The forecast for the period of August 15 to August 19 brings below average temperatures and above average precipitation. This pattern is represented by the average position of the 500 mb map below (at about 18,000 to 19,000 feet). The map continues the pattern that we have seen for most of this summer with a trough of low pressure off the West Coast. In fact forecast models suggest that this pattern continues through August 23. The main message with this forecast is below temperatures and precipitation should be limited given the time of year in which precipitation is generally light.