Agricultural Drought in North-Central Mexico - Monitoring and Predicting Agricultural Drought: A Global Study - page 135

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Figure 10.2 Variation in annual temperature for five states of Mexico, for the period from
1941 to 2000. Upper, lower, and middle points of a vertical line represent maximum, mean,
and minimum temperatures, respectively.

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The five north-central states are typified by hot summers and cold win-
te rs (figure 10.2) with moderate to low rainfall (García, 1981; Schmidt,
19 86). As a result, the region has a potential annual water loss through
ev apotranspiration that far exceeds the annual precipitation. The rains oc-
cu r mostly during the summer months, with extreme annual variability
(fi gure 10.3).

Line
——
-0.2
——
Shor
PgEn

El Niño/Southern Oscillation and Drought
R ecent research investigation about the effects of El Niño on the rainfall
di stribution in northern Mexico shows that this climatic phenomenon has
an influence on rainfall patterns. During El Niño years, rainfall was below
no rmal during summers and above normal during winters (Magaña et al.,

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Fig ure 10.3 Monthly mean rainfall values in the study area and for Mexico showing the
main rainfall season from June through September. Coahuila is the state with the smallest
value and Durango with the largest one. [Based on 60 years of data (1941-2000) collected
fro m the National Meteorological Service]