Possible Record Breaking Cold + Snow Sunday 1/25 - Tuesday 1/27

[psv88]

5 minutes ago, mob1 said:

Probably a touch warmer than 6Z aloft as sleet moves in just a tiny bit earlier. Still a good run, with 7+ inches (at 10 to 1) accumulated by the time sleet moves in. 

The actual surface temps seem colder. In my opinion it was a trend in the right direction 

[Joe4alb]

Just now, psv88 said:

The actual surface temps seem colder. In my opinion it was a trend in the right direction 

100% 

[Prue11]

2 minutes ago, donsutherland1 said:

My thinking about an upcoming significant snowfall in and around New York City remains intact following the 1/22 12z model cycle. Overall, the City remains on course to see its biggest snowstorm in nearly four or five years.

The storm will likely attain a Category 3 or, less likely but still possible, Category 4 rank on the Northeast Snowfall Impact Scale (NESIS). NESIS is based on a combination of the area affected by the storm, population in the affected areas, and snowfall amounts.

During the height of the storm, the dedridritic growth zone (DGZ) will have temperatures between -17°C and -12°C as per the soundings from multiple models, which is close to ideal for snow growth. The layers below it will be well-saturated, and surface temperatures will be very cold, reducing the risk of melting/riming. As a result, well-accumulating dendrites will be the predominant snowflake. Ratios during this time will probably range from 12:1 to 15:1. 

A classic paper can be found here: https://www.wpc.ncep.noaa.gov/research/snow2a/snow2a.pdf

Later on, warmer air will push into the mid levels (mainly between 650 mb and 800 mb), which will lead to a transition to lower ratios and then sleet for parts of the New York City area, including the City and nearby suburbs. There's a small chance that the storm could end as some freezing drizzle as it pulls away early Monday.

Taking into consideration the DGZ conditions, historic data for snowstorms with 1" or greater QPF, the various 12z model solutions, it appears that an good initial estimate for storm total snow and sleet in New York City and nearby areas will fall in the 6"-12" range. Areas to the south and east of New York City and its nearby suburbs could see 4"-8" amounts. Areas with 12"-18" are possible well north and west of New York City, most likely in parts of northeastern Pennsylvania, Orange County, Dutchess County, and Sussex County. A reasonable floor for New York City is 5". A reasonable ceiling is 14".

There remains a degree of uncertainty concerning mid-level and surface storm evolution and tracks, and a potential primary-secondary storm handoff. Model skill will improve markedly within another day. Estimates could be revised based on the subsequent guidance, as needed, but the initial estimate is probably a reasonable starting point. Areas north and west of New York City where ratios could be higher for a longer period of time and mixing could be less of an issue, will likely see higher amounts than New York City.

 

Don what time do you think the previous ends in nyc/li area Monday?

[MJO812]

9 minutes ago, winterwarlock said:

I think 6-12 region wide is a good early call

Agree

[MANDA]

3 minutes ago, winterwarlock said:

I think 6-12 region wide is a good early call

I'm more conservatively going with 6-10 at this point along the I78 and I80 Corridor.  Allowing for the mid level warming to be a little more aggressive than modeled.  Although the latest EURO has me leaning to much less mixing north of 80 and west of 287.  Still significant uncertainty on exactly how the 2ndary unfolds.  QPF very consistent at around 1" on all guidance.  Only if something totally unexpected happened with the 2ndary would that go up markedly.  Use 1" of QPF and the ratio of your choosing to to convert to snowfall and allow for sleet to mix where you believe it will mix in.

[Jersey_Snowhole]

Going with 4-8 here in Howell 

[Northof78]

For most in NYC subforum, NYC NWS downplaying any material mixing (outside of 'may mix with sleet/ice for a time near the coast'), and going with 6 - 12" and specific mention of areas of 12"+. Major snowstorm incoming...

