December 2023

[bluewave]

4 minutes ago, SnoSki14 said:

And we're the cooler region this month. The warmth out west has been ridiculous 

Yeah, the Northeast is closer to +5 for December and the upper Midwest is around +10.

 

[Allsnow]

6 minutes ago, bluewave said:

Yeah, the Northeast is closer to +5 for December and the upper Midwest is around +10.

 

MSP had close to 100 inches last winter, so I don’t exactly feel bad for their lack of winter haha 

[bluewave]

9 minutes ago, Allsnow said:

MSP had close to 100 inches last winter, so I don’t exactly feel bad for their lack of winter haha 

If we had the Christmas week departures that they are going to have, we would be in the low 70s instead of the 50s.

 

 

[Volcanic Winter]

Made it down to 26 this AM for a low. Looks like tomorrow AM will be the coldest of this brief stretch?

[EastonSN+]

I wonder if CPK November snowfall has been higher than December over the past 5 seasons. I know there was at least one major November snowfall event.

[Allsnow]

6 minutes ago, Volcanic Winter said:

Made it down to 26 this AM for a low. Looks like tomorrow AM will be the coldest of this brief stretch?

Definitely. Low 20’s outside urban area 

[Allsnow]

10 minutes ago, bluewave said:

If we had the Christmas week departures that they are going to have, we would be in the low 70s instead of the 50s.

 

 

I thought we would be warmer in the east (+5 nothing to sneeze at) if someone asked me back in early December. the standing wave really enhanced the warmth in the typical warm spots for a December Nino 

[EastonSN+]

Actually forgot about this biggie....

[bluewave]

4 minutes ago, Allsnow said:

I thought we would be warmer in the east (+5 nothing to sneeze at) if someone asked me back in early December. the standing wave really enhanced the warmth in the typical warm spots for a December Nino 

The MJO slowing in 7 this December focused the greatest departures over Canada and the Upper Midwest. It was the stall in 5 during the December 2015 El Niño that gave us the +13. 

[EastonSN+]

9 hours ago, Roger Smith said:

Yep, I still recall the "winter a thing of the past" chatter in the early 90s after 1987 to 1991 turned out so warm, not to mention talk in 2012 awkwardly followed by two polar vortex winters. The first time I recall hearing the "ski resorts will cease to exist" narrative was probably in 1991 after a couple of bad seasons. But most in Ontario, Quebec and the n.e. US have held on. I suppose the more marginal ones are either gone or struggling.

What is no doubt true is that probability is shifting, and I suppose eventually it could overwhelm winter, but at this point, maybe the old one in three good winters more like one in four or one in five. 

I always wonder too, will the atmosphere cook up a surprise ending to the warming, and create new and different climate regimes in arctic and subarctic regions that do not see large snowfalls in either this climate or the "background normal" 20th century climate. Cambridge Bay in Canada's western arctic normally has a snow cover of about 10 to 20 inches from December to about mid-may; what if a lot of Pacific moisture started to reach them on a regular basis in winter and topped up that cover (most of it falls in late Oct and Nov), increased it to 30-40 in, and it took all of June to melt (as was probably the case with the smaller snow cover of colder centuries like 18th and 19th for which we have only a few anecdotal exploration reports. The reason for glaciation to start is excess snow over snow melt, in subarctic regions. It is not a colder climate so much as a different moisture balance.

The surprise ending could be, in years where we succeed in stabilizing greenhouse gases, suddenly this new storm track and results kick in, and climate begins to cool. While we don't want a warmer climate, we also don't want to go too far in the other direction. (no political implications because by the time this might occur, we will be long gone). 

My first time hearing that GW was ending winter was 1988 and as a kid it was pretty disappointing, especially since the previous few winters were duds. Then the Thanksgiving snowstorm of 1989 hit. 

[EastonSN+]

GEFS now has the best H5 look in the LR. I know there is a bit of a split flow on the EPS, however still want less of a trough off the west coast and more heights over Greenland (to me this still looks like Canada is receiving PAC air). This is why I hate strong El ninos.

 

[EastonSN+]

Now THIS is the COD lol.

[Dark Star]

[suzook]

Moving outside of Atlanta next week from LI NY, I actually might see snow the 1st of the year!

[donsutherland1]

7 hours ago, snowman19 said:

 

The guidance has stepped back somewhat. Severe cold did not seem likely through at least the first week of January and perhaps beyond. The cold was also focused largely on the Southeast. The second week of January had shown more widespread cold, but nothing notable.

