December 2023

[WX-PA]

Just now, Allsnow said:

The negative Nao is pointless if the pacific is so horrible. We will have a -nao next week when you’re in the 50’s 

For a day or so..not for a week..And what December doesn't have temps in the 50's for a few days?

[Allsnow]

2 minutes ago, WX-PA said:

For a day or so..not for a week..And what December doesn't have temps in the 50's for a few days?

What’s the point? Its still way to warm for snow here even with a block 

[WX-PA]

1 minute ago, Allsnow said:

What’s the point? Its still way to warm for snow here even with a block 

Yea for the next week or so sure. I think the second half of the month will produce snow here as the Pacific improves with cold MJO phases. Listen you may be right, strong Nino in December usually means warm and snowless..However very rare to have a negative NAO with enso +2 in December.

[WX-PA]

Big drop in Enso 1 and 2..By March we will be negative..setting up for a La Nina next summer and fall

 

[the_other_guy]

38 minutes ago, MJO812 said:

Not only snowier but also colder. 

I had a rule of thumb in 90s. If it didnt snow by that last week of Dec it was going to be a winter with BN snow.

There were plenty of snowless or low snow Dec even then

[Stormlover74]

13 minutes ago, the_other_guy said:

I had a rule of thumb in 90s. If it didnt snow by that last week of Dec it was going to be a winter with BN snow.

There were plenty of snowless or low snow Dec even then

Well it snowed in 98 and we were below average that winter. It barely snowed in 92 but we ended up average and of course 89-90 had early snow but well below average

It probably does work out more times than not that no snow in December is bad news for a good winter. 94, 96, 97 and 99 were examples

[WX-PA]

7 minutes ago, Stormlover74 said:

Well it snowed in 98 and we were below average that winter. It barely snowed in 92 but we ended up average and of course 89-90 had early snow but well below average

It probably does work out more times than not that no snow in December is bad news for a good winter. 94, 96, 97 and 99 were examples

Actually if you remember it did snow a few days after Christmas in 97..it was a dusting, I dont know if that counts..The rest of the winter was a disaster until March when got our first and only snowfall.

[Stormlover74]

4 minutes ago, WX-PA said:

Actually if you remember it did snow a few days after Christmas in 97..it was a dusting, I dont know if that counts..The rest of the winter was a disaster until March when got our first and only snowfall.

Well yeah getting nothing in December is pretty rare.  That was our only measurable snow until the March storm

[Eduardo]

1 hour ago, WX-PA said:

Yea for the next week or so sure. I think the second half of the month will produce snow here as the Pacific improves with cold MJO phases. Listen you may be right, strong Nino in December usually means warm and snowless..However very rare to have a negative NAO with enso +2 in December.

I think the debate (that’s been hashed and rehashed several times these past few days) is whether and how quickly the MJO rotates through our beloved 8-1-2. Though as a winter-weather lover, I wish I wasn’t, I’m in @bluewave’s camp that the LR models these past two or so years have tended to depict a favorable MJO only to break it down in the short term.

@brooklynwx99has offered some good reasons why this year might be different than last (mostly ENSO-based, unless I’m misunderstanding), but so far I’m neither convinced nor excited. Continuity is weighty for me in this age of “stuck patterns.” Unless and until we see some sort of global shift in this Niña-esque setup, I have to assume that things are gonna remain pretty boring.

[donsutherland1]

For 2023, MJO passages through Phases 4-6 have lasted an average of 10.4 days with a standard deviation of 7.8 days. A standard deviation longer stay in Phases 4-6 would imply that the MJO would move beyond Phases 4-6 by December 18th. The longest Phase 4-6 passage this year was 24 days in duration. The second and third longest were 18 and 17 days respectively.

Select dynamical model forecasts for the MJO's departure from Phases 4-6:

Australian (bias corrected): December 10
Canadian: December 13
CFSv2 (bias corrected): December 14
ECMWF (bias corrected): December 16
GEFS (bias corrected): December 12

It should be noted that beyond a week, MJO forecasts aren't high skill forecasts. At the same time, variables other than the MJO also impact the evolution of synoptic patterns. Atlantic blocking, which is forecast to continue through most of the next 1-2 weeks could cap the magnitude of warmth in the East during the first 2-3 weeks of December. There could still be some abnormal warmth.

If the MJO exits Phases 4-6 near mid-month and if Atlantic blocking continues, one might see opportunities for more cold to start returning during the last 7 to perhaps 10 days of the month. This could mean readings begin to approach normal values (ECMWF weeklies) or perhaps somewhat below normal values (CFSv2 weeklies). Right now, there's no evidence to back some of the social media calls for late-month extreme cold in the East.

Beyond mid-month, skill is very low. Given the imminent AAM+ in a basinwide strong El Niño event, a slower progression to possible cooler readings might be more likely. It should be noted that if Atlantic blocking breaks down and Pacific blocking fails to develop (the persistent PDO- could be a barrier to the development of Pacific blocking), one could see a warmer outcome. All said, the Fantasyland time range is defined by uncertainty and that degree of uncertainty should be considered.

