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El Niño Tracker - January 2015

Friday, January 23, 2015

Originally published in the January 2015 Southwest Climate Outlook (SWCO)

Just when it looked like we were getting a more definitive answer regarding El Niño, ongoing lack of cooperation on the part of the atmosphere continues to muddy forecasts moving into 2015. Sea surface temperatures (SSTs) remain elevated across much of the equatorial Pacific Ocean (Fig. 1), and while temperature anomalies in the Niño 3.4 region are within the range of a weak El Niño event, they have declined in the past month (Fig. 2). It is a common refrain in forecast bulletins that a lack of coupling between ocean and atmosphere is responsible for decreased confidence in an El Niño event this winter. Additionally, a lack of temperature gradient along the equatorial Pacific and little in the way of El Niño wind patterns further reduce confidence that a stronger event is on the horizon.

Source: Australian Bureau of Meteorology

Source: NOAA-National Climatic Data Center

The most recent forecasts remain in a cautious holding pattern, pending the emergence of a more decisive signal. On Jan. 8, the NOAA-Climate Prediction Center (CPC) issued another El Niño Watch, assigning a 50 to 60 percent probability that an El Niño would form in the next two months, with forecaster consensus that this would be a weak event extending into late winter or early spring. On Jan. 9, the Japan Meteorological Agency continued its assessment that El Niño conditions had been present in the equatorial Pacific for multiple months but noted uncertainty as to the length or intensity of an El Niño event, with emphasis on a weak event that would transition to ENSO-neutral by early spring. On Jan. 15, the International Research Institute for Climate and Society (IRI) and CPC scaled back the probability of an El Niño formation to approximately 60 percent (Fig. 3) but indicated SST anomalies were sufficient enough to suggest a weak El Niño event was likely underway and would last through spring 2015. On Jan. 20, the Australian Bureau of Meteorology actually shifted its El Niño tracker status to neutral, given the fade in SST anomalies and lack of clear atmospheric signal. The North American multi-model ensemble shows a weak event that extends into summer (Fig. 4). 

Source: International Research Institute for Climate and Society

Source: NOAA-Climate Prediction Center

Vacillations in forecast percentages prompted the forecast community to describe current conditions as “El Limbo.” Despite lack of official status, El Niño-like conditions may already be driving winter patterns, and seasonal precipitation forecasts indicate an enhanced chance for above-average precipitation this winter across the Southwest, although confidence in this forecast is partially contingent on the strength of these El Niño conditions. 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. Ultimately, the above-average tropical storm season and the humidity that remained in the region may be indicative of the effect of El Niño-like conditions, even in the absence of a formal designation, and give some idea that the regional patterns have shifted in favor of El Niño formation.

Southwest Climate Outlook January 2015

Thursday, January 22, 2015

In the Jan 2015 Southwest Climate Outlook, we look back at 2014, including record temperatures for the Southwest, the recent trends in precipitation and drought, and forward into 2015 as we continue to wait for El Niño to give us a definitive answer.


Climate Summary/Forecasts

Precipitation: After an exceptionally dry November, a number of storms pushed into the Southwest in December and early January, but overall precipitation totals were highly variable across Arizona and New Mexico (Fig. 1). 

Source: High Plains Regional Climate Center - HPRCC

Temperature: December continued the yearlong trend of above-average temperatures, with Arizona logging the warmest year on record in 2014 (as did California and Nevada), and New Mexico at near-record levels (Fig. 2). The extended warm temperatures were in part attributable to well above-average humidity that extended long after the monsoon ended.  In particular, this kept nighttime lows above average, and we did not experience the typical pattern of cooling off and drying out in early fall.

Source: NOAA-National Climatic Data Center

Snowpack: While still relatively early in the season, snow water equivalent (SWE) remains low across Arizona and New Mexico, ranging from 0 to 70 percent of average in Arizona and 50 to 90 percent of average for most of New Mexico.  SWE in the upper elevations that feed into Arizona and New Mexico are faring a little better, with most of the basins reporting more than 70 percent of average and many reporting between 90 and 110 percent of average (Fig. 3).

Source: Natural Resources Conservation Service - NRCS

Water Supply: In December, total reservoir storage was 45 percent in Arizona (compared to 47 percent last year) and 23 percent in New Mexico (compared to 22 percent last year) (see reservoir storage, for details).

Drought: Continued consistent and repeated precipitation events, especially with El Niño-led above-average precipitation throughout the winter and spring, would push us in the right direction regarding long-term drought conditions. Alleviating the drought will take time however; widespread areas of the Southwest received well below-average precipitation over the past 12 to 36 months, with the Four Corners region, northeast New Mexico, and portions of southern Arizona experiencing the largest deficits in the past 12 months (Fig. 4).

