2024-2025 La Nina

[mitchnick]

24 minutes ago, jm1220 said:

We’ve essentially had a Nina background state in the Pacific since late 2018 because of the very warm W Pacific. Even the strong official El Niño last winter couldn’t really dislodge it. It goes to show that sometimes there’s too much attention to how warm/cold the E Pacific gets when the W Pacific is the other half of the equation. The warm W Pacific has kept the convection in the MC for the most part since late 2018, MJO in unfavorable phases and supercharged the Pacific jet. 

Probably should include the -PDO along with everything else.

[GaWx]

 For 3-4 weeks out this is quite impressive, especially as regards the 3rd shade of blue, which means 60-70% chance to average BN for a 2 week long period in ~30% of the lower 48. It also has ~2/3 of the lower 48 with a 50%+ chance for BN. You don’t see all of this too often these days to say the least, especially from the fairly conservative NOAA:

 

 

[bncho]

23 minutes ago, GaWx said:

 For 3-4 weeks out this is quite impressive, especially as regards the 3rd shade of blue, which means 60-70% chance to average BN for a 2 week long period in ~30% of the lower 48. It also has ~2/3 of the lower 48 with a 50%+ chance for BN. You don’t see all of this too often these days to say the least, especially from the fairly conservative NOAA:

 

 

I don’t give a fuck on how hard it may be, but I’m rooting for some kinda Jan 6-8, 1996 redux.

[Stormchaserchuck1]

7 hours ago, PhiEaglesfan712 said:

What was the PNA in February 1986, February 2006, and February 2021?

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

[Stormchaserchuck1]

2 hours ago, GaWx said:

 For 3-4 weeks out this is quite impressive, especially as regards the 3rd shade of blue, which means 60-70% chance to average BN for a 2 week long period in ~30% of the lower 48. It also has ~2/3 of the lower 48 with a 50%+ chance for BN. You don’t see all of this too often these days to say the least, especially from the fairly conservative NOAA

Yeah, I haven't seen a 3-4 week look like that in over a year. 

[bluewave]

The most interesting model trend to me for early to mid-January isn’t the cold showing up, but the stronger blocking NE of Hudson Bay. This could be related to the delayed freeze up. As I have noticed heights beating guidance there all month in the extended forecasts. If we can get a +PNA and -AO at the same time, a place like NYC can see a 4”+ snow event with such a pattern. But there is still an issue of how broad the trough underneath will be. NYC has had issues with broad troughs from west to east across the CONUS in the past during cold patterns. We got a suppressed storm in Jan 19 which gave 12” to DC in a cold pattern with uppers lows in the SW and NE. But my hope is that a possible stronger -AO this time around could compensate and this January window can produce for areas that missed out over the last few winters.

New run

Old run

 

 

[snowman19]

1 hour ago, bluewave said:

The most interesting model trend to me for early to mid-January isn’t the cold showing up, but the stronger blocking NE of Hudson Bay. This could be related to the delayed freeze up. As I have noticed heights beating guidance there all month in the extended forecasts. If we can get a +PNA and -AO at the same time, a place like NYC can see a 4”+ snow event with such a pattern. But there is still an issue of how broad the trough underneath will be. NYC has had issues with broad troughs from west to east across the CONUS in the past during cold patterns. We got a suppressed storm in Jan 19 which gave 12” to DC in a cold pattern with uppers lows in the SW and NE. But my hope is that a possible stronger -AO this time around could compensate and this January window can produce for areas that missed out over the last few winters.

New run

Old run

 

 

So much for all the non stop +TNH hype for weeks on end. If that’s correct, that’s not +TNH…..no Hudson Bay vortex 

[GaWx]

14 hours ago, Stormchaserchuck1 said:

Yeah, I haven't seen a 3-4 week look like that in over a year. 

