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Assessment of Climate Change in the Southwest United States pp 74–100Cite as

Present Weather and Climate: Evolving Conditions

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Part of the book series: NCA Regional Input Reports ((NCARIR))

Abstract

This chapter assesses weather and climate variability and trends in the Southwest, using observed climate and paleoclimate records. It analyzes the last 100 years of climate variability in comparison to the last 1,000 years, and links the important features of evolving climate conditions to river flow variability in four of the region’s major drainage basins. The chapter closes with an assessment of the monitoring and scientific research needed to increase confidence in understanding when climate episodes, events, and phenomena are attributable to human-caused climate change.

Chapter citation: Hoerling, M. P., M. Dettinger, K. Wolter, J. Lukas, J. Eischeid, R. Nemani, B. Liebmann, and K. E. Kunkel. 2013. “Present Weather and Climate: Evolving Conditions.” In Assessment of Climate Change in the Southwest United States: :A Report Prepared for the National Climate Assessment, edited by G. Garfin, A. Jardine, R. Merideth, M. Black, and S. LeRoy, 74–100. A report by the Southwest Climate Alliance. Washington, DC: Island Press.

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Reference

  • Ababneh, L. 2008. Bristlecone pine paleoclimatic model for archeological patterns in the White Mountain of California. Quaternary International 188:9–78.

    Article  Google Scholar 

  • Alley, W. 1984. The Palmer Drought Severity Index: Limitations and assumptions. Journal of Climatology and Applied Meteorology 23:1100–1109.

    Article  Google Scholar 

  • Anderson, L. 2011. Holocene record of precipitation seasonality from lake calcite18O in the central Rocky Mountains, United States. Geology 39:211–214.

    Article  CAS  Google Scholar 

  • Asmerom, Y., V. Polyak, S. Burns, and J. Rassmussen. 2007. Solar forcing of Holocene climate: New insights from a speleothem record, southwestern United States. Geology 35:1–4.

    Article  CAS  Google Scholar 

  • Bard, E., G. Raisbeck, F. Yiou, and J. Jouzel. 2000. Solar irradiance during the last millennium based on cosmogenic nucleides. Tellus 52B: 985–992.

    CAS  Google Scholar 

  • Barnett, T. P., and D. W. Pierce. 2008. When will Lake Mead go dry? Water Resources Research 44: W03201, doi:10.1029/2007WR006704.

    Article  Google Scholar 

  • Barnett, T. P., 2009. Sustainable water deliveries from the Colorado River in a changing climate. Proceedings of the National Academy of Sciences 106:7334–7338.

    Article  CAS  Google Scholar 

  • Barnett, T. P., D. W. Pierce, H. Hidalgo, C. Bonfils, B. Santer, T. Das, G. Bala, et al. 2008. Human-induced changes in the hydrology of the western United States. Science 319:1080–1083, doi:10.1073/pnas.0812762106

    Article  CAS  Google Scholar 

  • Benson, L.V., 1999. Records of millennial-scale climate change from the Great Basin of the western United States. In Mechanisms of global climate change at millennial time scales, ed. P. Clark, R. Webb, and L. Keigwin, 203–225. Geophysical Monograph Series 112. Washington, DC: American Geophysical Union.

    Chapter  Google Scholar 

  • Bonfils, C., B. D. Santer, D. W. Pierce, H. G. Hidalgo, G. Bala, T. Das, T.P. Barnett, et al. 2008. Detection and attribution of temperature changes in the mountainous western United States. Journal of Climate 21:6404–6424.

    Article  Google Scholar 

  • Bonnin, G. M., K. Maitaria, and M. Yekta. 2011. Trends in rainfall exceedances in the observed record in selected areas of the United States. Journal of the American Water Resources Association 46:344–353, doi:10.1111/j.1752-1688.2011.00603.x.

    Google Scholar 

  • Cayan, D. R., S. A. Kammerdiener, M. D. Dettinger, J. M. Caprio, and D. H. Peterson. 2001. Changes in the onset of spring in the western United States. Bulletin of the American Meteorological Society 82:399–415.

    Article  Google Scholar 

  • Cayan, D. R., T. Das, D. W. Pierce, T. P. Barnett, M. Tyree, and A. Gershunov. 2010. Future dryness in the southwest US and the hydrology of the early 21st century drought. Proceedings of the National Academy of Sciences 107:21271–21276, doi:10.1073/pnas.0912391107.

