The rains that occurred during the week of September 9th through the 16th, 2013 were different than what we typically see in Colorado. The event was caused by a block in the jet stream that held a low-pressure cell over the Great Basin and a highpressure cell over the Midwest stationary over the course of a week. These stationary circulations drew up moist, tropical air from both the Pacific Ocean and the Gulf of Mexico, dumping rain over New Mexico and Colorado for days. This type of rain event is rare for Colorado, with an estimated 1,000-year recurrence interval measured in the Northern Front Range.