The monsoon season officially ended on September 30th. Every major U.S. city along the Rio Grande experienced average to above-average precipitation (Figure 10). Even though Las Cruces, NM and El Paso, TX received the majority of their precipitation prior to August 25th, final totals for both cities were over an inch above average. Brownsville, TX received very steady precipitation over the entire season, ending the season near average.
For northern New Mexico, including Santa Fe and Albuquerque, monsoon precipitation was below average until a low-pressure system in Utah drew moisture into the state towards the end of September. Albuquerque saw record rainfall and Santa Fe received over an inch of rain on September 27th, leaving both cities slightly above average for the season. Similarly, late September storms in Laredo and Del Rio took the season from well below-average, to well above-average. On September 24th, precipitation in Laredo was more than 5 inches below average. Over the next four days, storms brought over 8 inches of rain, so that the city ended the season over 2 inches above average. Storms on September 26th dumped 5.30 inches of rain, flooding the area and nearby Nuevo Laredo, MX, and causing the Rio Grande to overflow its banks.
Figure 10 (above): Precipitation amounts (in inches), June 15 – September 30, for 2017 (light blue), compared to average (dark blue). Source: HPRCC
At the end of the monsoon, rains were above normal in northern Chihuahua and Coahuila, in addition to portions of northern and western Sonora. In the rest of the region, the rains fell short, with Sinaloa, western Durango and the lower Rio Bravo receiving below normal rainfall. Maximum rains accumulated from June 16 to September 30 with 900 mm (35.4 in) in Basaseachi, Chihuahua, 807 mm (31.7 in) in José López Portillo Dam, and 788.5 mm (31 in) in Joaquin Amaro, Zacatecas (Figure 11).
Figure 11 (above): Accumulated precipitation from 16 June-31 August and percent of normal during the same period based on 1981-2010. Source: SMN
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