2024-2025 La Nina

[LibertyBell]

3 hours ago, GaWx said:

At NYC using Don’s projected 3.2 BN for Feb, it would rival the 2009-10 DJF average. But it doesn’t appear to me it would be quite as cold as 2014-5, 2013-4, and 2010-1 (using same base). @donsutherland1what do you think?

much less snowy than any of those winters too, from what Chris said, this is the least snowy winter in over 30 years with an average temperature below 35.0

[LibertyBell]

2 hours ago, GaWx said:

 Below is the latest GEFS +PNA prediction. If it were to verify closely, DJF of 2024-5 would end up at or very near the highest +PNA on record (back at least to 1949-50):

 If the above were to verify closely, I’d project Feb PNA of ~+1.60, which would mean DJF PNA of +1.45! Current highest on record are these:

1976-7: +1.43

2015-6: +1.43

2002-3: +1.20

1969-70: +1.14

1982-3: +1.08

1960-1: +1.07

1963-4: +1.06

1986-7: +1.01

 Note that all of these were El Niño except the ENSO neutral 1960-1. The highest PNA on record currently for La Niña is only +0.86 (2000-01). So, that will be obliterated.

 

https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table

are we switching to a predominantly +PNA cycle now?

[LibertyBell]

49 minutes ago, donsutherland1 said:

If the numbers verify, Winter 2024-25 would have a seasonal mean temperature of 34.1° in New York City. That would be the coldest winter since 2014-15, which had a mean temperature of 31.7°.

least snowiest winter with a mean temperature below 35.0 in over 30 years, Don.

 

[GaWx]

7 minutes ago, LibertyBell said:

are we switching to a predominantly +PNA cycle now?

I don’t know. Potentially?

[PhiEaglesfan712]

21 hours ago, GaWx said:

Note that all of these were El Niño except the ENSO neutral 1960-1. The highest PNA on record currently for La Niña is only +0.86 (2000-01). So, that will be obliterated.

FWIW, I had February 2001 as my top analog for this February. Outside of the December 30, 2000 snowstorm, this winter has behaved almost similarly to that one in our area, in regards to temps/precip/snowfall. The winter of 2000-01, if I remember correctly, had that la nina mismatch.

[LibertyBell]

3 hours ago, PhiEaglesfan712 said:

FWIW, I had February 2001 as my top analog for this February. Outside of the December 30, 2000 snowstorm, this winter has behaved almost similarly to that one in our area, in regards to temps/precip/snowfall. The winter of 2000-01, if I remember correctly, had that la nina mismatch.

and ended quite ominously with the March 2001 bust....

[LibertyBell]

On 2/12/2025 at 10:10 AM, GaWx said:

 Below is the latest GEFS +PNA prediction. If it were to verify closely, DJF of 2024-5 would end up at or very near the highest +PNA on record (back at least to 1949-50):

 If the above were to verify closely, I’d project Feb PNA of ~+1.60, which would mean DJF PNA of +1.45! Current highest on record are these:

1976-7: +1.43

2015-6: +1.43

2002-3: +1.20

1969-70: +1.14

1982-3: +1.08

1960-1: +1.07

1963-4: +1.06

1986-7: +1.01

 Note that all of these were El Niño except the ENSO neutral 1960-1. The highest PNA on record currently for La Niña is only +0.86 (2000-01). So, that will be obliterated.

 

https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table

what made 1960-61 so historically snowy? I feel like we ignore neutral years.....1966-67 was another historically snowy season that was neutral from that same decade.

 

 

[PhiEaglesfan712]

1 hour ago, LibertyBell said:

what made 1960-61 so historically snowy? I feel like we ignore neutral years.....1966-67 was another historically snowy season that was neutral from that same decade.

 

 

I'm not sure about 1960-61, but 1966-67 is easy to explain. That was a classic example of a neutral year taking the shape of the previous ENSO state. 1966-67 behaved like an el nino, as the previous year was a strong el nino. 1992-93 was very similar to this.