 Spot on, Chuck! Last evening I discovered there’s a really good 3-4 week outlook archives section (issued once/wk since 2015-6). For the SE quadrant of the US, yesterday’s is THE most impressive for Jan (I mean based on % chance for BN) on record! It beat out the prior most impressive for Jan, that for 1/16-29/2016, a period that verified well in the SE quadrant with 4-6 BN. It had a major winter storm and flurries as far south as Gainesville, FL!

[bluewave]

53 minutes ago, snowman19 said:

So much for all the non stop +TNH hype for weeks on end. If that’s correct, that’s not +TNH…..no Hudson Bay vortex 

The biggest uncertainty going forward is how long we will be able to sustain the +PNA. Past December La Niña mismatches generally saw the +PNA reverse at some point in January. These were followed mostly by -PNA Februaries. But if there are other factors behind this +PNA that we haven’t detected, then not sure if we follow past events until we get more model data and verification further into the winter. The EPS weeklies are trying to show this shift in January. But not sure if they are just defaulting to La Niña climo. It’s possible that we still follow the La Niña progression even since this one was so weak. It will be interesting to see how things turn out. 

[GaWx]

 We’re still on pace for a shot at a new record high Dec PNA for non-Nino. Current projections are close to the +1.58 of 2020. Keep in mind that the tabular monthlies tend to be ~1.8 times the mean of the dailies.

Current highest tabular Dec +PNA for non-Nino:

2020: +1.58

1960: +1.46

1985: +1.39

2005: +1.38

2000: +1.23

 Where were the subsequent Jan tabular PNAs for these non-Nino high +PNA Dec?

2021 +0.19

1961 +1.41 (4th highest on record for non-Nino)

1986 +0.97 (tied for 7th highest on record for non-Nino)

2006 +0.43

2001: +1.51 (3rd highest on record for non-Nino)

Avg Jan for these 5: +0.90

 So, as @Stormchaserchuck1 was suggesting (actually he was suggesting for all ENSO), +PNA in Dec tends to carryover into Jan for non-Nino. Three of the 5 did strongly and one weakly. The other (2020-1) went to neutral. So, none even went to a weak -PNA. But caution is advised due to the sample size being small.

 

[snowman19]

16 minutes ago, bluewave said:

The biggest uncertainty going forward is how long we will be able to sustain the +PNA. Past December La Niña mismatches generally saw the +PNA reverse at some point in January. These were followed mostly by -PNA Februaries. But if there are other factors behind this +PNA that we haven’t detected, then not sure if we follow past events until we get more model data and verification further into the winter. The EPS weeklies are trying to show this shift in January. But not sure if they are just defaulting to La Niña climo. It’s possible that we still follow the La Niña progression even since this one was so weak. It will be interesting to see how things turn out. 

We’ll see, my guess is that a -PNA takes shape mid-late January 

[bluewave]

22 minutes ago, snowman19 said:

We’ll see, my guess is that a -PNA takes shape mid-late January 

That’s what the extended forecasts and past instances suggest at this time. Hoping the Hudson Bay warming event can at least give us enough of a block there for some over 4”+ snowfall potential in NYC during January. It’s such a strong event that the GFS is forecasting a big NH temperature jump.

 

[MJO812]

[so_whats_happening]

On 11/27/2024 at 10:33 PM, so_whats_happening said:

What I have found kind of crazy about this pattern is there is no retrograding features at all showing up. The overall trough/ridge pattern seem rather stuck even with a rotating MJO wave to try help kick things along. Even with this semi standing wave look, flow is still rather fast and we would need the buckled flow to buckle even more to really slow things down.

We do not have negatively tilted troughs showing up creating poleward flux onto the SPV so that will continue to strengthen slowly over time. 

