May in November to end; rain dead ahead

Rain?  Cumulative totals predicted here from the University of Arizona Hydro and Weather Dept.  Starts overnight Sunday.  For those too lazy to review the information at the link above, here is a map of the rainfall totals ending at 11 PM, November 21st:

Cum precip through 11-21-2016 11 PM AST

Note that within this swath, Catalina is predicted to get over an inch of rain!  Note that the swath is not very wide.  A wide swath of heavy rain would be one as wide as the State.  So, we have to figure that this is a lucky hit at this time, and count on something less as a virtual certainty since the swath above will move around as new model runs look at it.  Typically, they shift a little east over time in those future model runs.  Hope not.

Have cameras ready for a pretty sunrise.  Lots of high ice clouds up there.

The weather WAY ahead

Spaghetti suggests more rain chances after a several day dry spell following the Monday rains.  Check out the “pretty strong” indications that we are in the trough bowl as the month comes to an end, meaning troughs should be populating Arizona during the last days of November.  In turn, good November rains, and one seems to be in the high confidence pipeline for SE Arizona as a whole, means the spring wildflowers will be given a boost.  I will go on record here as now forecasting, if that’s what this is,  a wetter than normal November rain total1.  Our November average since 1977 is 0.96 inches.

The ensemble or spaghetti plot from the NOAA spaghetti factory from last evening's global data.
The ensemble or spaghetti plot from the NOAA spaghetti factory from last evening’s global data.

The End.


1This sentence will be deleted in the event of a drier than average November and will, therefore, not be on record.

By Art Rangno

Retiree from a group specializing in airborne measurements of clouds and aerosols at the University of Washington (Cloud and Aerosol Research Group). The projects in which I participated were in many countries; from the Arctic to Brazil, from the Marshall Islands to South Africa.


  1. Art,
    The operational GFS and thus the WRFGFS have been way too wet in the 3 plus day range this fall. I have no idea why.

  2. Hi, Mike,
    Thanks for that observation….
    We have noticed, offhand, some “disappointments.” There’s nothing worse than living in a desert and forecasting more rain than actually falls, and it really hurts when the models do it, since most of us go down with the ship, even if we back off some on the predicted totals! I hope the current blast from the NW is one in which Catalina does better than most areas.
    I guess we’ll see. (We’ve only had about 0.07 inches overnight; was hoping for at least a quarter of an inch….)

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