[LibertyBell]

8 minutes ago, PhiEaglesfan712 said:

I'm not sure about 1960-61, but 1966-67 is easy to explain. That was a classic example of a neutral year taking the shape of the previous ENSO state. 1966-67 behaved like an el nino, as the previous year was a strong el nino. 1992-93 was very similar to this.

ah, and 1993-94 is another example.

it's probably why la ninas after el ninos are so snowy too.

 

[Snowstorms]

2 hours ago, LibertyBell said:

what made 1960-61 so historically snowy? I feel like we ignore neutral years.....1966-67 was another historically snowy season that was neutral from that same decade.

 

 

1966-67 was almost borderline La Nina on ONI and MEI. Late bloomer like this year (coldest anomalies were late winter and spring). It lead to another cold neutral-borderline La Nina the following winter. Ironically 66-67 came on the heels of a strong El Nino with a ONI peak at 2.0, much like last year. So from an ENSO perspective, 66-67 is a good analog to this year.  

Ironically the PDO was primarily negative for much of the 60's with few periods of positive phases here and there. Although the PDO wasn't deeply negative that decade as it has been since 2019-20. Yet ironically despite the -PDO, we saw 4 El Nino's and only one La Nina that entire decade. I certainly believe the -PDO, which is being enhanced by the extreme marine heatwave near Japan, has been amplifying the string of warm winters and to some degree the frequent La Nina's. This combined with the continuing +AMO and two strong/super El Nino's since 2015 has certainly played a role in all the warm winters. I believe a healthy balance between neutral, El Nino, and La Nina is optimal and we haven't had that since the early-mid 2010s. And ideally a weak or mod El Nino. 

However, statistically speaking a -PDO between -0.5 to -1.5 is more favorable for snow/cold for the NE, New England, and the Great Lakes. A deeply -PDO has to much uncertainty for all of us. A +PDO is more beneficial for the Mid-Atlantic. Though one could argue against that too. DC averaged 23" in the 1960s vs. 16" in the 80s. But they require more than just a PDO phase for snowy patterns, much more volatility down there. 

The 1960's were a good decade here. Featured nothing but cold winters with an average snowfall of 53". I believe Central Park averaged 30" from 1960-1970. Quite a snowy decade for you guys too. Far cry from the +PDO dominated 1980s where Central Park only averaged 20". 

The 2000s and early 2010's were eerily similar to the 1960's with a similar -PDO type pattern. 

 

[GaWx]

 The models remain unanimous with a low of sub -5 AO on/near Feb 15th. Below is the latest GEFS. Today (2/13) it was at -3.7, which is actually lower than the -3.25 this chart shows. That gives me extra confidence that it will go sub -5 in 2 days:

 Sub -5 AOs are pretty rare and have always been accompanied and/or immediately followed by intense cold and/or wintry in parts and often much of the SE. Here are the ones during DJF since 1950:

 

1. 2/10-11/2021: major ZR GSO 2/12-13

2. 12/18/2010: significant to big snow one week later much of inland SE and light on coast

3. 2/6-7/2010, 2/14/2010: two winter storms (2/5, 2/12-13) affecting most of SE between them including some on coast 2/12-13

4. 1/2-6/2010: light snow N GA/very cold SE

5. 12/20-25/2009: winter storm mainly NC 12/18-19

6. 1/18-20/1985: 1-2 mainly light snows much of inland SE 1/17-20 followed by historic cold

7. 2/5-6/1978: several mainly light snows SE 2/2-9 including some on coast 2/8-9; very cold

8. 1/11-17/1977: snow events almost all of SE during and soon after including Miami and parts of Bahamas 1/19; very cold

9. 12/28-29/1976: several wintry events then into first few days of Jan inland SE; cold

10. 2/13-16/1969: major winter storm 2/15-17 Charlotte to GSP/Asheville; wintry precip most other areas within 2/14-17 including light on coast 

11. 1/28/1966: several wintry events 1/25-30 including on coast 1/27 and 1-2 majors much of NC; extreme cold 1/29-31

12. 1/21/1963: extreme cold the week following; several light wintry events inland

[LakePaste25]

The end of run EPS are showing signs of a Nino-like pacific jet extension, bringing the risk of mild temperatures across North America. Depending on how this shakes out, it could bring our first shot of spring-like temperatures, particularly the interior/areas not subject to CAD. If it verifies less extended (stops short of the west coast), then we likely continue to see colder than normal temperatures. There are currently mixed and competing ensemble signals in regards to this. 