I do feel the atmosphere is really trying to change going forward instead of trying to revert back to the same ol' humdrum. The fingerprint of the -PDO and background Nina-like state is still holding strong for now. The waters off of the NW coast of Australia are extremely warm right now. This may be something that needs to be watched as those waters are now some of if not the warmest in the equatorial ocean right now with the waters around 130E-180 are trying to cool a bit with these winds being stuck. I hope we can start to chip away at that warm pool in time. Outside of these few things nothing big seems to be on the horizon. I expect the PDO to be under -3 for the month of November which is a good thing to see. I am also not sure we get to a -.5 trimonthly, this next month should be very telling as we are pretty close to the typical Nina peak timeframe.

 

On 12/16/2024 at 9:17 PM, so_whats_happening said:

To me it just looks like a typical wave 1 response with little to no action on the european side to try the squeeze play. So your typical wave 1 response would be to have a warm Canada, we would typically also see a colder eastern Europe but with waters well above average in the Barents sea they tend to moderate just too much and it looks rather mild. We saw something similarish last year.

This is not to say it follow in the same path but if I had to take a guess.

Here is a nice write-up for one that occurred in 2016/17 season.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2021GL097024

The models have come around to some minor wave 2 pressure on the SPV over the last 5 days so we get some disruption and probably a flattening out of the SPV strength coming up here. What happens after that will be interesting Euro has a solid wave break over the Atlantic after this one setting up over Europe this week. So while it is technically an equatorward wave break which tends to help with some strengthening there was an attack on both sides of the SPV at the same time which will help put a squeeze. Now what comes of this will be important if we keep seeing the weakening of Gulf of Alaska style vortex and more ridging we can get this to connect from 500mb up. This will really start to put pressure on the SPV especially with Alaskan ridging and extension into the poles showing up into the new year. I don't like to look past 240 typically but some fun stuff showing up. This was last nights 00z Euro op run I mention the EPS wasn't terribly off the idea out to 240 it at least had the Alaskan polar ridging setup showing up just not the Atlantic wave break (this one more poleward) following so not as much pressure on the SPV as the GFS is trying. Here is a look at the GFS run for 00z op.

Just remember that operational will be a bit erratic but it is nice it does have some backup with the ensembles showing up. A progressive cool down does seem reasonable if we continue to get ridging into Alaska and some of the poles into the 5-9th period through the country, sustainability of these patterns still is a concern but we can cross that bridge in time. A lot of that sustainability will be of course help from Tropical forcing if we can still manage some semblance of  7/8/1 passage of the MJO just do not want to see a crash to COD and a pop back out around 2/3. Should really get some answers this week.

BTW managed just slightly under an inch of snowfall last night from the transfer and remaining upper level low and may get in on some snow squall action. Nice little blip of winter weather right now.

[jbenedet]

57 minutes ago, bluewave said:

That’s what the extended forecasts and past instances suggest at this time. Hoping the Hudson Bay warming event can at least give us enough of a block there for some over 4”+ snowfall potential in NYC during January. It’s such a strong event that the GFS is forecasting a big NH temperature jump.

 

Yea one of these patterns where you don’t much latitude because the mid level tracks are suppressed. 

[LibertyBell]

1 hour ago, bluewave said:

The biggest uncertainty going forward is how long we will be able to sustain the +PNA. Past December La Niña mismatches generally saw the +PNA reverse at some point in January. These were followed mostly by -PNA Februaries. But if there are other factors behind this +PNA that we haven’t detected, then not sure if we follow past events until we get more model data and verification further into the winter. The EPS weeklies are trying to show this shift in January. But not sure if they are just defaulting to La Niña climo. It’s possible that we still follow the La Niña progression even since this one was so weak. It will be interesting to see how things turn out. 

Even with winters like 1995-96 we eventually do get our big thaw, the difference is, it then flips back to real winter weather again.

2010-11 changed even more strongly, but that was also a stronger la nina than either 1995-96 or this one

Weak la ninas after el ninos are normally good for us, but no telling if that relationship still holds.

 

[bluewave]

1 hour ago, jbenedet said:

Yea one of these patterns where you don’t much latitude because the mid level tracks are suppressed. 

