2024-2025 La Nina

[TheClimateChanger]

17 hours ago, michsnowfreak said:

Interesting...warmer mins are more noticeable in summer than winter here. We still routinely go below zero most winters. Yet in summer, we almost never see 40s in July or August whereas we used to see the occasional night or two (the outlying areas still do..in fact they did last night lol).

The threaded record does show a positive regression, from a predicted value of 19.6F in 1875 to a predicted value of 21.3F in 2024. The LOESS curve helps to highlight the fact that the vast majority of recent winters have seen mean minima well above the values predicted by a linear regression, suggesting the linear regression is not fully capturing the trend and there has been an acceleration in the increase in winter minima since around 2000.

In fact, the trend is greatly affected by changes in site location and instrument exposure, suggesting mean winter minima have warmed faster than shown here. This will be addressed in a follow-up post.

Detroit [ThreadEx]

Detroit City Airport [KDET]

Detroit Metropolitan Wayne Airport [KDTW]

[snowman19]

1 hour ago, mitchnick said:

I have no idea how it ultimately turns out ONI-wise. Anything from a La Nada to barely moderate is still on the table imho, with weak Niña favored. Regardless of ONI, however, we're definitely stuck in a Niña background state which also leaves a wide variety of possibilities for the winter. If one is planning on issuing a winter forecast, I'd put off the issue date as long as possible. Lol

I don’t think winter forecasts should be put out until November. That said, as of right now, just looking at ENSO, 16-17 and 07-08 seem to be good matches

[TheClimateChanger]

In fact, we see the 1960s and 1970s "cold" spell pretty much evaporates when we correct for site location. Meaning the extreme cold minima present in those decades in Detroit are largely an artifact of moving the official observation site from the urban City Airport location to a low-density, semi-rural or ex-urban site well to the southwest.

We see a mean minima of 20.2F at City Airport for the period 1934-1950. The so-called warm winter period.

Shockingly, from 1966 to 1980 [the so-called cold winter period], the mean minimum temperature at Detroit City Airport was nearly 1F higher. 

But at the official observation site [KDTW], it was much colder with a mean minimum temperature more than 2F cooler than the 1934-1950 mean at City Airport and more than 3F cooler than the mean at City Airport for the corresponding time frame. No comparative data for 1934-1950 are available, since record keeping did not begin at the site until 1958. It became the official site for Detroit on July 1, 1966.

[TheClimateChanger]

Just now, TheClimateChanger said:

In fact, we see the 1960s and 1970s "cold" spell pretty much evaporates when we correct for site location. Meaning the extreme cold minima present in those decades in Detroit are largely an artifact of moving the official observation site from the urban City Airport location to a low-density, semi-rural or ex-urban site well to the southwest.

We see a mean minima of 20.2F at City Airport for the period 1934-1950. The so-called warm winter period.

Shockingly, from 1966 to 1980 [the so-called cold winter period], the mean minimum temperature at Detroit City Airport was nearly 1F higher.

But at the official observation site [KDTW], it was much colder with a mean minimum temperature more than 2F cooler than the 1934-1950 mean at City Airport and more than 3F cooler than the mean at City Airport for the corresponding time frame.

In recent decades, the difference between the two sites has gotten smaller as development has increased near the international airport. City Airport still tends to observe higher minima, however. The difference has shrunk to a bit less than 1F.

City Airport [2010-2024]

DTW [2010-2024]

 

[TheClimateChanger]

Looking at the historic station thread. We also see good reason to conclude that the minimum temperatures in the 19th century and early 20th century were colder than observed.

What we see is this:

There was a rooftop exposure in general through 1933, at ever increasingly tall buildings - presumably to accommodate wind and other measurements. A trend which reached its zenith atop the Majestic Building some 218 feet above the ground. From at least 1881 through April 1887, the thermometer was housed in an enclosure on a northwest window of the Board of Trade Building. Looking at the stated height above ground, this appears to have been housed on a 4-6th story window of a building that appears to have been between about 6 and 8 stories high judging by the roof height reported after the station was moved to the roof on May 1, 1887.

Rooftop stations have been observed to report higher temperatures than corresponding ground-based stations, and window stations even higher. With proper siting and a location away from the core urban heat island, it is likely that temperatures would have been substantially cooler than reported.

For more information on the Majestic Building, see: Majestic Building (Detroit) - Wikipedia

[TheClimateChanger]

So my conclusion is this: Winter minima have been increasing at Detroit. The trend is, however, lessened by the impact of anomalously cold minima temperatures observed in the first couple of decades after the official observation site moved to the southwest. In recent decades, the trend is actually overstated due to increasing urbanization in the vicinity of the international airport. Moving forward, I would expect mean winter minimum temperatures to continue to climb, reaching the mid 20s F by mid-century (2040s - 2060s) and 30F by the end of this century [perhaps even higher in a heightened carbon scenario].