 

[LibertyBell]

13 minutes ago, Snowstorms said:

1966-67 was almost borderline La Nina on ONI and MEI. Late bloomer like this year (coldest anomalies were late winter and spring). It lead to another cold neutral-borderline La Nina the following winter. Ironically 66-67 came on the heels of a strong El Nino with a ONI peak at 2.0, much like last year. So from an ENSO perspective, 66-67 is a good analog to this year.  

Ironically the PDO was primarily negative for much of the 60's with few periods of positive phases here and there. Although the PDO wasn't deeply negative that decade as it has been since 2019-20. Yet ironically despite the -PDO, we saw 4 El Nino's and only one La Nina that entire decade. I certainly believe the -PDO, which is being enhanced by the extreme marine heatwave near Japan, has been amplifying the string of warm winters and to some degree the frequent La Nina's. This combined with the continuing +AMO and two strong/super El Nino's since 2015 has certainly played a role in all the warm winters. I believe a healthy balance between neutral, El Nino, and La Nina is optimal and we haven't had that since the early-mid 2010s. And ideally a weak or mod El Nino. 

However, statistically speaking a -PDO between -0.5 to -1.5 is more favorable for snow/cold for the NE, New England, and the Great Lakes. A deeply -PDO has to much uncertainty for all of us. A +PDO is more beneficial for the Mid-Atlantic. Though one could argue against that too. DC averaged 23" in the 1960s vs. 16" in the 80s. But they require more than just a PDO phase for snowy patterns, much more volatility down there. 

The 1960's were a good decade here. Featured nothing but cold winters with an average snowfall of 53". I believe Central Park averaged 30" from 1960-1970. Quite a snowy decade for you guys too. Far cry from the +PDO dominated 1980s where Central Park only averaged 20". 

The 2000s and early 2010's were eerily similar to the 1960's with a similar -PDO type pattern. 

 

Thanks, my thinking is along the same lines.  And this is probably why la ninas after el ninos have been very snowy here.

1995-96 and 2010-11 are two other examples.

 

[Snowstorms]

16 minutes ago, LibertyBell said:

Thanks, my thinking is along the same lines.  And this is probably why la ninas after el ninos have been very snowy here.

1995-96 and 2010-11 are two other examples.

 

I prefer a healthy balance between the 3 (Nino, Nina, Neutral). Can't have one more than the other. 

That's why the pattern between 2000-2015 was good. PDO was negative 70% of the time and not super negative either and we had a healthy balance of 6 La Nina's, 4 neutral, and 5 El Nino's. 

[LibertyBell]

2 minutes ago, Snowstorms said:

I prefer a healthy balance between the 3 (Nino, Nina, Neutral). Can't have one more than the other. 

That's why the pattern between 2000-2015 was good. PDO was negative 70% of the time and not super negative either and we had a healthy balance of 6 La Nina's, 4 neutral, and 5 El Nino's. 

Yes, these three year la ninas interrupted by a super el nino and then more la ninas in a row is very unhealthy, particularly to the environment and ecosystem.

OT but at some point we're going to have to figure out how to regulate ocean currents and the climate.

 

[PhiEaglesfan712]

[Stormchaserchuck1]

On 2/12/2025 at 10:10 AM, GaWx said:

 Below is the latest GEFS +PNA prediction. If it were to verify closely, DJF of 2024-5 would end up at or very near the highest +PNA on record (back at least to 1949-50):

 If the above were to verify closely, I’d project Feb PNA of ~+1.60, which would mean DJF PNA of +1.45! Current highest on record are these:

1976-7: +1.43

2015-6: +1.43

2002-3: +1.20

1969-70: +1.14

1982-3: +1.08

1960-1: +1.07

1963-4: +1.06

1986-7: +1.01

 Note that all of these were El Niño except the ENSO neutral 1960-1. The highest PNA on record currently for La Niña is only +0.86 (2000-01). So, that will be obliterated.

