Phoenix, Arizona — November is expected to begin with a powerful cross-country storm that could bring heavy rain, flash flooding, mountain snow and severe thunderstorms to large parts of the United States. Forecast projections indicate that as many as 35 states could experience dangerous weather as the system moves from the Southwest toward the Plains, Midwest and East Coast.
The storm is expected to develop as a strong upper-level low near the Pacific Northwest directs a powerful Pacific jet stream toward the Southwest. The resulting weather system could affect millions of Americans beginning Friday and continuing into the middle of next week.
California Faces Heavy Rain Ahead of Halloween
Southern California is expected to experience moderate to heavy rainfall by Saturday, potentially disrupting Halloween celebrations and outdoor activities in major cities, including Los Angeles and San Diego.
Rain in San Diego on Halloween is relatively uncommon. The city has recorded measurable Halloween rainfall only nine times since 1850, with the most recent occurrence in 1987.
Arizona could also experience rain ahead of the main storm. Additional moisture is expected to move into the region between Saturday and Sunday, increasing rainfall chances through the weekend.
Arizona Could Receive Up to 5 Inches of Rain
As the storm moves inland, widespread rainfall is expected across parts of the Southwest through Monday morning.
Forecast projections indicate 1 to 2 inches or more of rain across portions of Arizona, with some areas between Phoenix and Flagstaff potentially receiving as much as 5 inches.
Flagstaff is already dealing with an unusually wet October, having recorded 5.69 inches of rainfall so far this month. If another 3 inches falls as projected, the additional precipitation could increase the potential for dangerous flash flooding.
A Level 2 out of 4 flash flood threat is in effect through the weekend, highlighting concerns about excessive rainfall and rapidly rising water.
Residents should remain alert for changing conditions, particularly in areas with poor drainage, low-lying roads and locations vulnerable to runoff.
Heavy Mountain Snow Could Hit the Sierra and Rockies
While lower elevations prepare for soaking rain, colder air moving into higher terrain could produce significant snowfall.
Snow is expected across mountain areas extending from the Sierra Nevada toward the Rocky Mountains. The southern Rockies could receive the heaviest accumulation, with forecast totals reaching 12 to 18 inches.
The combination of heavy precipitation and colder temperatures could create difficult travel conditions in mountain communities and along higher-elevation roads.
Drivers traveling through affected areas should watch for changing road conditions and possible snow-related travel disruptions.
Flash Flood Threat Expands Across the Plains and Midwest
By Monday, the storm is expected to move into the Plains and Midwest, carrying heavy precipitation farther east.
Nearly 40 million Americans could be under a Level 1 out of 4 flash flood threat on Monday, with the potential risk stretching from Texas toward Wisconsin.
Heavy rainfall could cause localized flooding, particularly where storms repeatedly move over the same locations.
The arrival of warmer, moisture-rich air ahead of an approaching cold front could also help create conditions favorable for stronger thunderstorms.
Severe Storm Threat Could Develop From Texas to the Southeast
From Tuesday into Wednesday, the approaching cold front could trigger severe thunderstorms across portions of Texas and the Southeast.
Forecast confidence remains limited because weather models disagree about where the developing low-pressure system will form and how strong it could become.
However, atmospheric conditions are expected to become increasingly favorable for storm development across parts of the southern United States.
Residents should monitor updated forecasts for possible severe thunderstorm watches and warnings as the system approaches.
Northeast Could See Heavy Rain by Thursday and Friday
The storm is expected to continue moving eastward from Wednesday onward, potentially bringing another round of widespread rainfall to the East Coast.
Texas Weather Alert: Up to 3 Inches of Rain Could Trigger Flash Flooding Across Multiple Areas
Major cities along the Interstate 95 corridor could experience rain Thursday and Friday, including Raleigh, North Carolina, Washington, D.C., New York City and Boston.
Some of these locations could receive their first rainfall in nearly two weeks as the system moves through.
The exact timing and rainfall amounts remain uncertain, but the developing storm could bring a significant change in weather conditions across several regions.
What Americans Should Watch as November Begins
The developing storm could bring several different weather hazards within a relatively short period, including flash flooding in the Southwest, heavy mountain snow, severe thunderstorms across the southern states and rainfall along the Northeast corridor.
Residents should keep track of local weather alerts, avoid driving through flooded roads and prepare for changing conditions, particularly in areas expecting heavy precipitation.
Are you in one of the states expected to be affected by this major storm? Share your local forecast and tell us whether you’re preparing for heavy rain, flooding, snow or severe thunderstorms.