My guess at this time (for the  region around NYC and Philadelphia):

December 1-20: Generally warmer than normal (possible peak warmth during December 10-15?)
December 21-25: Possibly turning somewhat cooler but maybe still above normal overall
December 26-31: Colder air, not necessarily Arctic cold, could begin to arrive (very low confidence)

Finally, I suspect that there will be frequent Atlantic blocking for December and January, as has often followed the development of strong Atlantic blocking during the last week of November. Such blocking should provide better opportunities for snowfall than had been present last winter.

 

[WX-PA]

6 minutes ago, Eduardo said:

I think the debate (that’s been hashed and rehashed several times these past few days) is whether and how quickly the MJO rotates through our beloved 8-1-2. Though as a winter-weather lover, I wish I wasn’t, I’m in @bluewave’s camp that the LR models these past two or so years have tended to depict a favorable MJO only to break it down in the short term.

@brooklynwx99has offered some good reasons why this year might be different than last (mostly ENSO-based, unless I’m misunderstanding), but so far I’m neither convinced nor excited. Continuity is weighty for me in this age of “stuck patterns.” Unless and until we see some sort of global shift in this Niña-esque setup, I have to assume that things are gonna remain pretty boring.

There was no favorable mjo phase last year in was 4-6 with an insane -PNA..Not the case this year.

[brooklynwx99]

7 minutes ago, Eduardo said:

I think the debate (that’s been hashed and rehashed several times these past few days) is whether and how quickly the MJO rotates through our beloved 8-1-2. Though as a winter-weather lover, I wish I wasn’t, I’m in @bluewave’s camp that the LR models these past two or so years have tended to depict a favorable MJO only to break it down in the short term.

@brooklynwx99has offered some good reasons why this year might be different than last (mostly ENSO-based, unless I’m misunderstanding), but so far I’m neither convinced nor excited. Continuity is weighty for me in this age of “stuck patterns.” Unless and until we see some sort of global shift in this Niña-esque setup, I have to assume that things are gonna remain pretty boring.

there is no reason why a borderline super Nino event wouldn’t lead to Nino conditions. perhaps you can look back and see that, but to forecast a lack of change is silly in my opinion

[Volcanic Winter]

15 minutes ago, donsutherland1 said:

For 2023, MJO passages through Phases 4-6 have lasted an average of 10.4 days with a standard deviation of 7.8 days. A standard deviation longer stay in Phases 4-6 would imply that the MJO would move beyond Phases 4-6 by December 18th. The longest Phase 4-6 passage this year was 24 days in duration. The second and third longest were 18 and 17 days respectively.

Select dynamical model forecasts for the MJO's departure from Phases 4-6:

Australian: December 10
Canadian: December 13
CFSv2 (bias corrected): December 14
ECMWF (bias corrected): December 16
GEFS (bias corrected): December 12

It should be noted that beyond a week, MJO forecasts aren't high skill forecasts. At the same time, variables other than the MJO also impact the evolution of synoptic patterns. Atlantic blocking, which is forecast to continue through most of the next 1-2 weeks could cap the magnitude of warmth in the East during the first 2-3 weeks of December. There could still be some abnormal warmth.

If the MJO exits Phases 4-6 near mid-month and if Atlantic blocking continues, one might see opportunities for more cold to start returning during the last 7 to perhaps 10 days of the month. This could mean readings begin to approach normal values (ECMWF weeklies) or perhaps somewhat below normal values (CFSv2 weeklies). Right now, there's no evidence to back some of the social media calls for late-month extreme cold in the East.

Beyond mid-month, skill is very low. Given the imminent AAM+ in a basinwide strong El Niño event, a slower progression to possible cooler readings might be more likely. It should be noted that if Atlantic blocking breaks down and Pacific blocking fails to develop (the persistent PDO- could be a barrier to the development of Pacific blocking), one could see a warmer outcome. All said, the Fantasyland time range is defined by uncertainty and that degree of uncertainty should be considered.

My guess at this time (for the  region around NYC and Philadelphia):

December 1-20: Generally warmer than normal (possible peak warmth during December 10-15?)
December 21-25: Possibly turning somewhat cooler but maybe still above normal overall
December 26-31: Colder air, not necessarily Arctic cold, could begin to arrive (very low confidence)

Finally, I suspect that there will be frequent Atlantic blocking for December and January, as has often followed the development of strong Atlantic blocking during the last week of November. Such blocking should provide better opportunities for snowfall than had been present last winter.

 

Thank you, Don. The detail and thoughtfulness of your write-ups is always super appreciated and insightful. 

[EastonSN+]

1 hour ago, Stormlover74 said:

Well it snowed in 98 and we were below average that winter. It barely snowed in 92 but we ended up average and of course 89-90 had early snow but well below average

It probably does work out more times than not that no snow in December is bad news for a good winter. 94, 96, 97 and 99 were examples

Agreed, although 92 was variable around this forum. Where I am in coastal CT that big noreaster was 6 inches of snow. 