[Wxoutlooksblog]

9 minutes ago, donsutherland1 said:

My thinking about an upcoming significant snowfall in and around New York City remains intact following the 1/22 12z model cycle. Overall, the City remains on course to see its biggest snowstorm in nearly four or five years.

The storm will likely attain a Category 3 or, less likely but still possible, Category 4 rank on the Northeast Snowfall Impact Scale (NESIS). NESIS is based on a combination of the area affected by the storm, population in the affected areas, and snowfall amounts.

During the height of the storm, the dedridritic growth zone (DGZ) will have temperatures between -17°C and -12°C as per the soundings from multiple models, which is close to ideal for snow growth. The layers below it will be well-saturated, and surface temperatures will be very cold, reducing the risk of melting/riming. As a result, well-accumulating dendrites will be the predominant snowflake. Ratios during this time will probably range from 12:1 to 15:1. 

A classic paper can be found here: https://www.wpc.ncep.noaa.gov/research/snow2a/snow2a.pdf

Later on, warmer air will push into the mid levels (mainly between 650 mb and 800 mb), which will lead to a transition to lower ratios and then sleet for parts of the New York City area, including the City and nearby suburbs. There's a small chance that the storm could end as some freezing drizzle as it pulls away early Monday.

Taking into consideration the DGZ conditions, historic data for snowstorms with 1" or greater QPF, the various 12z model solutions, it appears that an good initial estimate for storm total snow and sleet in New York City and nearby areas will fall in the 6"-12" range. Areas to the south and east of New York City and its nearby suburbs could see 4"-8" amounts. Areas with 12"-18" are possible well north and west of New York City, most likely in parts of northeastern Pennsylvania, Orange County, Dutchess County, and Sussex County. A reasonable floor for New York City is 5". A reasonable ceiling is 14".

There remains a degree of uncertainty concerning mid-level and surface storm evolution and tracks, and a potential primary-secondary storm handoff. Model skill will improve markedly within another day. Estimates could be revised based on the subsequent guidance, as needed, but the initial estimate is probably a reasonable starting point. Areas north and west of New York City where ratios could be higher for a longer period of time and mixing could be less of an issue, will likely see higher amounts than New York City.

 

I really do suspect that this is spot on. Unless there are repeated corrections in the modeling south and east, I think this will most likely be the summary of the storm. 

WX/PT 

[CentralNJSnowman]

4 minutes ago, Jersey_Snowhole said:

Going with 4-8 here in Howell 

Seems reasonable.  I'm in Monroe (maybe 10-15 miles northwest of you) and my best guess for my backyard is currently 6-9...although still wouldn't be surprised by substantial changes in either direction

[psv88]

6-12 is a great call in my view. In my view this is much simpler call than we are making it. 
 

6-12”, more or less depending on mixing. Temps below freezing throughout 

[Stormlover74]

3 minutes ago, Northof78 said:

For most in NYC subforum, NYC NWS downplaying any material mixing (outside of 'may mix with sleet/ice for a time near the coast'), and going with 6 - 12" and specific mention of areas of 12"+. Major snowstorm incoming...

They generally do this though

[Wxbear25]

19 minutes ago, mob1 said:

Probably a touch warmer than 6Z aloft as sleet moves in just a tiny bit earlier. Still a good run, with 7+ inches (at 10 to 1) accumulated by the time sleet moves in. 

It’s tough to line up 1 to 1 since temporal differences also impact these things, so a faster wave might look like it “warms faster” when in reality the whole process is just happening faster, including the precip arriving, etc.  ,

looking at the soundings, it looks slightly (but noticeably) colder

 

[donsutherland1]

14 minutes ago, Prue11 said:

Don what time do you think the previous ends in nyc/li area Monday?

Monday morning with maybe some snow showers into the afternoon. There are differences on the guidance and those details will become clearer in subsequent model cycles.

[jm1220]

4 minutes ago, psv88 said:

6-12 is a great call in my view. In my view this is much simpler call than we are making it. 
 

