Issued July 12, 2012, Vol. 8, Issue 5

Brad Udall – WWA Director
Jeff Lukas, Tim Bardsley, Eric Gordon, – Editors/Writers
Klaus Wolter, Gary Bates – Asst. Editors

We thank the following for their assistance with this special issue: Roger Pulwarty, Lisa Darby, Jim Verdin, and Chad McNutt, NIDIS; Taryn Hutchins-Cabibi, Colorado Water Conservation Board; Nolan Doesken, Wendy Ryan, and Becky Smith, Colorado Climate Center; Kevin Werner, NOAA Colorado Basin River Forecast Center; Chris Nicholson, Wyoming State Climate Office; and Joe Barsugli, NOAA ESRL Physical Science Division and WWA.


The 2012 Drought in Colorado, Utah, and Wyoming:
Severe drought has emerged across most of the region; conditions similar to 2002

A special issue in collaboration with NIDIS

This special issue of the IWCS, developed in collaboration with the National Integrated Drought Information System (NIDIS), focuses on the severe drought conditions that have emerged this year in Colorado, Utah, and Wyoming, and direct readers to additional sources for drought monitoring.

WWA and NIDIS have also released a two-page drought update that summarizes the information provided in this issue of the IWCS. The drought update is available here.

Overview of the 2012 drought

Under the influence of a second year of La Niña conditions, drought conditions emerged midway through the 2012 water year as below-average late-winter snowpacks were compounded by a very dry and warm spring. Spring and early summer runoff over most of the region was well below average, and in many basins worse than 2002 or other benchmark dry years (1977, 1992). In June, continued dry and hot conditions dried out vegetation and led to very large and intense wildfires in all three states, along with widespread range, pasture, and dryland crop losses. The US Drought Monitor as of July 10 showed severe or worse drought conditions covering all of Colorado, most of Utah, and about half of Wyoming (Figure DM-1).

A strong moisture surge into the region from July 5–9 saw up to 5" of rain in eastern Colorado, with most parts of the state receiving the first significant moisture (>0.5") in at least a month. Precipitation amounts were much less in Utah and Wyoming. This moisture has reduced fire danger, but only partially alleviates the long-term deficits in soil moisture and water supply in the region. The outlook for the drought shows some tentative indications for wetter conditions over the next several months. Conditions in the tropical Pacific are tipping towards El Niño, which tends to produce more moisture for the region for summer through the fall.

Since the onset of drought and the impacts so far have been similar to 2002, the comparison has been raised in many circles, particularly in Colorado. This issue will explore the different dimensions of the 2012 drought, and place most of them in the context of the 2002 drought.

Figure DM-1.
U.S. Drought Monitor for early July 2012, compared with early July 2002. Conditions were generally worse across the three-state region in 2002, except for north-central and northeastern Colorado, and far northwestern Utah. The widespread rains of July 59, 2012 led to very little change in the drought categories from the July 3 Drought Monitor, given the long-term precipitation deficits. (Source: US Drought Monitor archive:

Conditions leading into water year 2012 - Wetter than those preceding 2002, with both soil moisture and reservoirs generally above-average

The two water years preceding 2012 were slightly drier than average (2010) and mainly wetter than average (2011) over the three-state region. As a result, both soil moisture and reservoir storage at the start of the 2012 water year were generally higher than at the start of the 2002 water year, which was preceded by two years (2000 and 2001) that were much drier than average (Figure AC-1). Note that most years since 2000 have been drier than average across the region.

Figure AC-1. Precipitation for Colorado, Utah, and Wyoming for water years 20002011, as percent of the 19812010 average. The below-average Colorado statewide precipitation for Colorado in 2011 reflects the very dry conditions in the south-central and southeastern parts of the state, balancing out the very wet conditions in the mountains (Source: data from Westmap/PRISM,; plotted by Jeff Lukas, WWA)

2012 ENSO Conditions - For water year 2012 through spring, La Niña had a more typical influence compared to 2011; storms tracked north of the region, leaving us dry

The see-saw of ocean temperatures and winds in the tropical Pacific known as ENSO (El Nino-Southern Oscillation) affects our region by influencing the position of the jet stream which delivers Pacific storms and moisture to the western US. La Niña (cool-phase) events tend to be dry in the fall and spring across Utah, Colorado, and southern Wyoming, while central and northern Wyoming have a slight tendency towards wetter-than-average fall and spring seasons. During the mid-winter months (December–February), dry La Niña conditions tend to retreat to southern Utah and southeast Colorado, while higher elevations in Colorado (especially northern Colorado) and in western and northwestern Wyoming tend to be wet. The 2012 water year for the most part followed this pattern, but the high mountains of Colorado never experienced the above-average mid-winter precipitation that often occurs with La Niña. Storm tracks stayed consistently to the north of the region, particularly in the spring.

