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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)

Monthly Precipitation and Temperature: July precipitation was mostly below average to much below average in Arizona, while New Mexico ranged from above average to much below average (Fig. 1a). July temperatures were mostly above average to much above average in Arizona and New Mexico, with a small pocket of record warmest in southwestern New Mexico (Fig. 1b). The daily average temperature anomalies for Jul 1 – Aug 15 (Fig. 2) highlight the fluctuations at select stations around the region. (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)

Given the spatial variability of the monsoon, single weather stations are an imperfect measure. For example, if it rains at the station and not in surrounding areas or vice versa. 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-July. 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. (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 and forecasts focused on sea surface temperature (SST) anomalies and other oceanic and atmospheric indicators, all of which had generally remained consistent with a weak El Niño event (Figs. 1-2), at least until recently. On July 9, the Australian Bureau of Meteorology ended their ENSO Outlook and returned to ‘inactive’ status, identifying ENSO-neutral as the most likely outcome in 2019. On July 10, the Japanese Meteorological Agency (JMA) identified the end of this El Niño event, mostly due to the rapid dissipation of SST anomalies, as well as the return to normal for other atmospheric indicators. They called for a 60-percent chance of ENSO-neutral conditions to continue into Fall 2019. On July 11, the NOAA Climate Prediction Center (CPC) maintained their El Niño advisory based on the SST anomalies, but trends in oceanic and atmospheric conditions led them to expect this event would transition to ENSO-neutral in the next few months. On July 11, the International Research Institute (IRI) issued an ENSO Quick Look (Fig. 3), highlighting above-average SSTs consistent with a weak El Niño, but with most models predicting a transition to ENSO-neutral status by the end of summer. The North American Multi-Model Ensemble (NMME) shifted considerably in the last month, and now points towards a rapid decline to ENSO-neutral status by early fall (Fig. 4). (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)

May Precipitation and Temperature: May precipitation was mostly above average to record wettest in Arizona, and New Mexico ranged from below average to much above average but most of the state was average or above-average (Fig. 1a). May temperatures were below average or much below average across most of the Southwest (Fig. 1b). (read more)

Seasonal outlooks highlight persistent sea surface temperature (SST) anomalies consistent with a weak El Niño event (Figs. 1-2), while other atmospheric and oceanic indicators such as convective anomalies and sub-surface temperatures are less definitive. The so-called ‘spring predictability barrier’ further limits certainty. Forecast discussions focus on how long the event will last and the potential for a second year of El Niño. (read more)

April Precipitation and Temperature: April precipitation was average to much above-average in most of New Mexico, while Arizona ranged from below-average to above-average (Fig. 1a). April temperatures were almost entirely above-average to much above-average across the Southwest (Fig. 1b), while temperatures so far in May have been mostly below-average. (read more)