Western USA Update
It has been a very cool and damp weather pattern over a large part of the western United States so far this month. After a very cool and very wet May, most of the Rocky Mountain West, Great Basin and High Plains have experienced a cool first half of June.
The graphic below shows temperatures relative to normal for the past 30 days. The extensive areas of green and blue represent cooler than normal temperatures. Only the Pacific Northwest has been warmer than normal. The bullseye of cold has been centered over the Central Rockies of Wyoming, Utah, Nevada, Colorado, New Mexico and Arizona. The Dakotas south to Texas also quite cool.
Through the first half of June, only a few locations have had temperatures reach 90F.
The wet ground from the above normal rain/snow in May is having a lasting effect into June. High soil moisture tends to keep the air cooler. The graphic below shows precipitation above average (blue/green) in the same areas showing the below normal temperatures.
The very cool start to summer in the is likely to impact the start of the western monsoon season (increased thunderstorm activity) as the below normal temperatures may delay the start of the thunderstorm season in the Desert Southwest and Southern Rockies.