2025-2026 ENSO

[Stormchaserchuck1]

7/31 years since 1994 have been ENSO Neutral (using 5-month ONI classification)

Using 3-month classification, only 5/31 years since 1994 have been Neutral ENSO! 

[KakashiHatake2000]

2 minutes ago, Stormchaserchuck1 said:

Thanks!

I found this interesting

oh absolutely your welcome stormchasernick1

[Stormchaserchuck1]

18z GFS breaks 6000dm in the Rockies the last few days of July!

Interestingly, this is the August correlation to PDO (for negative like we have now, the correlation is opposite)

[KakashiHatake2000]

so stormchasernick1 what would this bring

[Stormchaserchuck1]

A warm Fall, I think. Also higher chances for a -PNA pattern this Winter. The Rockies ridge if it establishes towards the end of the month may bring heat east in waves. It will be interesting to see how long the High pressure stays there. 

[KakashiHatake2000]

oh i see thanks 

[KakashiHatake2000]

idk i think i would probably expect at least some cool down periods with that fall solstice

[Stormchaserchuck1]

+NAO/+AO regime is really strong right now. It will be interesting to see if it lasts into the Fall. Last year it ended in September. 

Developing La Nina should push some cold waves into the US through the NW and Upper Midwest - I'm curious to see how much it correlates to the pattern, and if it's actually developing "from the top down" (from the deeply negative PDO). I've researched ENSO subsurface and found that it has a higher correlation to the North Pacific 500mb pattern than surface SSTs.. subsurface is Neutral right now but the central-ENSO-subsurface has been cooling the last few days, there is a -2c pocket now. 

My main concern for Winter prospects with this developing Weak Nina is if we dry up the STJ again.. but this year has been so wet, it's almost counter-intuitive. I would guess it wouldn't be as dry as last year. Will have to analog that. 

[KakashiHatake2000]

gotcha stormchaserchuck1 thank you

[40/70 Benchmark]

3 hours ago, Stormchaserchuck1 said:

The difference between -0.4 or -0.6 ONI historically is a +10dm cold season difference in the Winter North Pacific High pressure

I think it will be even more moot relative to climo given the stable state of the west Pacific.

[40/70 Benchmark]

2 hours ago, Stormchaserchuck1 said:

A warm Fall, I think. Also higher chances for a -PNA pattern this Winter. The Rockies ridge if it establishes towards the end of the month may bring heat east in waves. It will be interesting to see how long the High pressure stays there. 

 

2 hours ago, Stormchaserchuck1 said:

+NAO/+AO regime is really strong right now. It will be interesting to see if it lasts into the Fall. Last year it ended in September. 

Developing La Nina should push some cold waves into the US through the NW and Upper Midwest - I'm curious to see how much it correlates to the pattern, and if it's actually developing "from the top down" (from the deeply negative PDO). I've researched ENSO subsurface and found that it has a higher correlation to the North Pacific 500mb pattern than surface SSTs.. subsurface is Neutral right now but the central-ENSO-subsurface has been cooling the last few days, there is a -2c pocket now. 

My main concern for Winter prospects with this developing Weak Nina is if we dry up the STJ again.. but this year has been so wet, it's almost counter-intuitive. I would guess it wouldn't be as dry as last year. Will have to analog that. 

Agreed.

[snowman19]

+NAO/+AO regime is really strong right now. It will be interesting to see if it lasts into the Fall. Last year it ended in September. 
Developing La Nina should push some cold waves into the US through the NW and Upper Midwest - I'm curious to see how much it correlates to the pattern, and if it's actually developing "from the top down" (from the deeply negative PDO). I've researched ENSO subsurface and found that it has a higher correlation to the North Pacific 500mb pattern than surface SSTs.. subsurface is Neutral right now but the central-ENSO-subsurface has been cooling the last few days, there is a -2c pocket now. 
My main concern for Winter prospects with this developing Weak Nina is if we dry up the STJ again.. but this year has been so wet, it's almost counter-intuitive. I would guess it wouldn't be as dry as last year. Will have to analog that. 

Given the very strong -PMM (cold waters off of Baja down to Hawaii) that has developed, if it continues, my guess is that the STJ is very muted this winter. -PMM correlates to a weak STJ, especially when combined with -ENSO.

To your other point about fall….I’m really starting to think this coming met fall (Sept, Oct, Nov) is warmer to way warmer than normal due in large part to the ridiculous -PDO that has developed. My early guess is that we see a lot of -PNA/RNA. And likely +WPO….given the heatwave in the WPAC off Japan. It would also not surprise me if this fall is drier than normal….probably not as dry as last fall, but a solidly drier than normal fall would not shock me at all….

[40/70 Benchmark]

1 hour ago, snowman19 said:

Given the very strong -PMM (cold waters off of Baja down to Hawaii) that has developed, if it continues, my guess is that the STJ is very muted this winter. -PMM correlates to a weak STJ, especially when combined with -ENSO.

To your other point about fall….I’m really starting to think this coming met fall (Sept, Oct, Nov) is warmer to way warmer than normal due in large part to the ridiculous -PDO that has developed. My early guess is that we see a lot of -PNA/RNA. And likely +WPO….given the heatwave in the WPAC off Japan. It would also not surprise me if this fall is drier than normal….probably not as dry as last fall, but a solidly drier than normal fall would not shock me at all….

