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Climate of 2006 - April
New Mexico
Division 6
Drought
National Climatic Data Center, 15 May 2006
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Regional Overview /
Paleo Perspective
 Regional Overview
Paleoclimatic Perspective
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April 2006, Pre-Instrumental Perspective, Central New Mexico
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New Mexico has been experiencing very dry conditions for much of the last seven years. The Central Highlands section of the state (climate division 6) has been especially hard hit. New Mexico Division 6 had the eighth driest "year" (May-April) in the 1895-2006 historical record during 2005-2006 and ranked second driest for several seasons (see table above). The cumulative 60-month precipitation graph is shown to the right. While the last 5 to 7 years generally have been dry, the aggregate deficits of the 1950s were much drier.
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April 2006 brought little relief to this winter's severe drought in the Southwest. New Mexico division 6 received only 1.08 inches of precipitation (21% of the 1950-2000 average) from November 2005-April 2006, which virtually ties 1904 (1.07 inches) as the driest November-April period since records began in 1895.
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The graph below (annual values in light blue, 5-year weighted average in dark blue) shows the winter (November- April) precipitation, 1895-96 to 2005-06, for New Mexico Division 6. The graph also shows a 989-year tree-ring reconstruction (1000-1988; annual values in light red, 5-year smoothed values in dark red) of November-April precipitation for central New Mexico (Division 6). This reconstruction was generated by Ni et al. (2002) from long, moisture-sensitive tree-ring records from the Southwest. The correlation between the annual values of the tree-ring reconstruction and November-April precipitation is 0.649, indicating a moderate degree of shared variance. The reconstruction places the winter precipitation variability of the last century in central New Mexico into a much longer perspective.
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The tree-ring reconstruction shows multi-year periods of persistent winter drought (orange bars on the graph) that appear to be more severe than any in the past century, such as events in the 1080s, 1660s, and 1780s. Conversely, the period 1326-1362 (blue bar) was persistently wet, and longer than any such period of the last century, with only one winter during this 37-year interval reconstructed as being drier than the long-term mean. Because of the moderate uncertainty around the reconstructed values, it is difficult to determine how often extreme one-year winter droughts similar to 1904 and 2006 have occurred. The reconstruction does show 10 years with less than 2 inches of winter precipitation, or about one per century, though these years are not evenly distributed over time.
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In addition to its severity, the current winter drought in New Mexico is notable for being preceded by two wet winters; 2004 and 2005 had 128% and 183% of average precipitation, respectively, during November-April. Swetnam and Betancourt (1998) analyzed fire occurrence in the Southwest from 1700-1900 using a network of fire-scarred trees and tree-ring reconstructions of summer Palmer Drought Severity Index (PDSI). Their work shows that the largest fire years (in terms of spatial extent) tended to occur during severe drought years that were preceded by 1-3 wet years, which encouraged the growth of fuels. Hopefully, in 2006, sufficient moisture will come to the Southwest in time to avoid repeating this pattern.
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Resources:
- Divisional climate data, including precipitation for New Mexico Division 6 as shown above, can be obtained from NCDC.
- The reconstruction of winter precipitation for New Mexico Division 6 can be obtained from the NOAA-NCDC Paleoclimatology Branch.
References:
- Ni, F., Cavazos, T., Hughes, M. K., Comrie, A. C. and Funkhouser, G. 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.
- Swetnam, T. W., and Betancourt, J. L. 1998. "Mesoscale disturbance and ecological response to decadal climatic variability in the American Southwest." Journal of Climate 11: 3128-3147.
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