[George001]

7 hours ago, snowman19 said:

16-17 and 07-08 are starting to look good matches for this Niña 

07-08 is actually my top analog, though I do think this Nina will be weaker than that one. That’s just me nitpicking though, it’s still a great analog given the subsurface similarities, -PDO, high solar etc. I’m more skeptical of 2016-2017 because that was a modoki. I’m not discounting it or anything, I just don’t think it’s as good as some other analogs. 

[snowman19]

2 minutes ago, George001 said:

07-08 is actually my top analog, though I do think this Nina will be weaker than that one. That’s just me nitpicking though, it’s still a great analog given the subsurface similarities, -PDO, high solar etc. I’m skeptical of 2016-2017 because that was a modoki. That one did also come off a big Nino though.

Agree about 07-08, very decent match, I know Ray agrees. However, I think 16-17 is also a good ENSO match. I didn’t realize how close 16-17 was as well until @bluewave made that post about it this morning

[bluewave]

49 minutes ago, snowman19 said:

Agree about 07-08, very decent match, I know Ray agrees. However, I think 16-17 is also a good ENSO match. I didn’t realize how close 16-17 was as well until @bluewave made that post about it this morning

The one difference is that the PDO started positive and went to neutral in 16-17. This time we have a very strong -PDO. So not sure if the combo this time around would support some of the better snowstorms we had that winter despite the warmth. But even just a little better than the last few winters in the snowfall department would be nice.

[Stormchaserchuck1]

Sometimes you have to be aware of a small sample size. I remember in the early 2000s, everyone would get excited about a Weak La Nina, because the historical map was cold. The meteorology is, X event correlates to Y. The stronger X is, the stronger Y, and the weaker X is, the weaker Y. But in the early 2000s, a small sample size showed we have a high likelihood of -NAO and I think some +PNA with Weak-Nina's, based on like 10 examples. (for map below "Weak Nina" is -0.5 to -1.0 DJF ONI). 

Then roll forward to the 2000s, and with more data added, the -PNA skew of the map evens out.. this is why I say beware of analogs behind sun phases, because a small sample, when there are so many things happening, could give a false result. It's more important to know the mechanism behind what it is. 

2005+ Weak La Nina's (DJF ONI -0.5 to -1.0):

Combined the two maps now looks like a La Nina, but it didn't in the early 2000s, leading to a lot of excitement over Weak La Nina's back then.

I think I posted something earlier in this thread, where 13 Moderate/Strong ENSO events had a combined +100dm PNA/yr, and 8 Weak ENSO events had a combined +50dm PNA/yr. That's right where it should be, Now (but not 20 years ago). 

[mitchnick]

14 minutes ago, Stormchaserchuck1 said:

Sometimes you have to be aware of a small sample size. I remember in the early 2000s, everyone would get excited about a Weak La Nina, because the historical map was cold. The meteorology is, X event correlates to Y. The stronger X is, the stronger Y, and the weaker X is, the weaker Y. But in the early 2000s, a small sample size showed we have a high likelihood of -NAO and I think some +PNA with Weak-Nina's, based on like 10 examples. (for map below "Weak Nina" is -0.5 to -1.0 DJF ONI). 

Then roll forward to the 2000s, and with more data added, the -PNA skew of the map evens out.. this is why I say beware of analogs behind sun phases, because a small sample, when there are so many things happening, could give a false result. It's more important to know the mechanism behind what it is. 

2005+ Weak La Nina's (DJF ONI -0.5 to -1.0):

Combined the two maps now looks like a La Nina, but it didn't in the early 2000s, leading to a lot of excitement over Weak La Nina's back then.

I think I posted something earlier in this thread, where 13 Moderate/Strong ENSO events had a combined +100dm PNA/yr, and 8 Weak ENSO events had a combined +50dm PNA/yr. That's right where it should be, Now (but not 20 years ago). 

If you blow JB's 95/96 analog, he'll never forgive you.

[Stormchaserchuck1]

5 minutes ago, mitchnick said:

If you blow JB's 95/96 analog, he'll never forgive you.

If the ENSO subsurface weakens to Neutral in the Fall, it's not far off, although we have a -PDO and so far, +NAO N. Atlantic SST predictor index for the Winter, so I wouldn't use it.. 

[snowman19]

3 hours ago, mitchnick said:

If you blow JB's 95/96 analog, he'll never forgive you.