ECMWF Forecasts for January 8-15, 2024:

CFSv2 Week 4 Forecasts:

For the Northeast, the first week of January might well see readings closer to normal than they have been. That regime could continue through the second week of the month. If cross-polar flow can develop, the cold would be more widespread and significant. The record low North American snow cover will play a role in constraining the magnitude of the cold, so I don't expect to see any single-digit readings through the first half of December unless strong cross-polar flow can develop, which appears unlikely right now.

Of course, the guidance at that range is low skill, but the persistent ongoing basinwide strong El Niño, PDO-, and limited North American snow cover all argue for taking a more conservative (milder) path when it comes to expectations about the magnitude, duration, and extent of the cold. Additional risks are posed by the possibility that a PNA- could develop early in January, which would heighten the risk of any available cold air dumping into the West.

Finally, the AO reached +3.000 yesterday. Total snowfall through January 10th for cases when the AO reached +3 or above during December 15-25 is generally less than 3" with numerous cases of an inch or less. The highest amount was 6.4" during winter 2013-2014. The character of that emerging winter was dramatically different from that of 2023-24. December 8-9, 2013 saw 8.6" of snow fall in Philadelphia and 12.0" fall in Wilmington, DE. The last week of December saw much of Canada covered by significant cold. Extraordinary warmth is likely in much of Canada during the close of December. In parts of Canada, December monthly record warm temperatures are possible.

Unless things begin to change e.g., real signs for the commencement of cross-polar flow begin to emerge, my thinking is:

1. The pattern will change during the first week of January. A period of 1-2 (maybe 3 weeks) of generally near normal temperatures will develop for the northern Mid-Atlantic and New England areas. Farther south will be somewhat colder than normal. The Northeast could see short stretches of below normal readings during this period, but severe cold seems unlikely.

2. There will be a few (maybe 1-3) opportunities for measurable snow in the New York City area, but snowfalls will likely be on the lighter side (<2").

Beyond that, the extent and impact of the forecast weakening of the stratospheric polar vortex will help influence the evolution of events.

 

 

 

[NittanyWx]

1 hour ago, bluewave said:

The MJO slowing in 7 this December focused the greatest departures over Canada and the Upper Midwest. It was the stall in 5 during the December 2015 El Niño that gave us the +13. 

I don't think the MJO 'slowed' at all.  I think you had a Kelvin wave continue to traverse as expected, but the signal was overamplified by modeling.  It was less coherent as you rolled forward.

I also think the biggest issue was PV displacement on the other side of the pole.  Can't blame that entirely on tropical forcing.  It was a source region issue.  I asked this same question when the weeklies were showing this +PNA for the last week of Dec...what air are you advecting? 

 

[donsutherland1]

57 minutes ago, EastonSN+ said:

My first time hearing that GW was ending winter was 1988 and as a kid it was pretty disappointing, especially since the previous few winters were duds. Then the Thanksgiving snowstorm of 1989 hit. 

Climate change won't end winter in the New York City area anytime soon. Winters will continue to grow shorter and warmer overall, as has been occurring. As winter temperatures continue to rise, NYC will cross a threshold where the impact of the rising warmth more than offsets the increase in precipitation. At that time, seasonal snowfall will decline, as it has in such cities as Richmond and Washington. Based on the climate model forecasts for mean winter temperatures and snowfall data for the Mid-Atlantic region that has reached those forecast levels, New York City's annual snowfall (30-year average) could fall to around 20" by the mid-2030s. There will still be some high snowfall winters and big snowstorms. At the same time, I wouldn't be surprised if the record low figure of 2.3" from winter 2022-23 is tested again at some point.

At present, it is too soon to know whether the recent drop off in snowfall indicates that the transition toward a generally less snowy regime has started. I suspect that stochastic variability and climate change are both involved. If the transition is underway, it would be in its early stages. Central and especially northern New England might see further increases in seasonal snowfall into the 2030s, as the benefits of added moisture continue to outweigh the impact of warming there. 

[Allsnow]

5 minutes ago, NittanyWx said:

I don't think the MJO 'slowed' at all.  I think you had a Kelvin wave continue to traverse as expected, but the signal was overamplified by modeling.  It was less coherent as you rolled forward.

I also think the biggest issue was PV displacement on the other side of the pole.  Can't blame that entirely on tropical forcing.  It was a source region issue.  I asked this same question when the weeklies were showing this +PNA for the last week of Dec...what air are you advecting? 

 

Makes you wonder if the pv wasn’t so weak (displaced off the pole) would the upper Midwest have been colder? 

