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Southwest Climate Outlook June 2018

Precipitation and Temperature: The Southwest was characterized by below-average precipitation in May, ranging locally from record driest to near average (Fig. 1a). Temperatures were above average to much-above average across most of the Southwest, with small pockets of record-warm conditions in the northwest corner of New Mexico and along the eastern edge of the state (Fig. 1b). The March through May period exhibited similar patterns of mostly drier-than-average to record-dry precipitation (Fig. 2a) and much-above-average to record-warm temperatures (Fig. 2b). Water-year precipitation to date (Oct 2017 – May 2018) highlights how dry most of the region has been at a longer timescale, with below-normal to record-dry conditions across Arizona and above-normal to record-dry conditions in New Mexico (Fig. 3).

Monsoon & Tropical Activity: The Pacific tropical storm season got off to a strong start with Aletta and Bud, the former as an early start to the season in May, and the latter bringing well-above-normal June precipitation to parts of the Southwest (see Monsoon/TS tracker).

Snowpack & Streamflow Forecast: Snow was all but gone from the Southwest by June, and snow water equivalent (SWE) for the Upper Colorado River Basin remain below average, with only the upper Great Basin and Pacific Northwest having any semblance of above-normal snowpack. Warm and dry conditions continue to affect streamflow and runoff timing – a pattern that extends to the Upper Colorado River Basin, where streamflow forecasts are all well-below average.

Drought: Drought-designated areas continued to expand from last month. In the June 21 U.S. Drought Monitor, Arizona and New Mexico saw further increases in the extent and intensity of drought (Fig. 4). These designations reflect short-term precipitation deficits, above-normal temperatures at monthly and seasonal timescales, and longer-term drought that tracks the cumulative effect of extended periods of warmer- and drier-than-normal conditions. The surge of tropical storm activity (Bud) in mid-June brought a welcome reprieve from ongoing dry conditions, but the next realistic hope for drought relief is the summer monsoon. The extent of its impact will depend on when it starts and how much (and how regularly) precipitation actually falls.

Wildfire: The National Significant Wildland Fire Potential Outlook for June identified above-normal wildland fire risk across the Southwest except for eastern New Mexico and far northwestern Arizona, while the outlook for July calls for the fire risk to return to normal (Fig. 5a-b) in anticipation of monsoon moisture abating the risk. Southeastern Arizona and portions of New Mexico received precipitation linked to the remnants of Tropical Storm Bud, but regional patterns are not indicative of an early start to widespread monsoon activity (see Monsoon Tracker). A late start to the monsoon could extend the fire-risk window, especially if long periods of dry lightning—a major ignition risk in June and July—precede precipitation. The region has been relatively fortunate in 2018, with less lightning-caused fire activity than might have been expected (Fig. 6), given the exceptionally warm and dry conditions over the winter and above-normal fine-fuel loading and continuity.

El Niño Tracker: Neutral conditions are present in oceanic and atmospheric indicators, and longer-term outlooks indicate increasing chances of an El Niño event in 2018. Both the timing and the probability of an El Niño event are still uncertain, but most forecasts highlighted an increased chance of El Niño forming compared to last month, with now nearly twice the chance compared to ENSO neutral conditions (see ENSO tracker). Notably, there is nearly zero chance of a La Niña event in 2018.

Precipitation and Temperature Forecast: The three-month outlook for June through August calls for increased chances of above-normal precipitation in Arizona and western New Mexico, with equal chances in central and eastern New Mexico (Fig. 7, top). The outlook calls for increased chances of above-average temperatures for the entire Southwest (Fig. 7, bottom).

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ENSOHUB:  
Not part of ENSO Hub
MONSOONHUB:  
Unrelated to SW Monsoon
DROUGHTHUB:  
Non-Drought Hub Related

Rio Grande-Bravo Outlook May 2018

Forecasts favor above-average temperatures and equal chances for below-, average, and above-average precipitation for the Rio Grande/Bravo Basin through August.


