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Monthly Archive

El Niño Tracker - July 2015

Monday, July 20, 2015

El Niño conditions continue for a fifth straight month, and at this point, forecasters are relatively bullish that we are witnessing the development of a moderate-to-strong event that could rival 1997 in absolute magnitude later this year. The most recent outlooks from various sources offer a consistent cluster of forecasts calling for a clear El Niño signal that is maintained or even strengthens well into early 2016. Forecasts focused on the persistence of sea-surface temperature (SST) anomalies (Figs.1 - 2) along with weakening trade winds, ongoing convective activity in the central and eastern Pacific, and El Niño-related ocean-atmosphere coupling.

On July 7, the Australian Bureau of Meteorology maintained its tracker at official “El Niño” status, identifying a strengthening El Niño (in part due to increased tropical storm activity), and projecting the event as likely to persist through the end of 2015 and into 2016. On July 10, the Japan Meteorological Agency identified strengthening El Niño conditions in the equatorial Pacific, and forecast that the current El Niño conditions were likely to last until winter. On July 9, the NOAA-Climate Prediction Center (CPC) extended its El Niño advisory with a greater than 90-percent chance that El Niño will continue through winter 2015-2016, and an 80-percent chance it will last into early spring 2016. It cited the increasingly positive SST anomalies in the central and eastern Pacific and ongoing ocean-atmospheric coupling and convection activity as indicators of an ongoing and strengthening event (Fig. 3). On July 16, the International Research Institute for Climate and Society (IRI) and CPC forecasts indicated continued strengthening of El Niño through 2015 and into 2016, with a moderate event likely becoming a strong event by summer or early fall and lasting into early 2016. The North American multi-model ensemble currently shows a moderate event extending through early summer, with potential for a strong event by mid-summer or early fall (Fig. 4).

It is clear that we are in the midst of an ongoing and strengthening El Niño event.  If this event remains on the current trajectory, it could surpass the strongest El Niño events of recent decades (1997 in particular), with implications for both Southwest and global communities. 

In May and early June, we witnessed exactly the sort of patterns we might expect to see in Arizona and New Mexico under El Niño conditions—above-average precipitation and below-average temperatures. If El Niño persists into winter 2015-2016, particularly if it remains a moderate-to-strong event, we would likely continue to see above-average precipitation in the Southwest (Fig. 5). Although the presence of El Niño conditions often has been associated with a delay in the start of the monsoon, this year the monsoon began early. However, a resurgent El Niño signal now may be pushing back and could work to disrupt the monsoon ridge, leading to one or more ‘breaks’ in the monsoon. The event could also lead to a repeat of 2014’s above-average eastern Pacific tropical storm season, when conditions favorable to El Niño were thought to be driving increased tropical storm activity in the Southwest in September and October.

Image Source - Australian Bureau of Meteorology

Image Source - National Climatic Data Center

Image Source - International Research Institute for Climate and Society

Image Source - NOAA - Climate Prediction Center

Image Source - NOAA Climate.gov

Monsoon Summary - (June 15 - July 16)

Thursday, July 16, 2015

After a few anomalous incursions of tropical moisture in early June, we saw an early beginning to the monsoon in mid- to late June, a few weeks ahead of the typical start date (Fig. 1). Regional dewpoint/humidity readings for June illustrate the multiple incursions of tropical moisture, followed by the onset of monsoon conditions later in the month (Fig. 2).

The monsoon ridge was able to set up early, leading to a number of precipitation events (including above-average precipitation) across the Southwest starting in the last week of June. As recently as last month, we had been anticipating a delayed start to the monsoon, as El Niño conditions tend to suppress its onset. However, the opposite occurred, possibly due to a record-strong Madden Julian Oscillation (MJO) pattern that temporarily suppressed El Niño’s typical influence on the subtropical ridge. We have seen some weakening of the monsoon ridge since July 5, likely due to El Niño convection picking back up, but it remains to be seen what the overall impact of El Niño will be on this year’s monsoon.

In the first month of the monsoon, most of New Mexico and much of eastern Arizona received well-above-average precipitation (Fig. 3a-b), albeit with a wide range of precipitation totals across the region (Fig. 4a-b). Western Arizona (particularly the southwest and northwest corners) are notable exceptions to this pattern, although these regions typically receive far less monsoon precipitation overall.  The percent of days with rain highlights the regularity of monsoon precipitation thus far, with much of eastern Arizona and most of New Mexico recording rain events (>0.01”) on 35-50 percent of days since Jun 15 (Fig. 5a-b). The daily intensity index (Fig. 6a-b) further illustrates the steady nature of most of this monsoon precipitation, where higher values indicate much of the rain fell in a single event and lower values indicate more frequent and less intense events.

CLIMAS Climate and Society Graduate Fellow Rebecca Lybrand in the News

Tuesday, July 7, 2015

The full version of this story was originally published in UANews on July 6, 2015

To Rebecca Lybrand, calling soil "dirt" is simplistic and diminishes its importance to plants, animals and humans. So why is soil, the foundation of life, constantly being referred to as "dirt"? (read more on UANews.org)

June 2015 SW Climate Podcast - Tropical Storms, Monsoon, Wildfire & El Niño

Wednesday, July 1, 2015

In the June 2015 edition of the CLIMAS SW Climate Podcast, Mike Crimmins and Zack Guido recap the month of June, including the quick transition from cool and wet to hot and muggy conditions.  The discuss the impact of tropical storms on the region, the early start to this season, and what this may or may not mean in terms of relationship to monsoon patterns.  They turn to El Niño, and the impact the El Niño signal may be having on the region, both looking back at the past few months, but in particular looking forward at what this could mean for the southwest in terms of precipitation patterns over the next 12 months.

  • 0:00 Introduction
  • 1:15 June Recap- Temperature, Precipitation, Influence of Tropical Storms, etc.
  • 8:00 Links to the Monsoon - System is setting up - what we've seen so far, and what we can expect moving forward.
  • 15:00 Monsoon and (early arriving) tropical storms, and the impending El Niño event - how big of a role will ENSO play in the monsoon?  tropical storms?
  • 22:30 Looking back to the El Niño event of 97-98 - how does this one compare?  Could it be even bigger?  What would that mean for the Southwest?
  • 26:00 Looking towards the rest of summer, fall and winter - Given persistent El Niño- short term effects (temp & precip) vs. impact on long term trends (like drought).
  • 29:00 Wrapping up and looking forward.

Please note: we are aware of the intermittent audio glitches in the recording, and are working towards a solution.  They are brief and shouldn't interfere with the overall podcast, but we apologize for any inconvenience.