Nora could impact southwestern US as a tropical rainstorm
By Adam Douty, AccuWeather senior meteorologist
Updated Aug. 28, 2021
Hurricane Nora remained just over 1,000 miles away from the southwestern United States early Saturday, but AccuWeather meteorologists were already monitoring the possibility that the tropical system may produce flooding to the region for the middle and end of next week.
As Nora tracks northward near or across northwestern Mexico, it is expected to lose wind intensity early next week. This will not stop the storm from bringing tropical downpours and the threat of flash flooding to the southwestern U.S.
Forecasters cautioned that although Nora may no longer be designated a tropical storm or hurricane by the time it reaches the Southwest, it could still make its presence felt.
This AccuWeather Enhanced RealVue™ Satellite loop shows Hurricane Nora Saturday morning, local time, while churning to the southwest of Mexico.
“Nora may bring a dose of tropical moisture to parts of Arizona, Utah, New Mexico and Colorado that could lead to flash flooding during the middle and end of next week,” said AccuWeather Senior Meteorologist Rob Miller.
Nora will likely lose wind intensity and transition to a tropical rainstorm later next week as it encounters dry air coming from the deserts across northwest Mexico.
It is uncommon for a tropical system to remain organized and track into the Southwest,” said Miller. However, there is a chance that Nora could remain a tropical rainstorm as it moves into Arizona, he noted.
Forecasters say that moisture from tropical systems tracking near northwest Mexico typically gets pulled into the Southwest where it can enhance rainfall across the region.
If Nora can maintain an organized circulation as a tropical rainstorm while moving into Arizona, a more concentrated swath of heavy rain is possible along its track. In this scenario, more significant flash flooding could unfold across a narrow zone in southern and central Arizona.
If Nora’s circulation falls apart faster and just the storm’s moisture is pulled north, there will still be a threat for flash flooding, though it will be more isolated in nature.
Regardless, as Nora and its moisture spread farther to the north, the threat for flash flooding will spread into portions of southern Utah, northwestern New Mexico and into Colorado toward the end of the week as rain moves out of Arizona, according to Miller.
Much of Arizona has received above-average rainfall since the beginning of the monsoon season in June. Phoenix, Flagstaff and Tucson have all seen close to, or above twice their normal rainfall during this time.
Drought conditions across the western United States as of Aug. 27, 2021.
This rain has helped to lessen some of the drought concerns in the region, though much of Arizona remains in a moderate to severe drought.
Exceptional drought remains across much of California, southern Nevada and Utah where rainfall has been lighter over the summer months and wildfires continue to rage.
While Nora’s moisture may bring scattered showers and thunderstorms to the exceptional drought areas in southern Utah, it seems unlikely that it will be enough to make noticeable improvements in the drought. Other than some of the desert locations in Southern California and Nevada that may experience isolated thunderstorms, those states should remain dry and hot through the coming week. |
