ZUMWALT WEATHER AND CLIMATE ANNUAL REPORT ( )

ZUMWALT WEATHER AND CLIMATE ANNUAL REPORT (26-29) FINAL DRAFT (9 AUGUST 21) J.D. HANSEN 1, R.V. TAYLOR 2, AND V.S. JANSEN 3 INTRODUCTION The Zumwalt Prairie in northeastern Oregon is a unique grassland ecosystem. In the northeastern portion of this relict grassland, The Nature Conservancy (TNC) manages the 13, ha (33, acre) Zumwalt Prairie Preserve. The preserve is managed for the conservation of the native grassland, shrubland, aquatic, and riparian ecosystems that occur there. Research investigating the effects of various land management practices, including prescribed fire and grazing, is being conducted by TNC and Figure.1. Location of the Zumwalt Weather Station on the Zumwalt Prairie Preserve in northeast Oregon. collaborators, including Oregon State University and Oregon Department of Fish and Wildlife. One challenge to both management and research is incorporating data on weather and climate into this work. Because climate plays such an important role in everything from when the first 1 Ecologist, Turtle Mt. Environmental Consulting, 6521 US Hwy 97, Toppenish, WA 98948 USA (jimbobtoo@aol.com) 2 Northeast Oregon Regional Ecologist, The Nature Conservancy, 96 S River St, Enterprise, OR 97828 USA (rtaylor@tnc.org) 3 Northeast Oregon Science and Stewardship Technician, The Nature Conservancy, 96 S River St, Enterprise, OR 97828 USA (vjansen@tnc.org) 1

buttercup blooms and the first swallows make their nests to the number of cattle a pasture can support, the availability of reliable, accurate data is crucial. Because there was no existing weather station nearby 4, TNC established the Zumwalt Weather Station (ZumWxStn), in 26. This report summarizes temperature and precipitation data collected from ZumWxStn from 26 through 29. This is the first weather summary ever completed for this weather station. Follow-up reports are planned each year. MATERIALS AND METHODS ZUMWXSTN: DETAILS AND HISTORY The Zumwalt Weather Station, located at 45.577745 N and 116.971754 W, 29 km (18 mi) NE Enterprise, Oregon, is at an elevation of 1337 m (4385 ft) (Figure 1), and was installed in August of 25. It collects hourly data on precipitation, temperature, wind speed and direction, and humidity. Precipitation was recorded by the Campbell Scientific TE525 Tipping Bucket Rain Gage in.1 inch increments, which were later converted to mm. Temperatures were measured by using the Campbell Scientific Model HMP 45C Temperature, which contains a Platinum Resistance Temperature detector (PRT) (Figure 2). The weather station is maintained by TNC staff in the Northeast Oregon Field Office. DATA ANALYSIS AND MANAGEMENT Figure 2. The Zumwalt Weather Station. Data were downloaded periodically by TNC staff, and imported into an MS/ACCESS database, which is stored at TNC s Northeast Oregon Field Office on the shared, network drive (i.e., the T drive ). Mean, standard error of mean (SEM), and regressions were calculated using the statistical programs on Microsoft Office Excel (Microsoft Corporation, Redmond, WA). Growing Degree Days (GDD) were calculated using the equation, GDD = ((T max + T min )/2) 1 C 4 Nearest stations are Enterprise 2NNE, Roberts Butte, Harl Butte, Enterprise RS, and Joseph. 2

Temp. ( C) Temp. ( F) where T max is the maximum hourly temperature value for the 24 hr period and T min the minimum. We used a value of -1 C for T base.. Frost-free days (FFD) were calculated as the number of days within a given month or year for which the minimum temperature was greater than C. RESULTS AND DISCUSSION TEMPERATURE Monthly mean temperatures were similar through the study period (Figure 3). July was always the warmest month. Early 27 and late 28 were warmer than other years. The first freezing temperatures generally occurred in late summer but varied considerably across the period: 8 August 26, 1 September 27, 24 July 28, 8 September 29. The last frosts occurred in late spring: 3 May 26, 26 Jun 27, 1 June 28, and 9 June 29. The coldest recorded temperature for the study was -26.6 C (-15.9 F) on 21 January 28. Monthly Mean Temperature 25 2 15 26 27 28 29 7 6 1 5 5 4-5 -1 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month 3 2 Figure 3. Daily mean temperature ( C, F) per month (n = 28 to 31, depending on month) observed at the Zumwalt Weather Station (18 miles NE of Enterprise, Oregon) from 26 to 29. 3