Models have been underestimating the 500mb heights near Hudson Bay all month. So that open water could be playing a role. Notice how the biggest model error recently has been underestimating the forecast ridge there next week. Could approach record levels for this time of year. 
 

New run

Old run

Possible record 500mb heights for this time of year

 

[mitchnick]

Odds of maintaining a +PNA in January are increasing.  @GaWx

[GaWx]

31 minutes ago, mitchnick said:

Odds of maintaining a +PNA in January are increasing.  @GaWx

That’s the highest daily WCS since Apr per the chart. Equivalent NOAA likely now down to only -2 from ~~-4 ~Oct 10! MTD ~~-2.5 to -2.8 but rising and could mean full Dec will be ~-2.2 to -2.6 (or ~~-2.4) vs Nov’s -3.24 and Oct’s -3.78.  That could mean a top 11-15 Oct-Dec rise (back 170 years).

[bluewave]

2 hours ago, LibertyBell said:

Even with winters like 1995-96 we eventually do get our big thaw, the difference is, it then flips back to real winter weather again.

2010-11 changed even more strongly, but that was also a stronger la nina than either 1995-96 or this one

Weak la ninas after el ninos are normally good for us, but no telling if that relationship still holds.

 

We didn’t get the great December snowfall response around NYC Metro like we got from past +PNA La Ninas  in December 1995, 2000, 2005, 2017, and 2020. The Pacific Jet was much stronger this time around and the Atlantic side blocking was also much weaker. So it was a warmer and less snowy outcome than those years. Hopefully, we can at least put together a 4”+ event in early to mid-January in NYC. I know people get excited when they see cold on the maps since it has been a rarity recently, but there are many that would rather have snow to go along with the cold. So cold temperatures plus snow would make many happy in early to mid-January. 

[LibertyBell]

11 minutes ago, bluewave said:

We didn’t get the great December snowfall response around NYC Metro like we got from past +PNA La Ninas  in December 1995, 2000, 2005, 2017, and 2020. The Pacific Jet was much stronger this time around and the Atlantic side blocking was also much weaker. So it was a warmer and less snowy outcome than those years. Hopefully, we can at least put together a 4”+ event in early to mid-January in NYC. I know people get excited when they see cold on the maps since it has been a rarity recently, but there are many that would rather have snow to go along with the cold. So cold temperatures plus snow would make many happy in early to mid-January. 

I noticed some of the other winters mentioned where we had 1"+ between the start of winter and Christmas were also la ninas where we didn't have huge snowstorms but at least we had some moderate events.  1983-84 and 1998-99.  Are these two good analogs for this winter?  Both also came after el ninos, although they were much stronger than this one (and the la ninas those two winters were also much stronger.)

 

 

[GaWx]

Oct-Dec PDO rises of 1.25+ during cold ENSO since 1854:

1878, 1882, 1892, 1894, 1910, 1921, 1924, 1943, 1949, 1962, 2000, 2005, 2007

2024 will likely join these

[PhiEaglesfan712]

26 minutes ago, LibertyBell said:

I noticed some of the other winters mentioned where we had 1"+ between the start of winter and Christmas were also la ninas where we didn't have huge snowstorms but at least we had some moderate events.  1983-84 and 1998-99.  Are these two good analogs for this winter?  Both also came after el ninos, although they were much stronger than this one (and the la ninas those two winters were also much stronger.)

 

 

1983-84 definitely is not because that was a +PDO winter. 1998-99 is an okay analog. That was the winter when we switched back to -PDO. Thing I don't like about 98-99 was that December 98 was really warm right up until a few days before the "Christmas Miracle" snowstorm on Dec. 23-24. We had a good 3 weeks of snow until mid-January, then nothing really until mid-March.

[LibertyBell]

52 minutes ago, PhiEaglesfan712 said:

1983-84 definitely is not because that was a +PDO winter. 1998-99 is an okay analog. That was the winter when we switched back to -PDO. Thing I don't like about 98-99 was that December 98 was really warm right up until a few days before the "Christmas Miracle" snowstorm on Dec. 23-24. We had a good 3 weeks of snow until mid-January, then nothing really until mid-March.

