The Northwest continues under of a trough of low pressure that will be off our coast at times over the next 6 to 10 day period. Thus, the weather patterns for the July 31to August 4 period will feature below normal temperatures. However, with these patterns we will have some days that are above average but this cool weather regime will be the main theme.
The map below depicts this cool pattern as this has the mean position of the 500 mb map (18,000 to 19,000 foot level) which has the trough of low pressure off the Washington Coast. This feature, the trough of low pressure, tends to control the weather patterns to a large extent. This forecast was issued on July 26, 2011.