December 24 2025: The ECMWF’s ERA5 monthly data is out for past November 2025. I’ve updated our method to apply 2024 data only towards projection of November 2025. for my part, I’m anchored to the Colorado River Basin and the connected states. Especially Arizona in this case, which saw some record rains in places last month. Several actual years of observations are mapped below culminating in the November 2025 specific rainfall at lower left, and the projection exercise for that same month, (again using only 2024 data) at lower right.
Another way to estimate the skill of the projection is through a residual map such as the raw difference between the two data sets.
These will be produced as standard output for all closed projections. All draft and all rights reserved.