    Article  CAS  Google Scholar 

  • Christensen, N. S., and D. P. Lettenmaier. 2007. A multimodel ensemble approach to assessment of climate change impacts on the hydrology and water resources of the Colorado River Basin. Hydrology and Earth System Sciences 11:1417–1434.

    Article  Google Scholar 

  • Cook, E. R., C. Woodhouse, C. M. Eakin, D. M. Meko, and D. W. Stahle. 2004. Long-term aridity changes in the western United States. Science 306:1015–1018.

    Article  CAS  Google Scholar 

  • Cook, E. R., R. Seager, R. R. Heim, R. S. Vose, C. Herweijer, and C. Woodhouse. 2009. Megadroughts in North America: Placing IPCC projections of hydroclimatic change in a long-term paleoclimate context. Journal of Quaternary Science 25:48–61, doi: 10.1002/jqs.1303.

    Article  Google Scholar 

  • Dai, A. 2011. Characteristics and trends in various forms of the Palmer Drought Severity Index (PDSI) during 1900–2008. Journal of Geophysical Research 116: D12115, doi:10.1029/2010JD015541.

    Article  Google Scholar 

  • Daly, C. 2006. Guidelines for assessing the suitability of spatial climate data sets. International Journal of Climatology 26:707–721.

    Article  Google Scholar 

  • Daly, C., M. Halbleib, J. I. Smith, W. P. Gibson, M. K. Doggett, G. H. Taylor, J. Curtis, and P. A. Pasteris. 2008. Physiographically-sensitive mapping of temperature and precipitation across the conterminous United States. International Journal of Climatology 28:2031–2064.

    Article  Google Scholar 

  • Dettinger, M. D., and D. R. Cayan. 1995. Large-scale atmospheric forcing of recent trends toward early snowmelt runoff in California. Journal of Climate 8:606–623.

    Article  Google Scholar 

  • Fall, S., A. Watts, J. N. Gammon, E. Jones, D. Niyogi, J. Christy, and R. Pielke Sr. 2011. Analysis of the impacts of station exposure on the U.S. Historical Climatology Network temperatures and temperature trends. Journal of Geophysical Research 116: D14120.

    Article  Google Scholar 

  • Fritze, H., I. T. Stewart, and E. Pebesma. 2011. Shifts in western North American runoff regimes for the recent warm decades. Journal of Hydrometeorology 12:989–1006.

    Article  Google Scholar 

  • Fulp, T. 2005. How low can it go? Southwest Hydrology 4 (2):16–17, 28.

    Google Scholar 

  • Gershunov, A., and T. P. Barnett. 1998. Interdecadal modulation of ENSO teleconnections. Bulletin of the American Meteorological Society 79:2715–2725.

    Article  Google Scholar 

  • Graumlich, L. J. 1993. A 1000-year record of temperature and precipitation in the Sierra Nevada. Quaternary Research 39:249–255.

    Article  Google Scholar 

  • Grissino-Mayer, H., 1996. A 2129-year reconstruction of precipitation for northwestern New Mexico, U.S.A. In Tree Rings, environment and humanity: Proceedings of the international conference, Tucson, Arizona, 17–21 May 1994, ed. J. S. Dean, D. M. Meko, and T. W. Swetnam, 191–204. Tucson, AZ: Radiocarbon, Dept. of Geosciences, University of Arizona.

    Google Scholar 

  • Groisman, P. V., R. W. Knight, T. R. Karl, D. R. Easterling B. Sun, and J. H. Lawrimore. 2004. Contemporary changes of the hydrological cycle over the contiguous United States: Trends derived from in situ observations. Journal of Hydrometeorology 5:64–85, doi: 10.1175/1525–7541.

    Article  Google Scholar 

  • Hidalgo, H. G., T. Das, M. D. Dettinger, D. R. Cayan, D. W. Pierce, T. P. Barnett, G. Bala, et al. 2009. Detection and attribution of stream flow timing changes to climate change in the western United States. Journal of Climate 22:3838–3855, doi:10.1175/2009JCLI2470.1.

    Article  Google Scholar 

  • Hirsch, R. M., and K. R. Ryberg. 2011. Has the magnitude of floods across the USA changed with global CO2 levels? Hydrological Sciences Journal 57:1–9, doi:10.1080/02626667.2011.621895.

    Article  Google Scholar 

  • Hoerling, M., J. Eischeid, and J. Perlwitz. 2010. Regional precipitation trends: Distinguishing natural variability from anthropogenic forcing. Journal of Climate 23:2131–2145.