How much did you get in the Christmas Miracle snowstorm, sounds like an amazing surprise and perfectly timed too!

 

[donsutherland1]

Some updates on last week’s thoughts:

1. Peak high temperatures were as follows: Baltimore: 64°; Boston: 60° ; Detroit: 54°; New York City: 59°; Newark: 61°; Philadelphia: 63°; Portland, ME: 56°; Washington, DC: 65°

2. No significant (6” or above) snowfalls occurred in the Great Lakes Region or the Middle Atlantic Region. Snowfall amounts included:  Baltimore: Trace; Chicago: 2.2”; Detroit: 1.1” ; New York City: 1.8”; Philadelphia: Trace; Toronto: 4.2 cm (1.7”); and, Washington, DC: Trace

On December 20-21, a storm brought the season’s first measurable snowfall to New York City and Philadelphia. Amounts were: Boston: 5.2”; New York City: 1.8”; Philadelphia: 0.1”; Baltimore: Trace; and, Washington, DC: Trace. The outcome of a December 20-21 storm in the Mid-Atlantic and southern New England areas was almost identical to that of a system on February 16, 1980 when Boston picked up 5.3” of snow, New York City received 1.6”, and no snow was recorded in Philadelphia, Baltimore, and Washington, DC.

3. During December 17-20, Portland, OR saw temperatures reach 8° or more on each day. The temperature also hit a record high of 60° on December 18^th. During December 17-21, Seattle saw temperatures average 7° or above normal on each day. Seattle set a record high of 55° on December 18^th and tied the record of 59° on December 20^th. Phoenix set record highs of 83° on December 18, December 19, and December 20. That was the first time Phoenix experienced three consecutive 80° readings during the second half of December. The prior latest such streak occurred during December 6-8, 1939.

Five thoughts going forward:

The strongest cold shot so far this season is overspreading the Mid-Atlantic and southern New England areas. New York City and Philadelphia will see the temperature fall into the teens for the first time this season.

It will turn milder near midweek across the Great Lakes, Mid-Atlantic, and New England areas. Chicago could approach or reach 50° by the end of the week.

No significant snow is likely from Washington, DC to New York City through the remainder of December.

Phoenix will remain on track for its warmest December and warmest year on record.

The week ahead will be mild and wet in the Pacific Northwest

Long-Range:

Colder air will begin to push into the eastern half of the United States during the first week of January. The second week of January has the potential to feature widespread colder-than-normal readings before slow moderation develops near or after mid-month.

The pattern could also become more conducive toward bigger snowfalls in the Great Lakes Region eastward to the Middle Atlantic and New England states. Whether there will be storminess to coincide with the cold will remain to be seen, as some of the long-range guidance keeps conditions relatively dry through at least the first week of January.

Some of the long-range guidance suggests that an EPO+/AO+/PNA- pattern could develop in late January. That would imply that the month of January could end with warmer than normal readings.

Teleconnection forecasts beyond two weeks are not skillful.

[PhiEaglesfan712]

39 minutes ago, LibertyBell said:

How much did you get in the Christmas Miracle snowstorm, sounds like an amazing surprise and perfectly timed too!

 

About 2 in, but even as recently as the 22nd morning, temps were in the mid-60s. Earlier in the month, temps were in the 70s. That snowstorm came out of the blue.

