21 Sep 2022 | 04:30 AM UTC
US: Adverse weather forecast across parts of the Southwest, Northwest, and West North Central regions through early Sept. 23
Severe weather forecast across parts of the Southwest, Northwest, and West North Central regions through early Sept. 23. Flooding possible.
Event
Heavy rainfall and thunderstorms are forecast across parts of the Southwest, Northwest, and West North Central regions through at least early Sept. 23. Heavy rainfall may result in floods and flash floods and storms may be accompanied by strong wind gusts, hail, and possible tornadoes.
Government Advisories
As of late Sept. 20, the National Weather Service (NWS) has issued flood watches and advisories across Arizona, western Colorado, northwestern New Mexico, and central and southern Utah.
The NWS's Weather Prediction Center (WPC) has warned of a "Moderate Risk" (Level 3 on a four-tier scale) of excessive rainfall across southwestern Colorado and the Four Corners Region Sept. 21 through early Sept. 22. A "Slight Risk" of excessive rainfall is in place across portions of Arizona and New Mexico through early Sept. 21, across Arizona northeastward into far southern Wyoming and from far northwestern Wyoming northwestwards into far southeastern Washington and far northeastern Oregon Sept. 21, and over southwestern Colorado and northwestern New Mexico as well as the northern Idaho Panhandle and far western Montana Sept. 22 through early Sept. 23.
The NWS's Storm Prediction Center (SPC) has warned of a "Slight Risk" of severe thunderstorms (Level 2 on a five-tier scale) from northern Utah into southern Idaho Sept. 21. Storms in the Slight Risk regions are not forecast to be widespread or long-lived. Isolated intense storms are possible; however, widespread damage is unlikely. Isolated intense storms are possible, which may contain hail, damaging winds, and a few tornadoes. Officials could update and possibly extend the coverage of weather alerts over the coming days.
Hazardous Conditions
Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites located downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where heavy rainfall has saturated the soil.
Authorities could issue mandatory evacuation orders for flood-prone communities over the coming days and tornado warnings advising the public to shelter in place. Disruptions to electricity and telecommunications services are possible where severe weather impacts utility networks.
Transport
The severe weather will likely contribute to transport disruptions throughout the region. Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters.
Severe weather will also likely trigger flight delays and cancellations at airports across the affected region, including but not limited to Phoenix International (PHX) and Albuquerque International Sunport (ABQ) airports. Flooding could block regional rail lines; freight and passenger train delays and cancellations are likely in areas that see heavy rainfall and potential track inundation.
Localized business disruptions may occur in flood- or tornado-hit areas; some businesses might not operate at full capacity because of damage to facilities, possible evacuations, and some employees' inability to reach work sites.
Advice
Monitor local media for weather updates and related advisories. Confirm all transport reservations and business appointments before travel. Make allowances for localized travel delays and potential supply chain disruptions where flooding has been forecast. Do not drive on flooded roads. Review contingency plans and be prepared to move quickly to shelter if tornado warnings are issued. Charge battery-powered devices in the case of prolonged electricity outages.