    Article  Google Scholar 

  • Hoerling, M. P., and A. Kumar. 2003. The perfect ocean for drought. Science 299:691–694.

    Article  CAS  Google Scholar 

  • Kahya, E., and J. A. Dracup. 1993. U.S. streamflow patterns in relation to the El Niño/Southern Oscillation. Water Resources Research 29:2491–2503.

    Article  Google Scholar 

  • Knowles, N., M. D. Dettinger, and D. R. Cayan, 2006. Trends in snowfall versus rainfall in the western United States. Journal of Climate 19:4545–4559.

    Article  Google Scholar 

  • Kunkel, K. E., D. R. Easterling, K. Hubbard, and K. Redmond. 2004. Temporal variations in frost-free season in the United States: 1895–2000. Geophysical Research Letters 31: L03201, doi:10.1029/2003GL018624.

    Article  Google Scholar 

  • Kunkel, K. E., D. R. Easterling, K. Redmond, and K. Hubbard. 2003. Temporal variations of extreme precipitation events in the United States: 1895–2000. Geophysical Research Letters 30:1900–1903, doi:10.1029/2003GL018052.

    Article  Google Scholar 

  • Liverman, D. M., and R. W. Merideth, Jr. 2002. Climate and society in the U.S. Southwest: The context for a regional assessment. Climate Research 21:199–218.

    Article  Google Scholar 

  • MacDonald, G. M. 2007. Severe and sustained drought in Southern California and the West: Present conditions and insights from the past on causes and impacts. Quaternary International 173/174:87–100, doi:10.1016/j.quaint.2007.03.012.

    Article  Google Scholar 

  • MacDonald, G. M., and A. M. Tingstad. 2007. Multicentennial precipitation variability and drought occurrence in the Uinta Mountains region, Utah. Arctic, Antarctic and Alpine Research 39:549–555.

    Article  Google Scholar 

  • MacDonald, G.M., K. V. Kremenetski, and H. Hidalgo. 2008. Southern California and the perfect drought: Simultaneous prolonged drought in Southern California and the Sacramento and Colorado River systems. Quaternary International 188:11–23, doi:10.1016/j.quaint.2007.06.027.

    Article  Google Scholar 

  • MacDonald, G. M., D. W. Stahle, J. Villanueva Diaz, N. Beer, S. J. Busby, J. Cerano-Paredes, J. E. Cole, et al. 2008. Climate warming and twenty-first century drought in southwestern North America. EOS Transactions AGU 89:82.

    Article  Google Scholar 

  • Mann, M. E., Z. Zhang, M. K. Hughes, R. S. Bradley, S. K. Miller, S. Rutherford, and F. Ni. 2008. Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia. Proceedings of the National Academy of Sciences 105:13252–13257, doi:10.1073/pnas.0805721105.

    Article  CAS  Google Scholar 

  • McCabe, G. J., and D. M. Wolock. 2007. Warming may create substantial water supply shortages in the Colorado River Basin. Geophysical Research Letters 34: L22708, doi:10.1029/2007GL031764.

    Article  Google Scholar 

  • Meehl, G., C. Tibaldi, G. Walton, D. Easterling, and L. McDaniel. 2009. Relative increase of record high maximum temperature compared to record low minimum temperature in the US. Geophysical Research Letters 36: L23701, doi:10.1029/2009GL040736.

    Article  Google Scholar 

  • Meko, D. M. 2001. Reconstructed Sacramento River system runoff from tree rings. Report prepared for the California Department of Water Resources, July 2001.

    Google Scholar 

  • Meko, D. M., 2008. Streamflow reconstruction, Rio Grande River at Otowi Ridge, 1450–2002. Prepared for the Rio Grande Basin Workshop, 30 May 2008, New Mexico State University Extension, Albuquerque, New Mexico.http://treeflow.info/riogr/riograndeotowinatural.txt

    Google Scholar 

  • Meko, D. M., and C. A. Woodhouse. 2005. Tree-ring footprint of joint hydrologic drought in Sacramento and Upper Colorado River Basins, western USA. Journal of Hydrology 308:196–213.

    Article  Google Scholar 

  • Meko, D. M., C. A. Woodhouse, C. A. Baisan, T. Knight, J. J. Lukas, M. K. Hughes, and M. W. Salzer. 2007. Medieval drought in the Upper Colorado River Basin. Geophysical Research Letters 34: L10705.

