The University of Arizona

Monthly Archive | CLIMAS

Monthly Archive

El Niño Tracker Update - Late November 2014

Friday, November 21, 2014

From the Nov 20, 2014 Southwest Climate Outlook

The long-awaited El Niño event projected to develop during winter 2014 – 2015 has yet to send a decisive signal regarding an official start, but a number of factors have increased forecasters’ confidence that one will emerge. The strength of this event still remains in question, however with the most likely projection still centering on a weak or weak to moderate event.

On Nov 6, the NOAA-Climate Prediction Center (CPC) issued an El Niño Watch, assigning a 58 percent probability that an El Niño would form and that it most likely would be weak. This forecast was based on a slight increase of sea surface temperatures (SSTs) across the eastern equatorial Pacific, linked to the contribution of the Kelvin wave (discussed last month), which helped warm SSTs in the eastern Pacific.  The CPC also reported the “ongoing lack of clear atmosphere-ocean coupling” (discussed in our previous Southwest Climate Podcasts) reduced confidence in the forecast.  On Nov 18, the Australian Government Board of Meteorology increased its El Niño tracker status from El Niño Watch to El Niño Alert, with a 70 percent probability of an El Niño developing in winter 2014–2015.  This outlook was based on a recent surge in above-average temperatures in the tropical Pacific Ocean (Fig. 1) and the Southern Oscillation Index (Fig. 2), which exceeded the El Niño threshold for the past three months, despite a lack of complete cooperation on the part of atmospheric conditions.

The Nov. 20 International Research Institute for Climate and Society (IRI) and CPC forecast reiterated these points, as the SSTs have exceeded the threshold for weak El Niño conditions, even while some of the atmospheric variables have yet to point towards an El Niño event. The mid-November forecast subsequently upped the probability of El Niño conditions developing to 75 percent (Fig. 3), and the North American multi-model ensemble shows a weak to moderate event peaking in mid to late winter and extending into the spring (Fig. 4).  

The strength of the event, if and when it forms, will matter. The impacts associated with weak El Niño events are generally less certain than those of a moderate or strong event, with past weak events bringing both dry and wet conditions to the Southwest U.S. during the winter. Seasonal precipitation forecasts still indicate an enhanced chance of above-average precipitation over the upcoming winter, but confidence in this forecast is partially contingent on the strength of the emerging El Niño event. It should also be noted that the signal for the Pacific Decadal Oscillation (PDO) has moved into a positive phase, which bodes well for increased precipitation this winter, especially since the El Niño-Southern Oscillation (ENSO) and PDO signals have the potential to enhance, rather than work against, the other.

2014 Pacific Hurricane Season Recap - Focused on the Southwest

Friday, November 21, 2014

From the Nov 20, 2014 Southwest Climate Outlook

The 2014 Pacific hurricane season was the most active season on record since 1992, with 20 named storms (Fig. 1). Fourteen of those storms developed into hurricanes, including eight major hurricanes (category 3 or greater), also breaking a record held since 1992. This meets or exceeds the high end of the NOAA-Climate Prediction Center (CPC) seasonal forecast (May 22), which predicted 14 to 20 named storms, seven to 11 hurricanes, and three to six major hurricanes. The Pacific hurricane forecast was tied to the ongoing El Niño forecast discussion, as conditions linked to the formation of an El Niño event (e.g., decreased wind shear in the tropical Pacific) also favored increased hurricane frequency and intensity in the Pacific region, and it is safe to say this season did not disappoint.  Conversely, the Atlantic hurricane season was relatively quiet, with eight named storms, six of which became hurricanes, including two major ones.  This was also in line with NOAA-CPC projections of seven to 12 named storms, three to six hurricanes, and up to two major hurricanes.

Seasonal Summary and Impact on the Southwest

The season started off strong and early with Hurricane Amanda on May 24 and continued with a number of early season tropical storms and hurricanes. A few early seasons storms, including Amanda, affected portions of Mexico but largely avoided the Southwest U.S. Most followed the typical early season pattern of staying out in the Pacific Ocean.  Notably, Hurricanes Iselle and Julio headed towards the Hawaiian Islands in late July and early August, with only Iselle actually making landfall.  As the season progressed, later season storms followed the expected pattern of recurving back into the Pacific Coast (see additional resources), and a number of major hurricanes, notably Marie, Norbert (with an assist from Atlantic Hurricane Dolly), Odile, and Simon, veered into the Pacific coast and brought considerable moisture into the Southwest. These incursions of rainfall made substantial contributions to the region’s overall monsoon totals; without them, the Southwest likely would be looking at a very different monsoon picture (i.e., below-average precipitation), particularly in September.