95-96 is the worst “analog” you could possibly use for this winter. Totally laughable. It figures JB is using it, I would expect no less from that clown

[snowman19]

5 hours ago, bluewave said:

The one difference is that the PDO started positive and went to neutral in 16-17. This time we have a very strong -PDO. So not sure if the combo this time around would support some of the better snowstorms we had that winter despite the warmth. But even just a little better than the last few winters in the snowfall department would be nice.

16-17 is good as far as the ENSO evolution and the +QBO, but like you said the PDO doesn’t match, neither does solar or AMO

[raindancewx]

This is probably a good winter for flipping conditions from anti-logs.

Just flip a weak El Nino, with a -QBO, low-solar, and very +PDO, -AMO conditions.

1976: Weak El Nino, -QBO, Solar Min, PDO+ (+1.5), -AMO

1986: Weak El Nino, -QBO, Solar Min, PDO+ (+1.8), -AMO

Anti 1976, 1986 blend (-7 to +7 scale)

As a sanity check, you can see it is already working to some extent.

June had the non-flipped 1976 and 1986 work as a better match, which makes sense to me as the QBO / ENSO state just flipped in July really.

Anti 1976-77 and 1986-87 isn't a very cold winter, but it's probably one of the coldest Feb-Apr periods on record for the US.

[raindancewx]

Anti 1976-77 and 1986-87 (flip of a -QBO, Weak/Mod El Nino, with low solar, +PDO, -AMO conditions)

[michsnowfreak]

9 hours ago, George001 said:

07-08 is actually my top analog, though I do think this Nina will be weaker than that one. That’s just me nitpicking though, it’s still a great analog given the subsurface similarities, -PDO, high solar etc. I’m more skeptical of 2016-2017 because that was a modoki. I’m not discounting it or anything, I just don’t think it’s as good as some other analogs. 

2007-08 analog is music to my ears.

[Stormchaserchuck1]

I wouldn't be surprised if it was a near average to above snowfall season in the interior Northeast and Great Lakes.. +NAO actually has a higher +precip correlation than temps north of 40N. 

Especially if we are drier through the Fall.. since 2003, these dry periods have gone really wet after we started to approach drought conditions. It's happened about 20/20 times. I was saying this could also make the SE, US more prone to a Hurricane hit this year vs previous years. 

Coming up in late July will be our 6th moderate to strong +NAO period this year.. and I think we had like 2-3 in all of the past 4 years combined. I say that's important because it's changing the N. Atlantic SSTs to +nao roll-forwards. +NAO's favor storm tracks that go up through the Appalachians or Ohio Valley in the wintertime, Add a -PNA to that, and we could actually get some big storms riding up through the Midwest. 

The key I think will be if we tend toward +EPO or -EPO. +EPO is a big rainstorm pattern. -EPO will give some of you guys snow. Both are possible in La Nina, but there is a pretty strong correlation with -pdo and +epo. 

[snowman19]

7 hours ago, raindancewx said:

This is probably a good winter for flipping conditions from anti-logs.

Just flip a weak El Nino, with a -QBO, low-solar, and very +PDO, -AMO conditions.

1976: Weak El Nino, -QBO, Solar Min, PDO+ (+1.5), -AMO

1986: Weak El Nino, -QBO, Solar Min, PDO+ (+1.8), -AMO

Anti 1976, 1986 blend (-7 to +7 scale)

As a sanity check, you can see it is already working to some extent.

June had the non-flipped 1976 and 1986 work as a better match, which makes sense to me as the QBO / ENSO state just flipped in July really.

Anti 1976-77 and 1986-87 isn't a very cold winter, but it's probably one of the coldest Feb-Apr periods on record for the US.

Nice anti-log find. Talk about total polar opposites of this year. Besides PDO, ENSO, QBO, solar, AMO, those years (76-77, 86-87) were also +PMM. Literally every signal is opposite to this year

[mitchnick]

10 hours ago, snowman19 said:

95-96 is the worst “analog” you could possibly use for this winter. Totally laughable. It figures JB is using it, I would expect no less from that clown

I have no idea if he's using it this year. The post was intended to be facetious. 

[snowman19]

[GaWx]

2 hours ago, snowman19 said:

 

 If those ENSO SSTa maps were to verify closely, I’d call it neither E based nor Modoki but rather an “in between” Niña of sorts.

[bluewave]

1 hour ago, GaWx said:

 If those ENSO SSTa maps were to verify closely, I’d call it neither E based nor Modoki but rather an “in between” Niña of sorts.

The main takeaway from those forecast maps is that the marine heatwave east of Japan maintains or even slightly becomes stronger heading into the winter. So regardless of the La Niña intensity we will need a mismatch along the lines of Jan 22 or elements of 21-22. Otherwise we will get another winter similar to the last 2 which were warm and relatively snowless. So hoping to get some more clues as we head into the fall as to whether we can see some improvement over the last few winters.