[bluewave]

13 minutes ago, NittanyWx said:

I don't think the MJO 'slowed' at all.  I think you have a Kelvin wave continue to traverse as expected, but the signal was overamplified by modeling.

 

I also think the biggest issue was PV displacement on the other side of the pole.  Can't blame that entirely on tropical forcing.

The RMM charts this month really didn’t do the forcing justice near the MJO 7 region. The VP anomalies in that region were some of the strongest on record for the first 3 weeks of December. So it was the record Nino 4s with the MJO action slowing into the circle in 6-7. El Niños usually feature the forcing further to the east. But it was the MJO interaction along with Nino 4s which produced the record warmth across Canada and the Northern Tier. 
 

 

 

[SACRUS]

 

Down to 27 last night and should remain in the upper 30s today.

 

[SACRUS]

 

Records:

 

Highs:

EWR: 64 (2013)
NYC: 65 (2013)
LGA: 62 (2018)

 

Lows:

EWR: 0 (1942)
NYC: -2( (1871)
LGA: -1 (1942)


Historical:

 

 

1892 - Portland, OR, was buried under a record 27.5 inches of snow. (21st-24th) (The Weather Channel)

1929 - An exceptional storm produced snow from the Middle Rio Grande Valley of Texas to southern Arkansas. The storm produced 26 inches of snow at Hillsboro TX, 18 inches at El Dorado AR, and 14 inches at Bossier LA. (21st-22nd) (David Ludlum) (The Weather Channel)

1964 - A great warm surge from the Pacific Ocean across Oregon and northern California brought torrential rains on a deep snow cover resulting in record floods. (David Ludlum)

 

1967: An F4 tornado traveled 33 miles across Iron and Washington Counties in Missouri during an unusual time of day, 12:45 to 1:20 am. The tornado killed 3 and injured 52 others. Most of the intense damage occurred in the town of Potosi, about 55 miles southwest of St. Louis. The tornado swept through the business district, destroying City Hall, library, a large supermarket, and a shopping center complex. Northeast of town, two people were killed when their home was swept from its foundation. The Red Cross reported 24 homes and trailers, along with 14 businesses destroyed. 81 other houses and trailers were damaged.

1987 - High winds continued along the eastern slopes of the Rockies. During the morning hours winds gusted to 64 mph at Cheyenne WY, and reached 97 mph near Boulder CO. Gale force winds prevailed across the Great Lakes Region. (The National Weather Summary) (Storm Data)

1988 - Seven cities in the eastern U.S. reported record high temperatures for the date, including Charleston SC with a reading of 78 degrees. A storm in the northwestern U.S. produced 22 inches of snow at Idaho City ID in two days, and up to two feet of snow at Happy Camp CA. Ski resorts in Idaho reported three to six feet of snow on the ground. (The National Weather Summary) (Storm Data)

1989 - Forty cities in the north central U.S., including thirteen in Iowa, reported record low temperatures for the date. Havre and Jordan, MT, tied for honors as the cold spot in the nation with morning lows of 43 degrees below zero, and the temperature remained close to 40 degrees below zero through the daylight hours. Dickinson ND reported a morning low of 33 degrees below zero and a wind chill reading of 86 degrees below zero. The high for the date of 16 degrees below zero at Sioux Falls SD was December record for that location. (The National Weather Summary)

1998 - Cold air spread into the southern San Joaquin Valley of California. For the next four nights, temperatures in the agricultural portions of Fresno, Tulare, and Kern counties dropped below 28 degrees for several hours at a time. In some locations, temperatures dipped into the teens. The California citrus industry suffered more than $600 million in damages due to the extreme cold.

[NittanyWx]

9 minutes ago, bluewave said:

The RMM charts this month really didn’t do the forcing justice near the MJO 7 region. The VP anomalies in that region were some of the strongest on record for the first 3 weeks of December. So it was the record Nino 4s with the MJO action slowing into the circle in 6-7. El Niños usually feature the forcing further to the east. But it was the MJO interaction along with Nino 4s which produced the record warmth across Canada and the Northern Tier. 
 

I'm very aware of how amplified the signal was...which is why I don't use the RMM's operationally.  I think they're perhaps the worst way to illustrate tropical forcing to a forecaster.

 

The reason VP was amplified is due to the strongly anomlous ENSO 4' SSTs yes, but there was also a traversing Kelvin Wave in the region which is and was clearly identifiable.  Also had a couple of SHEM cyclones spawn out of that pattern.  My point is that during the month forcing did shift east, h5 pattern had the appearance of more favorable for cold, but source region was still not conducive for colder conditions.