[LibertyBell]

51 minutes ago, donsutherland1 said:

Some updates on last week’s thoughts:

 

1. Peak high temperatures were as follows: Baltimore: 64°; Boston: 60° ; Detroit: 54°; New York City: 59°; Newark: 61°; Philadelphia: 63°; Portland, ME: 56°; Washington, DC: 65°

 

2. No significant (6” or above) snowfalls occurred in the Great Lakes Region or the Middle Atlantic Region. Snowfall amounts included:  Baltimore: Trace; Chicago: 2.2”; Detroit: 1.1” ; New York City: 1.8”; Philadelphia: Trace; Toronto: 4.2 cm (1.7”); and, Washington, DC: Trace

 

On December 20-21, a storm brought the season’s first measurable snowfall to New York City and Philadelphia. Amounts were: Boston: 5.2”; New York City: 1.8”; Philadelphia: 0.1”; Baltimore: Trace; and, Washington, DC: Trace. The outcome of a December 20-21 storm in the Mid-Atlantic and southern New England areas was almost identical to that of a system on February 16, 1980 when Boston picked up 5.3” of snow, New York City received 1.6”, and no snow was recorded in Philadelphia, Baltimore, and Washington, DC.

 

3. During December 17-20, Portland, OR saw temperatures reach 8° or more on each day. The temperature also hit a record high of 60° on December 18^th. During December 17-21, Seattle saw temperatures average 7° or above normal on each day. Seattle set a record high of 55° on December 18^th and tied the record of 59° on December 20^th. Phoenix set record highs of 83° on December 18, December 19, and December 20. That was the first time Phoenix experienced three consecutive 80° readings during the second half of December. The prior latest such streak occurred during December 6-8, 1939.

 

Five thoughts going forward:

 

The strongest cold shot so far this season is overspreading the Mid-Atlantic and southern New England areas. New York City and Philadelphia will see the temperature fall into the teens for the first time this season.

 

It will turn milder near midweek across the Great Lakes, Mid-Atlantic, and New England areas. Chicago could approach or reach 50° by the end of the week.

 

No significant snow is likely from Washington, DC to New York City through the remainder of December.

 

Phoenix will remain on track for its warmest December and warmest year on record.

 

The week ahead will be mild and wet in the Pacific Northwest

 

Long-Range:

 

Colder air will begin to push into the eastern half of the United States during the first week of January. The second week of January has the potential to feature widespread colder-than-normal readings before slow moderation develops near or after mid-month.

 

The pattern could also become more conducive toward bigger snowfalls in the Great Lakes Region eastward to the Middle Atlantic and New England states. Whether there will be storminess to coincide with the cold will remain to be seen, as some of the long-range guidance keeps conditions relatively dry through at least the first week of January.

 

Some of the long-range guidance suggests that an EPO+/AO+/PNA- pattern could develop in late January. That would imply that the month of January could end with warmer than normal readings.

 

 

 

Teleconnection forecasts beyond two weeks are not skillful.

 

Lost in all this is that Phoenix has had a truly WILD year.

Set records for consecutive record number of 100+ days as well as highest average monthly and seasonal temperatures.

October was pretty wild for all of us because a large part of the country had zero or nearly zero rainfall that month.

 

[donsutherland1]

23 minutes ago, LibertyBell said:

Lost in all this is that Phoenix has had a truly WILD year.

Set records for consecutive record number of 100+ days as well as highest average monthly and seasonal temperatures.

October was pretty wild for all of us because a large part of the country had zero or nearly zero rainfall that month.

 

Phoenix also recorded 21 consecutive record-tying or record-breaking high temperatures, by far a new national record. Today, Phoenix has tied its record high (so far). This year, it has tied or broken 124 daily record highs, record high lows, or record high means.

[LibertyBell]

2 minutes ago, donsutherland1 said:

Phoenix also recorded 21 consecutive record-tying or record-breaking high temperatures, by far a new national record. Today, Phoenix has tied its record high (so far). This year, it has tied or broken 124 daily record highs, record high lows, or record high means.

Wild Don, is this a world record for any city for one year?

124 daily records!

 

[donsutherland1]

31 minutes ago, LibertyBell said:

Wild Don, is this a world record for any city for one year?

124 daily records!

 

Unfortunately, a lot of international data is not accessible, so it's difficult to be sure.