Temp. ( C) Temp. ( F) Other yearly minimum temperatures were: -26.4 C (-15.5 F) on 18 February 26, -26.3 C (-15.3 F) on 8 December 29, and -25. C (-13. F) on 12 January 27. The maximum yearly temperatures were: 35.2 C (95.4 F) on 23 July 26, 34.9 C (94.8 F) on 5 July 27, 33.9 C (93. F) on 17 August 28, and 32.9 C (91.2 F) on 2 August 29. The summer of 27 was an apparent anomaly with the last frost occurring after the highest temperature for that year. Despite minor temperature variations from year to year, the mean monthly temperatures were fairly consistent across the period (Figure 4). Mean (± SEM) Monthly Temp. 26-9 25 2 15 1 7 6 5 5-5 -1 Jan Feb Mar Apr May Jun Month Jul Aug Sep Oct Nov Dec 4 3 2 Figure 4. Mean (± SEM) of monthly temperatures ( C) (n = 4) observed at the Zumwalt Weather Station (18 miles NE of Enterprise, Oregon) from 26 to 29. The months with the fewest FFD were May through September, with all years having a similar overall pattern (Figure 5). A greater number of total FFD occurred in 26 and 27 than in 28 and 29 (Figure 5). In spite of a few extreme variations, the number of FFD for each month was relatively consistent and demonstrates a regular pattern of seasonal climate during the study period. 4

Total Days Total Days Monthly FFD 35 3 25 2 26 27 28 29 15 1 5 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Cumulative FFD 2 18 16 14 12 1 8 6 4 2 26 27 28 29 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Figure. 5. Monthly (top) and cumulative (bottom) frost-free days (FFD) observed at the Zumwalt Weather Station (18 miles NE of Enterprise, Oregon) from 26 to 29. Cold late winter and spring temperatures resulted in few growing degree days (GDD) in late winter and early spring. Monthly GDD accelerated during May, with July as the peak month 5

GDD C GDD C followed by August (Figure 6). The GDD accumulations were greater for 26 and 27 than for 28 and 29 (Figure 6). Monthly GDD C 35 3 25 26 27 28 29 2 15 1 5 ` Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Cumulative GDD C 12 1 8 6 4 26 27 28 29 2 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Figure 6. Monthly (top) and cumulative (bottom) growing degree days (GDD) observed at the Zumwalt Weather Station (18 miles NE of Enterprise, Oregon) from 26 to 29. 6

Precip. (mm) Precip. (in) The growing season on the Zumwalt Prairie is relatively short, which impacts plant phenology, insect development, and other biological and ecological factors. Plants with GDD requirements > 1 would have difficultly blooming before the first frosts. In comparison, the total GDD on the Palouse grassland in Idaho range from 356 at Grangeville to 3949 at Moscow (Lichthardt & Moseley, 1997). Thus, the relatively cold climate of the Zumwalt Prairie may prevent certain exotic plants from being established. Similarly, invertebrate pollinators may not be active after the summer. These ecological factors limit the floral diversity of the site. PRECIPITATION Precipitation varied from year to year (Figure 7). The driest year was 27 (total = 263 mm, 1.4 in) where as the wettest was 29 (total = 384 mm, 15.1 in). These annual precipitation levels are similar to other temperate arid grasslands. Mean (±SEM) Monthly Precipitation 45 4 35 3 25 2 15 1 5 26 27 28 29 Year 1 Figure 7. Mean (± SEM) total monthly precipitation (n=12), by year, observed at the Zumwalt Weather Station (18 miles NE of Enterprise, Oregon) from 26 to 29. Late spring was usually the wettest time of the year (Figure 8). In 29, precipitation in June was unusually high (121 mm, 4.9 in) surpassing the next highest month during the study by 61% 7

Precip. (mm) Precip. (in) (May 28). Precipitation in September 26 was also high (67 mm, 2.7 in). July was the driest month for all years, never exceeding 1 mm (.4 in). Seasonally, the months with the greatest variation in total precipitation were May, June, and September (Figure 8), where as the snow months (late fall and winter) and July were consistent from year to year. Monthly Total Precipitation 14 12 1 26 27 28 29 5 4 8 6 4 2 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month 3 2 1 Figure 8. Precipitation observed, by month, at the Zumwalt Weather Station (18 miles NE of Enterprise, Oregon) from 26 to 29. SUMMARY The Zumwalt Prairie Preserve provides an example of a unique native, arid grassland in the Pacific Northwest. Because of its geophysical setting, having a relatively high elevation within the rain shadow of adjacent mountains, it obtains much of its moisture during the spring, followed by a short growing season. The amount of annual rain/snowfall is irregular. Because the ZumWxStn is only 4 years old we cannot gauge what is normal precipitation or temperature at this point. Typically, a period of record of 3 years is required to establish climatic normals. Nonetheless, we can now say with confidence that spring and summer of 28 were colder than 27 and examine other relative differences. Comparisons of data from the ZumWxStn with other stations in the region having much longer records of observation could provide important insights. 8