El pronóstico favorece temperaturas superiores a la media, las precipitaciones tiene igualdad de condiciones por debajo, al promedio y superiores a la media para la Cuenca Río Grande|Bravo hasta agosto.

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PDF File Spanish:  
ENSOHUB:  
Not part of ENSO Hub
MONSOONHUB:  
Unrelated to SW Monsoon
DROUGHTHUB:  
Non-Drought Hub Related

Southwest Climate Outlook May 2018

Precipitation and Temperature: The Southwest was characterized by below-average precipitation in April, ranging locally from record driest to near average (Fig. 1a). Temperatures were mostly above average for yet another month, with record-warm conditions along the eastern third of Arizona and the edge of western New Mexico, but also with a band of average to below-average temperatures on the eastern edge of New Mexico (Fig. 1b). Water-year precipitation to date (Oct 2017 – Apr 2018) ranged from below average to record dry in Arizona, and from above average to record dry in New Mexico (Fig. 2). Temperatures for the same period reached record highs across most of southern Arizona and southwestern New Mexico and were above average to much-above average across the rest of the region (Fig. 3).

Snowpack & Streamflow Forecast: Snow water equivalent (SWE) values remained well-below average across the Southwest, although in Arizona and most of New Mexico, few stations had any snowpack and SWE to report. Warm and dry conditions continue to affect streamflow and runoff timing: streamflow forecasts for Arizona and New Mexico are all well-below average (Fig. 4).

Drought: Drought-designated areas continue to expand from last month. In the May 15 U.S. Drought Monitor, Arizona and New Mexico saw further increases in the extent and intensity of drought (Fig. 5), particularly in northeastern Arizona and northern New Mexico. These designations reflect short-term precipitation deficits, above-normal temperatures at monthly and seasonal timescales, and longer-term drought that tracks the cumulative effect of extended periods of warmer- and drier-than-normal conditions. May is typically dry in the Southwest, so normal conditions may not alter drought designations much.  The next realistic hope for drought relief is the summer monsoon, but the extent of its impact will depend on when it starts and how much precipitation actually falls.

Wildfire: The National Significant Wildland Fire Potential Outlook for June identified above-normal wildland fire risk across the Southwest except for eastern New Mexico and far northwestern Arizona (Fig. 6). Warm and dry conditions this winter, in conjunction with above-normal fine-fuel loading and continuity, are major drivers of the elevated risk. The July outlook takes into account the anticipated decrease in fire risk during the monsoon and returns to normal wildland fire potential for most of the Southwest. However, a late start to the monsoon could extend the fire risk window, while an early start could help end it sooner.

ENSO & La Niña: The La Niña event is officially over with a return to neutral conditions across oceanic and atmospheric indicators, although the event was waning for the past few months. We have entered the period of the spring “predictability barrier” during which there is limited ability to forecast the ENSO status for the next several months. Climatological patterns suggest relatively equal chances of either an El Niño event starting up or ENSO neutral conditions continuing, with virtually zero chance for a La Niña event. By mid-summer, the forecasts and outlooks will have better information to determine the ENSO trajectory for late summer and fall.

Precipitation and Temperature Forecast: The three-month outlook for June through August calls for equal chances of above- or below-average precipitation in most of Arizona and New Mexico, with the exception of northern Arizona and northwestern New Mexico, where there are increased chances of above-normal precipitation (Fig. 7, top). The outlook calls for increased chances of above-average temperatures (Fig. 7, bottom) for the entire western United States.

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ENSOHUB:  
Not part of ENSO Hub
MONSOONHUB:  
Unrelated to SW Monsoon
DROUGHTHUB:  
Non-Drought Hub Related

Rio Grande-Bravo Outlook April 2018

Forecasts favor above-average temperatures and average to below-average precipitation for the Rio Grande/Bravo Basin through July.


Los pronósticos favorecen las temperaturas superiores a la media y las precipitaciones a inferiores a la media para la cuenca Río Grande|Bravo hasta julio.