Source: High Plains Regional Climate Center - HPRCC

ENSO: The most recent NOAA-Climate Prediction Center forecast scaled back its forecast for El Niño this year, albeit only slightly.  Ongoing lack of atmospheric cooperation continues to sow confusion, despite generally above-average temperature anomalies in the Niño 3.4 region (see El Niño tracker, for details).

Precipitation Forecasts: The Jan. 15 NOAA-Climate Prediction Center seasonal outlook continues to predict above-average precipitation through the winter and into early spring for the southwest. This forecast is likely linked to El Niño-favorable conditions, but the extent of their impact remains to be seen (Fig. 5).

Temperature Forecasts: The Jan. 15 NOAA-Climate Prediction Center temperature forecasts remain split across the region, with elevated chances for above-average temperatures along the West Coast and eastward into Arizona and increased chances for below-average temperatures along the Gulf Coast into New Mexico. This pattern is projected through the winter and into the spring (Fig. 6).

Source: NOAA-Climate Prediction Center

Jan 2015 SW Climate Podcast: 2014 Year in Review, and Stuck in El Limbo

Wednesday, January 21, 2015

In the January Southwest Climate Podcast, Zack Guido is back and joins Mike Crimmins to discuss the state of the climate in 2014, including the record year for Arizona and the near record year for New Mexico.  They also talk about weather systems that affected our most recent temperature and precipitation patterns, the ongoing uncertainty with El Niño, or as some have started referring to it, "El Limbo", and the state of precipitation and drought in the southwest.  They wrap things up looking at the seasonal outlooks and the projected trends for the coming year. 

Intro 0:00
Climate Summary: Temperature and Precipitation, weak and spotty storms in December and January 1:50
Winter Storms: Water storage and winter precipitation patterns 8:00
Weather vs. Climate: Weather variability vs. Climate patterns, "El Limbo", and winter precip patterns given these trends 13:00
2014 Record Year: 2014 Temperature Records Recap 22:00
Precip and Drought: Winter patterns and drought - how much moisture "solves" the drought  24:00
Looking Forward: Jetstreams & Winter Weather Patterns + Seasonal Forecasts 27:30

If you have a question you'd like answered, you can email Zack Guido (zguido@email.arizona.edu) or Ben McMahan (bmcmahan@email.arizona.edu) with "CLIMAS Podcast Question" in the subject line. You can also tweet us @CLIMAS_UA or post a question on facebook

Transcript: Coming Soon

Suggested Source/Citation:

CLIMAS: Climate Assessment for the Southwest, (2015). 2014 Year in Review, and Stuck in El Limbo . [podcast] CLIMAS Southwest Climate Podcast. Available at: climas.arizona.edu/podcast/jan-2015-sw-climate-podcast-2014-year-review-and-stuck-el-limbo [Date Accessed]

Notes from an Applied Climatologist: Dec 2014 Rainlog Climate Summary

Monday, January 5, 2015

After a very dry and warm November, the weather pattern turned more wintry and active in December bringing some much needed precipitation to Arizona. The first major weather event of the month occurred in the first couple of days as a weak low pressure system interacting with plentiful subtropical moisture brought widespread precipitation to much of Arizona on the 2nd through the 4th of December. This was a relatively warm storm with very high snow levels. Rainloggers from Prescott to Flagstaff reported total rainfall (very few reports of snow) of 1 to 2 inches with this storm system. Much lighter precipitation amounts were recorded by Rainloggers in far southeastern Arizona with amounts of less 0.2 inches.

A much colder storm system pushed through the state towards the middle of the month with lower snow levels and more accumulating snow to higher elevation areas. Precipitation amounts were much lighter with this system, though, with Rainloggers from Tucson to Phoenix to Prescott reporting total precipitation amounts of 0.25 to 0.5 inches over the period of December 12th to the 14th. Some higher amounts close to an inch were reported near Sedona and Show Low with much lower amounts (less than 0.2” inches) observed across far southeast Arizona.

The active weather pattern continued for the rest of the month with quick moving storm systems hitting the state on the 17th and again on Christmas day with light precipitation and snow to higher elevation areas. The month and year ended with a very cold and wet storm system moving through Arizona on New Year’s Eve bringing snow to low desert areas and several feet of snow to mountain locations.

Even with the active weather pattern, only parts of central and southern Arizona near Tucson observed average to above-average precipitation for the month. Much of the rest of the state didn’t keep pace and observed below-average precipitation for December. The latest update of the U.S. Drought Monitor shows that all of Arizona continues to observe short-term drought conditions with little change over the past several weeks.

Overall, 2014 was a strange year of extremes with much of Arizona observing a very dry winter last year and very active summer monsoon season. This left much of southern Arizona with near average precipitation due to the heavy summer precipitation canceling out the dry conditions of last winter. Far northern Arizona still observed below-average precipitation for the year due to both dry winter and summer conditions. All of Arizona observed much above average temperatures for the year with many locations observing their warmest year on record. The Tucson National Weather Service reports that 2014 was the warmest year on record for Tucson with observations going back to 1895.