January 2025

[MJO812]

Just now, snowman19 said:

Would not surprise me in the slightest if we are in a full blown -PNA regime after mid-January. This La Niña is not going to be denied. The Niña strengthening we’ve seen since November to this point in time has been nothing short of historic for this late in the season. The response in the NPAC is just lagged. This winter would have to completely defy the laws of physics to never see a canonical response 

We have been averaging positive with the PNA. There are no signs of it going negative in the near future. 

Just enjoy the pattern change in early to mid January instead of worrying about what's going to happen in late winter.

Anything past 300 hours is gravy.

[mattinpa]

3 minutes ago, MJO812 said:

In the past it hasn't but how can we make the same assumption ? This winter is already starting out better than the past winters. Enjoy model watching and the pattern changing after next week.

Yep fine to be cautiously optimistic. A somewhat cold December was a solid start and the warm ups haven’t gone on and on.

[bluewave]

31 minutes ago, MJO812 said:

We have been averaging positive with the PNA. There are no signs of it going negative in the near future. 

Just enjoy the pattern change in early to mid January instead of worrying about what's going to happen in late winter.

Anything past 300 hours is gravy.

The +PNA hasn’t been the issue this month. The much faster Northern Stream of Pacific Jet than forecast has been a very big player. So we keep getting storms racing across the country from west to east too far to the north. While it was nice getting those two light snowfall events over the past week, we missed out on the heavier 6”+ events which were common during past +PNA La Niña Decembers. Those years we didn’t have such a dominant Northern Stream which allowed for better coastal snowstorm tracks with enough cold air in place. The older runs for the first week of January underestimated the Pacific Jet influence and now they are correcting stronger. So you would want to see a weaker week two forecast actually make it to under 168 hrs for NYC to have a shot at a 4”+ event. 


New run stronger Pacific Jet into the West Coast than originally forecast for next week with lower 500 mb heights there

Old run 

[EastonSN+]

7 minutes ago, bluewave said:

The +PNA hasn’t been the issue this month. The much faster Northern Stream of Pacific Jet than forecast has been a very big player. So we keep getting storms racing across the country from west to east too far to the north. While it was nice getting those two light snowfall events over the past week, we missed out on the heavier 6”+ events which were common during past +PNA La Niña Decembers. Those years we didn’t have such a dominant Northern Stream which allowed for better coastal track snowstorm development along the coast with enough cold air in place. The older runs for the first week of January underestimated the Pacific Jet influence and now they are correcting stronger. 

Did we have a break in the fast jet for the 2021-2022 winter, or was there another factor that counteracted it? That winter had a KU event and a heavy snow event in December and was above average snowfall region wide. If there was another Factor counteracting it that may be what we need to look out for incoming periods until the jet finally starts to slow down at some point in the future.

[SnowGoose69]

35 minutes ago, MJO812 said:

Are you serious?  Both models look really nice after NYD. Snow threats will eventually pop up .

 

The only problem I see is the overall look has degraded in regards to storm potential.  The D10-16 look now resembles more 12/1-12/7 than what it showed a few dayd back which is the classic stormier look.  This now seems more cold and dry

[EastonSN+]

1 minute ago, SnowGoose69 said:

 

The only problem I see is the overall look has degraded in regards to storm potential.  The D10-16 look now resembles more 12/1-12/7 than what it showed a few dayd back which is the classic stormier look.  This now seems more cold and dry

I referenced it at some point in the past however the look does seem to favor areas south of us, we need more of a Southeast ridge or a sharper PNA or east-based EPO to allow a storm to head north. That being said I would rather take the look that I'm seeing across the entire model suite as opposed to a full continent torch or a trough to Baja. This is a case where a storm ejecting East followed by a dip in the PNA could allow the storm to override the cold air.

[EastonSN+]

On the topic of suppression what the GFS is showing is the risk. Conscious that this is just one op run however just utilizing to show a point.

[LibertyBell]

53 minutes ago, snowman19 said:

Would not surprise me in the slightest if we are in a full blown -PNA regime after mid-January. This La Niña is not going to be denied. The Niña strengthening we’ve seen since November to this point in time has been nothing short of historic for this late in the season. The response in the NPAC is just lagged. This winter would have to completely defy the laws of physics to never see a canonical response 

This might be controversial, but I'd rather have a La Nina than an El Nino.  El Nino winters torch early and seem to enhance the effects of global warming.  Thanks to La Nina we at least got a cold and somewhat snowy holiday period.  I'll take this over a torch December and praying for a fluke January/February blizzard which is what you need to get to normal snowfall in an el nino. This is MUCH better.

[LibertyBell]

58 minutes ago, MJO812 said:

In the past it hasn't but how can we make the same assumption ? This winter is already starting out better than the past winters. Enjoy model watching and the pattern changing after next week.

this is exactly why I'll take a la nina over the typical el nino torch December

 

[eduggs]

1 hour ago, MJO812 said:

Are you serious?  Both models look really nice after NYD. Snow threats will eventually pop up .