[GaWx]

1 minute ago, bluewave said:

The main takeaway from those forecast maps is that the marine heatwave east of Japan maintains or even slightly becomes stronger heading into the winter. So regardless of the La Niña intensity we will need a mismatch along the lines of Jan 22 or elements of 21-22. Otherwise we will get another winter similar to the last 2 which were warm and relatively snowless. So hoping to get some more clues as we head into the fall as to whether we can see some improvement over the last few winters.

 Indeed, as a result, these maps continue to suggest a strong -PDO this winter regardless of what many WxBell CFS runs have shown. Note that I’m saying “WxBell CFS” runs as opposed to just saying “CFS” runs because Tropical Tidbits’ CFS runs have shown nothing of the sort and also show a strong -PDO. The WxBell CFS algorithms have issues.

[PhiEaglesfan712]

17 hours ago, raindancewx said:

This is probably a good winter for flipping conditions from anti-logs.

Just flip a weak El Nino, with a -QBO, low-solar, and very +PDO, -AMO conditions.

1976: Weak El Nino, -QBO, Solar Min, PDO+ (+1.5), -AMO

1986: Weak El Nino, -QBO, Solar Min, PDO+ (+1.8), -AMO

Anti 1976, 1986 blend (-7 to +7 scale)

As a sanity check, you can see it is already working to some extent.

June had the non-flipped 1976 and 1986 work as a better match, which makes sense to me as the QBO / ENSO state just flipped in July really.

Anti 1976-77 and 1986-87 isn't a very cold winter, but it's probably one of the coldest Feb-Apr periods on record for the US.

Probably not going to happen, but anti-86/87 would be a really fun next 3 years. We'd be getting a strong la nina that peaks in the summer/early fall 2025, followed by super el nino in 2026-27 (the anti-88/89). That would be unprecedented, so I expect the anti-86/87 analog to fall apart within 3 years. Or if the super el nino still forms, there would be an ENSO neutral season or two first (following the 2024-26 la nina).

The anti-76/77 analog does better in the long run. We'd be getting record warm winters and cooler springs here at PHL the next 3 years. 77-78 is pretty much the same setup as 76-77 (which we would be getting in 2024-25 and 2025-26), and anti-78/79 is pretty much 2019-20 (which we would be getting in 2026-27), before a weak la nina in 2027-28.

[snowman19]

6 hours ago, GaWx said:

 If those ENSO SSTa maps were to verify closely, I’d call it neither E based nor Modoki but rather an “in between” Niña of sorts.

Correct. Hybrid or whatever you want to call it. It’s just continuing the trend like all of the other models of NOT showing an east-based La Niña. In fact, at no point since the spring did any models show that. Which is why I’m mystified by the east-based Niña talk on Twitter. Maybe there’s some secret model that none of us know about showing an east-based La Niña? If there is, it must use the same algorithm as the Wxbell CFS that shows a +PDO….

[Stormchaserchuck1]

Well this is what it looks like right now

Nino 4 minus Nino 3 is a pretty high reading. That warmth near the Philippines will likely not cool in time for the Winter.. 

Since year 2000, Nino 4 (warm) minus Nino 1.2 (cool) has been in a league of its own. 

[Terpeast]

9 minutes ago, Stormchaserchuck1 said:

Well this is what it looks like right now

Nino 4 minus Nino 3 is a pretty high reading. That warmth near the Philippines will likely not cool in time for the Winter.. 

Since year 2000, Nino 4 (warm) minus Nino 1.2 (cool) has been in a league of its own. 

I know this is just skin temps, but that cool area breaking up the marine heat wave is interesting - west of Hawaii starting 20N at on NEward. Was there a recent storm along that way?  

[Stormchaserchuck1]

14 minutes ago, Terpeast said:

I know this is just skin temps, but that cool area breaking up the marine heat wave is interesting - west of Hawaii starting 20N at on NEward. Was there a recent storm along that way?  

I'm not sure. 

This is what 1995's PDO looked like right now

[GaWx]

2 hours ago, Stormchaserchuck1 said:

Well this is what it looks like right now

Nino 4 minus Nino 3 is a pretty high reading. That warmth near the Philippines will likely not cool in time for the Winter.. 

Since year 2000, Nino 4 (warm) minus Nino 1.2 (cool) has been in a league of its own. 

 

2 hours ago, Terpeast said:

I know this is just skin temps, but that cool area breaking up the marine heat wave is interesting - west of Hawaii starting 20N at on NEward. Was there a recent storm along that way?  

Why does that look so cold on the equator, near and W of Hawaii, in the S Pac, off the SE US, etc? That doesn’t look right.

 For example, here’s the latest CRW, which looks much closer to reality: