Historic Flood Threat Spreads Across U.S. Plains and Midwest After Hurricane Polo Remnants

Historic flooding swept the Desert Southwest earlier this week as the remnants of Hurricane Polo pushed an unprecedented plume of moisture across the region. Now that moisture is being sheared by a plunging jet stream and is spreading northward, creating a widespread flood threat for the Plains and Midwest over the next couple of days. The situation is remarkable not only for the volume of rain but also for its geographic reach and timing—late‑September rainfall of this magnitude is rare for many of the affected states.

What makes this situation impressive

The atmosphere contains near‑record levels of moisture for late September over parts of the Southwest, Texas, and Oklahoma. According to the National Weather Service, “Looking back through history, heavy rains from the remnants of tropical systems are very rare across western Kansas,” meteorologist Jonathan Finch noted in a forecast discussion. Tropical rain is unusual for these latitudes, and the amount being lofted over southern Arizona, New Mexico, and far‑west Texas is at or slightly above historical benchmarks.

The moisture will not dissipate quickly as the tropical system weakens; instead, it will continue to feed showers and thunderstorms that are expected to sweep eastward, affecting a broad swath of the country.

Happening now

A historic plume of moisture is currently moving northward through northern Mexico, New Mexico, and Colorado and into Texas, with rainfall rates reaching up to 2 inches per hour. Radar imagery (see below) shows the intense bands as they progress, and local authorities have issued alerts for dry washes, slot canyons, burn scars, and already‑flooded areas.

Any watches or warnings issued by the National Weather Service are overlaid on the radar, giving residents real‑time guidance on where the most dangerous conditions exist.

How much rain could fall

Forecasters are projecting rainfall totals that could overwhelm drainage systems across the central United States. Here are the anticipated accumulations:

• Southern Plains: 3 to 5 inches of rain, with locally higher amounts, is possible from parts of Texas into Oklahoma, including Dallas, Austin, and San Antonio. This would rank among the heaviest rain events in eastern Oklahoma since June and in the Dallas‑Fort Worth Metroplex since early July.
• Central Plains/Midwest: A swath of 3‑5 inches or more is expected from parts of Kansas to southern Nebraska, northern Missouri, southern Iowa, and northern Illinois.

These totals raise the risk of flash flooding, especially in urban areas, low‑lying valleys, and regions with extensive burn scars from recent wildfires.

Flood threat timeline

The deep tropical moisture carried by Polo’s remnants will linger for several days, moving eastward with the jet stream. The threat will evolve as the storm system interacts with cold fronts.

Wednesday’s threat: Flooding shifts a bit eastward, with red‑highlighted pockets of higher risk extending into Texas, Oklahoma, and Colorado—including Oklahoma City and Omaha. The atmosphere is unstable enough to support severe storms that could bring hail, damaging winds, and even an isolated tornado.

Thursday’s threat: The flood zone expands further east to the Southern Plains and the Great Lakes region, stretching from Texas to Michigan. The heaviest rain is again forecast for a swath of Texas that includes Dallas and the Hill Country.

Weekend outlook: By the weekend, the tropical system itself will be long gone, but its moisture will still linger. A cold front will drive the remaining storm activity eastward, bringing days of rain to the Southeast. Forecast models show the highest accumulations in the Gulf Coast states, where tropical moisture will combine with stalled frontal boundaries.

How to stay safe during flash floods

When heavy rain threatens, never try to drive through a flooded road. It can be difficult to gauge water depth, especially at night, so obey the simple rule: “Turn around. Don’t drown,” as the National Weather Service advises.

Driving into floodwaters can submerge a vehicle in seconds, trapping occupants and making rescue extremely hazardous. If you encounter a road closure or warning, find an alternate route or wait until conditions improve.

Flash flood warnings are issued when flooding is either already happening or imminent based on rainfall rates and radar trends. When you hear one, check local forecasts, avoid travel if possible, and stay away from low‑lying areas and near‑stream banks.

If a flash flood emergency is declared, treat it as a life‑threatening situation. Move to higher ground if you are in a flood‑prone location, and never return to your home or neighborhood until officials declare it safe.

“When heavy rain threatens, never try to drive through a flooded road. … Turn around. Don’t drown.” – National Weather Service

Flooding recap

Monday’s storms already left a trail of damage across the Southwest. In Laughlin, Nevada, Casino Drive and the Laughlin River Walk beneath the Edgewater Casino were submerged, and one vehicle became stuck in mud about 75 miles south‑southeast of Las Vegas.

California’s desert communities saw widespread vehicle flooding in Bullhead City, Needles, and Indio Hills. Utah experienced a flooded yard and basement in Hurricane, while a large cargo container was swept down the East Fork of the Virgin River, striking the U.S. 89 bridge near Mt. Carmel.

Rainfall totals from September 27‑29 across the Southwest ranged from 1‑3 inches, with the highest confirmed total of 3.91 inches recorded in Bullhead City, Arizona. Albuquerque, New Mexico, received over 2 inches, pushing the month’s total toward double the typical September average.

Tuesday morning, a box truck was swept away by floodwaters north of Phoenix; the driver escaped unharmed. Another rescue was carried out in the metro area after a motorist ignored water warnings and became stranded.

Several washes and sections of Interstate 10 between Tucson and Phoenix were flooded, disrupting travel. New Mexico’s arroyos and creeks also rose to dangerous levels, inundating roads and underpasses. In addition to flooding, strong winds exceeding 65 mph and two tornado reports were recorded in northwest Texas on Tuesday evening.

The National Weather Service has since issued post‑event analyses highlighting the rarity of the moisture plume and the speed at which the flooding developed. While the immediate threat has passed, many communities are still assessing damage and preparing for potential residual flooding in the coming days.

As of today, the remnants of Hurricane Polo have dissipated, but the atmospheric river it created continues to influence weather patterns. Officials are urging residents to remain vigilant, especially in low‑lying areas, and to keep an eye on local alerts as the system’s moisture gradually clears.

News, Science, Government, Health, Society, Education, Communities, Transportation, Floods, Hurricanes, Weather, United States, Southwest Region, Plains, Midwest, Arizona, New Mexico, Texas, Oklahoma, Kansas, Colorado, Nevada, Utah, California, Flash flood safety, National Weather Service, Disaster preparedness, Severe weather, Storm tracking