I am serious. Trof axis and shortwave spacing and timing look poor for local snow on the GFS and CMC out past 10 days. Snow threats may or may not pop up regardless of what ensemble averaged anomaly charts look like.

[eduggs]

1 hour ago, MJO812 said:

I don't see anything wrong with the gefs and eps.

Ensemble charts are averages of dozens of individual runs. That's why a great ensemble "look" often does not lead to a snowy outcome locally. The details are everything with snowstorms and ensembles don't resolve the details.

[brooklynwx99]

7 minutes ago, eduggs said:

Ensemble charts are averages of dozens of individual runs. That's why a great ensemble "look" often does not lead to a snowy outcome locally. The details are everything with snowstorms and ensembles don't resolve the details.

they’re definitely much more useful than OP runs past 7 days out, though. they’re used to identify periods of risk. i’ve seen way too much emphasis on day 10-15 OP runs recently on multiple forums and i find it odd

[MJO812]

8 minutes ago, eduggs said:

I am serious. Trof axis and shortwave spacing and timing look poor for local snow on the GFS and CMC out past 10 days. Snow threats may or may not pop up regardless of what ensemble averaged anomaly charts look like.

The pattern on the models look the best that we have seen in years. It's not only 1 model showing it. 

The MJO is also going in our favor which is huge. January is going to be a fun month for winter lovers ( cold and hopefully snow)

[bluewave]

1 hour ago, EastonSN+ said:

Did we have a break in the fast jet for the 2021-2022 winter, or was there another factor that counteracted it? That winter had a KU event and a heavy snow event in December and was above average snowfall region wide. If there was another Factor counteracting it that may be what we need to look out for incoming periods until the jet finally starts to slow down at some point in the future.

Yeah, the Pacific Jet backed off in January 2022 keeping the main ridge axis anchored near the West Coast for much of the month. So this allowed a coastal storm track to take over with cold air in place ahead of the storms. It was the last 30”+ snowfall month on Long Island. 

[eduggs]

1 minute ago, brooklynwx99 said:

they’re definitely much more useful than OP runs past 7 days out, though. they’re used to identify periods of risk

2 problems with that:

1. The correlation between "favorable periods" and local snowfall is relatively low.

2. Ensemble means out past 10 days have a degree of uncertainty that is large relative to the regional synoptic scale.

In other words, model error at that time range significantly exceeds the average synoptic different between rain vs. snow or storm vs no storm. And regional snowfall is driven more by shortwaves in the flow than the longwave "pattern." Since ensembles are heavily diluted by averaging out past 10 days, they cannot "see" the shortwaves that make or break snowstorms for us. That's why modeled favorable patterns fail to portend significant snowfall far more often than they successfully predict it (esp outside mountainous regions). The uncommonness of significant snow as a Bayesian backround state also has to be considered, regardless of what the ensembles look like.

[eduggs]

8 minutes ago, MJO812 said:

The pattern on the models look the best that we have seen in years. It's not only 1 model showing it. 

The MJO is also going in our favor which is huge. January is going to be a fun month for winter lovers ( cold and hopefully snow)

I think you have a short memory. There have been several very favorable looking periods over the past 3 winters that all failed to precede significant snow in our area. I want big snow as much as anyone. But we're ultimately going to need to see it on operation runs inside 7 and particularly 5 days before excitement is warranted.

[eduggs]

13 minutes ago, brooklynwx99 said:

they’re definitely much more useful than OP runs past 7 days out, though. they’re used to identify periods of risk. i’ve seen way too much emphasis on day 10-15 OP runs recently on multiple forums and i find it odd

Agreed that operational runs are nearly useless past 7 days. Ensembles are decent for airmass forecasting, okay for general storm prediction, and poor for snow forecasting at that time range.

[LibertyBell]

9 minutes ago, eduggs said:

2 problems with that:

1. The correlation between "favorable periods" and local snowfall is relatively low.

2. Ensemble means out past 10 days have a degree of uncertainty that is large relative to the regional synoptic scale.

In other words, model error at that time range significantly exceeds the average synoptic different between rain vs. snow or storm vs no storm. And regional snowfall is driven more by shortwaves in the flow than the longwave "pattern." Since ensembles are heavily diluted by averaging out past 10 days, they cannot "see" the shortwaves that make or break snowstorms for us. That's why modeled favorable patterns fail to portend significant snowfall far more often than they successfully predict it (esp outside mountainous regions). The uncommonness of significant snow as a Bayesian backround state also has to be considered, regardless of what the ensembles look like.

This is why it's safer to assume we'll see a few 1-3 inch events like we got in January 2009 rather than some blockbuster event, especially in such a fast flow pattern.  It's not a matter of luck but of the actual pattern regardless of the state of the indices.