    Article  Google Scholar 

  • Menne, M. J., and C. N. Williams, Jr. 2009. Homogenization of temperature series via pairwise comparisons. Journal of Climate 22:1700–1717, doi:10.1175/2008JCLI2263.1.

    Article  Google Scholar 

  • Millar, C. I., J. C. King, R. D. Westfall, H. A. Alden, and D. L. Delany. 2006. Late Holocene forest dynamics, volcanism, and climate change at Whitewing Mountain and San Joaquin Ridge, Mono County, Sierra Nevada, CA, USA. Quaternary Research 66:273–287.

    Article  Google Scholar 

  • Milly, P. C. D., K. A. Dunne, and A. V. Vecchia. 2005. Global pattern of trends in streamflow and water availability in a changing climate. Nature 438:347–350.

    Article  CAS  Google Scholar 

  • Mote, P. W., A. F. Hamlet, M. P. Clark, and D. P. Lettenmaier. 2005. Declining mountain snowpack in western North America. Bulletin of the American Meteorological Society 86:39–49.

    Article  Google Scholar 

  • Muhs, D. R., T. W. Stafford, J. B. Swinehart, S. D. Cowherd, S. A. Mahan, C. A. Bush, R. F. Madole, and P. B. Maat. 1997. Late Holocene eolian activity in the mineralogically mature Nebraska Sand Hills. Quaternary Research 48:162–176.

    Article  CAS  Google Scholar 

  • Ni, F., T. Cavazos, M. K. Hughes, A. C. Comrie, and G. Funkhouser, 2002. Cool-season precipitation in the southwestern USA since AD 1000: Comparison of linear and nonlinear techniques for reconstruction. International Journal of Climatology 22:1645–1662.

    Article  Google Scholar 

  • Palmer, W. C. 1965. Meteorological drought. Research Paper No. 45. Washington, DC: U.S. Weather Bureau.

    Google Scholar 

  • Pederson, G. T., S. T. Gray, C. A. Woodhouse, J. L. Betancourt, D. B. Fagre, J. S. Littell, E. Watson, B. H. Luckman, and L. J. Graumlich. 2011. The unusual nature of recent snowpack declines in the North American Cordillera. Science 333:332–335, doi: 10.1126/science.1201570.

    Article  CAS  Google Scholar 

  • Pielke, R. Sr., N. Doesken, O. Bliss, T. Green, C. Chaffin, J. Salas, C. Woodhouse, J. Lukas, and K. Wolter. 2005. Drought 2002 in Colorado: An unprecedented drought or a routine drought? Pure and Applied Geophysics 162:1455–1479.

    Article  Google Scholar 

  • Pierce, D., T. Barnett, H. Hidalgo, T. Das, C. Bonfils, B. Santer, G. Bala, et al. 2008. Attribution of declining western US snowpack to human effects. Journal of Climate 21:6425–6444, doi:10.1175/2008JCLI2405.1.

    Article  Google Scholar 

  • Rajagopalan, B., K. Nowak, J. Prairie, M. Hoerling, B. Harding, J. Barsugli, A. Ray, and B. Udall. 2009. Water supply risk on the Colorado River: Can management mitigate? Water Resources Research 45: W08201, doi:10.1029/2008WR007652.

    Article  Google Scholar 

  • Ralph, F. M., M. D. Dettinger, A. White, D. Reynolds, D. Cayan, T. Schneider, R. Cifelli, et al. 2011. A vision of future observations for western US extreme precipitation events and flooding: Monitoring, prediction and climate. Report to the Western States Water Council, Idaho Falls.

    Google Scholar 

  • Redmond, K. T., and R. W. Koch. 1991. Surface climate and streamflow variability in the western United States and their relationship to large scale circulation indices. Water Resources Research 27:2381–2399, doi:10.1029/91WR00690.

    Article  Google Scholar 

  • Regonda, S. K., B. Rajagopalan, M. Clark, and J. Pitlick. 2005. Seasonal cycle shifts in hydroclimatology over the western United States. Journal of Climate 18:372–384.

    Article  Google Scholar 

  • Roos, M. 1991. A trend of decreasing snowmelt runoff in Northern California. In Proceedings of the 59th Western Snow Conference, April 12–15, 1991, Juneau, Alaska, 29–36. Juneau, AK: Western Snow Conference.

