Tropical Storm Rosa Fueling a Flood Threat in Southwest United States
October 1, 2018
Tropical Storm Rosa could trigger dangerous flash flooding in some areas.
- Tropical Storm Rosa is spreading rain into the Southwest U.S.
- The rain could trigger dangerous flash flooding in some areas.
- Rosa will make landfall in the Baja California Peninsula Monday.
- The landfall location of Rosa will be unusually far north in Mexico.
Rain from Tropical Storm Rosa is already soaking the Southwest where dangerous flash flooding may develop in parts of the region early this week.
The center of Rosa will make landfall on the Baja California Peninsula later Monday, but moisture from the storm has already been fueling rain in Arizona and southeast California since Sunday afternoon.
Floodwaters surged across sections of Highway 95 in San Bernardino County, California, early Monday morning, depositing rocks and other debris across the road.
Monday and into Tuesday, widespread rainfall will affect parts of Arizona, southeastern California, southern and eastern Nevada, Utah and perhaps northwestern New Mexico and parts of western Colorado.
Flooding could occur in urban areas, normally dry washes, small streams and slot canyons. Debris flows are also possible near recent wildfire burn scars.
The National Weather Service has issued flash flood watches for Monday and/or Tuesday from western Arizona into southern and eastern Nevada, southeastern California, Utah, southwestern Colorado, far southeastern Idaho and extreme southwestern Wyoming. This includes Phoenix, Flagstaff, Las Vegas and Salt Lake City.
Projected track for Tropical Storm Rosa. National Weather Service
The National Hurricane Center expects 2 to 4 inches of rainfall in central and southern Arizona, with isolated amounts up to 6 inches possible in the mountains of central Arizona. Elsewhere across the Desert Southwest, central Rockies and the Great Basin, 1 to 2 inches, with isolated totals up to 4 inches, are anticipated.
Although separate from Rosa, parts of coastal and interior California will see rain Tuesday and into Wednesday from the area of low pressure helping to lift the storm and its remnants into the Southwest. That area of low pressure will also continue the chance of showers and storms across the interior West on Wednesday.
Although flooding is a very serious concern, some of this rainfall will likely be beneficial since the Southwest is currently experiencing drought conditions. According to the U.S. Drought Monitor, just over 40 percent of Arizona is experiencing at least extreme drought, the second-highest category.
Locally gusty winds are also possible in southern Arizona Tuesday morning.
Swells from Rosa will contribute to life-threatening surf and rip-current conditions for portions of the Southern California coast through Tuesday.
- Blue Monster Prep