Archive for the ‘Climate’ Category

April Southwest Climate Outlook

Friday, April 27th, 2012

 

Southwest Climate Outlook

Vol. 11 Issue 4

Source: Holly Lawson

Photo Description: A hummingbird laps cactus nectar near the Rincon Mountains in southern Arizona. The deserts and high country in the Southwest are aflutter with flowers and pollinators, even after a dry winter.

April Climate Summary

Drought– Moderate or more severe drought covers most of Arizona and New Mexico. Central and southern Arizona and eastern New Mexico are the only areas in the West classified with extreme or exceptional drought.

Temperature– Temperatures across most of the Southwest in the last 30 days were 2 to 6 degrees F warmer than average.

Precipitation– Precipitation in most of Arizona and southern and western New Mexico measured less than 50 percent of average in the last 30 days, continuing a dry stretch that began around January 1.

ENSO– The La Niña event is transiting to ENSO-neutral conditions; neutral conditions are expected to persist through the May–July. Signs of a developing El Niño are on the horizon.

Climate Forecasts– Forecasts call for above-average temperatures through the monsoon. Precipitation forecasts, however, are less definitive, as monsoon forecasts historically have been about as accurate as a coin flip.

The Bottom Line– Had it not been for the cavalcade of storms that drenched many parts of Arizona and New Mexico in December 2011, precipitation deficits would be much higher across the Southwest. Since January 1, rain and snow have measured less than 50 percent of average across the region, and it has been similarly dry in the Upper Colorado River and Rio Grande basins. In these regions, snowpacks are below average and most stations report that the water contained in snowpacks is less than 50 percent of average. The scant snow this winter is feeding low spring streamflow projections across the region. Inflow into Lake Powell, for example, is expected to be 3.5 million acre-feet less than average, or 44 percent of average. Relief from expanding and intensifying drought may not come until the monsoon begins this summer, but it is unclear when the monsoon will begin in earnest or how much rain it will deliver. Although monsoon forecasts are not definitive, there is higher confidence that temperatures will be above average in coming months, in part because summer months have become progressively warmer in recent decades.

Read more >

In this issue…

Feature Article…

Cinnamon Snow: Flecks of Dust Alter Western Water Supplies

News Flash…

Setting the stage for continual assessments of the Colorado River Basin

Includes…
Recent Conditions

Temperature
Precipitation
U.S. Drought Monitor
AZ Drought Status
NM Drought Status
AZ Reservoir Levels
NM Reservoir Levels
Southwest Snowpack

Forecasts

Temperature Outlook
Precipitation Outlook
Seasonal Drought Outlook
Streamflow Forecast
Wildland Fire Outlook
El Niño Status and Forecast

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AtmosNews: Climate variation, change, or both?

Monday, April 16th, 2012

 

–Burning fossil fuels has led to a warmer, moister atmosphere and a shifting background for extreme weather and climate events, according to a study that analyzes noteworthy weather events from the last two years.

http://www2.ucar.edu/atmosnews/research/6801/climate-variation-change-or-both

 

Climas: April La Niña Drought Tracker

Friday, April 13th, 2012

 

A Publication by CLIMAS
April 11, 2012 / Volume 2 / Issue 5

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Preface

La Niña returned for a second consecutive winter and affected the weather and climate of the Southwest. Drought is widespread and intense, and the expectation for drier-than-average conditions will likely expand impacts. This publication provides climate and drought information from experts and credible sources in order to help the region stay abreast of evolving drought conditions, drought impacts, and climate changes.

Drought Conditions

drought conditions thumbnail

La Niña delivered a second consecutive dry winter, with precipitation totaling less than 75 percent of average across most of the Southwest between October 1 and April 9.
In soggy winters, the westerly winds loop down from the north and combine with damp air wafting from the tropics, which has not been the case this winter. Read more

Snowpack

The amount of water contained in the snowpack, or snow water equivalent (SWE), was well below average in Arizona and New Mexico on April 5; snowpacks in many basins in both states were less than 25 percent of average.

