Rainy and windy weekend as remnants of Tropical Storm Rachel move into Arizona

Tucson residents should prepare for a wet, windy weekend followed by a sharp cooldown as moisture from the remnants of Tropical Storm Rachel spreads across Southern Arizona. Rain has been limited to isolated and scattered storms in the Tucson area so far, while more widespread coverage has remained northwest of the city. Forecasters expect showers and thunderstorms to become more common this evening and continue into Sunday, with gusty winds, blowing dust and brief periods of heavy rain creating travel concerns.

The strongest winds are expected Sunday, when a Wind Advisory is scheduled to run from the morning through the evening. Winds across the Tucson area could reach 25 to 35 mph, with gusts between 45 and 55 mph. Blowing dust is possible overnight and is considered more likely Sunday. Monday should remain breezy, but winds are not expected to be as strong as they are Sunday. Residents driving through open areas, especially where dust can quickly reduce visibility, should be prepared for changing conditions.

Storms could bring more than rain. The forecast includes a continuing possibility of isolated severe weather tonight and Sunday, primarily in the form of strong to severe winds, small hail and locally heavy rainfall. Very western Pima County, including Ajo, faces an isolated tornado threat tonight. That risk is expected to shift northwest Sunday, with northern Pinal County included in the area of concern. Even where storms are not severe, short bursts of heavy rain could create difficult conditions in normally dry washes and low water crossings.

The immediate Tucson forecast calls for a 40 percent chance of showers and thunderstorms tonight, with mostly cloudy skies, a low near 71 degrees and breezy conditions. Sunday is expected to be mostly sunny overall, with a 30 percent chance of storms and a high near 84. Sunday night brings a smaller, 10 percent storm chance, a low around 65 and continued breezes. On Columbus Day, the chance of showers and thunderstorms falls to 20 percent, with partly sunny skies, a high near 82 and lingering wind.

The cooler air will become increasingly noticeable after the weekend. Tuesday carries a 30 percent chance of showers and thunderstorms and a high near 78, followed by mostly cloudy conditions and a low near 57. Wednesday should be mostly sunny, with a high near 77. Forecast lows are expected to be around 56 Wednesday night, then rise into the lower 60s later in the week as skies clear. High temperatures may return to the 80s late in the week, but forecasters expect readings to remain below normal for a time.

Rachel weakened from a tropical storm as it approached northern Baja California and moved onshore late Saturday night, according to the broader regional forecast. Its post tropical remnants spread heavy rain into Southern California and southern Nevada, including Las Vegas, before continuing into Arizona. The system produced significant coastal flooding and powerful surf in Southern California, while portions of the Southwest faced the possibility of receiving one to two inches of rain, an amount that can represent more than two months of precipitation in some desert locations.

The most serious flooding concerns outside Tucson extend from Riverside County in southeastern California through northwest Arizona and southern Nevada into the slot canyon areas of southwestern Utah. Flash flood threats were rated at levels one and two on a four level scale in those regions. Arizona communities remain vulnerable as additional storm moisture moves through, particularly along creeks, normally dry washes, swimming areas and locations affected by recent wildfires. Officials are warning people not to drive through flooded low water crossings, where water depth and current can change quickly.

Rachel's arrival comes as the Southwest experiences a notable fall weather transition and, in some places, a need for precipitation after an exceptionally dry year. Another fall storm system is expected to move across northern Arizona, bringing additional showers and thunderstorms into parts of the state Monday and early Tuesday. In the Phoenix area, forecasters said some locations could receive another quarter inch of rain through Tuesday, along with wind gusts of 30 to 35 mph and temperatures dropping from the mid 80s Monday into the 70s by the middle of the week. The combination of tropical moisture and the incoming fall system means Tucson residents should monitor updates, secure loose outdoor items, allow extra time for travel and take flooding seriously even when rainfall at their location appears light.