 

I understand a lot of folks want to boil weather down to one single element causing a forecast miss.  The MJO component wasn't as badly forecasted as you think.  And the PV displacement had an absolutely crucial role to play in this moment, particularly as VP200 signature improved.

[NittanyWx]

I boil the late Dec cold misses from a lot of folks down to an error in analyzing source region, not an error in model diagnosis of MJO.  Yes the MJO 'signal' as it were lost some steam as it rolled forward, which may have tripped people up.  But those weeklies, even with that h5 look were still very warm and will verify pretty well considering lead time.

[MJO812]

35 minutes ago, donsutherland1 said:

The guidance has stepped back somewhat. Severe cold did not seem likely through at least the first week of January and perhaps beyond. The cold was also focused largely on the Southeast. The second week of January had shown more widespread cold, but nothing notable.

ECMWF Forecasts for January 8-15, 2024:

CFSv2 Week 4 Forecasts:

For the Northeast, the first week of January might well see readings closer to normal than they have been. That regime could continue through the second week of the month. If cross-polar flow can develop, the cold would be more widespread and significant. The record low North American snow cover will play a role in constraining the magnitude of the cold, so I don't expect to see any single-digit readings through the first half of December unless strong cross-polar flow can develop, which appears unlikely right now.

Of course, the guidance at that range is low skill, but the persistent ongoing basinwide strong El Niño, PDO-, and limited North American snow cover all argue for taking a more conservative (milder) path when it comes to expectations about the magnitude, duration, and extent of the cold. Additional risks are posed by the possibility that a PNA- could develop early in January, which would heighten the risk of any available cold air dumping into the West.

Finally, the AO reached +3.000 yesterday. Total snowfall through January 10th for cases when the AO reached +3 or above during December 15-25 is generally less than 3" with numerous cases of an inch or less. The highest amount was 6.4" during winter 2013-2014. The character of that emerging winter was dramatically different from that of 2023-24. December 8-9, 2013 saw 8.6" of snow fall in Philadelphia and 12.0" fall in Wilmington, DE. The last week of December saw much of Canada covered by significant cold. Extraordinary warmth is likely in much of Canada during the close of December. In parts of Canada, December monthly record warm temperatures are possible.

Unless things begin to change e.g., real signs for the commencement of cross-polar flow begin to emerge, my thinking is:

1. The pattern will change during the first week of January. A period of 1-2 (maybe 3 weeks) of generally near normal temperatures will develop for the northern Mid-Atlantic and New England areas. Farther south will be somewhat colder than normal. The Northeast could see short stretches of below normal readings during this period, but severe cold seems unlikely.

2. There will be a few (maybe 1-3) opportunities for measurable snow in the New York City area, but snowfalls will likely be on the lighter side (<2").

Beyond that, the extent and impact of the forecast weakening of the stratospheric polar vortex will help influence the evolution of events.

 

 

 

Too far out to say if or how much snow we will get. Pattern change is finally coming. 

[TriPol]

Want there that Norlurn over LI back around this time in 1988?

[bluewave]

11 minutes ago, NittanyWx said:

I'm very aware of how amplified the signal was...which is why I don't use the RMM's operationally.  I think they're perhaps the worst way to illustrate tropical forcing to a forecaster.

 

The reason VP was amplified is due to the strongly anomlous ENSO 4' SSTs yes, but there was also a traversing Kelvin Wave in the region which is and was clearly identifiable.  Also had a couple of SHEM cyclones spawn out of that pattern.  My point is that during the month forcing did shift east, h5 pattern had the appearance of more favorable for cold, but source region was still not conducive for colder conditions.

 

I understand a lot of folks want to boil weather down to one single element causing a forecast miss.  The MJO component wasn't as badly forecasted as you think.  And the PV displacement had an absolutely crucial role to play in this moment, particularly as VP200 signature improved.

The MJO component needed to be anticipated by examining the usual model biases at the longer lead times which was being discussed here back during the fall. Long range guidance like the ECMWF is usually very good at identifying the ENSO input but can’t see the correct MJO phases or amplitude very far in advance. So the model had the stock El Niño ridge over Canada. This was fine for getting the location of the departures correct. But the magnitude of the warmth greatly exceeded the expectations back in late November. The missing piece of the puzzle was the dominant and much warmer MJO 7 composite in the December means rather than the vanilla El Niño composite which is typically much cooler with the ridge axis displaced further NW. 

