Thursday, May 21, 2015

Living with drought: is the drought over now?

Our state climatologist, Dr. Doug Boyle, reports that every storm prompts questions about whether we are no longer in drought conditions.  As of May 19, the U.S. Drought Monitor map of conditions in Nevada indicated that the storms have had little effect (see below), even though we have recorded slightly less than 0.5 inches for the month of May at the Washoe Evapotranspiration project's station on the University of Nevada campus (see http://www.washoeet.dri.edu/washoeEt.html for this excellent resource). 

Other data on the Washoe ET site provide a more complete picture of why a half an inch of rain in a week did little to change the picture.  Our estimated potential evapotranspiration (the amount of water returned to the atmosphere by the combined evaporation and by plant transpiration) for May is 4.0 inches, 8 times more than what has come so far as rainfall.  That means that even if our storms are high duration, low intensity storms, the soil is dry because evapotranspiration moves a lot of water from the soil profile into the atmosphere.  It would take a lot of rainy days to replenish soil moisture enough to change the National Drought Monitor Map. 

For more information about our drought and how to cope with it, visit www.LivingwithDrought.com.  Good resource for a wide range of interests.