Our Catalina summer rains and when they come

Below is an updated chart showing the frequency of rain in Catalina from June 1st through September 30th.  These data are mostly the courtesy of Our Garden here in Catalina on Stallion Place, supplemented in the past few years by obs here on Wilds Road.  Thought you’d like to see this to get your day started thinking about rain. Its pretty self-explanatory, which saves me a lot of work.


For really pretty charts of temperatures and rain frequencies, go here to WeatherSpark, a very nice site.  No stations at our elevation and near us are available in their station list for Arizona, however.  We are, as you know,  very much affected by our higher elevation than those longterm stations around us like Tucson (rain increases in Arizona mainly with elevation) and because of our nearness to the Catalina Mountains which are a spawning ground for the summer showers that often affect us.

 The weather ahead

Models are still showing rain creeping into SE AZ tomorrow.  If nothing else, we should see some Cumulonimbus tops off to the SE by late afternoon or evening.

Here, from the U of WA, valid for tomorrow evening at 8 PM AST.  Note lightly colored regions in SE AZ:

Looking WAY out ahead, the NOAA spaghetti factory has turned out plots that make it seem like the summer rain season will get started for real (steadily) on July 4-5th, as suggested by the rain frequency chart above. Here what came out for 5 PM AST, July 5th, some 14 days from now that makes that seem likely.


Note that dark region to the north of Arizona, that region mostly located in Utah and Colorado.  This spaghetti plot/ensemble runs of the model after introducing slight errors or changes in “initial conditions” those at the very start of the model run.  That dark region represents a pretty strong signal in the data that our big fat anticyclone (at 500 millibars, around 20,000 feet here in the summertime) will be located in a favorable position for good rains here in southern Arizona.  The red lines are those lines that pretty much represent the boundaries of that high, and you can see that they are located to the south of us, as well as to the north.  In the summer, you want to be in a LOT of red lines to the south of the high, representing in this case, nice easterly flow with a lot of humidity in it across northern Mexico.

Looking forward to seeing some real rain, and how this plays out.

The End