Specific Impacts and Looking Forward

In the Southwest, we are accustomed to the seasonal threat of flooding associated with intense monsoon precipitation, but these storms are generally highly variable spatially and relatively short. Hurricane Odile, as it lumbered into the Southwest, presented a unique threat; it had the potential for widespread flooding over a large area and over a number of days. In a worst case scenario, it could have moved slowly across the Tucson region, and dumped six or more inches of rain across the city and Pima County, not to mention additional flood potential from mountain runoff.  

This scenario posed unique challenges for emergency managers tasked with planning and preparing without sensationalizing or inciting fear in the community. Forecasters faced a related challenge of accurately characterizing a storm for which there was limited data available as it moved over data-poor regions of Mexico, knowing that the results of their forecast would be used to make widespread decisions that could prove costly if wrong. The lack of quality data, combined with apprehension about underestimating the threat of Odile, likely contributed to elevated predictions and certain planning decisions. 

Ultimately, Odile swung south of its predicted path by about 70 miles, leading to substantial rain events and considerable flooding in the southeastern corner of Arizona and across portions of southern New Mexico (Fig. 1). Tucson may have avoided the worst-case scenario in terms of hurricane impacts, but lingering effects may be more costly.  The general public derided many of the forecasts as inaccurate or unreliable, saw sensational coverage from outside media sources, and were subject to considerable disruptions associated with school, road, and government closures despite no actual flooding in town. These circumstances may contribute to a decreased likelihood to act on emergency decrees in the near future.

In the coming months, CLIMAS researchers will work with regional planners and officials to further explore the experience of Odile as it relates to emergency management planning and forecasting.

Southwest Climate Outlook November 2014

Thursday, November 20, 2014

From the Nov 20, 2014 Southwest Climate Outlook

Precipitation: Little precipitation fell in Arizona from mid-October to mid-November following the official end of the monsoon on September 30. New Mexico recorded some precipitation of note, mainly in the southeastern corner and in scattered pockets of the central and north-central parts of the state. This is a marked change from monsoon precipitation and the substantial contributions made by the incursions of tropical storms, but this drop-off in rainfall is typical for this time of year; November joins April as one of the driest months for the region.

Temperature: Most of Arizona and New Mexico were warmer than average in the past 30 days, a pattern that was consistent across much of the Southwest. The cold front that brought winter weather to much of the U.S. in mid-November also stretched into the region, but with limited effect and primarily in portions of eastern and southeastern New Mexico. There was a shift towards colder temperatures across the region in the last few days (at time of publication), and while the air feels colder given the previously above average temperatures, the temperatures are close to historical averages. 

Snowpack: Sporadic early winter precipitation resulted in below to above-average snowpack levels across the region. It remains to be seen how much of this early season snowpack will remain, and an above-average snowpack is needed this winter to improve storage in the Upper Colorado and Rio Grande basins. Water Supply: In October, total reservoir storage was 46 percent (compared to 47 percent last year) in Arizona, while total reservoir storage was 22 percent (compared to 21 percent last year) in New Mexico.

Drought: Above-average monsoon precipitation and an active Pacific hurricane season provided some short-term drought relief in the Southwest. Long-term drought relief was limited by the inconsistency of precipitation coverage and the runoff and evaporation associated with high-intensity precipitation events. The likelihood of an El Niño event continues to offer hope for additional drought relief, as these events are typically associated with increased winter precipitation in the region.

ENSO: The latest ENSO projections indicate a 70-75 percent chance that an El Niño event will develop this winter. Some experts believe that conditions are already in place, and that it is only a matter of time before the El Niño event is officially declared. There is less confidence, however, that a moderate to strong event will form and uncertainty about whether a weak event will drive winter precipitation much above average.

Precipitation Forecasts: The NOAA-Climate Prediction Center is calling for elevated chances for above-average precipitation through the winter and into early spring. These predictions are thought to be picking up on both the possibility of an El Niño event this winter and the impact of the Pacific Decadal Oscillation. 

Temperature Forecasts: The NOAA-Climate Prediction Center temperature forecasts are split across the region, with elevated chances for above-average temperatures along the West Coast, extending eastward into Arizona, and with increased chances for below-average temperatures along the Gulf Coast into New Mexico.

Also in this issue:

Upcoming: CLIMAS Climate & Society Fellows Event - Nov 14, 2014

Monday, November 10, 2014

After a year of research, The Climate Assessment for the Southwest’s first Climate and Society Fellows will present the results of their work on Friday, November 14, from 11 a.m. – 12:30 p.m., in room 531 of the Marshall Building.

