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

Supplemental Figures for the January 2012 La Niña Drought Tracker

Supplemental Figure 1. La Niña events often push the jet stream north, causing storms that originate in the Pacific Ocean to waft into the Pacific Northwest more than into southern regions like Arizona and New Mexico. Figure source: National Oceanic and Atmospheric Administration.

Supplemental Figure 2. The average strength and orientation of wind measured at the 500 millibar level between December 1 and 23 shows the general position of the swift jet stream. The red line denotes the average position of the jet stream during the period in which numerous winter storms swept into the region. Because the air flowed south from the Pacific Northwest, the region experienced colder-than-average temperatures; some of the storms ferried from the north mixed with tropical moisture from the south to produce widespread and large rain and snow accumulations. Figure was modified from a graphic produced by the NOAA Earth Systems Research Laboratory.

Supplemental Figure 3. Numerous winter storms flowed into Arizona and New Mexico in December, delivering widespread rain and snow that tallied more than 150 percent of the December average in most of the Southwest. All of the precipitation occurred before December 25; dry conditions have since set in. Figure source: High Plains Regional Climate Center.

Supplemental Figure 4. The amount of water contained in snowpacks, or snow water equivalent (SWE), is measured at many snow telemetry sites (SNOTEL) around the West. As of January 1, many of the sites in the Upper Colorado and Rio Grande basins were measuring less than 75 percent of average. Southern Arizona and New Mexico have experienced some of the highest above average SWE in the West. Figure source: Natural Resources Conservation Service.

Supplemental Figure 5. Between 60 and 90 percent of the La Niña events during 1950–2008 contributed to precipitation totals between 0.4 (10 mm) and 2 inches (50 mm) below the December–February average in many parts of Arizona. This suggests conditions likely will be dry in the coming months, and these statistics feed the below-average precipitation outlooks and the forecasts for expanding or persisting drought issued by NOAA-CPC. The image on the right displays the percent of La Niña events in which the anomalies in the left image occurred, (10 mm equals about 0.4 in.). The years of the La Niña events are indicated at the bottom of the figure. Figure source: NOAA-Climate Prediction Center.

Supplemental Figure 6. Probabilistic El–Niño Southern Oscillation (ENSO) forecasts suggest a high likelihood the current La Niña will persist into spring 2012. The event is currently on the margin of weak and moderate but could intensify and reach a moderate strength. Figure source: International Research Institute for Climate and Society.

Supplemental Figure 7. Based in large part on La Niña’s effect on decreasing precipitation in Arizona and New Mexico, the January 5 Seasonal Drought Outlook calls for persisting, intensifying, and developing drought conditions in many parts of the region. Figure source: NOAA-Climate Prediction Center.

Supplemental Figure 8. The first spring streamflow forecast issued by the Natural Resources Conservation Service (NRCS) on January 1 suggests Arizona river basins may experience below-average January–May streamflows. These forecasts likely will change in the ensuing months, when more of the total winter precipitation has accumulated. Despite copious winter flows, the expectation that La Niña will continue is fueling this outlook. In Arizona, streamflow forecasts are made every two weeks between January 1 and April 1. Figure source: Natural Resources Conservation Service.

Supplemental Figure 9. Numerous storms wafting from the north brought cold temperatures to the region during December. Most of the Southwest experienced temperatures of more than 2 degrees Fahrenheit below average, with many regions in New Mexico experiencing temperatures of more than 4 degrees below average. Figure source: High Plains Regional Climate Center.