OOPS. I was listening to a Southwest CLIMAS podcast, originating at the U of AZ, and realized I missed in the above graph what can only be termed an “ineffectual Niño” that which occurred in 1986-88 and did not produce a precipitation “signal” here. How lame was that?
So, while we are excited about the prospects of extra rain this winter due to the current, supersized El Niño, like all things weather, some doubt must be in place.
These data are mostly from Our Garden, 1977-78 through 2011-12, located at Columbus and Stallion. The data after that are from Sutherland Heights, Catalina, some 2 mi or so to the SE of that site, and about 300 feet higher in elevation. So there is a bit of what we would call a “heterogeneity” in the data.
The downward trend is misleading, since the Our Garden record began with extremely wet water years, due to a combination of a shift in the Pacific Decadal Oscillation that occurred in 1977-78 (a shift that squelched the then record West Coast drought) and a Niño or two.
That kind of downward trend shown for Catalina in cool season precip does not show up in the Statewide averages for the whole year, anyway, shown below.
Those annual data show the usual oscillations between drier and wetter epochs in Arizona. In the plot below, you can see that had the Catalina record started in 1950 or so, there would likely be little in the way of a trend since so many of those years were drier than average. You can also see the effect of the PDO change in the late 1970s where year after year was above for the State of Arizona as a whole.
The weather ahead
Rain, tropical skywater, still appears headed our way around the 4-6th of October.