Snowpacks at many individual monitoring sites in Arizona completely melted about about a month earlier than average. Read more

Forecast

The precipitation outlook for April-June calls for equal chances for above-, below-, or near-average precipitation in most of Arizona and New Mexico.
This period represents the driest time of year, when only about 12 percent of the annual precipitation falls. Read more

Final Word

La Niña will likely transition into ENSO-neutral conditions by the end of April, although the atmosphere, which has a delayed response to changes in ENSO events, will still be influenced by La Niña for a longer period.

The Seasonal Drought Outlook calls for drought to persist, intensify, or develop in all of Arizona and New Mexico during during the March-May period. Read more

Climate Assessment for the Southwest | 715 North Park Avenue | Tucson | AZ | 85719

 

UCAR: Whither our winters?

Monday, April 9th, 2012

 

Whither our winters?

The winter of 2011–12 was the second in a row to feature La Niña, the quasi cyclic cooling of the eastern tropical Pacific—but the two seasons departed from the La Niña script in strikingly different ways.

http://www2.ucar.edu/atmosnews/opinion/6666/whither-our-winters

 

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UCAR: Twisters and teleconnections

Saturday, April 7th, 2012

 

Twisters and teleconnections

—Why might a cooling of the Pacific Ocean help stoke tornadoes in the United States? Researchers are beginning to dig deeper into the connections between severe U.S. thunderstorms and the sea.

http://www2.ucar.edu/atmosnews/opinion/6717/twisters-and-teleconnections

 

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CLIMAS – March Southwest Climate Outlook

Thursday, March 22nd, 2012

 

March 21, 2012

Southwest Climate Outlook

Vol. 11 Issue 3

Source: Bob Maddox

Photo Description: Storms have been few and far between in the Southwest this winter, leaving most of the region drier than average. A storm beginning on March 18, however, delivered much needed moisture to Tucson, where this photo was taken, and many other parts of Arizona. The event also brought several spurts of grauple, or soft hail.

March Climate Summary

Drought– Drought conditions continue to expand and intensify across Arizona, while severe drought continues to grip much of New Mexico.

Temperature– Several storms in February resulted in slightly below-average temperatures in Arizona and western New Mexico. The storms dodged eastern New Mexico, causing warmer-than-average temperatures there.

Precipitation– Precipitation in most of Arizona and New Mexico has been less than 75 percent of average in the past month.

ENSO– The current La Niña event is running out of steam and is expected to end by late April. ENSO-neutral conditions are forecast to hold sway through the spring and summer seasons.

Climate Forecasts– Warming trends in recent decades are driving forecasts for above-average spring and summer temperatures in the Southwest. Precipitation forecasts for these periods, however, are less definitive—monsoon season forecasts have historically been about as accurate as a coin flip.

The Bottom Line– Below-average rain and snow is almost guaranteed for many parts of the Southwest this winter in large part because of La Niña’s influence. Despite a recent winter storm that brought much needed moisture to the Southwest around March 18, snowpacks and precipitation across most of the region are mostly below average. Similar to last year, January and February were dry, and rain and snow tallied less than 50 percent of average in these months in many parts of the Southwest. As a result, drought has expanded and intensified, most notably in Arizona. The scant precipitation is also driving forecasts that call for a 40 percent chance that spring flows in the Verde, Salt, and Gila rivers will be less than 60 percent of average, while the Rio Grande likely will be less than 90 percent of average. The Upper Colorado River Basin, which received historically high snowpacks during last winter’s La Niña event, also likely will experience well below-average streamflows this spring and summer. While the La Niña event is expected to end in April, spring storms in the Southwest—most notably in Arizona—are often few and far between, presenting few opportunities to overcome shortfalls in precipitation before the monsoon begins.

Read more >

In this issue…

Feature Article…

Warmer Led to Drier: Dissecting the 2011 Drought in the Southern U.S.

News Flash…

Comprehensive report on climate change in the Southwest open to public comment

Includes…
Recent Conditions

Temperature
Precipitation
U.S. Drought Monitor
AZ Drought Status
NM Drought Status
AZ Reservoir Levels
NM Reservoir Levels
Southwest Snowpack

Forecasts

Temperature Outlook
Precipitation Outlook
Seasonal Drought Outlook
Streamflow Forecast
El Niño Status and Forecast

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Climate Assessment for the Southwest | 715 North Park Avenue | Tucson | AZ | 85721