2024-2025 La Nina

[GaWx]

The bc GEFS and EPS MJO forecasts are on two different planets for end of Dec/Jan 1st: forecasting battle of the titan ensembles

GEFS bc stalled in moderate phase 7 not far from phase 6/not favorable to cold as H5 shows:

EPS bc headed into left side of circle 7/8: more favorable to cold potential E US: note that H5 is going toward restrengthening +PNA

[Terpeast]

All we can glean from the above is that we'll be in mjo 7 by the end of the month. What happens after that is anyone's guess.

[TheClimateChanger]

14 hours ago, chubbs said:

You have to be careful using raw data from multiple station sites with different baseline temperatures; airport vs downtown for instance.  Per NOAA, who corrects for site differences, the past 10 winters in Cook county (2015-2024) were 4.6F warmer than 1895-1930 and the last 5 years (2020-2024) 5.8F warmer.

Independently, Madison,Wisconsin Lake freeze data going back to 1852 shows much shorter duration of ice cover now vs the 19'th century and the 1960s and 1970s don't stand out as cold decades. (Mendota and Monona Lakes below.)

https://climatology.nelson.wisc.edu/first-order-station-climate-data/madison-climate/lake-ice/history-of-ice-freezing-and-thawing-on-lake-monona/

You know what they say, there are lies, there are damn lies, and then there are statistics.

Here's how to manufacture a massive cooling trend from a trendless data. Move the station further and further away from the lake and present with no adjustment or even proper context. In fact, falsely claim the cooling should be even more pronounced if not for the ever-growing UHI effect.

Chicago "thread" [Mean winter temps from 1926-27 to 1993-94]

University of Chicago [Mean winter temps from 1926-27 to 1993-94]

We can see using a fixed site (in this case, the University of Chicago), the 1960s and 1970s were somewhat colder than the preceding decades, but not to the extent shown on the threaded record. By the 1980s and early 1990s, temperatures had recovered and were already exceeding many of the past decades. Overall, a flat trend over that interval with a cyclical cooling and warming superimposed on the trend. Much more in line with the NOAA values for Cook County.

[LakePaste25]

No indication that we are returning to a -PNA prior to mid-January. Everything looks on track to turn colder to start the New Year. 

[GaWx]

13 minutes ago, LakePaste25 said:

No indication that we are returning to a -PNA prior to mid-January. Everything looks on track to turn colder to start the New Year. 

Regarding colder to start new year, EPS/GEPS agree but last few GEFS don’t, which I feel are likely largely MJO related. We’ll see which is closer to being correct regarding MJO/Pacific:

[LakePaste25]

7 minutes ago, GaWx said:

Regarding colder to start new year, EPS/GEPS agree but last few GEFS don’t, which I feel are likely largely MJO related. We’ll see which is closer to bring correct regarding MJO/Pacific:

While it does delay the cold and prolong the jet extension against other guidance, it isn’t really showing any canonical -PNA Nina pattern. 

[PhiEaglesfan712]

7 minutes ago, LakePaste25 said:

While it does delay the cold and prolong the jet extension against other guidance, it isn’t really showing any canonical -PNA Nina pattern. 

Yeah, here are the subsequent Jan PNAs for non-Nino high PNA Dec, following warm Nov:

2021 +0.19 (Dec 2020: +1.58)

2006 +0.43 (Dec 2005: +1.38)

1986 +0.97 (Dec 1985: +1.39)

Based on these analogs, the PNA should be slightly positive (between 0 and 1). By the way, all of these years had warmer Januarys, and delayed cold until February.