Extremes of Opportunity: Examining Recent Trends in Warm Season Extreme Precipitation for New Mexico River Basins

TitleExtremes of Opportunity: Examining Recent Trends in Warm Season Extreme Precipitation for New Mexico River Basins
Publication TypeConference Proceedings
Year of Conference2018
AuthorsPoshtiri, Maryam Pournasiri, Towler Erin, Llewellyn Dagmar, and Prein Andreas F.
Conference Name86th Annual Western Snow Conference
Conference LocationAlbuquerque, New Mexico

We explore recent trends in precipitation characteristics within the state of New Mexico and southern Colorado, relevant to the Rio Grande and Pecos basins, where increasing temperatures and decreasing snowpack threaten to reduce the water available for storage and use. To determine how changing precipitation could potentially help to mitigate decreasing water supply, we examine both magnitude and frequency of daily precipitation characteristics for the warm season (June - October) and individual months therein, with a focus on the upper quantiles and extremes within the period 1981 to 2017. We find that the dominant sign of the precipitation trend depends on the season/month examined. Negative trends dominate the warm season, June, and August, while positive trends dominate July and for some September indicators. However, the majority of locations in the study area did not show any significant trends. The increasing trends for the July indicators show the most potential for water supply, with the location of these significantly positive trends mainly concentrated in the southeastern and eastern part of the study region. The frequency of days above the 99th daily precipitation quantile for September also shows increasing trends at some southern and southeastern locations, but this heavy precipitation could be difficult to capture for water supply. However, across most characteristics examined, we find that significant trends are more detectable in the frequency indicators than in the magnitude indicators. As such, for times and locations showing increasing trends, this suggests that water managers looking to exploit changes in precipitation might not need to plan for larger events, but rather for more frequent events. (KEYWORDS: decreasing snowpack, extreme precipitation, warm season, trends, New Mexico)