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Monthly Precipitation and Temperature: August precipitation was much below average in most of Arizona, while most of New Mexico ranged from above average to much below average, and both states saw small pockets of record driest conditions (Fig. 1a). August temperatures were much above average to record warmest in Arizona and New Mexico (Fig. 1b). The daily average temperature anomalies for Aug 1 – Sep 17 highlight the fluctuations at select stations around the region (Fig. 2) (Read More).

Forecast Roundup: Seasonal outlooks and forecasts based on sea surface temperature (SST) anomalies (Figs. 1-2) and other oceanic and atmospheric indicators have all identified the end of this El Niño event. On Aug 6, the Australian Bureau of Meteorology maintained their ENSO Outlook at ‘inactive’, stating that “all climate models indicate the tropical Pacific is likely to remain ENSO-neutral for the rest of 2019”. On Aug 8, the NOAA Climate Prediction Center (CPC) issued their final El Niño advisory, which reflects the end of oceanic and atmospheric conditions indicative of El Niño. They called for a 50-55% chance of ENSO-neutral conditions persisting through winter 2019-2020. On Aug 8, the International Research Institute (IRI) issued an ENSO Quick Look (Fig. 3), confirming the end of El Niño as SSTs returned to normal in July. Their models see ENSO-neutral as the most likely outcome, but with “higher chances for El Niño than La Niña”. On Aug 9, the Japanese Meteorological Agency (JMA) highlighted a return to normal SSTs and other atmospheric indicators and maintained their call for a 60-percent chance of ENSO-neutral conditions to continue until winter 2019. The North American Multi-Model Ensemble (NMME) is within the range of ENSO-neutral and is forecast to remain there through 2019 and into 2020 (Fig. 4). (Read More)

Given the spatial variability of the monsoon, single weather stations are an imperfect measure, but they do provide an opportunity to track long term averages compared to the current year. Figure 1 compares 2019 precipitation to date with 2018 and climatology. This reveals 2019 is lagging behind average in terms of precipitation and is also a significant departure from 2018’s widespread activity by mid-August. Dewpoint temperatures and daily precipitation for the same five stations (Fig. 2) illustrate that while increased dewpoint temperatures do not guarantee monsoon precipitation, it is rare to see monsoon precipitation in the absence of these elevated dewpoint temperatures. Regional monsoon precipitation totals (Fig. 3) demonstrate variable precipitation in the Southwest, with much of the region lagging behind average accumulated precipitation through mid-July (Fig. 4). Percent of days with rain highlight areas with more regular rainfall events (Fig. 5). Mid-August is the approximate monsoon midpoint*, so there is time for below average areas to catch up, since a relatively late start does not necessarily mean decreased activity over the entire monsoon. (Read More)

June Precipitation and Temperature Recap: June precipitation was variable in Arizona, ranging from record driest to above average, with a majority of the region recording average to below average precipitation, while New Mexico was mostly average with pockets of both below and above average precipitation (Fig. 1a). June temperatures were mostly average in Arizona and New Mexico, with pockets of above and below average temperatures (Fig. 1b). Daily average temperature anomalies for Jun 1 – Jul 15 demonstrate the fluctuations above and below average (Fig. 2). (Read More)

Forecast Roundup: Seasonal outlooks are based on the persistence of sea surface temperature (SST) anomalies consistent with a weak El Niño event (Figs. 1-2), along with the presence of other atmospheric and oceanic indicators (convective anomalies, sub-surface temperatures). On June 10, the Japanese Meteorological Agency (JMA) noted persistent SST anomalies along with atmospheric and sub-surface indicators of El Niño, and called for a 70-percent chance of these conditions continuing into summer, and a 60-percent chance to last into fall. On June 11, the Australian Bureau of Meteorology maintained their ENSO Outlook at watch status, calling for a 50-percent chance of an El Niño event in 2019. (read more)