Home » Supplemental Figures for the May 2012 La Niña Drought Tracker

Supplemental Figures for the May 2012 La Niña Drought Tracker

Supplemental Figure 1. This winter has been a one-month wonder. More than 200 percent of average precipitation fell in most of Arizona and New Mexico in December, providing a significant proportion of the total winter rain and snow. The other winter months generally were drier than average. Source: High Plains Regional Climate Center

Supplemental Figure 2. Dry weather combined with expected windy conditions (typical during the April–July period) has elevated the risk of wildland fires in parts of the Southwest. Source: National Interagency Fire Center

Supplemental Figure 3. Many forecast models project ENSO-neutral conditions will persist through the summer. In the past when winter La Niña events rapidly transitioned to ENSO-neutral conditions during the May–June period, which occurred during the 2012 summer, most of New Mexico was drier than average during the July–September period, while parts of southern Arizona were slightly wetter than average. The map displays the average July–September precipitation for the nine summers since 1950 when La Niña rapidly transitioned to ENSO neutral conditions in the May–June period. The nine summers occurred in 1951, 1963, 1976, 1985, 1996, 2000, 2001, 2008, and 2011. Figure source: Western Regional Climate Center

Supplemental Figure 4. Some forecast models project the development of El Niño in the coming months. In the past when winter La Niña events rapidly transitioned to an El Niño event during the May–June period, most of New Mexico was wetter than average during the July–September period, while most of Arizona was drier than average. The map displays the average July–September precipitation for the six summers since 1950 when La Niña rapidly transitioned to ENSO-neutral conditions in the May–June period. The six summers occurred in 1957, 1965, 1972, 1997, 2006, and 2009. Figure source: Western Regional Climate Center

Supplemental Figure 5. Below-average snowfall and recent warm temperatures have led to earlier-than-average snow melt in the Upper Colorado River and Rio Grande basins; snowpacks at many monitoring sites have completely melted. Low snowpacks are contributing to below-average spring and summer streamflow projections. Source: Natural Resources Conservation Service

Supplemental Figure 6. Below-average precipitation in the Upper Colorado River Basin has led to very low spring streamflow projections. There is a 50 percent chance that the total April–July inflow to Lake Powell will be below 44 percent of average, which amounts to about 4.5 million acre-feet less than average, according to the May 1 forecast. This forecast is the same as one month ago. Source: Natural Resources Conservation Service

Supplemental Figure 7. The seasonal temperature outlook, which is partly based on recent warming trends, calls for a 50–60 percent chance of warmer-than-average conditions for the May–July period in most of Arizona and New Mexico. Source: NOAA-Climate Prediction Center

Supplemental Figure 8. There is high uncertainty in the evolution of ENSO during the coming months. Probabilistic ENSO forecasts suggest a strong likelihood that ENSO-neutral conditions will persist through the June–August period, but many forecast models indicate that an El Niño may develop this summer or fall. Source: International Research Institute for Climate and Society

Supplemental Figure 9. The Seasonal Drought Outlook calls for drought to persist or intensify in most of Arizona and New Mexico during the May–July period. The months preceding the onset of the monsoon, which usually occurs in early July, are historically dry and therefore offer few opportunities for widespread and heavy rain and snow needed to improve drought conditions. Southwestern New Mexico and southeastern Arizona may experience some drought improvement if the monsoon begins on time and delivers average or above-average rain. Source: NOAA-Climate Prediction Center

Supplemental Figure 10. The April–June period is historically the driest season for most of the Southwest. Less than 12 percent of the total annual precipitation falls in this period for most of Arizona and southwestern New Mexico. The percentages were calculated using 1961–1990 data. Source: Western Regional Climate Center

Supplemental Figure 11. Precipitation during the previous 90 days (between February 7 and May 6) was below average in the Upper Colorado River Basin. In parts of the high country in Utah and Colorado, from which a large portion of the water in the Colorado River originates, less than 50 percent of average rain and snow fell. The scant precipitation caused low snowpacks, which, in turn, have led to well below-average streamflow forecasts. Source: High Plains Regional Climate Center

Supplemental Figure 12. Above-average temperatures in the past 30 days helped melt snowpacks across the Southwest and Rocky Mountains. Temperatures have been particularly warm in the Upper Colorado River and Rio Grande basins. Source: High Plains Regional Climate Center