Heavy rain and flood risk for Arizona and New Mexico as tropical moisture from Priscilla and Raymond arrives
Back-to-back tropical storms — Priscilla and Raymond — are forecast to channel deep tropical moisture into the U.S. Southwest between October 10 and 14 2025, causing a multi-day rain event and creating an elevated flash-flood risk across Arizona and New Mexico.
Satellite image of Tropical Storms Priscilla and Raymond at 23:20 UTC on October 9, 2025. Credit: NOAA/GOES-East, RAMMB/CIRA, The Watchers
A predecessor rain event (PRE) associated with Tropical Storm Priscilla is forecast to deliver the first wave of tropical moisture into the U.S. Southwest from late October 9 (LT) and continuing through October 11.
CW3E West-WRF ensembles show widespread precipitation totals of 40–75 mm (1.5–3 inches), with isolated totals of over 100 mm (4 inches) along the Mogollon Rim and mountainous areas of central Arizona and south-western New Mexico.
The Weather Prediction Center (WPC) has placed central Arizona under a moderate risk (level 3 of 4) of excessive rainfall, with surrounding slight and marginal-risk areas extending into New Mexico, Utah, and Colorado. Forecast accumulations exceed 50 mm (2 inches) over a broad region from Phoenix to Durango based on the latest QPF fields.
Image credit: CW3E
Image credit: CW3E
After the first phase, Tropical Storm Raymond is expected to approach the Mexican coast by late October 11 and inject additional tropical moisture northward, starting a second rainfall episode from October 12 to 14.
Model ensembles forecast rainfall totals of 25–50 mm (1–2 inches) across the same general region, with locally higher amounts in the White Mountains and San Juan Mountains.
Hydrologic outlooks from the Colorado Basin River Forecast Center (CBRFC) indicate rising river stages across southern Arizona and western New Mexico.
While most gauges are forecast to remain below flood stage, the Gila River near Maricopa and tributaries in southeastern Arizona could approach or exceed action levels if both systems produce near-maximum totals.
Further north, a separate Pacific trough is forecast to draw a high-intensity integrated vapor transport (IVT > 01400 kg m-1 s-1) plume into California and the Pacific Northwest during October 15–17.
The strongest orographic precipitation is expected along the Sierra Nevada and Coast Ranges, with moderate precipitation extending into the Great Basin.
The combined events will bring short-term drought relief across portions of the Southwest, with some watersheds being forecast to receive up to 30% of their annual precipitation over a single week.
References:
1 CW3E Precipitation Update – CW3E – October 9, 2025
Rishav Kothari is Editor-in-Chief of The Watchers, where he runs the newsroom and covers earthquakes, volcanoes, severe weather and space weather.
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