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ENSOHUB:  
Not part of ENSO Hub
MONSOONHUB:  
Unrelated to SW Monsoon
DROUGHTHUB:  
Non-Drought Hub Related

Southwest Climate Outlook April 2018

Precipitation and Temperature: Precipitation varied across the Southwest in March, but temperatures remained warm throughout the region. Precipitation amounts ranged from record driest to above average (Fig. 1a). Temperatures ranged from average to above average in Arizona, and from above average to much-above average in New Mexico (Fig. 1b). 2018 year-to-date (Jan-Mar) precipitation ranged from near average to much-below average (Fig. 2a), while temperatures for the same period were above average to much-above average (Fig. 2b).

Snowpack and Water Supply: Above-average temperatures and below-average precipitation resulted in snowpack and snow water equivalent (SWE) values that are well-below average across the Southwest (and much of the western United States) (Fig. 3). These warm and dry conditions also affected streamflow and runoff timing: streamflow forecasts for Arizona and New Mexico are all well-below normal (Fig. 4).

Drought: Drought-designated areas were expanded in the April 17 U.S. Drought Monitor, with Arizona and New Mexico documenting increases in the extent and intensity of drought. Nearly 90​ ​percent of Arizona is class​i​f​ied​ as experiencing severe (D2) or extreme (D3)​ drought​, with a pocket of exceptional drought (D4) in the north​-​central region (Fig. 5). Approximately 70​ ​percent of New Mexico is classified as experiencing severe (D2) or extreme (D3)​ drought​, with a notable increase ​in drought intensity ​​from south to north, where exceptional drought (D4) has emerged. These designations reflect short-term precipitation deficits, above-normal temperatures at monthly and seasonal timescales, and longer-term drought that tracks the cumulative effect of extended periods of warmer- and drier-than-normal conditions.

Wildfire: The National Significant Wildland Fire Potential Outlook for May identified above-normal wildland fire risk for eastern New Mexico and the borderlands region in New Mexico and southeastern Arizona, as well as higher-elevation regions in the Upper Colorado River Basin (Fig. 6). The June outlook expands above-normal fire risk to include nearly all of Arizona and New Mexico. Warm and dry conditions this winter, in conjunction with above-normal fine-fuel loading and continuity, are major drivers of the elevated risk, and the Southwest Coordinating Center increased to preparedness level 3 on April 12, reflecting growing concern about fire risk.

ENSO & La Niña: Oceanic and atmospheric conditions remain broadly indicative of a weak La Niña event, but are clearly waning, and trends in these anomalies indicate an imminent return to ENSO-neutral conditions. Most forecasts and outlooks are tracking the gradual decay to ENSO-neutral conditions over spring, and some agencies have already declared this La Niña event over (see La Niña tracker for details). Regardless of when this La Niña event officially ends (or ended), the onset of the characteristically warmer and drier spring conditions in the Southwest means the region is unlikely to see much if any additional precipitation before this summer’s monsoon. Looking back over cool-season precipitation (see Cool Season Precipitation Recap for details), the low seasonal total and relatively few number of days with measurable precipitation are certainly consistent with the reduced precipitation we might expect in a La Niña year.

Precipitation and Temperature Forecast: The three-month outlook for April through June calls for equal chances of above- or below-average precipitation in Arizona and New Mexico (Fig. 7, top) and increased chances of above-average temperatures (Fig. 7, bottom) for the entire southwestern United States.

17
ENSOHUB:  
Not part of ENSO Hub
MONSOONHUB:  
Unrelated to SW Monsoon
DROUGHTHUB:  
Non-Drought Hub Related

The Southwestern Monsoon - Presentations and Q&A

Join us for presentations and a Q&A about: recent monsoon research projects at UA, how the National Weather Service anticipates and responds to the monsoon, the tools and resources that CLIMAS produces and uses to characterize the monsoon, and an upcoming CLIMAS research collaboration with the National Weather Service.

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