I’ve heard many complaints about this year’s winter forecast and how far off it was. Here is an excellent discussion of how seasonal forecasts are made and how they can be off. They show that for what we knew in November, a typical La Nina pattern was the most reasonable forecast. The things that changed our winter from a typical La Nina to an oddball season were factors that were not around at the beginning of the season and were not predictable using current methods. The chart below shows how unusual this winter was compared to previous strong La Ninas. You can read more at https://www.climate.gov/news-features/blogs/enso/did-northern-hemisphere-get-memo-years-la-ni%C3%B1a.

Pattern correlations between the individual La Niña and average La Niña December – January 500 hPa geopotential height anomalies north of 15°N for the 13 strongest La Niña episodes since 1950. Positive values indicate at least some degree of pattern matching, with 1 indicating a perfect match, and negative values indicate a mismatch between the two patterns. NOAA Climate.gov figure with NCEP/NCAR Reanalysis data obtained from the NOAA Physical Sciences Laboratory.