SUMMARY: The combination of ample Gulf and Pacific tropical moisture (in part from Tropical Storms Manuel (Pacific) and Ingrid (Gulf) which inundated Mexico), stalled frontal systems, and upsloping conditions produced widespread heavy to copious rainfall (widespread 2 to 6 inches, locally 12 to 18 inches especially near Boulder, Colo.) and severe flash flooding in parts of New Mexico and Colorado. Moderate to heavy rains (1.5 to 4 inches) also drenched portions of Arizona, eastern Nevada, Utah, Wyoming, south-central Montana, western sections of Nebraska, Kansas, Oklahoma, and northern and southern Texas. September monsoonal rains have generated welcome relief from the drought in the Southwest, central Rockies and High Plains, but unfortunately have been accompanied by flash flooding.

Elsewhere, a pair of cold fronts during the week brought relief from last week’s unseasonable heat in the Midwest and Northeast, along with light to moderate rain that generally prevented further deterioration of conditions. Hit and miss (mostly miss) showers occurred in the Southeast, with the most significant rains (more than 2 inches) limited to southern Florida.

Warm and mostly dry weather returned to the Northwest after a wet first week of September. Wet weather continued across most of Alaska, while decent windward showers returned to the Hawaiian Islands.