6-12”, more or less depending on mixing. Temps below freezing throughout 

This reminds me of the 12/17/20 storm overall-SWFE type system that transfers to a coastal system. 8” here from that one. 

[SnoSki14]

22 minutes ago, Winter Wizard said:

Ceiling on this is very high, there will be a large swath of 12"+ totals across the Northeast. For the City and coast itself however, there is a twofold concern related to the transfer from primary low to secondary: mid-level warming and arguably more consequentially the dry slotting. I would not be 100% on major totals at this point, but potential is there. First bonafide MECS in 5 years. 

Agree 100% 

Rare possibility of more upside than downside I think. Also if precip falls hard enough near the transition zone that we could hold onto snow longer boosting amounts by 2-4" 

[Nibor]

7 minutes ago, Stormlover74 said:

They generally do this though

Yeah they did the same back in December saying they weren’t expect mixing. 

[winterwarlock]

10 minutes ago, psv88 said:

6-12 is a great call in my view. In my view this is much simpler call than we are making it. 
 

6-12”, more or less depending on mixing. Temps below freezing throughout 

exactly...6-12 covers alot of bases to the public without setting yourself up for failure with 12-18 initial maps which if fear Mt holly will do based on their discussions the past day and their insistence on using the faulty nbm

of course stress the potential in the northern areas you could get those 15 inch plus amounts and toward the coast especially toward southern jersey you could get 3-4 inches before a changeover to ice and maybe plain rain

[psv88]

8 minutes ago, jm1220 said:

This reminds me of the 12/17/20 storm overall-SWFE type system that transfers to a coastal system. 8” here from that one. 

i think this system is colder. Half the storm will be in the teens

[Wannabehippie]

1 hour ago, Stormlover74 said:

I like this map right now

I am west of Wayne. I will take a 10"-15" snow total.

[Winterweatherlover]

17 minutes ago, psv88 said:

6-12 is a great call in my view. In my view this is much simpler call than we are making it. 
 

6-12”, more or less depending on mixing. Temps below freezing throughout 

Agree for once this storm isn't that hard to predict given the amount of wiggle room we have even for small trends north or south. 6-12 seems like a good bet for most, possibly 12+ those who stay all snow.

[Wxbear25]

Too low for LI imo.

Agreed. Even if we mix with/change to sleet, the WAA is going to come in like a banshee, and EVERYTHING is going to stick immediately given how cold it is preceding the storm

[Wannabehippie]

From what can see on the forecast models, the secondary low being even 20 miles further south and east would likely eliminate any mixing issues from the NYC/LI/CT area. The cold air at the surface will definitely be very stubborn to get out.

[JonClaw]

[SnoSki14]

I hope we don't get 6-8" of snow with 2" of sleet on top. With temps as cold as they are that'll create a giant skating rink with horrendous plowing & travel conditions. 

That's far worse impact wise than a pure 12-15" snowstorm 

[Winterweatherlover]

Just now, JonClaw said:

I wonder if they expect a south tick given the highest amounts are in the southern zones?  NVM I realize this is only through 7 PM Sunday.

[wthrmn654]

So is euro trending slowly to the gfs idea? Guess time will only tell now. 

[OrangeCTWX]

1 minute ago, JonClaw said:

Only through 7pm Sunday fyi 

[the_other_guy]

35 minutes ago, MJO812 said:

Agree

Too low. 8-14 would be a good early call

[wthrmn654]

1 minute ago, JonClaw said:

Why is there event total 1 am Sunday to 7 pm Sunday... that isn't even the total event? Or am I missing something

[Stormlover74]

2 minutes ago, SnoSki14 said:

I hope we don't get 6-8" of snow with 2" of sleet on top. With temps as cold as they are that'll create a giant skating rink with horrendous plowing & travel conditions. 

That's far worse impact wise than a pure 12-15" snowstorm 

That's the most likely scenario unfortunately