The 90s in general were a dumpster fire for snowfall.

[bluewave]

2 hours ago, Allsnow said:

The negative Nao is pointless if the pacific is so horrible. We will have a -nao next week when you’re in the 50’s 

Yeah, the TPV with this -NAO shifted over to Eurasia leaving a mild Pacific air mass in place across North America. As we found out in recent years, -NAO and -AO patterns can be very mild for us. This isn’t like the old days around 2010 when big -AO and -NAO drops meant cold. I think Don had a great post a while back on how the -AO and -NAO has become warmer for us. 

 

[EastonSN+]

1 minute ago, bluewave said:

Yeah, the TPV with this -NAO shifted over to Eurasia leaving a mild Pacific air mass in place across North America. As we found out in recent years, -NAO and -AO patterns can be very mild for us. This isn’t like the old days around 2010 when big -AO and -NAO drops meant cold. I think Don had a great post a while back on how the -AO and -NAO has become warmer for us. 

 

Isn't it just bad luck that the cold air is on the other side of the globe (not non-existent).

It's only been a few years cannot say for certain that NAOs no longer work. 

[Stormlover74]

5 minutes ago, EastonSN+ said:

Agreed, although 92 was variable around this forum. Where I am in coastal CT that big noreaster was 6 inches of snow. 

The 90s in general were a dumpster fire for snowfall.

Yeah it depends if we're just talking about central park or not. Certainly north and west has done well in Decembers that were shutouts near the coast

[jm1220]

5 minutes ago, EastonSN+ said:

Isn't it just bad luck that the cold air is on the other side of the globe (not non-existent).

It's only been a few years cannot say for certain that NAOs no longer work. 

Yes-I wonder if something could be causing the PV to locate over Siberia or if it’s just been bad luck. Later into Jan, we won’t need arctic cold for snow, just a good enough airmass not totally ruined by Pacific garbage and a good storm track. Once the waters cool down we have more leeway to work with near the city. 

[psv88]

4 hours ago, EastonSN+ said:

My memory is probably off, but I remember Decembers being snowy in the 80s with snowless Marches. The 90s were mostly warm, early 90s snowy Marches snowless Decembers. Late 90s warm and snowless year round . The 2000s Decembers were great however it almost NEVER snowed in March, then the 2010s it flipped and we lost December and and gained March.

Agreed. March now a winter month, December fall

[qg_omega]

1 hour ago, bluewave said:

Yeah, the TPV with this -NAO shifted over to Eurasia leaving a mild Pacific air mass in place across North America. As we found out in recent years, -NAO and -AO patterns can be very mild for us. This isn’t like the old days around 2010 when big -AO and -NAO drops meant cold. I think Don had a great post a while back on how the -AO and -NAO has become warmer for us. 

 

with the block we are +2 to +4, without it we would be +6 to +8

[SnoSki14]

1 hour ago, bluewave said:

Yeah, the TPV with this -NAO shifted over to Eurasia leaving a mild Pacific air mass in place across North America. As we found out in recent years, -NAO and -AO patterns can be very mild for us. This isn’t like the old days around 2010 when big -AO and -NAO drops meant cold. I think Don had a great post a while back on how the -AO and -NAO has become warmer for us. 

 

Many posters in the New England forum say last Dec was just bad luck despite the huge block but there was more to it than that. 

[Brian5671]

3 hours ago, Allsnow said:

The negative Nao is pointless if the pacific is so horrible. We will have a -nao next week when you’re in the 50’s 

Yep there’s more to a good pattern than just Atlantic blocking.  We went through this last December.

[Brian5671]

Good day to get Xmas stuff up here it’s 55 and partly sunny 

[donsutherland1]

1 hour ago, bluewave said:

Yeah, the TPV with this -NAO shifted over to Eurasia leaving a mild Pacific air mass in place across North America. As we found out in recent years, -NAO and -AO patterns can be very mild for us. This isn’t like the old days around 2010 when big -AO and -NAO drops meant cold. I think Don had a great post a while back on how the -AO and -NAO has become warmer for us. 

 

Today (1991-20), December days with an AO of -1 or below are as cold as all December days were during 1961-90 in NYC.

[EastonSN+]

21 minutes ago, SnoSki14 said:

Many posters in the New England forum say last Dec was just bad luck despite the huge block but there was more to it than that. 

I agree with them, they have some really good experts there. Now, it was not bad luck as in timing as much as it was the trough in the West was too deep and overpowered the block. It's that simple. It was not the beginning of the end of blocking as we know it. 

[MJO812]

46 minutes ago, Brian5671 said:

Good day to get Xmas stuff up here it’s 55 and partly sunny 

My apartment has been done since Thanksgiving. 

[nycwinter]

 58 in the city..

[psv88]

10 minutes ago, nycwinter said:

 58 in the city..

58 here, 61 at Newark 

[SnoSki14]

1 hour ago, Brian5671 said:

Good day to get Xmas stuff up here it’s 55 and partly sunny 

Thank god for blocking or it would be near 70 today 

[MJO812]

Disgusting outside