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Monthly Archive | CLIMAS

Monthly Archive

Southwest Climate Outlook April 2019 - Climate Summary

Thursday, April 25, 2019

March Precipitation and Temperature: March precipitation was average to above-average across most of Arizona, New Mexico and west Texas, while the upper basin of the Colorado River was much above-average (Fig. 1a). March temperatures were average to above-average in Arizona and New Mexico, despite most of the United States being average to below-average (Fig. 1b).

 

Seasonal Precipitation and Temperature: Jan-Mar precipitation demonstrated a distinct pattern; Arizona and most of the Southwest recorded above-average to much above-average precipitation, while most of New Mexico and west Texas were average to below-average (Fig. 2a). Temperatures for the same period were average to above-average in New Mexico and west Texas, and average to below-average in Arizona and much of the rest of the Southwest (Fig. 2b). Water year precipitation (since Oct. 1) highlights wetter-than-average conditions in the west, with most of Arizona and New Mexico above normal (top 33-percent) or much above-normal (top 10-percent)(Fig. 3).

 

 

Drought: The Apr. 9 U.S. Drought Monitor (USDM) continues to show improvements in drought conditions in the western United States. Arizona is mostly clear of drought designations, and the intense drought in the four corners region and northern New Mexico have shown additional improvements in the USDM drought categorization compared to last month (Fig. 4).

 

Snowpack & Water Supply: Snow water equivalent (SWE) for stations in southern and central Arizona and New Mexico are below 25-percent of average, although late season calculations can be deceptive given low average values. The northern (higher elevation) stations in AZ and NM range from 110- to over 200-percent of average (Fig. 5), and the lower Colorado River Basin stations range from 125- to over-200 percent of average (see April 2019 Streamflow Forecast).

 

Wildfire, Health, and Safety: Wildfire risk maps reflect the wet winter, with normal to below-normal fire risk in the Southwest in May, but above-normal risk across southern Arizona in June (Fig. 6), an increase tied to concerns over senescence of abundant fine fuels in lower elevations. Wet winter conditions and a warm spring also catalyzed a tremendous wildflower season in the Southwest, although allergy sufferers will note the trade-offs associated with air quality and abundant pollen.

 

El Niño Tracker: Atmospheric and oceanic conditions are in line with a weak El Niño, and the sea surface temperature (SST) anomalies officially reached the threshold for an El Niño event spanning from late 2018 to present. The current discussion is focused on when these conditions might revert to normal, likely in mid-to-late 2019, but with the possible persistence of this El Niño through 2019 and into early 2020 (see El Nino Tracker).

Precipitation and Temperature Forecast: The three-month outlook for May through July calls for increased chances of above-normal precipitation in eastern Arizona and western New Mexico, and increased chances of below-normal precipitation in western Arizona, eastern New Mexico, and west Texas (Fig. 7, top). The three-month temperature outlook calls for equal chances of normal, above-normal, and below-normal temperatures across Arizona, New Mexico, and Northern Mexico (Fig. 7, bottom).

 


Online Resources

  • Figures 1-2 - National Centers for Environmental Information - ncei.noaa.gov
  • Figure 3, 5 - Western Regional Climate Center - wrcc.dri.edu
  • Figure 4 - U.S. Drought Monitor - droughtmonitor.unl.edu
  • Figure 6 - National Interagency Fire Center - droughtmonitor.unl.edu
  • Figure 7 - International Research Institute for Climate and Society - iri.columbia.edu

Southwest Climate Outlook - El Niño Tracker - April 2019

Thursday, April 25, 2019

El Niño Tracker: Seasonal outlooks and forecasts emphasize clear atmospheric and oceanic conditions that are consistent with a weak El Niño event, and the discussion has shifted to how long the event will last. On Apr. 10, the Japanese Meteorological Agency (JMA) highlighted that El Niño conditions had persisted in March, and with an 80-percent chance of these conditions lasting until summer. On Apr. 11, the NOAA Climate Prediction Center (CPC) maintained their El Niño advisory, identifying both oceanic and atmospheric conditions consistent with a weak El Niño event. Their outlook maintained a 65-percent chance of El Niño lasting through summer, and 50- to 55-percent of it lasting through fall.  On Apr. 11, the International Research Institute (IRI) issued an ENSO Quick Look (Fig. 1), highlighting above-average sea surface temperatures (SSTs) and atmospheric conditions consistent with El Niño over the past few months. On Apr. 16, the Australian Bureau of Meteorology elevated their tracker to an El Niño alert, with a 70-percent chance of an El Niño event in the coming months. The North American Multi-Model Ensemble (NMME) points toward a weak El Niño lasting into fall 2019 (Fig. 2).

Summary: Sea surface temperatures (SSTs) are above-average across most of the equatorial Pacific (Figs. 3-4) and atmospheric conditions further indicate an established El Niño. The event officially met the diagnostic criteria at the end of March, with five consecutive months or greater where the 3-month SST anomalies were above the threshold of 0.5 C.  What does this mean for the region? The first three months of 2019 support the idea that El Niño brings enhanced precipitation to the region (see Fig. 2 on p. 2), but we are also approaching a warmer and drier time of year, so there is less of a precipitation signal to influence. El Niño conditions are also associated with enhanced eastern Pacific tropical storm activity, which could see tropical storms increase our warm season precipitation totals in direct ways (i.e. storms that push into the region) or that provide additional moisture and instability that enhances monsoon activity. The uncertainty associated with forecasts during the so called “spring predictability barrier” make predictions more speculative than certain, but the persistence of an El Niño would seem to suggest additional opportunities for precipitation events over the warm season. These additional opportunities could augment monthly and seasonal totals, and depending on timing and intensity, help mitigate wildfire risk or boost reservoir storage.

 


Online Resources

  • Figure 1 - International Research Institute for Climate and Societyiri.columbia.edu
  • Figure 2 - NOAA - Climate Prediction Center - cpc.ncep.noaa.gov
  • Figure 3 - Australian Bureau of Meteorology - bom.gov.au/climate/enso
  • Figure 4 - NOAA - Climate Prediction Center - cpc.ncep.noaa.gov