 

https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table

Good research Larry, like always, but this is not +PNA

[GaWx]

14 minutes ago, Stormchaserchuck1 said:

Good research Larry, like always, but this is not +PNA

Thanks, Chuck.

 Why is there a discrepancy between your map and the CPC? The graph below shows all days within 1/15-2/11 to be either +PNA (1/15-17 and 2/6-11) or neutral (1/18-2/5). So, 9 days +PNA and 19 days neutral meaning a mean of weak +PNA.

[Stormchaserchuck1]

45 minutes ago, GaWx said:

Thanks, Chuck.

 Why is there a discrepancy between your map and the CPC? The graph below shows all days within 1/15-2/11 to be either +PNA (1/15-17 and 2/6-11) or neutral (1/18-2/5). So, 9 days +PNA and 19 days neutral meaning a mean of weak +PNA.

CPC apparently changed their reading some time ago.. and it's ... not even really close. There was a time in September I think too where there was N. Pacific High pressure and they said it was like a +2.5 PNA lol.  I don't know.. someone said they keep the old calculation on another website, and that one has been -PNA for the last month. You can see the clear Pacific-North-American 3 wave pattern in the map I posted. It does run into the EPO domain a little, but is mostly south of Alaska and over the Ocean.. a clear -PNA. 

This also isn't going to be close to one of the most +PNA Winter's on record.. the 500mb map isn't like that at all.  I just don't know how the CPC has +PNA in that time if there is a string of High pressures from the Gulf of Alaska to NE Asia! I don't know what to say... maybe it's better just to look at 500mb or SLP maps and make your own call.  They also had many +NAO's when there was a Greenland block lately too.. maybe they use something that is completely independent from H5? I don't know.. 

[Terpeast]

I agree with you, Chuck. I do some of this for a living now, and when others were saying "this is the most +PNA period" I thought something wasn't right. When tracking multiple snow events for mby, I didn't see a classic +PNA much of the time. If anything, it was mostly neutral with an AK ridge with some troughing undercutting it out west.

[Stormchaserchuck1]

16 hours ago, Terpeast said:

I agree with you, Chuck. I do some of this for a living now, and when others were saying "this is the most +PNA period" I thought something wasn't right. When tracking multiple snow events for mby, I didn't see a classic +PNA much of the time. If anything, it was mostly neutral with an AK ridge with some troughing undercutting it out west.

Congrats!  

It's better to look at 500mb and make your own determination.. a lot of times lately they have called -NAO's, +NAO. There was a 4 year period actually where the H5 over Greenland was +90dm and they had it >+1.00 NAO for the 4 years.. It's ok if SLP disconnected a little, but these are big differences we are talking about! 

Someone from the NW, US mentioned to me how it was their 4th coldest Jan 15-Feb 15 since 1950.. I was like, in such a +PNA period! Then I looked, and that's not +PNA at all lol. 

 

[donsutherland1]

Some updates on last week’s thoughts: 

1. Los Angeles picked up 2.12” of rain during February 12-13. San Francisco saw 2.29” during February 11-13.

2. The New York City area will likely experience experienced its biggest snowstorm of the season during February 8-9 when 3.1” of snow fell. Boston saw 5.5” of snow, as southern New England saw somewhat less snow than had been expected. However, Portland picked up 10.1” of snow during February 8-9.

A second storm brought 6.4” of snow to Washington, DC during February 11-12. That was Washington’s second 6” or above snowstorm of the season. The last time Washington, DC saw two 6” or above snowstorms in a winter was 2013-2014.

3. Chicago picked up 3.0” of snow during February 11-13 while 3.8” fell in Detroit during February 12-13.  

Three Thoughts Going Forward:

1. A significant precipitation event will affect the Northeastern U.S. Albany, Boston, New York City, and Philadelphia could see 1”-2” of precipitation with locally higher amounts tonight and tomorrow.

