Southwest Climate Outlook - El Niño Tracker - April 2020
Assistant Research Professor, Arizona Institutes for Resilience
Assistant Professor of Anthropology, School of Anthropology
Ben McMahan joined CLIMAS after completing a PhD in Sociocultural Anthropology at the University of Arizona. His dissertation research was on hurricanes and disaster on the U.S. Gulf Coast, where he focused on
- Human interactions in dynamic social and environmental contexts,
- Risk perception and landscape changes during and after disaster, and
- Social network and policy responses to governance issues related to the acute threats of disaster; as they layer onto long term environmental issues and landscape scale changes.
He was also a key contributor to UA Bureau of Applied Research in Anthropology (BARA) collaborative/trans-disciplinary research on the social, economic, and environmental impacts of the US Oil and Gas industry (2007-2011), and the aftermath of the Deepwater Horizon oil spill (2010-2013).
At CLIMAS, his research activities included tracing how climate information is incorporated into regional decision maker networks, leading CLIMAS team research on the risks and effects of climate extremes, and collaborative research on the effects of climate variability on phenology and temporality of native plants in the region. He was also responsible for working to develop collaborative research opportunities and outreach efforts at CLIMAS, and as part of ongoing assessment and science/strategic planning, he contributed to strategic planning used to prioritize future research and outreach directions. He also coordinated publication of the monthly Southwest Climate Outlook, produced the Southwest Climate Podcasts, and was the online editor for CLIMAS’ blog - Southwestern Oscillations.
There are positive sea surface temperature (SST) anomalies across the equatorial Pacific (Figs. 1-2). Forecasts expect conditions will stay within the range of ENSO-neutral through at least summer 2020, with hints at a possible La Niña later in 2020.
Forecast Roundup: On Apr 9, the NOAA Climate Prediction Center (CPC) issued its ENSO diagnostic discussion with an inactive alert status. The CPC called for a 60-percent chance of ENSOneutral through summer 2020 and remains the most likely outcome through fall 2020. On Apr 9, the International Research Institute (IRI) issued an ENSO Quick Look (Fig. 3), noting “SSTs…near the borderline of El Niño during early April,” but no corresponding atmospheric conditions. They highlight that most models remain warm through spring with cooling over summer and also call for ENSOneutral conditions through fall 2020. On Apr 10, the Japanese Meteorological Agency (JMA) maintained its call for a 60-percent chance of ENSO-neutral conditions to last until summer 2020. On Apr 14, the Australian Bureau of Meteorology maintained their ENSO outlook at an inactive status but did highlight that a few models were beginning to suggest the possibility of a La Niña. The Feb 2020 North American Multi-Model Ensemble (NMME) remains borderline El Niño but shows steady movement into ENSO-neutral territory through the summer, and approaching La Niña conditions later in 2020 (see dashed black line, Fig. 4).
Summary: SST anomalies hovered at the El Niño border for months. To be considered an El Niño event, the three-month SST average would need to stay above the El Niño threshold for five consecutive months, and the atmosphere would need to cooperate (i.e. ‘oceanicatmospheric coupling’), neither of which has happened. ENSOneutral conditions are forecast to last through summer and into fall, with recognition of the challenges associated with the spring predictability barrier (i.e., the difficulty of accurate forecasts made this time of year). In the Southwest, ENSO-neutral winters produce some of the wettest and driest winters (and everything in between). This winter has been particularly wet across parts of the Southwest, especially when averaged across longer timescales (such as seasonal or water-year; for details see pp 1-2 of this outlook, and the Mar 2020 SW Climate Outlook). The next few months are typically dry in much of the arid Southwest, so any precipitation will be welcome (but not necessarily expected). We look to the onset of the monsoon for the next period of regular precipitation activity.
- Figures 1 - Australian Bureau of Meteorology - bom.gov.au/climate/enso
- Figure 2 - NOAA - Climate Prediction Center - cpc.ncep.noaa.gov
- Figure 3 - International Research Institute for Climate and Society - iri.columbia.edu
- Figure 4 - NOAA - Climate Prediction Center - cpc.ncep.noaa.gov