From the article, it looks like precipitation has varied normally, but temperature has been increasing: > Now, the researchers say, warming climate appears to

From the article, it looks like precipitation has varied normally, but temperature has been increasing: > Now, the researchers say, warming climate appears to be pushing the divide east. In the northern plains, rainfall has not changed much, but temperatures are going up, increasing evaporation from the soil. Further south, concurrent shifts in wind patterns are in fact causing less rain to fall. Either way, this tends to push western aridity eastward. Data collected since about 1980 suggests that the statistical divide between humid and arid has now shifted closer to the 98th meridian, some 140 miles east. You can see the statewide temperature increase over time here: http://climate.ok.gov/index.php/climate/climate_trends/temperature_history_annual_statewide/CD00/tavg/Annual/oklahoma_climate http://climate.ok.gov/index.php/climate/climate_trends/tempe...