We hope that the publishing of this very first Zumwalt Climate Report will prove useful to managers, scientists, weed control contractors, and cow bosses. Any feedback you have can be forwarded to any of the authors of this report. LITERATURE CITED Lichthardt, J., and R. K. Moseley. 1997. Status and conservation of the Palouse grassland in Idaho. U.S. Fish & Wildlife Service, P.O. No. 1442-5-395. 29 pp. 9

APPENDIX 1 TEMPERATURE AND PRECIPITATION TABLES Table 1. Daily mean temperature ( C, F) per month (n = 28 to 31, depending on month) from 26 to 29 from the Zumwalt Weather Station on the Zumwalt Prairie Preserve, 29 km (18 mi) NE Enterprise, Oregon. Daily Mean Temperature 26 27 28 29 Month C F C F C F C F Jan -.6 3.9-5.6 22. -5.4 22.2-3.4 25.8 Feb -3.6 25.5 -.3 31.5-1.7 29. -1. 3.3 Mar.1 32.2 3.2 37.8-1.2 29.8-1.6 29.2 Apr 4.6 4.4 4.5 4. 1.3 34.3 3.4 38. May 9.6 49.2 8.8 47.9 8.3 46.9 8.9 48.1 Jun 13.7 56.6 12.7 54.8 11.4 52.5 12.3 54.2 Jul 19.6 67.2 2.6 69. 16.6 61.9 17.1 62.7 Aug 15.9 6.7 16.3 61.4 16.2 61.2 16.5 61.6 Sep 11.7 53.1 1.9 51.7 11.5 52.8 14. 57.1 Oct 4.6 4.3 5.8 42.4 8.8 47.9 3.7 38.6 Nov.7 33.3 -.3 31.6 3. 37.4.7 33.2 Dec -2.9 26.9-3.6 25.5-4.6 23.6-6.8 19.8 1

Table 2. Mean (± SEM) of monthly temperatures ( C, F) (n = 4) from 26 to 29 from the Zumwalt Weather Station on the Zumwalt Prairie Preserve, 29 km (18 mi) NE Enterprise, Oregon. C F Month Mean SEM Mean SEM Jan -3.8 1.2 25.2 2.1 Feb -1.6.7 29.1 1.3 Mar.1 1.1 32.3 2. Apr 3.4.8 38.2 1.4 May 8.9.3 48..5 Jun 12.5.5 54.5.9 Jul 18.5 1. 65.2 1.7 Aug 16.2.1 61.2.2 Sep 12..7 53.7 1.2 Oct 5..5 41..9 Nov 1..7 33.9 1.2 Dec -4.5.9 23.9 1.5 Table 3. The number of frost-free days (FFD) per month between 26 and 29 at the Zumwalt Prairie Preserve, 29 km (18 mi) NE Enterprise, Oregon. Year Month 25 26 27 28 29 Jan 3 1 1 Feb 2 4 2 1 Mar 4 7 2 Apr 8 7 2 5 May 2 18 21 16 Jun 3 27 26 27 Jul 3 31 28 31 Aug 31 31 3 31 3 Sep 22 22 19 2 24 Oct 16 11 13 11 8 Nov 1 8 6 9 3 Dec 6 4 2 1 1 11

Table 4. Cumulative frost-free days (FFD) for years between 26 and 29 at the Zumwalt Prairie Preserve, 29 km (18 mi) NE Enterprise, Oregon. Year Month 25 26 27 28 29 Jan 3 1 1 Feb 5 5 3 1 Mar 9 12 3 3 Apr 17 19 5 8 May 37 37 26 24 Jun 67 64 52 51 Jul 97 95 8 82 Aug 31 128 125 111 112 Sep 53 15 144 131 136 Oct 69 161 157 142 144 Nov 7 169 163 151 147 Dec 76 173 165 152 148 Table 5. Growing degree days (GDD) per month by year (26 to 29) for the Zumwalt Prairie Preserve, 29 km (18 mi) NE Enterprise, Oregon. Year Month 26 27 28 29 Jan.... Feb. 1.1.. Mar 1.2 25.4. 3.5 Apr 29.8 38.4 2.2 31.7 May 11.7 11.7 76.8 1.1 Jun 162.1 158.6 134.1 129.6 Jul 286.6 35.1 241.2 244.6 Aug 239. 243.7 234.4 231.5 Sep 162.8 147.1 169.7 26.8 Oct 53.3 49.1 69.6 18.6 Nov 6.2 16.3 12.7 6.6 Dec.... 12