Never know in this "new, warmer climate"....I feel like two consecutive very dry winters will be tough to pull off...especially above anout 40 N, where we aren't so dependent upon the STJ and get more N stream action.

[snowman19]

Never know in this "new, warmer climate"....I feel like two consecutive very dry winters will be tough to pull off...especially above anout 40 N, where we aren't so dependent upon the STJ and get more N stream action.

The correlation to drier than normal with a strong -PDO and -ENSO was in fall, not so much winter if I remember correctly. The correlation to a warmer to much warmer than normal fall with strong -PDO with -ENSO was a really strong tendency

[40/70 Benchmark]

19 minutes ago, snowman19 said:

The correlation to drier than normal with a strong -PDO and -ENSO was in fall, not so much winter if I remember correctly. The correlation to a warmer to much warmer than normal fall with strong -PDO with -ENSO was a really strong tendency

Oh, okay...I was talking about winter.

[michsnowfreak]

On 7/15/2025 at 9:30 AM, chubbs said:

You are mixing city and airport. Days with highs below 32, 15 and 5 at Ann Arbor, indicate that last winter would have been unusually warm 100+ years ago.

 

On 7/15/2025 at 11:46 AM, bluewave said:

Steady decline in winter below 0° low temperatures. While the 50°+ winter highs have increased at even a faster pace. So Ann Arbor is representative of many other areas.

Nearly all first order sites have had multiple moves in their period of record. Its completely normal and its done for the sole purpose of making the temps more equal/representative. Using the official threaded data is not "mixing".

Ann Arbor is NOT a first order station, but it is one of the few that has a continuous record in the same location dating back to the 1880s.

As said, when they are not a first order station, I use all elements (temp, precip, snowfall) with caution. Especially pre-1920. But since you brought it up, I notice you didnt include snowfall. Ann Arbors snowfall has more than doubled since records began - thats one hell of a regression line up (see attached). 26.3" to 56.3"

I also note how relatively consistent Ann Arbors winter temps have been the last 100 years:
1930s- 27.3F
1940s- 26.3F
1950s- 27.7F
1960s- 26.3F
1970s- 24.9F
1980s- 26.0F
1990s- 27.9F
2000s- 27.4F
2010s- 27.5F

Last 100 years avg: 26.9F, 2024-25: 26.6F. No, 2024-25 was not a "warm" winter.

However, the ENTIRE point of my post, which as usual was turned into something different once the usuals got involved, was the discussion how regardless of a warming climate, severe winter cold shots are still occurring.  

Since the 1890s, this is how many times each decade saw a temp of -10F or colder:

1890s- 12
1900s- 8
1910s- 13
1920s- 4
1930s- 5
1940s- 2
1950s- 0
1960s- 3
1970s- 8
1980s- 11
1990s- 4
2000s- 1
2010s- 12
So the 2010s saw the most -10F or colder temps since the 1910s. In fact, the 2010s saw more such temps than the 1920s-50s or 1930s-60s COMBINED. 

[bluewave]

1 hour ago, michsnowfreak said:

But since you brought it up, I notice you didnt include snowfall. Ann Arbors snowfall has more than doubled since records began - thats one hell of a regression line up (see attached). 26.3" to 56.3"

I also note how relatively consistent Ann Arbors winter temps have been the last 100 years:
1930s- 27.3F
1940s- 26.3F
1950s- 27.7F
1960s- 26.3F
1970s- 24.9F
1980s- 26.0F
1990s- 27.9F
2000s- 27.4F
2010s- 27.5F

 

The only thing consistent about Ann Arbor’s winter temperatures since the late 1800s has been a steady warming trend. December is up +4.3° with Jan at +3.2° and February +6.1°.

The snowfall has seen a nice increase over this period as you pointed out. This could be a function of the warming winters holding more moisture while still being sufficiently cold enough to increase the snow. It’s one of the benefits of living in a colder region. But this benefit isn’t held by other less warm regions which have seen a steady decrease in snowfall with their rising temperatures.

But relative to other parts of Michigan which can really cash in on lake effect snows, the SE corner was never a particularly wintry  part of the state compared to areas further north. But at least places like Ann Arbor have seen a decent improvement relative to the old days which didn’t see as much snow. 
 

 

[Stormchaserchuck1]

603dm ridge over the Rockies on 18z GFS! I wonder what the US record is. 

[GaWx]

11 minutes ago, Stormchaserchuck1 said:

603dm ridge over the Rockies on 18z GFS! I wonder what the US record is. 

Maybe this will help some:

https://stormtrack.org/threads/highest-500-mb-height-in-history.8224/#:~:text=The source for 1994 onward,22 had no 600 line.

 

[Stormchaserchuck1]

4 minutes ago, GaWx said:

Maybe this will help some:

https://stormtrack.org/threads/highest-500-mb-height-in-history.8224/#:~:text=The source for 1994 onward,22 had no 600 line.

Thanks! Then it looks like it peaks even higher the next day.. getting close to 604dam around where that thread said the previous high was located. 

Interesting how much it matches the PDO composite for August.