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.

[donsutherland1]

The importance of recognizing that the upcoming event will be a low- to very low-ratio event in New York City cannot be overstated. Most of the guidance keeps NYC above freezing throughout the storm. While model solutions showing 6"+ snow appear attractive, the early surface temperature forecasts and early soundings suggest that such figures based on a 10:1 ratio will likely be far off the mark.

Since 1869, there have been 9 storms during January 1-15, 1869-2023 that had minimum temperatures above freezing and measurable snowfall.  The ratios for such storms were exceptionally low:

Notice also that the highest ratios, which occurred with systems that produced less than 0.50" precipitation occurred during the 19th century when New York City's heat island was less formidable than it is today.

Even as the 0z ECMWF upped its snowfall totals (10:1 ratios), the share of ensemble members showing 10" or more snow did not increase and those showing 4" or more decreased. That could be an early indication that the range is starting to narrow toward a lighter snowfall event. Given the early sounding forecasts and the historic data from above, I believe NYC remains in line for 1" of snowfall with perhaps up to 3" if things come together. IMO, 6" or more is out of the question for New York City and its surrounding area within at least 30 miles. There could also be more downside risk than upside risk.

Things that could lead to a snowier outcome:

1. A stronger high in eastern Canada

2. A deeper, colder air mass

3. A weaker shortwave in the Southwest

In short, be wary of 10:1 snowfall maps. The upcoming storm will be coming into a marginal air mass. Such maps offer very little guidance with such air masses.

[EastonSN+]

2 minutes ago, donsutherland1 said:

The importance of recognizing that the upcoming event will be a low- to very low-ratio event in New York City cannot be overstated. Most of the guidance keeps NYC above freezing throughout the storm. While model solutions showing 6"+ snow appear attractive, the early surface temperature forecasts and early soundings suggest that such figures based on a 10:1 ratio will likely be far off the mark.

Since 1969, there have been 9 storms during January 1-15, 1869-2023 that had minimum temperatures above freezing and measurable snowfall.  The ratios for such storms were exceptionally low:

Notice also that the highest ratios, which occurred with systems that produced less than 0.50" precipitation occurred during the 19th century when New York City's heat island was less formidable than it is today.

Even as the 0z ECMWF upped its snowfall totals (10:1 ratios), the share of ensemble members showing 10" or more snow did not increase and those showing 4" or more decreased. That could be an early indication that the range is starting to narrow toward a lighter snowfall event. Given the early sounding forecasts and the historic data from above, I believe NYC remains in line for 1" of snowfall with perhaps up to 3" if things come together. IMO, 6" or more is out of the question for New York City and its surrounding area within at least 30 miles. There could also be more downside risk than upside risk.

Things that could lead to a snowier outcome:

1. A stronger high in eastern Canada

2. A deeper, colder air mass

3. A weaker shortwave in the Southwest

In short, be wary of 10:1 snowfall maps. The upcoming storm will be coming into a marginal air mass. Such maps offer very little guidance with such air masses.

Thanks Don,

I noticed that the EPS intensity is deeper (low). If the high pressure in Canada remains at the current modeled level, would the old "storm makes its own cold air" scenario work here, or would the storm pressure need to be sub 992/rapidly drop?

[Tatamy]

7 minutes ago, bluewave said:

Yeah, two issues in play. The actual ratios and the raw model cold biases. But even the MOS numbers have been too cold at times this winter. That’s why I wouldn’t  even think about specific accumulations until under 72 hrs or even 24 hrs in a marginal situation like this.

I asked Snowman but you might know the answer to this.  What variables are used to calculate the total snowfall positive depth change?  

[donsutherland1]

3 minutes ago, EastonSN+ said:

Thanks Don,

I noticed that the EPS intensity is deeper (low). If the high pressure in Canada remains at the current modeled level, would the old "storm makes its own cold air" scenario work here, or would the storm pressure need to be sub 992/rapidly drop?

The EPS is better and there could be some degree of dynamic cooling. I suspect that once one gets 30 miles or so outside of NYC, there will be 3"-6" amounts.

[wdrag]

Hi!  Haven read anything since last eve... I'm sure there was consternation with the 00z/06z GEFS-GFS. Fortunately the EPS is back up as is the CMCE. No change to my own overall thinking since the thread inception, NYC 1-4" to be further adjusted if needed. Just caught Don's post about rations.  Good post.

Won't be back to post til sometime this eve. Was on call First Aid driver overnight with two calls.  

Enjoy as you can what's coming 6-7 (split short waves makes this a 24 hour event instead of one bombing 12 hour storm), 9-10 and now looks more and more 13-14. I know if you dont get 4" of snow, unhappiness.  s LI looks worst chance 1". At least this was a tracker.  It's coming but exact details of snowfall etc tbd.  

[Northof78]

This is a decent airmass, highs in upper 30s and dry will do it every time without too much of an issue in early January

[bluewave]

7 minutes ago, EastonSN+ said:

Thanks Don,

I noticed that the EPS intensity is deeper (low). If the high pressure in Canada remains at the current modeled level, would the old "storm makes its own cold air" scenario work here, or would the storm pressure need to be sub 992/rapidly drop?

My only issue with the Euro and EPS after the upgrades around 2014 and 2015 is how erratic the model has been with east coast lows. We have either seen outright long range suppressed solutions which correct NW closer to storm time. At other times  there have been overamped lows with are modeled too deep and get weaker and more strung out closer to storm time. I used to really like the model for EC storm tracks in the period from Sandy to Nemo. But something really changed with the model after that period.

[donsutherland1]

4 minutes ago, Tatamy said:

I asked Snowman but you might know the answer to this.  What variables are used to calculate the total snowfall positive depth change?  

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

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

[MJO812]

Just now, bluewave said:

My only issue with the Euro and EPS after the upgrades around 2014 and 2015 is how erratic the model has been with east coast lows. We have either seen outright long range suppressed solutions which correct NW closer to storm time. At other there have been overamped lows with are modeled to deep and get weaker and more strung out closer to storm time. I used to really like the model for EC storm tracks in the period from Sandy to Nemo. But something really changed with the model after that period.

Eps and Euro have been too amped recently ever since the upgrade.

[jm1220]

20 minutes ago, Tatamy said:

There is no law in the annals of physics that states that snow has to fall at a ratio of 10:1.  There seems to be a lot of people who believe that it does however that is not the case.

That’s why I hate when these snow maps get posted. In this situation it won’t reflect reality for many. 

[Tatamy]

1 minute ago, donsutherland1 said:

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

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

Great article- Thank you!

[MJO812]

9z sref

[ILoveWinter]

34 minutes ago, MJO812 said:

It's January , not March with the sun angle .

Gfs wouldn't work here anyway but Euro would for a few inches.

Also, won't this be mostly an overnight event? This certainly would help to accumulate a few inches within the city. 

[bluewave]

7 minutes ago, MJO812 said:

Eps and Euro have been too amped recently ever since the upgrade.

They were too amped with the January 2015 blizzard and too suppressed with the January 2016 blizzard. 

[MJO812]

1 minute ago, bluewave said:

They were too amped with the January 2015 blizzard and too suppressed with the January 2016 blizzard. 

Remember when the Euro use to nail storms a week out ?

[MJO812]

2 minutes ago, ILoveWinter said:

Also, won't this be mostly an overnight event? This certainly would help to accumulate a few inches within the city. 

Yes 

I think 1-3 is the best bet for NYC atm with most of the accumulations on colder surfaces unless surface temps get colder.

[donsutherland1]

5 minutes ago, jm1220 said:

That’s why I hate when these snow maps get posted. In this situation it won’t reflect reality for many. 

And some wind up posting exaggerated snowfall totals from such maps on Social Media which creates real headaches for the professional community. It creates perceptions that the professional community of private- and public-sector meteorologists are "wrong" when the exaggerated amounts don't verify, as is typically the case for extreme solutions that have little support. Such maps are starting to be called out more frequently on social media. But there is no sign yet that the pushing of reckless speculation is slowing.

One such map:

If everything went right, Allentown would have a shot at 6"-12", but right now 4"-8" seems likely (downside risk is greater than upside risk). The latest NBE forecast is for just under 6" there.

[psv88]

The city has a bigger problem in marginal storms than the north shore of the island. We’ve seen many marginal storms at 32 throughout and gotten plenty of snow. A nighttime storm with decent rates will work for us, so long as temps are 33 or below. 
 

my thought is that from the southern state parkway north will be good for a sloppy few inches. South of the southern state probably a sloppy inch or so

[MJO812]

2 minutes ago, donsutherland1 said:

And some wind up posting exaggerated snowfall totals from such maps on Social Media which creates real headaches for the professional community. It creates perceptions that the professional community of private- and public-sector meteorologists are "wrong" when the exaggerated amounts don't verify, as is typically the case for extreme solutions that have little support. Such maps are starting to be called out more frequently on social media. But there is no sign yet that the pushing of reckless speculation is slowing.

One such map:

If everything went right, Allentown would have a shot at 6"-12", but right now 4"-8" seems likely (downside risk is greater than upside risk). The latest NBE forecast is for just under 6" there.

This is from Henry Marguisity.  This guy has been hyping stuff more than JB for decades.

[bluewave]

7 minutes ago, MJO812 said:

Remember when the Euro use to nail storms a week out ?

Yeah, it had an epic run from Sandy to Nemo. But struggled with Boxing Day in that short range run that went too far east while the GFS was correct further west. Believe it did better with the storms the previous season. Wish they would create a model skill score just for East Coast storm tracks. Bet the Euro and EPS would score lower than the headline global skill scores which always get touted. 

[jm1220]

1 minute ago, psv88 said:

The city has a bigger problem in marginal storms than the north shore of the island. We’ve seen many marginal storms at 32 throughout and gotten plenty of snow. A nighttime storm with decent rates will work for us, so long as temps are 33 or below. 
 

my thought is that from the southern state parkway north will be good for a sloppy few inches. South of the southern state probably a sloppy inch or so

You can even see from the… snow maps lol that notched area near the city and southern Nassau into Suffolk there’s less accumulation than areas starting around Great Neck and heading east. We’re maybe 2 degrees colder here but that can make all the difference like the 2/28 storm last winter. I lived in the “notch” for many years and got screwed over many times. 

[jm1220]

8 minutes ago, donsutherland1 said:

And some wind up posting exaggerated snowfall totals from such maps on Social Media which creates real headaches for the professional community. It creates perceptions that the professional community of private- and public-sector meteorologists are "wrong" when the exaggerated amounts don't verify, as is typically the case for extreme solutions that have little support. Such maps are starting to be called out more frequently on social media. But there is no sign yet that the pushing of reckless speculation is slowing.

One such map:

If everything went right, Allentown would have a shot at 6"-12", but right now 4"-8" seems likely (downside risk is greater than upside risk). The latest NBE forecast is for just under 6" there.

It’s absolutely bogus. I don’t know how the guy has any clients since he’s been a joke for years. Unless this is what he releases to weenies to get clicks/likes/new subscribers and for the paid customers something different. 

[North and West]

And some wind up posting exaggerated snowfall totals from such maps on Social Media which creates real headaches for the professional community. It creates perceptions that the professional community of private- and public-sector meteorologists are "wrong" when the exaggerated amounts don't verify, as is typically the case for extreme solutions that have little support. Such maps are starting to be called out more frequently on social media. But there is no sign yet that the pushing of reckless speculation is slowing.
One such map:

If everything went right, Allentown would have a shot at 6"-12", but right now 4"-8" seems likely (downside risk is greater than upside risk). The latest NBE forecast is for just under 6" there.

Aptly named “weather madness”


.

[Allsnow]

1 hour ago, SnoSki14 said:

Bluewave is just telling it like it is. I know many don't want to hear it but  the airmass is definitely marginal. 

He's just illustrating the challenges. I would honestly be surprised to see much for the coast. 

You will be fine in North Jersey 

[North and West]

It’s absolutely bogus. I don’t know how the guy has any clients since he’s been a joke for years. Unless this is what he releases to weenies to get clicks/likes/new subscribers and for the paid customers something different. 

Easy: sell people what they want and tell people what they want to hear. We all fall for it, whether it’s politicians or job offers.


.

[donsutherland1]

From NWS Boston:

[bluewave]

3 minutes ago, donsutherland1 said:

From NWS Boston:

This happens all the time with rainstorms but many just pay attention to storm tracks and exact amounts when the chance of snow is involved. 

[MJO812]

6 minutes ago, jm1220 said:

It’s absolutely bogus. I don’t know how the guy has any clients since he’s been a joke for years. Unless this is what he releases to weenies to get clicks/likes/new subscribers and for the paid customers something different. 

I use to watch his videos all the time back in the day. He always wore his big daddy hat when a storm was coming.

[cleetussnow]

I expect this to jump around a lot as we get closer to 48 hrs, even 36 hrs just like the NWS Boston suggest.  I feel like this has happened a lot over the few years with coastals.  

[Brian5671]

25 minutes ago, North and West said:

Easy: sell people what they want and tell people what they want to hear. We all fall for it, whether it’s politicians or job offers.


.

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