    Google Scholar 

  • Ropelewski, C. F., and M. S. Halpert. 1986. North American precipitation and temperature patterns associated with the El Niño/Southern Oscillation (ENSO). Monthly Weather Review 114:2352–2362.

    Article  Google Scholar 

  • Routson, C. C., C. Woodhouse, and J. T. Overpeck. 2011. Second century megadrought in the Rio Grande headwaters, Colorado: How unusual was medieval drought? Geophysical Research Letters 38: L22703, doi:10.1029/2011GL050015.

    Article  Google Scholar 

  • Salzer, M. W., and K. F. Kipfmueller. 2005. Reconstructed temperature and precipitation on a millennial timescale from tree rings in the southern Colorado Plateau, USA. Climatic Change 70:465–487.

    Article  CAS  Google Scholar 

  • Salzer, M., M. Hughes, A. Bunn, and K. Kipfmueller. 2009. Recent unprecedented tree-ring growth in bristlecone pine at the highest elevations and possible causes. Proceedings of the National Academy of Sciences 106:20348–20353.

    Article  CAS  Google Scholar 

  • Seager, R., R. Burgman, Y. Kushnir, A. Clement, E. R. Cook, N. Naik, and J. Miller. 2008. Tropical Pacific forcing of North American medieval megadroughts: Testing the concept with an atmosphere model forced by coral reconstructed SSTs. Journal of Climate 21:6175–6190.

    Article  Google Scholar 

  • Stahle, D. W., E. R. Cook, M. K. Cleaveland, M. D. Therrell, D. M. Meko, H. D. Grissino-Mayer, E. Watson, and B. H. Luckman. 2000. Tree-ring data document 16th century megadrought over North America. EOS Transactions AGU 81:121, doi:10.1029/00E00076.

    Article  Google Scholar 

  • Stegner, W. 1987. The American West as living space. Ann Arbor: University of Michigan Press.

    Google Scholar 

  • Stevens, M. B., J. F. González-Rouco, and H. Beltrami. 2008. North American climate of the last millennium: Underground temperatures and model comparison. Journal of Geophysical Research 113: F01008, doi: 10.1029/2006JF000705.

    Article  Google Scholar 

  • Stewart, I., D. Cayan, and M. Dettinger. 2005. Changes towards earlier streamflow timing across western North America. Journal of Climate 18:1136–1155.

    Article  Google Scholar 

  • Stine, S. 1994. Extreme and persistent drought in California and Patagonia during mediaeval time. Nature 369:546–549.

    Article  Google Scholar 

  • Tingstad, A. H., and G. M. MacDonald. 2010. Long-term relationships between ocean variability and water resources in northeastern Utah. Journal of the American Water Resources Association 46:987–1002.

    Article  Google Scholar 

  • Touchan, R., C. Woodhouse, D. Meko, and C. Allen. 2010. Millennial precipitation reconstruction for the Jemez Mountains, New Mexico, reveals changing drought signal. International Journal of Climatology 31:896–906.

    Article  Google Scholar 

  • Woodhouse, C.A., and P. M. Brown. 2001. Tree-ring evidence for Great Plains drought. Tree-Ring Research 57:89–103.

    Google Scholar 

  • Woodhouse, C. A., 2003. A 431-year reconstruction of western Colorado snowpack. Journal of Climate 16:1551–1561.

    Article  Google Scholar 

  • Woodhouse, C. A., D. M. Meko, G. M. MacDonald, D. W. Stahle, and E. R. Cook. 2010. A 1,200- year perspective of 21st century drought in southwestern North America. Proceedings of the National Academy of Sciences 107:21283–21288, doi:10.1073/pnas.0911197107.

    Article  CAS  Google Scholar 

  • Woodhouse, C. A., G. T. Pederson, and S. T. Gray. 2011. An 1800-year record of decadal-scale hydroclimatic variability in the Upper Arkansas River Basin from bristlecone pine. Quaternary Research 75:483–490, doi:10.1016/j.yqres.2010.12.007.

    Article  Google Scholar 

  • Yarnal, B., and H. F. Diaz. 1986. Relationships between extremes of the Southern Oscillation and the winter climate of the Anglo-American Pacific Coast. Journal of Climate 6:197–219.

