Analysis of Climate Variability over the Yakima Valley: The Weather As a Decision Support System

Climate and particularly temperatures are always a topic of major interest for Agriculture worldwide. The production and quality of grapes, apples, cherries in the Yakima and the Columbia Valleys is likely to be affected by changes in meteorological and climatic conditions. Meteorological conditions influence the processes responsible for the crops growth and development. The Pacific Northwest is a vast region that encompasses a number of broad viticultural commonalities, and a significant number of orchards. The climatic variability determines differences in the quality of the vintage in the case of grapes and the quality of the fruit for cherries and apples. What is really cold? What is really warm? Are questions that give us the possibility to detect lower and higher temperatures between and within seasons, temporal distribution of the temperature and other climatic variables which combined with measurements of the quality and growing of the crop give us information on how these crops respond to climate variability. The overall goal of this study was to analyze the responses of the inter and intra-annual changes in climatic variables in a specific area of the Yakima and Columbia Valleys. Long-term historical weather was obtained and analyzed for the most representatives weather stations and the ones that have longest series of data  from an Agricultural Weather Network - AgWeatherNet encompasses 178 automated weather stations located mostly in the irrigated regions of eastern Washington State and in the border of Oregon, standard AgWeatherNet weather variables include air temperature, relative humidity, dew point temperature, soil temperature at 8 inches, rainfall, wind speed, wind direction, solar radiation and leaf wetness.

Analysis of maximum, minimum, mean and temperature trends, were included, as well as analysis of solar radiation and precipitation. The rate of change of increasing or decreasing temperature based on 15 minute data intervals were studied. The correlation of these climatic variables and the general yield and quality observed from some of the crops was determined. This project compiles a series of data that demonstrates how significant changes in temperatures can affect yields. Detecting levels of lower and higher temperatures between and within seasons and other climatic variables can help growers to determine expected yield responses in a given area.