2. The February 17-21 period could see the temperature average more than 10° below normal in parts of the Central Plains, including Des Moines, Kansas City, and Omaha. The coldest temperature could reach -10° or below in all three cities.   There is a chance that Chicago could experience a subzero low temperature. The last time Chicago saw a subzero low temperature after February 14^th was during March 4, 2019 when the mercury fell to -3°.

3. A significant (6” or more) snowfall is likely in parts of the East, particularly from Washington, DC to Atlantic City during February 19-20.  Significant snow is possible but not assured in Baltimore, Philadelphia, and New York City. There is a chance that 10” or more snow could fall in parts of the Middle Atlantic region. Should Washington pick up 6” or more snow, that would be the third time this winter that the City had seen 6” or more snow during a storm. The last winter with three or more such storms was Winter 2009-2010 when there were four such storms.

Longer-Range:

The preponderance of guidance has now shifted toward a cooler than normal temperatures in much of the eastern United States, except for the Southeast during the second half of February overall. Precipitation for the Great Lakes Region and Northeast could be above normal during the second half of February. The Southwest will likely wind up warmer than normal.

 There are growing indications that a significant pattern realignment could occur near the end of February or during the start of March.

[so_whats_happening]

35 minutes ago, donsutherland1 said:

Some updates on last week’s thoughts: 

1. Los Angeles picked up 2.12” of rain during February 12-13. San Francisco saw 2.29” during February 11-13.

2. The New York City area will likely experience experienced its biggest snowstorm of the season during February 8-9 when 3.1” of snow fell. Boston saw 5.5” of snow, as southern New England saw somewhat less snow than had been expected. However, Portland picked up 10.1” of snow during February 8-9.

A second storm brought 6.4” of snow to Washington, DC during February 11-12. That was Washington’s second 6” or above snowstorm of the season. The last time Washington, DC saw two 6” or above snowstorms in a winter was 2013-2014.

3. Chicago picked up 3.0” of snow during February 11-13 while 3.8” fell in Detroit during February 12-13.  

Three Thoughts Going Forward:

1. A significant precipitation event will affect the Northeastern U.S. Albany, Boston, New York City, and Philadelphia could see 1”-2” of precipitation with locally higher amounts tonight and tomorrow.

2. The February 17-21 period could see the temperature average more than 10° below normal in parts of the Central Plains, including Des Moines, Kansas City, and Omaha. The coldest temperature could reach -10° or below in all three cities.   There is a chance that Chicago could experience a subzero low temperature. The last time Chicago saw a subzero low temperature after February 14^th was during March 4, 2019 when the mercury fell to -3°.

3. A significant (6” or more) snowfall is likely in parts of the East, particularly from Washington, DC to Atlantic City during February 19-20.  Significant snow is possible but not assured in Baltimore, Philadelphia, and New York City. There is a chance that 10” or more snow could fall in parts of the Middle Atlantic region. Should Washington pick up 6” or more snow, that would be the third time this winter that the City had seen 6” or more snow during a storm. The last winter with three or more such storms was Winter 2009-2010 when there were four such storms.

Longer-Range:

The preponderance of guidance has now shifted toward a cooler than normal temperatures in much of the eastern United States, except for the Southeast during the second half of February overall. Precipitation for the Great Lakes Region and Northeast could be above normal during the second half of February. The Southwest will likely wind up warmer than normal.

 There are growing indications that a significant pattern realignment could occur near the end of February or during the start of March.

Yea I went too warm for Boston in the February forecast, bummer. Also impressed by the overall snow amounts so far this year in the mid atlantic was expecting better than the last few years but being at average to possibly quickly going to above average is nice to see.

Glad an overall wetter pattern whether it be rain or snow is taking place, still in a severe drought so any bit helps.

[Wannabehippie]

On 2/13/2025 at 2:49 PM, LibertyBell said:

Yes, these three year la ninas interrupted by a super el nino and then more la ninas in a row is very unhealthy, particularly to the environment and ecosystem.

OT but at some point we're going to have to figure out how to regulate ocean currents and the climate.

 

I feel like any attempts by humans to regulate ocean currents and the climate will just further f things up.
 

[bluewave]

Another big EPAC WWB like we have been seeing in recent years boosted Nino 1+2 back above +1 again.