[Dark Star]

41 minutes ago, donsutherland1 said:

Climate change won't end winter in the New York City area anytime soon. Winters will continue to grow shorter and warmer overall, as has been occurring. As winter temperatures continue to rise, NYC will cross a threshold where the impact of the rising warmth more than offsets the increase in precipitation. At that time, seasonal snowfall will decline, as it has in such cities as Richmond and Washington. Based on the climate model forecasts for mean winter temperatures and snowfall data for the Mid-Atlantic region that has reached those forecast levels, New York City's annual snowfall (30-year average) could fall to around 20" by the mid-2030s. There will still be some high snowfall winters and big snowstorms. At the same time, I wouldn't be surprised if the record low figure of 2.3" from winter 2022-23 is tested again at some point.

At present, it is too soon to know whether the recent drop off in snowfall indicates that the transition toward a generally less snowy regime has started. I suspect that stochastic variability and climate change are both involved. If the transition is underway, it would be in its early stages. Central and especially northern New England might see further increases in seasonal snowfall into the 2030s, as the benefits of added moisture continue to outweigh the impact of warming there. 

As good climatic forecast as any can be.  With the NYC metro area outpacing the global warming average temperatue, I think it is possible snow becomes more an anomaly around here, despite being at the "early stage"?

[NittanyWx]

16 minutes ago, bluewave said:

The MJO component needed to be anticipated by examining the usual model biases at the longer lead times which was being discussed here back during the fall. Long range guidance like the ECMWF is usually very good at identifying the ENSO input but can’t see the correct MJO phases or amplitude very far in advance. So the model had the stock El Niño ridge over Canada. This was fine for getting the location of the departures correct. But the magnitude of the warmth greatly exceeded the expectations back in late November. The missing piece of the puzzle was the dominant and much warmer MJO 7 composite in the December means rather than the vanilla El Niño composite which is typically much cooler with the ridge axis displaced further NW. 

 

This is why these tools aren't meant to be viewed in isolation, there are more tools at your disposal than that.  I did use a stratospheric signal, however, in conjunction with a view that PV displacement into Siberia would cause a significant source region issue for the month across the continent.  When you overlaid that with December Nino analogs and an ongoing tropical forcing signal which argued dominant forcing in a bad place you had about 5 different factors pointing very warm into the continental US.

 

I see what's put out on weather twitter, I see what gets put out by vendors...I see a lot of folks blaming the MJO and I don't think that's right in this case.  I think it was forecasters underweighting other signals in lieu of overweighting MJO phase progression.  For the life of me I don't understand sometimes the obsession with the tropical space as the answer to all.  In this case, it wasn't.

 

You had VP progression, you had some h5 response and....you still didn't have a source region.  The reason you didn't have a source region is a combination of about 3 or 4 different things happening at the same time.

[NittanyWx]

For the record, these were the temp anomalies shown for this Christmas week during the first week of December:

 

 

and current (yes, I know shorter time horizon):

 

 

If you had copy/pasted EC Weeklies as a forecaster, you feel pretty damn good about how this turned out.  Rare that you get modeling in that strong of a conviction aligned with the seasonal work.

[bluewave]

17 minutes ago, NittanyWx said:

 

This is why these tools aren't meant to be viewed in isolation, there are more tools at your disposal than that.  I did use a stratospheric signal, however, in conjunction with a view that PV displacement into Siberia would cause a significant source region issue for the month across the continent.  When you overlaid that with December Nino analogs and an ongoing tropical forcing signal which argued dominant forcing in a bad place you had about 5 different factors pointing very warm into the continental US.

 

I see what's put out on weather twitter, I see what gets put out by vendors...I see a lot of folks blaming the MJO and I don't think that's right in this case.  I think it was forecasters underweighting other signals in lieu of overweighting MJO phase progression.  For the life of me I don't understand sometimes the obsession with the tropical space as the answer to all.  In this case, it wasn't.

 

You had VP progression, you had some h5 response and....you still didn't have a source region.  The reason you didn't have a source region is a combination of about 3 or 4 different things happening at the same time.

The greater underlying issue is our rapidly warming climate. This has produced the record warming in the Western Pacific which in turn leads to slower and more amplified MJO 4-7 phases. So there were several underlying issues compounding the warmth potential in addition to the oversimplified El Niño means warm December explanations. The reason the source regions were working against us for cold is the combination of all the factors I mentioned above.

+10 monthly departures over parts of North America have become more common and just can’t be reduced to saying it’s expected during an El Niño. DFW went +13.2 in the December 2021 La Niña when there was an interaction with the very amplified MJO 6-7 even by RMM chart standards which worked in that case.