ENSO conditions are currently transitioning to El Niño (warm-phase) conditions, and the implications of this are explored in the last section.


2012 Water Year Precipitation – A wet start, then turning increasingly dry
, capped by an extremely dry June

Water year 2012 got off to a wet start in the Intermountain West, with above-average precipitation in nearly all basins in October. November was more mixed, with generally wet conditions in Wyoming and dry in Utah and Colorado. December saw very dry conditions in western Colorado and most of Utah, while southeastern Colorado was very wet. January was again mostly dry across the region, except for northern Utah and western Wyoming. February was the last month with wet conditions for the mountains, except northern Utah, which flipped back to dry.

March was extremely dry, with most of the region seeing less than 50% of average March precipitation, and eastern Colorado seeing virtually none. April was almost as dry, and then May, typically one of the wettest months, was also very dry except for south-central Colorado and northern Wyoming. March–May 2012 ended up as the 4th driest spring on record (1895–2012) in Wyoming and Colorado, and the 5th driest in Utah.

June again was extremely dry, and water-year precipitation departed further from average conditions. Wyoming experienced its driest June statewide out of 118 years, while Colorado and Utah both had their 2nd driest June (Figure PR-1).

So for the water year through June, a mixed first five months followed by an extremely dry March–June added up to dry conditions across all of the region except for pockets in northern and southwest Wyoming, and southern Colorado (Figure PR-2). The very driest conditions, with less than 50% of average precipitation, were in southern and northeast Utah, and northwest Colorado, and most of the key mountain headwaters had less than 70% of average precipitation. But as dry as water year 2012 has been, 2002 was yet drier over the same period in nearly all parts of the region (Figure PR-2).

Figure PR-1. Percent of average precipitation for June 2012 (left), with June 2002 (right) for comparison. Both graphics use a 19952010 normal. (Source: NWS COOP station and SNOTEL site observations, plotted by Gary Bates, NOAA ESRL Physical Science Division)


Figure PR-2. Percent of average precipitation for the current water year to date, October 2011–June 2012 (left), with October 2001June 2002 (right) for comparison. Both graphics use a 19952010 normal. Note that the few spots of above-average precipitation are (Source: NWS COOP station and SNOTEL site observations, plotted by Gary Bates, NOAA ESRL Physical Science Division)

Thus far in July (through July 11), above-average precipitation has fallen in northeastern, central, and southwestern Colorado, northeastern Wyoming, and central Utah. Some portions of northeastern and north-central Colorado have received more than the average monthly precipitation for July. The rest of the region has received less, or no, precipitation.



2012 Spring and early summer temperatures – Extremely warm spring exacerbated the precipitation deficit

The dry weather patterns in March also caused very warm conditions across the region, with temperatures up to 12°F above average, and 3–7°F above average in the mountain regions. The warm air exacerbated the effects of the low precipitation on the snowpack, initiating snowmelt. April continued the warm trend, with temperatures 2–6°F above average across most of the region. May was not as warm, but temperatures were still 0–4°F above average across the region except in northwest Wyoming, which was cooler than average. Altogether, the March-May period was the 2nd warmest spring in Colorado in the past 118 years, the 3rd warmest in Wyoming and the 8th warmest in Utah. This extended warmth hastened the meltout of the already-low snowpack.

While April 2002 was an extremely warm month across the region, similar to March 2012, March and May 2002 were cooler than average. Thus while water year 2012 was not as dry through May as 2002, the very warm spring in 2012 exacerbated the precipitation departure and likely brought conditions "on the ground" (snowpack and runoff, soils and vegetation) closer to those of 2002.

June 2012 continued the streak of warm months, with temperatures 2–8°F above average across the region. The hottest area was eastern Colorado, with many record daily highs in late June, including a tie for the all-time highest statewide temperature for Colorado with 114°F in Las Animas on June 23rd. The extreme heat contributed to several large and destructive wildfires across the region, described in a later section.

Figure TE-1. March-May temperatures in 2012 were 27°F above normal across the three-state region, and also much warmer than the same period in 2002. The 1981-2010 normal was used. (Source: NOAA ESRL PSD Climate Analysis Branch, plotted from NOAA NCDC divisional data,



2012 Snowpack – Much below-average peak in March, and a very early meltout

The region’s snowpacks began with a good base in October, but with the generally dry weather they fell behind the average accumulation curve by January 1 in all areas except for northern Wyoming. After near-average to above-average snowfall in February, March brought very little new snow, unusually warm temperatures, and a very early onset of depletion. Most basins saw the snowpack peak at near-record or record-low levels in early or mid-March, 4–8 weeks ahead of normal, and in many basins ahead of the very early peak in 2002 (Figures SN-1 to SN-3). Conditions were better in the Upper Green River basin than in the rest of the Upper Colorado River basin.