Table 6. Cumulative growing degree days (GDD) for years between 26 and 29 at the Zumwalt Prairie Preserve, 29 km (18 mi) NE Enterprise, Oregon. Year Month 26 27 28 29 Jan.... Feb. 1.1.. Mar 1.2 26.4. 3.5 Apr 31. 64.9 2.2 35.2 May 141.7 166.6 97.1 135.3 Jun 33.8 325.1 231.2 264.9 Jul 59.4 63.2 472.4 59.5 Aug 829.4 873.9 76.8 741. Sep 992.3 121.1 876.5 947.8 Oct 145.6 17.1 946.1 966.4 Nov 151.8 186.4 958.8 973. Dec 151.8 186.4 958.8 973. Table 7. Mean (± SEM) of total monthly precipitation (mm, inches) (n=12) for each year from 26 to 29 at Zumwalt Weather Station on the Zumwalt Prairie Preserve, 29 km (18 mi) NE Enterprise, Oregon. mm inches Year Mean SEM Mean SEM 26 31. 5.2 1.2.2 27 21.9 3.5.9.1 28 25. 5.1 1..2 29 32. 9.5 1.3.4 13

Table 8. Monthly total precipitation (mm, inches) from 26 to 29 on the Zumwalt Prairie Preserve, 29 km (18 mi) NE Enterprise, Oregon. Year 26 27 28 29 Month mm inches mm inches mm inches mm inches Jan 15.5.6 8.6.3 19.6.8 29.7 1.2 Feb 12.4.5 2.8.8 1.9.4 1.7.4 Mar 39.1 1.5 15.2.6 22.1.9 29. 1.1 Apr 43.4 1.7 25.4 1. 27.7 1.1 21.8.9 May 45.5 1.8 32.5 1.3 75.2 3. 69.1 2.7 Jun 42.2 1.7 35.6 1.4 21.8.9 121.2 4.8 Jul 6.6.3 9.7.4 8.6.3 6.1.2 Aug 3.7 1.2 6.9.3 24.6 1. 25.9 1. Sep 67.3 2.7 8.1.3 22.9.9.5. Oct 9.1.4 39.4 1.6 7.4.3 34. 1.3 Nov 36.1 1.4 34.8 1.4 3.5 1.2 21.3.8 Dec 24.1 1. 25.7 1. 28.2 1.1 15.2.6 Table 9. Mean (± SEM) monthly total precipitation (mm, inches) from 26 to 29 at Zumwalt Weather Station on the Zumwalt Prairie Preserve, 29 km (18 mi) NE Enterprise, Oregon. mm inches Month Mean SEM Mean SEM Jan 18.4 4.4.7.2 Feb 13.7 2.4.5.1 Mar 26.4 5.1 1..2 Apr 29.6 4.8 1.2.2 May 55.6 1. 2.2.4 Jun 55.2 22.4 2.2.9 Jul 7.7.8.3. Aug 22. 5.2.9.2 Sep 24.7 14.9 1..6 Oct 22.5 8.3.9.3 Nov 3.7 3.3 1.2.1 Dec 23.3 2.8.9.1 14

APPENDIX 2 STATISTCAL MODELS TEMPERATURE Average temperature for a given month can be expressed by the six-term polynomial regression equation, y = -.1x 6 +.491x 5 -.9291x 4 + 8.4944x 3-38.899x 2 + 86.56x - 75.92, (r 2 =.992), where y is temperature ( C) and x is time by month. Hence, previous and future deviations of mean monthly temperatures can be shown using this mathematical model. Changes from historical temperatures can be demonstrated and climate trends anticipated. Yearly cumulative GDD for the study can be accurately described by six-term polynomial regression equation, y =.19x 6 -.5952x 5 + 6.2234x 4-23.793x 3 + 3.779x 2 + 5.4587 x - 19.699, (r 2 =.9993), where y is cumulative GGD and x is time by sequence of month during the year. Cumulative FFD per year can be precisely described by six-term polynomial regression equation, y = -.1x 6 +.191x 5 -.5614x4 + 6.987x 3-25.681x 2 + 45.685 x - 24.534, (r 2 =.9998), where y is cumulative FFD and x is time by sequence of month during the year. PRECIPITATION The best six-term equation to describe monthly precipitation is y =.2x 6 -.397x 5 + 1.3375x 4-18.65x 3 + 112.5x 2-37.13 x + 38.6 (r 2 =.5822), where y is total amount (mm) and x is time by month. This mathematical model demonstrates how difficult it is to predict future rain and snow storms. 15