Home » Supplemental Figures for the April 2011 La Niña Drought Tracker

Supplemental Figures for the April 2011 La Niña Drought Tracker

Supplemental Figure 1. SSpring and summer streamflow forecasts calls for above-average flows in many basins in the Upper Colorado River watershed and below-average flows in many most basins in Arizona and New Mexico. For example, projections made on March 15 for the Salt, Verde, and Gila river basins in Arizona call for a 50 percent chance that streamflow will be at or above 22, 55, and 10 percent of average, respectively, between March 15 and May 31. In the Upper Colorado River Basin, however, there is a 50 percent chance that inflow into Lake Powell will be more than 116 percent of average. Figure Source: Natural Resources Conservation Service.

 

Supplemental Figure 2. The Upper Colorado River Basin is experiencing above-average snow water equivalent (SWE) in most of its sub-watersheds, which bodes well for above-average spring streamflow. Currently, there is a 50 percent chance that inflow into Lake Powel will be 116 percent of average. Spring streamflow for the Rio Grande above Otowi Bridge, on the other hand, has a 50 percent chance of being only 63 percent of average. SWE is measured by Snow Telemetry (SNOTEL) stations. Figure Source: Natural Resources Conservation Service.

 

Supplemental Figure 3. Only a small percent of the annual precipitation falls in the April–June season in Arizona and western New Mexico. The historically dry period means that relief from mounting drought severity likely will not occur until the monsoon season begins in earnest around early July. Figure Source: Western Regional Climate Center.

 

Supplemental Figure 4. There is no snowpack at Baldy Snow Telemetry (SNOTEL) site in the Upper Salt River in the White Mountains in east-central Arizona. Low snowfall and warm late February and early March temperatures contributed to an earlier-than-average snowpack melt. Figure Source: Natural Resources Conservation Service.

 

Supplemental Figure 5. There is no snowpack at Promontory Snow Telemetry (SNOTEL) site in the Little Colorado River Basin in central Arizona. SWE was below average for most of the winter and rapidly melted beginning at the end of February. On average, the Promontory area has snow through the middle of March. Figure Source: Natural Resources Conservation Service.

 

Supplemental Figure 6. Snow water equivalent (SWE) is about one-third of the historical average for April 1 at the Wesner Springs Snow Telemetry (SNOTEL) site in the Pecos basin in northern New Mexico. The snowpack also began melting earlier than average. Figure Source: Natural Resources Conservation Service.

 

Supplemental Figure 7. Snow water equivalent (SWE) is currently less than half of the historical average for April 1 at the Bateman Snow Telemetry (SNOTEL) site in the Rio Chama Basin in northern New Mexico. The snowpack also began melting earlier than average. Figure Source: Natural Resources Conservation Service.

 

Supplemental Figure 8. Between 60 and 80 percent of the La Niña events during 1950–2008 contributed to precipitation totals between 0.4 (10 mm) and 1.2 (30 mm) inches below the March–May average in New Mexico. This suggests that conditions likely will be dry in the coming months, and these statistics feed the below-average precipitation forecasts and the forecasts for expanding drought issued by the NOAA–Climate Prediction Center. On the other hand, La Niña does not impact Arizona during these months. The image on the right displays the percent of La Niña events in which the anomalies in the left image occurred. (Ten millimeters equals about 0.4 inches). The year of La Niña events analyzed is indicated at the bottom of the figure. Figure Source: NOAA–Climate Prediction Center.

 

Supplemental Figure 9. El Niño–Southern Oscillation (ENSO) forecasts indicate the current La Niña event likely will fizzle out in the summer. Source: International Research Institute for Climate and Society.

 

Supplemental Figure 10. Temperatures in March have been warmer than average in nearly all of Arizona and New Mexico. In the White Mountains, temperatures have been between 4 and 8 degrees F warmer than average, contributing to rapid melting of spring snowpack. Figure Source: High Plains Regional Climate Center.

 

Supplemental Figure 11. La Niña events do not have a significant influence on April–June temperatures in most of Arizona and New Mexico. There have, however, been warming trends during these months, suggesting conditions will be warmer than average during the next three months. The top image pair displays the percent of La Niña events in which the temperature anomalies in the left image occurred. The years of the La Niña events analyzed is indicated at the bottom of the figure. The middle panel describes the recent temperature trends during these La Niña years. The bottom panel is the combination of the two panels. (Ten millimeters equals about 0.4 inches). Figure Source: NOAA–Climate Prediction Center.

 

Supplemental Figure 12. Drought conditions have deteriorated in nearly all of Arizona and New Mexico in the last six months. In southern parts of both states, drought has worsened by as much as four U.S. Drought Monitor classes. For these areas, conditions worsened from having a no drought classification in late September to extreme drought designation at the end of March. The colors and drought classes match those of the US Drought Monitor (see Figure 2 in main document).

 

Supplemental Figure 12. Based in large part on La Niña’s effect on decreasing precipitation in New Mexico, recent trends for warming, and the occurrence of the historically dry spring April–June months, the March 17 Seasonal Drought Outlook calls for persisting, intensifying, and expanding drought conditions in nearly all of Arizona and New Mexico. Figure Source: NOAA–Climate Prediction Center.