A fierce thunderstorm raced through Northwest Colorado on Tuesday, dumping rain and hail on sun-parched land and bringing the first significant precipitation of the summer monsoon season.
Hail up to a half-inch in diameter was reported to the National Weather Service's Grand Junction forecast office, meteorologist Jim Daniels said. Total precipitation amounts were not available, though a map on the National Weather Service Web site forecasted between a half-inch and 1 inch of rain from the storm system.
The afternoon storm followed a steady rainfall that soaked Steamboat Springs early Tuesday morning.
The Steamboat Springs Police Department, Routt County Sheriff's Office and Steamboat Springs Fire Department did not report any emergencies or accidents related to the brief storm. Yampa Valley Electric Association did not experience any power outages as of Tuesday afternoon.
The storm drenched much of the area, including Hahn's Peak, where Dana Morton said lightning, thunder and heavy rain persisted for about half an hour Tuesday afternoon. By 3 p.m., however, the fast-moving system had given way to sunny skies, she said.
Heavy rain and pea-sized hail also hit Clark, said The Clark Store employee, Bev Sorensem.
The tropical moisture moved into the northwest section of the state from Wyoming, pushed southward by disturbances within the upper atmosphere, Daniels said.
Tropical moisture is a telltale sign of the southwest monsoon, which typically affects the weather of western Colorado and eastern Utah from mid-July to late August, Daniels said. The fact that Tuesday's storm came from the north is atypical of monsoon circulation.
"I guess you could say in the past week we've seen the start of the monsoon season, though it's come in a different form than it usually takes," Daniels said.
The southwest monsoon begins when a large area of high pressure over the Pacific Ocean moves eastward, shifting the wind pattern and bringing increased moisture from south to north.
Monsoonal storms slammed areas of the Front Range over the weekend and caused mudslides and flooding in some areas.
Daniels predicted another monsoonal surge of moisture this weekend, when the chance of precipitation will increase.
There remains a possibility of isolated thundershowers today and Thursday, though drier air and warm temperatures likely will yield weather conditions similar to those of last week.
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