 

 

[Stormchaserchuck1]

A pretty explainable sequence... A Scandinavia/NW Russia block happened, registering over +5820dm in mid-Winter. That area, especially Scandinavia is a loading pattern for -AO.. That -AO took. And is now -5!

Due in part to +QBO, the AO is now expected to rise back to +2.5 That is a +7.5 index move in less 1 week!  +QBO coupled with Weak Nina favors a cold 10mb, which goes with +AO at a Day+0 correlation. Due in part because of the record QBO, the AO is racing back to positive, and will be one of the most extreme short term moves on record [CPC]. 

[PhiEaglesfan712]

On 2/15/2025 at 8:48 AM, so_whats_happening said:

Yea I went too warm for Boston in the February forecast, bummer. Also impressed by the overall snow amounts so far this year in the mid atlantic was expecting better than the last few years but being at average to possibly quickly going to above average is nice to see.

Glad an overall wetter pattern whether it be rain or snow is taking place, still in a severe drought so any bit helps.

That was pretty apparent at the beginning of the month. I was there on the Feb. 1-2 weekend, and we got down to 9F overnight. I knew Boston was in for a cool month.

[40/70 Benchmark]

On 2/13/2025 at 8:13 AM, PhiEaglesfan712 said:

FWIW, I had February 2001 as my top analog for this February. Outside of the December 30, 2000 snowstorm, this winter has behaved almost similarly to that one in our area, in regards to temps/precip/snowfall. The winter of 2000-01, if I remember correctly, had that la nina mismatch.

Been nothing like that season in New England in terms of snow snowfall.

[bluewave]

1 hour ago, Stormchaserchuck1 said:

Due in part to +QBO, the AO is now expected to rise back to +2.5 That is a +7.5 index move in less 1 week!  +QBO coupled with Weak Nina favors a cold 10mb, which goes with +AO at a Day+0 correlation. Due in part because of the record QBO, the AO is racing back to positive, and will be one of the most extreme short term moves on record [CPC]. 

These record swings in a short period time have become the new normal as the Arctic has rapidly warmed. We just experienced one back in October. Then our last -5 back in 2021 also experienced a steep rise. So these -AOs don’t lock in for longer periods like they used to in the past. 

Greatest AO swings on record in around a month or less since 1950 and the date on which the maximum difference from low to high or high to low occurred with the numerical value of the swing

https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.daily.ao.nao.pna.aao.gdas.120days.csv
 

https://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.ao.index.b500101.current.ascii

 

#1……+10.790……3-11-21

#2…...+9.401…….1-16-16

#3……+9.256……3-2-56

#4……+9.039……4-21-13

#5……+8.522……1-25-05

#6…...+8.462…..1-15-77

#7…….+8.268….3-16-68

#8…….+7.793….2-25-01

#9…….+7.731….3-23-86

#10……+7.720…2-4-11
 

#11……+7.641…..3-5-70

#12…..+7.502…..1-19-85

#13……+7.387….3-20-78

#14……+7.240….10-23-24

#15……+7117……1-23-52

#16…..+7.066…1-24-08

#17……+7.043…3-19-15

#18……+7.038…2-10-76

[GaWx]

Today’s preliminary CPC PNA of +1.39 is the highest daily CPC PNA of this winter. And it will be rising further with a target near +1.75 ~Feb 21st. That would be the highest CPC PNA on any winter day since 12/7/2020! 

 

 Per GEFS, I’m currently projecting a Feb CPC PNA of ~+1.60. That along with the +1.70 of Dec and +1.05 of Jan would give a DJF averaged CPC PNA of +1.45. The current highest DJF averaged CPC PNA (back to 1950-1) are the +1.43 of 2015-6 and the +1.41 of 1976-7, both El Niños. So, 2024-5 still has a shot at having the strongest DJF averaged CPC PNA on record (back to 1950-1). It will obliterate the current highest La Niña CPC PNA of +0.89 (2000-01).

 Note that I was careful to always call this the “CPC PNA” as opposed to just “PNA” due to Chuck and others questioning the CPC calculations of the CPC PNA in parts of late Jan and early Feb.