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Monthly Archive

Southwest Climate Outlook - El Niño Tracker - November 2019

Wednesday, November 27, 2019

As with last month, warm waters have been lingering in the equatorial Pacific (Figs. 1-2). The consensus is on subseasonal variability and not borderline El Niño conditions, and they are expected to revert back to close to normal over winter and spring. Seasonal outlooks and forecasts all point to ENSO-neutral conditions lasting through 2019 and into 2020. 

 

Forecast Roundup: On Nov 11, the Japanese Meteorological Agency (JMA) highlighted lingering warmer-than-normal SSTs in the western equatorial Pacific, but saw cooling subsurface temperatures, and maintained their call for a 60-percent chance of ENSO-neutral conditions to continue until spring 2020. On Nov 12, the Australian Bureau of Meteorology maintained their ENSO Outlook at ‘inactive’ noting the slightly warmer than average oceanic conditions, but with atmospheric indicators “generally neutral”. On Nov 14, the NOAA Climate Prediction Center (CPC) issued their ENSO diagnostic discussion with an inactive alert status. They noted the positive SST anomalies and adjusted their forecast chances of ENSO-netural conditions to 70-percent (winter) and 60 to 65-percent (spring). On Nov 19, the International Research Institute (IRI) issued an ENSO Quick Look (Fig. 3), noting “oceanic warming is attributed to intraseasonal variability”. Their forecasts see ENSO-neutral as the most likely outcome, but remain at “slightly higher chances for El Niño than La Niña”. The Nov 2019 North American Multi-Model Ensemble (NMME) saw a bounce back towards positive SST anomalies in October, but is generally predicted to return and remain within the range of ENSO-neutral through 2019 and into 2020 (Fig. 4).

 

Summary: Despite recent short term warming in SSTs, atmospheric conditions remain within the range of ENSO-neutral, and ENSO-neutral remains the most likely outcome for 2019 into spring 2020. So what does this mean for the Southwest?  The short answer is, it is hard to say. ENSO-neutral winters have produced some of the wettest and driest winters (and everything in between). Rather than a signal that drags our chances wet (as with El Niño) or dry (as with La Niña), ENSO-neutral calls for equal chances of either (or just a normal winter). This means we will continue to monitor sub-seasonal and short term forecasts for insight into upcoming events, but that within the bounds of a “typical” southwestern winter, pretty much anything is on the table.


Online Resources

  • Figure 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

Southwest Climate Outlook November 2019 - Climate Summary

Tuesday, November 26, 2019

Monthly Precipitation and Temperature: October precipitation in Arizona ranged from below average to record driest, while most of New Mexico was average to above average (Fig. 1a). October temperatures were mostly average to below average in Arizona and New Mexico (Fig. 1b). The daily average temperature anomalies for Oct 1 – Nov 19 (Fig. 2) highlight the fluctuations at select stations around the region including a number of cold spells.

 

Annual Precipitation and Temperature: Total precipitation for 2019 (Jan-Oct) in Arizona was mostly average to above average, except for the four corners region, while New Mexico was drier with below average conditions across most of the state (Fig. 3a). Mean temperatures in 2019 so far are mostly average to above average in Arizona and above average to much above average in New Mexico (Fig. 3b).

 

Snowpack & Water Supply: Early season can change quickly, but as of November 18, many Arizona basins are above median snowpack, while New Mexico, Colorado and Utah, are mostly below average (Fig 4). Many of the reservoirs in the region are at or above the values recorded at this time last year, but most are below their long-term average (see Arizona and New Mexico reservoir storage). There have been improvements over the last year, but concerns remain about the recent below average precipitation, along with the accumulated water resource deficits associated with multiple years of drought.

Drought: Drought conditions continue to expand across the Southwest in the Nov. 12 U.S. Drought Monitor (USDM) (Fig. 5). Little precipitation in October, a below average monsoon, and limited incursions of tropical moisture this fall, all contributed to the return of drought designations in much of Arizona and western New Mexico. A large pocket of Severe Drought (D2) is centered on the Arizona/Utah border, but extends well into Arizona, Utah, Colorado, and New Mexico, with Moderate Drought (D1) and Abnormally Dry (D0) making up the characterizations for much of the rest of the Southwest.

 

Tropical Storm Activity: The eastern North Pacific hurricane season has been near normal with 19 named storms and 4 major hurricanes (category 4 or above) (Fig. 6). Climatology for the same period is approximately 16.5 named storms and 4.3 major hurricanes. Accumulated Cyclonic Energy in 2019 is at 97.5, with 131 the average total by this date.

ENSO Tracker: Oceanic and atmospheric conditions are generally consistent with an ENSO-neutral outlook for 2019 and into 2020 (see ENSO-tracker for details).

Precipitation and Temperature Forecast: The three-month outlook for November through January calls for increased chances of above-normal precipitation in much of New Mexico, but equal chances of above or below normal precipitation across most of the rest of the Southwest. (Fig. 7, top). The three-month temperature outlook calls for increased chances of above-normal temperatures across most of the U.S. Southwest and northern Mexico (Fig. 7, bottom).

 

Online Resources

  • Figures 1,3 - National Centers for Environmental Information - ncei.noaa.gov
  • Figure 2 - Climate Assessment for the Southwest - climas.arizona.edu
  • Figure 4 - Natural Resources Conservation Service - nrcs.usda.gov
  • Figure 5 - U.S. Drought Monitor - droughtmonitor.unl.edu
  • Figure 7 - International Research Institute for Climate and Society - iri.columbia.edu