Summer has settled in across the Inland Northwest. As of early this week, temperatures were climbing into the 90s in many locations. At Spokane International Airport, we had several 90-degree days with more in the forecast.
A very strong ridge of high pressure is building across our region, right around our full moon phase that often produces very warm temperatures during the summer. The latest long-term upper-air forecast models show this ridge intensifying next week. It’s quite possible that we may come near, or even top the 100-degree mark in Spokane and Coeur d’Alene sometime in the next week.
Behind this very hot weather pattern, we may see some scattered showers or thunderstorms pop up, especially over the higher terrain toward the end of next week. The new moon lunar phase beginning July 26 may also produce some showers or a thunderstorm, but more hot weather is expected into August as the strong ridge of high pressure dominates the weather picture.
This is not good news for California, currently suffering from one of the worst droughts in recorded history. My family in the Sacramento area told me that numerous fires broke out during the Fourth of July holiday weekend as the area is extremely dry from prolonged drought.
As the ridge continues to build across the West, the circulation around this high should allow some moisture to move in from Mexico northward into the very dry Southwest. The annual monsoon season often begins in early to mid-July and brings nearly 50 percent of an entire year’s precipitation to Phoenix and other communities in Arizona, New Mexico and even into southeastern California. In southeastern Arizona, rainfall amounts in July and August can account for as much as 75 percent of the total moisture for a year.
If the high pressure ridge moves far enough to the north, some of that moisture can eventually work its way into Southern Idaho and southern Washington.
The upcoming fall looks wetter, especially in November, thanks to the warming waters in the south-central Pacific Ocean. If El Nino is strong enough, snowfall for this next winter should be much below normal.