    Article  Google Scholar 

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Author information

Authors and Affiliations

  1. (NOAA, Earth System Research Laboratory), USA

    Martin P. Hoerling

  2. (U.S. Geological Survey and Scripps Institution of Oceanography), USA

    Michael Dettinger

  3. (University of Colorado, CIRES), USA

    Klaus Wolter, Jeff Lukas, Jon Eischeid & Brant Liebmann

  4. (NASA, Ames), USA

    Rama Nemani

  5. (NOAA Cooperative Institute for Climate and Satellites, North Carolina State University, and National Climate Data Center), USA

    Kenneth E. Kunkel

  6. (NOAA), USA

    Arun Kumar

Authors
  1. Martin P. Hoerling
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  2. Michael Dettinger
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  3. Klaus Wolter
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  4. Jeff Lukas
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  5. Jon Eischeid
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  6. Rama Nemani
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  7. Brant Liebmann
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  9. Arun Kumar
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Editors and Affiliations

  1. Institute of the Environment, University of Arizona, N. Park Ave Ste. 532 845, 85721, Tucson, Arizona, USA

    Gregg Garfin

  2. University of Arizona, USA

    Angela Jardine , Robert Merideth , Mary Black  & Sarah LeRoy , ,  & 

Appendices

Appendix

Table A5.1 comparison of annual surface temperatures in the southwest Temperature in the Southwest
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Table A5.2 Comparison of annual precipitation in the Southwest
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Figure A5.1
figure 9

The 1901–2010 trends in annual averaged daily temperature (TAVG, top), daily maximum temperature (TMAX, second panel), and daily minimum temperature (TMIN, third panel). Units are the change in °C/110yrs, and stronger positive (negative) trends shown in dark grey (light grey). Bottom panel is the 1901–2010 trend in annual averaged precipitation. Units are the total change expressed as percent of annual climatology, and positive (negative) trends are shown in light grey (dark grey). Larger circle sizes denote greater magnitude trends. Trends are computed at station locations using the GHCN (Version 3) raw monthly (unadjusted) data. Results are shown only for locations having at least 90 years of available data. Filled stations denote statistically significant trends at 95% confidence based on a parametric t-statistic. Stations with temperature (precipitation) changes less than 0.5°C (5%) are denoted with a + symbol. The fraction of stations with significant trends is 61%, 40%, and 63% for TAVG, TMAX, and TMIN respectively. The fraction of stations with significant trends in precipitation is 16%. Source: Menne and Williams (2009).

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Endnotes

  1. i

    Table 5.1 and 5.2 present temperature and precipitation conditions for the first decade of the twenty-first century, respectively, and compare those conditions against 100-year averages of the previous century. Shown also are the rankings of the recent decadal conditions relative to the ten decades of the twentieth century, both for the Southwest as a whole and for the six individual states comprising the region. The tables assess average temperature, maximum temperature, minimum temperature, and precipitation. The data are based on the monthly PRISM analysis (Daly 2006) which incorporates physiographic features (e.g., complex topography and coastal zones) in the process of generating climate grids from available in situ data, the consequence of which is to substantially improve analyses in the Western United States relative to other climate analyses (Daly et al. 2008).

  2. ii

    Data used in Tables 5.1 and 5.2 are based on 2.5 mile (4km) resolution PRISM analyses (data available at: http://www.prism.oregonstate.edu/products/matrix.phtml?view=data). For purposes of long period trend estimates, we present diagnoses conducted at station locations, rather than from gridded data, and examine those sites that possess historical observations spanning most of the 1901–2010 period.

  3. iii

    The trends were calculated at station locations based on Global Historical Climate Network (GHCN) Version 3 (Menne and Williams 2009; data available at http://www.ncdc.noaa.gov/ ghcnm/v3.php).

  4. iv

    Another measure of heat and cold waves is discussed in Chapter 7, Sections 7.2 and 7.3.

  5. v

    Drought is defined here as having at least a -1 (or lower) PDSI intensity.

  6. vi

    These included the Southwest as well as drainage basins in the Cascades, Blue Mountains of Oregon, and the northern Rockies of Idaho and Montana.

  7. vii

    Analysis of a subset of the Cook et al. dataset, covering only the Southwest region, shows DAI variability across the Southwest over the last 1,200 years to be very similar to that across the larger area depicted in Figure 5.7.

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Hoerling, M.P. et al. (2013). Present Weather and Climate: Evolving Conditions. In: Garfin, G., Jardine, A., Merideth, R., Black, M., LeRoy, S. (eds) Assessment of Climate Change in the Southwest United States. NCA Regional Input Reports. Island Press, Washington, DC. https://doi.org/10.5822/978-1-61091-484-0_5

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