Weather That's Good for Grass

Spring precipitation in northern Utah is often highly variable in space and time making generalizations difficult.  Below is the departure from average precipitation over the past 30 days (through 1200 UTC/0600 MDT this morning) over northern Utah and the surrounding regions.  The central Wasatch are running above average and The Salt Lake Valley near or slightly above average.  Other areas are drier, such as the Uinta Basin and West Desert south of Dugway.  

Has the past 30 days been wet or dry?  The answer to that question clearly depends on location, location, location.  

By and large, the Salt Lake Valley, however, has seen near average precipitation and weather that's "good for grass."  

For soils and plants, precipitation amount can be important, but also frequency.  If most of the precipitation we received fell in a big storm in mid April, we'd be seeing lots of brown lawns by now.  Instead, we've had fairly regular precipitation.  Over the past 30 days, the University of Utah has received almost 2.8 inches of precipitation (blue line below, scale on right).  This has been produced by several storm systems with the longest dry period about 8 days.  

Additionally, there were three well-separated wet periods around April 22-23, May 1-4, and last night.  Each of these provided a decent soaking.  Temperatures have also been near average.  If you live in the Salt Lake Valley, chances are you still don't need to run your sprinklers.  

It does appear, however, that we will see the highest temperatures of the year so far on Sunday.  I think we've hit 79 three times so far this year at the Salt Lake City Airport, twice in March and once in May.  Sundays high temperature forecast is 82.  We'll need another good soaking storm after that to extend the "good for grass" weather deep into next week.