in a bit stronger than last night and keeps the fun going with some light-er snow all day sunday. lets hops the cmc and euro show something a little more amped and we find a happy middle ground. im hoping for a solid 5-6inches in white plains. i do wonder though since i've only lived down here for a year and half and experienced snow twice in this region, would y'all consider white plains a "coastal" area? 

[Allsnow]

Boom 

[Franklin0529]

1 minute ago, Allsnow said:

Boom 

Confluence looks weaker. Might be too warm for city east 

[mikeysed]

CMC is looking like the GFS

[vegan_edible]

cmc said 988 low

[MJO812]

Cmc

[winterwx21]

CMC warmer. It has NYC right near the mixing line most of the storm. 

[Snowlover11]

1 minute ago, vegan_edible said:

gfs in a bit stronger than last night and keeps the fun going with some light-er snow all day sunday. lets hops the cmc and euro show something a little more amped and we find a happy middle ground. im hoping for a solid 5-6inches in white plains. i do wonder though since i've only lived down here for a year and half and experienced snow twice in this region, would y'all consider white plains a "coastal" area? 

yes and no, white plains is obviously the 287 line which in most borderline storms stays snow alot longer than even the “lower” section of westchester/bronx. if your near or NW of of 287 you should definitely be able to cash in several inches here.

[Allsnow]

Just now, Franklin0529 said:

Confluence looks weaker. Might be too warm for city east 

LI definitely to warm This run. Nyc and west will be fine with surface temps 33-34 

[MJO812]

Just now, winterwx21 said:

CMC warmer. It has NYC right near the mixing line most of the storm. 

It's fine. It usually runs warm.

[Allsnow]

1 minute ago, winterwx21 said:

CMC warmer. It has NYC right near the mixing line most of the storm. 

988 east of acy big hit western areas 

[jm1220]

5 minutes ago, vegan_edible said:

gfs in a bit stronger than last night and keeps the fun going with some light-er snow all day sunday. lets hops the cmc and euro show something a little more amped and we find a happy middle ground. im hoping for a solid 5-6inches in white plains. i do wonder though since i've only lived down here for a year and half and experienced snow twice in this region, would y'all consider white plains a "coastal" area? 

There’s a trailing S/W that could linger precip/snow if it’s timed well. It enhances things for SNE. 

[winterwx21]

1 minute ago, Allsnow said:

988 east of acy big hit western areas 

Yep but not much for NYC. It's quite a bit warmer than the 0z run. 

[vegan_edible]

3 minutes ago, Snowlover11 said:

yes and no, white plains is obviously the 287 line which in most borderline storms stays snow alot longer than even the “lower” section of westchester/bronx. if your near or NW of of 287 you should definitely be able to cash in several inches here.

thank u friend from across the tappan zee

[Snowlover11]

the city is playing with fire here so far during 12z model suite. 1-3”-2-4” but at this point im sure it would be big news since they gone nearly 700 days without an 1” recorded.

[MJO812]

1 minute ago, winterwx21 said:

Yep but not much for NYC. It's quite a bit warmer than the 0z run. 

1-3 is realistic 

[Allsnow]

Gfs still trying for front end 1/10. That’s a huge 1040 high north of us 

[winterwx21]

2 minutes ago, MJO812 said:

1-3 is realistic 

Yep I think that would be a good early call for NYC if you had to make one, but it's very early to be making a call. A long way to go. 

[jm1220]

1 minute ago, Snowlover11 said:

the city is playing with fire here so far during 12z model suite. 1-3”-2-4” but at this point im sure it would be big news since they gone nearly 700 days without an 1” recorded.

We have a small window near the city between the storm being too warm/NW and weak sauce/SE. It’s possible the storm goes through those goalposts but it’ll be tough.