CEDAR CITY, UTAH — The flash flood threat across Utah is growing. The National Weather Service has expanded its Moderate Risk (Level 3 of 4) for excessive rainfall farther north across the state for Sunday, November 1, and the Slight Risk (Level 2 of 4) now includes the Salt Lake City metro and the Wasatch Front. An atmospheric river is pushing an unusually large amount of Pacific moisture into the Southwest, with 1 to 3 inches of rain possible across parts of Utah and locally higher amounts. Soils are already saturated in many areas, so much of this rain could quickly turn into runoff. The biggest concern remains southern Utah, where flash flooding, dangerous runoff and debris flows are possible.
Moderate Risk Expands North Along Interstate 15
The Weather Prediction Center’s Day 2 Excessive Rainfall Outlook, valid from 6 a.m. MDT Sunday to 6 a.m. MST Monday, November 2, shows two Moderate Risk areas:
- Southwest and central Utah, stretching north along Interstate 15 from the St. George and Cedar City areas toward the Interstate 15 and Interstate 70 junction, and south into the Arizona Strip
- The Four Corners, covering southeast Utah and southwest Colorado, near Cortez and Durango
A Moderate Risk means there is at least a 40 percent chance of rainfall exceeding flash flood guidance within 25 miles of any point.
The expanded zone along Interstate 15 includes several large burn scars near the I-15 and I-70 junction, which are especially vulnerable to debris flows.
Slight Risk Reaches Salt Lake City
The Slight Risk area, with at least a 15 percent chance of flash flooding, now covers a much larger part of the region:
- The Salt Lake City metro and the Wasatch Front, including Provo and Ogden
- Much of central and eastern Utah
- Northern Arizona, including Flagstaff and the Mogollon Rim
- Areas of central Arizona toward Phoenix
- Western Colorado, including Grand Junction
Along the Wasatch Front, heavy rain could cause localized urban flooding, with water collecting on streets, underpasses and in low-lying neighborhoods.
Marginal Risk Across the West
A Marginal Risk (Level 1 of 4) surrounds the higher-risk zones, covering:
- Southern Nevada, including Las Vegas
- Western Arizona
- Northern Utah and southern Idaho
- Western Colorado and northwest New Mexico
A separate Marginal Risk area appears over parts of Nebraska and South Dakota.
Why the Flood Threat Is So Serious
An atmospheric river is a long, narrow band of deep moisture flowing from the Pacific Ocean. Moisture with this event is near record levels for this time of year.
Several factors make the setup dangerous:
- Saturated soils from recent heavy rain
- Burn scars that absorb little water
- Steep terrain, canyons and slot canyons that funnel runoff
- Repeated rounds of heavy rain over the same areas
Southern Utah has already seen significant flooding this month. In Hurricane, Utah, floodwaters sent cars and storage units floating down streets and rushed through horse corrals. Another round of heavy rain could make an already difficult situation worse.
Florida Also Under a Flood Risk
The same outlook includes a Slight Risk along Florida’s Atlantic coast, from northeast Florida south toward Miami, as Florida’s first El Niño-fueled storm brings 2 to 4 inches of rain to parts of the peninsula. A Marginal Risk covers the rest of Florida and the Gulf Coast toward Louisiana.
Prepare Now in Southern Utah
Residents in southern Utah should start preparing now:
- Know your evacuation routes, especially near burn scars
- Pay attention to emergency alerts and Flash Flood Warnings
- Avoid slot canyons, washes and low-water crossings
- Move vehicles and livestock to higher ground
- act quickly if warnings are issued
Never drive through flooded roads. Just 1 to 2 feet of moving water can sweep away most vehicles.
Don’t Wait for the Water to Rise
Forecasters are urging residents not to underestimate this storm. Plan now, prepare now and don’t wait until water is rising…