[eduggs]

Nothing on the 12z ECM out past 10 days either. Well other than rain.

[eduggs]

2 minutes ago, LibertyBell said:

This is why it's safer to assume we'll see a few 1-3 inch events like we got in January 2009 rather than some blockbuster event, especially in such a fast flow pattern.  It's not a matter of luck but of the actual pattern regardless of the state of the indices.

That's slightly more optimistic than I would mentally lock in. But statistically it's not unreasonable.

[lee59]

https://www.weather.gov/media/okx/Climate/CentralPark/BiggestSnowstorms.pdf

 

Above shows all the snowstorms of 12 inches or more in Central Park since 1869. That is over 150 years of records. Of the 37 storms listed, 11 have happened since the year 2000. I think we became a little spoiled in thinking this was the new norm. The lack of snow the past few years, I don't think is the new norm either, we shall see.

[EastonSN+]

4 minutes ago, eduggs said:

Nothing on the 12z ECM out past 10 days either. Well other than rain.

This is entertainment at this range however I would be more than happy with a light to moderate event like this one on the ECM 

[EastonSN+]

3 minutes ago, lee59 said:

https://www.weather.gov/media/okx/Climate/CentralPark/BiggestSnowstorms.pdf

 

Above shows all the snowstorms of 12 inches or more in Central Park since 1869. That is over 150 years of records. Of the 37 storms listed, 11 have happened since the year 2000. I think we became a little spoiled in thinking this was the new norm. The lack of snow the past few years, I don't think is the new norm either, we shall see.

Agreed 100%. The periods of 1955 through 1969 and the period of 2000 through 2018 skewed our viewpoint of what average snowfall is and how many KU events actually occur. Perhaps I have the benefit of living through the 80s and '90s where there was a total of three above average snowfall Winters in New York City. Also regarding KU events I only remember 1983 1993 1995 and 1996 4ku events. 1970 through 1999 had a grand total of five above average snowfall Winters in New York City. 

[EastonSN+]

20 minutes ago, eduggs said:

I think you have a short memory. There have been several very favorable looking periods over the past 3 winters that all failed to precede significant snow in our area. I want big snow as much as anyone. But we're ultimately going to need to see it on operation runs inside 7 and particularly 5 days before excitement is warranted.

Agreed historically big snow is rare in our area outside of the two periods I referenced in a post above. On a side note two of the perceived good looking periods we had in the past we're not really great looks given that we had a trough to Baja which no amount of blocking could ever overcome. The modeling at medium and long range failed to link the southeast ridge to the nao which should have been picked up giving the depth of the trough out west and the position of the trough.

[LibertyBell]

13 minutes ago, eduggs said:

That's slightly more optimistic than I would mentally lock in. But statistically it's not unreasonable.

It's easier to predict cold than snow most definitely.

As far as NYC is concerned, at peak cold, I think single digit temperatures are a high probability.  Not 0 or below because that's very rare anyway but 5 or so might be a reasonable possibility.

[eduggs]

1 minute ago, EastonSN+ said:

Agreed historically big snow is rare in our area outside of the two periods I referenced in a post above. On a side note two of the perceived good looking periods we had in the past we're not really great looks given that we had a trough to Baja which no amount of blocking could ever overcome. The modeling at medium and long range failed to link the southeast ridge to the nao which should have been picked up giving the depth of the trough out west and the position of the trough.

Yeah exactly. In hindsight it's easy to identify what went wrong. But model ensembles 10-15+ days in advance miss key details.

[LibertyBell]

8 minutes ago, EastonSN+ said:

Agreed 100%. The periods of 1955 through 1969 and the period of 2000 through 2018 skewed our viewpoint of what average snowfall is and how many KU events actually occur. Perhaps I have the benefit of living through the 80s and '90s where there was a total of three above average snowfall Winters in New York City. Also regarding KU events I only remember 1983 1993 1995 and 1996 4ku events. 1970 through 1999 had a grand total of five above average snowfall Winters in New York City. 

and no HECS or above 29" winter between 1983-84 and 1991-92

[EastonSN+]

17 minutes ago, LibertyBell said:

This is why it's safer to assume we'll see a few 1-3 inch events like we got in January 2009 rather than some blockbuster event, especially in such a fast flow pattern.  It's not a matter of luck but of the actual pattern regardless of the state of the indices.

Unfortunately our last good period the trough was positioned a bit too far east to allow for any East Coast development hopefully this next period the trough access  could be slightly further west and allow for more of a Southeast ridge to allow for coastal development we shall see.

[snowman19]

I wonder how many great digital day 10-15 snowstorm patterns at 500mb we’re going to shovel this winter? 

[rclab]

7 minutes ago, snowman19 said:

I wonder how many great digital day 10-15 snowstorm patterns at 500mb we’re going to shovel this winter? 

Probably as many as it takes …. Have a Happy and a Merry …. As always ….