Climate and Weather Monitoring at Washita Battlefield National Historic Site: Water Year 2022

Southern Plains Network scientists monitoring grasslands (an important Vital Sign across the Southern Plains) at Washita Battlefield National Historic Site, Cheyenne, Oklahoma.

NPS

Overview

Together, climate and hydrology shape ecosystems and the services they provide, particularly in arid and semi-arid ecosystems and across the Southern Plains (Woodhouse and Overpeck 1998). Understanding changes in climate, groundwater, and surface water is key to assessing the condition of park natural resources—and often, cultural resources.

At Washita Battlefield National Historic Site (Figure 1), Southern Plains Network scientists study how ecosystems may be changing by taking measurements of key resources, or “vital signs,” year after year—much as a doctor keeps track of a patient’s vital signs. This long-term ecological monitoring provides early warning of potential problems, allowing managers to mitigate them before they become worse. At Washita Battlefield National Historic Site, we monitor climate, among other vital signs.

Reporting is by water year (WY), which begins in October of the previous calendar year and goes through September of the water year (e.g., WY2022 runs from October 2021 through September 2022). This article reports the results of climate monitoring at Washita Battlefield National Historic Site (Figure 1) in WY2022.

Reference: Woodhouse, C. A., and J. T. Overpeck. 1998. 2000 years of drought variability in the central United States. Bulletin of the American Meteorological Society 79(12): 2693–2714. https://doi.org/10.1175/1520-0477(1998)079%3C2693:YODVIT%3E2.0.CO;2

Figure 1. Monitored weather station near Washita Battlefield National Historic Site in WY2022.

NPS

Washita Battlefield National Historic Site.

NPS

Climate and Weather

There is often confusion over the terms “weather” and “climate.” In short, weather describes instantaneous meteorological conditions (e.g., it’s currently raining or snowing, it’s a hot or frigid day). Climate reflects patterns of weather at a given place over longer periods of time (seasons to years). Climate is the primary driver of ecological processes on earth. Climate and weather information provide context for understanding the status or condition of other park resources.

Methods

A National Oceanic and Atmospheric Administration Cooperative Observer Program (NOAA COOP) weather station (CHEYENNE OK 6 SW 341743) is located 5.0 miles (8.0 km) south of Washita Battlefield National Historic Site and has been operational since 2009 (see Figure 1). The long-term averages used for comparison in this report were calculated by NOAA based on data from the period of record, 2009–2020. This station provides a reliable climate dataset used for analyses in this climate report. Data from this station are accessible through Climate Analyzer.

Results for Water Year 2022

Precipitation

Annual precipitation near Washita Battlefield National Historic Site in WY2022 was 17.53″ (44.5 cm; Figure 2), which was 9.30″ (23.6 cm) less than the long-term annual average. Monthly precipitation totals in October, June, and August of WY2022 were near or higher than the long-term averages. November, December, January, February, April, and September were much drier, receiving 0–25% of the long-term monthly rainfall averages. Extreme daily rainfall events (≥ 1″; 2.54 cm) occurred on 4 days, less than the average annual frequency of 6.8 days. Extreme rainfall events occurred on 21 March 2022 (1.04″; 2.6 cm), 01 June 2022 (2.01″; 5.1 cm), 08 June 2022 (1.33″; 3.4 cm), and 21 August 2022 (2.44″; 6.2 cm).

Air Temperature

The mean annual maximum temperature in WY2022 was 75.6°F (24.2°C), 4.3°F (2.4°C) above the long-term average. The mean annual minimum temperature in WY2022 was 49.8°F (9.9°C), 1.5°F (0.8°C) above the long-term average. The mean maximum temperature in December was much warmer, 14.8°F (8.2°C) above the long-term average. Temperatures during the rest of the year were generally warmer than average, with the exception of the winter months (January—March) when mean minimum temperatures were cooler than average. Extremely hot temperatures (≥ 98°F; 36.7°C) occurred on 41 days on in WY2022, nearly twice the long-term average frequency (22 days). Extremely cold temperatures (≤ 20°F; -6.7°C) occurred on 22 days, slightly more than the average frequency (18.6 days).

Figure 2. Climogram showing monthly precipitation and mean maximum and minimum air temperature in water year 2022 and the long-term averages at the CHEYENNE OK 6 SW station near Washita Battlefield National Historic Site. Data source: climateanalyzer.org.

NPS

Drought

Reconnaissance drought index (Tsakiris and Vangelis 2005) provides a measure of drought severity and extent relative to the long-term climate. It is based on the ratio of average precipitation to average potential evapotranspiration (the amount of water loss that would occur from evaporation and plant transpiration if the water supply was unlimited) over short periods of time (seasons to years). The reconnaissance drought index for Washita Battlefield National Historic Site indicates that WY2022 was drier than the WY2010–2022 average, from the perspective of both precipitation and potential evapotranspiration (Figure 3).

Reference: Tsakiris G., and H. Vangelis. 2005. Establishing a drought index incorporating evapotranspiration. European Water 9: 3–11.

Figure 3. Reconnaissance drought index for CHEYENNE OK 6 SW near Washita Battlefield National Historic Site, water years 2010–2022. Drought index calculations are relative to the time period selected (2009–2022). Choosing a different set of start/end points may produce different results. Data source: climateanalyzer.org.

NPS

Authors: Kara Raymond, Andy Ray

Please cite this report as
Raymond, K., and A. Ray. 2023. Climate and Weather Monitoring at Washita Battlefield National Historic Site: Water Year 2022. Southern Plains Network, National Park Service, Pecos, New Mexico.