This summer has rivaled some of the hottest and worst wildfire seasons in memory for much of Montana, the Pacific Northwest and Northern Rockies. But this very large entity has influenced much of the country in a different way. and it's all about the circulation.
The monsoon high is a seasonal high pressure that tends to develop right over Colorado in the summer. With a clockwise flow around high pressure, above-average temperatures were felt up the West Coast, across the Northern Rockies into the Northern Plains. However, from the desert southwest through most of the central and eastern areas, a northerly flow is responsible for a cooler than average July and the first part of August.
Looking at precipitation and the influence of the monsoon high is very evident. The Pacific Northwest across the Northern Rockies into the Northern Plains has been very dry, but more of the country had an average or wetter July than normal. From New England to the deep south, all the way through the four-corner states and surprisingly even southern California has had well above average precipitation.
The monsoon high is beginning to break down for this year, allowing much needed rain to move into parched areas desperate for rain.