The Climate & Society Graduate Fellows Program supports currently enrolled University of Arizona graduate students.  The fellows are given $5,000 and a year to work on a specific project of their choice.  While their work must be focused around climate research and decision making, they can come from any degree-granting program. 

This program began with the need for an engaged subset of students interested in use inspired science.

“We have been trying for about 5 years to build a cohort or group of students who are interested in climate and society interactions, as well as learning about the way CLIMAS operates in between academia and stakeholders,” said Gigi Owen, an assistant staff scientist for CLIMAS.  ”There is a growing body of literature and group of people doing engaged climate research and we wanted to have a hand in training students in this type of work.”

The Principle Investigators of CLIMAS have had graduate students helping with their own projects for several years. “That is like the bread and butter of CLIMAS,” said Owen.  However, that position is more like a job and sometimes students are not fully engrossed by the research. 

While graduate students still work with CLIMAS researchers, “we thought if students were paid to conduct their own research, rather than someone else’s, they would be more excited,” said Owen.

The fellowship also gives the students more freedom.  While most of the CLIMAS projects take place in Arizona and New Mexico, the fellowship is open to conducting research anywhere in the world. 

“It is expanding our geographical scope,” said Owen “It is helping build that literature about engaged climate and society research, even though the research may be outside of CLIMAS’ geographical sphere.”

CLIMAS wants its fellows to start learning skills to communicate and work with others outside of academia.  “It is one of the few fellowships that really drives that point,” said Owen.  “It gives you money to start that engagement process.” 

Four fellows will be presenting their work on Friday.

Rebecca Lybrand’s research is on the connection between soils and climate in the Southwest and beyond.  The goal is her project is to create two short films that document her research as a soil scientist across the Santa Catalina Mountains in Arizona.  One film will use a “science message” and the other, a “science story.”

Ling- Yee Huang focused on achieving scientific literacy in the classroom. The project involves developing an integrated climate science and climate law curriculum for the James E. Rogers College of Law at the University of Arizona.  The final curriculum will be a template than can be adapted for other law schools, practitioner, law makers and judiciary. 

Chris Guiterman conducted use inspired research to guide tribal forest management.   He worked with the Navajo Forestry Department foresters to address their needs.  The study will provide an improved assessment of forest response to climate change that is vital to natural resource planning and management, 

Sarah Truebe assessed speleothem sampling methods of paleoclimate research.  The methods used to extract past climate information from speleotherms are destructive because sampling occurs along the growth axis. The final product will be a peer-reviewed methodology assessment, giving managers and scientists a place to start when wanting to sample in a more conservation-friendly way.

Notes from an Applied Climatologist - Oct 2014 Rainlog Climate Summary

Friday, November 7, 2014

Very warm conditions and a couple of unusually wet days characterized the weather of October across Arizona. The month started off rather quiet as an exiting cold front left relatively cool and dry conditions in its wake over the first couple of days of October. A strong ridge of high pressure was able to nose its way back into the Southwest during the first week of the month rapidly pushing temperatures back up to near-record levels across Arizona with temperatures well into the upper 90’s across the low deserts. This rapid warmup was followed by a rapid cool down with an impressive rain event that unfolded across southern Arizona on October 8th and 9th. The busy eastern Pacific tropical storm season wasn’t done with Arizona yet with tropical storm Simon helping to guide abundant moisture into the region just in time for it to interact with a weak trough of low pressure swinging in from the west. This produced several rounds of heavy rain primarily across southern Arizona with many Rainloggers in the Tucson area reporting 1-2” of total precipitation. Rainlogger north and east of Phoenix and across southeast Arizona also reported decent rainfall totals of 0.5 to 1.5” inches with this tropical event.

The weak trough moving through the region kept temperatures in check for a few days before the ridge was back with the heat. This lasted until a weak low pressure system wandered in from the Pacific towards Arizona on the 18th and 20th of the month helping to fire off isolated thunderstorm across primarily central and southern parts of the state. Rainlog reports of precipitation were spotty with this event with some isolated reports of over 1” near Phoenix and south of Tucson with many obervers from Sierra Vista to Globe to Show Low reporting 0.3 to 0.5” inches with these storms.

The month rounded out with more near-record warmth and overall dry conditions. Precipitation totals for the month were generally above average across southern Arizona which saw the bulk of the storm activity and below-average across the northern half of the state which observed very little to no rainfall for the month. The Tucson National Weather Service Office reports that October of 2014 was the 3rd warmest on record and the record when considering only low temperatures. Across the state temperatures were generally 2-6 deg F above-average. Even with the unusually wet conditions across the southern part of the state, longer-term drought conditions persist across all of Arizona. Our eyes now turn towards the winter with the continued hope of an emerging El Nino bringing hopefully average to above-average precipitation for the Southwest.