The rapid depletion of the snowpack continued in April, with only a few storms briefly slowing the meltout. The trajectory of depletion was similar to that of 2002 in many basins. May saw virtually no new snow, and continued warm weather, and even the highest-elevations sites melted out or nearly so. Of 21 representative SNOTEL sites in the Upper Colorado Basin, 11 sites had their lowest-ever peak SWE this spring, 15 had the earliest date of peak SWE, and 17 had the earliest date of meltout.

Figure SN-1. Basin snow-water-equivalent (SWE) accumulation and depletion plot for the Colorado River above Cisco, UT, including the Colorado Headwaters and Gunnison Basin. (Source: NOAA NWS Colorado Basin River Forecast Center;

Figure SN-2. Basin snow-water-equivalent (SWE) accumulation and depletion plot for the Yampa River above Maybell, CO. The 2012 snowpack peaked slightly lower than in 2002, and about 3 weeks earlier. (Source: NOAA NWS Colorado Basin River Forecast Center;


Figure SN-3. Basin snow-water-equivalent (SWE) accumulation and depletion plot for the Wasatch Front, Utah, including the SNOTEL sites in the Weber, Provo, Bear (in Utah), and Duchesne River basins. (Source: NOAA NWS Colorado Basin River Forecast Center;




2012 Streamflow and Reservoirs – No real peak flow in most basins, very low spring-summer runoff

As the snowpack fell further behind average conditions after January 1, the forecasts for spring-summer runoff likewise dropped from one month to the next. The April 1 and May 1 forecasts fell into the range of 2002 and 1977 (and 1992 in northern Utah), with most of the region anticipating flows from 30%–70% of average. The observed flows in March and April 2012 were actually near or above average in many basins as most of the (meager) snowpack melted and ran off very early.

As expected, flows in May were well below average, and by June, flows in most basins were below the 10th percentile, with an increasing number of gages seeing record-low daily and 7-day flows by late June (Figure ST-1). Statewide, streamflows were overall lowest in Colorado, with over 70% of gages with flow below the 10th percentile, followed by Utah (40% of gages) and Wyoming (25% of gages). Compared to other dry years in the 2000s, statewide flow rankings in 2012 through July 1 in Wyoming were not as low as in 2001, 2002, and 2007; in Utah, not as low as in 2002; and in Colorado, not as low as in 2002.

Figure ST-1. Statewide rankings for Wyoming, Utah, and Colorado, of daily average streamflows since 1999 across a set of long-term USGS stream gages, relative to the long-term record at those gages. The number of stream gages in the analysis varies by state, year, and season but ranges from about 50 to 130 gages per state in summer. (Source: USGS,; plotted by Jeff Lukas, Western Water Assessment.)

With the widespread much-below-average inflows this water year, many reservoirs across the region had less storage at the end of June than the average for the date. Of the 14 reservoirs summarized in Figure RES-1, 9 had below-average storage at the end of June 2012. But due to much above-average inflows in 2011, nearly all reservoirs still have more storage this summer than in 2002. Of the 14 reservoirs, only Lake Powell is lower this year than in 2002. With July and August 2012 inflows also expected to also be much below average, storage should be expected to decline relative to average conditions through the summer.

  Reservoir June 2012 storage (af) June 2002 storage (af) Average on 6/30 2012
% of avg
% full
% full
Capacity (af)
COLORADO Dillon Reservoir 238,000 184,000 249,000 96% 92% 72% 257,304
Turquoise Lake 87,401 77,647 116,562 75% 68% 60% 129,390
Lake Granby 419,861 216,739  432,955 97% 78% 40% 539,758
Blue Mesa 483,086 447,964  695,200 69% 58% 54% 829,500
Pueblo 190,235 101,486  160,500 119% 81% 43% 235,000
UTAH Strawberry 954,984 880,006  710,000 135% 86% 80% 1,106,500
Jordanelle 289,879 274,482  298,511 97% 94% 89% 309,000
Bear Lake 1,102,000 568,400  972,100 113% 85% 44% 1,302,000
Lake Powell 15,294,215 16,110,750  19,801,000 77% 63 66 24,322,000
WYOMING Fontenelle 315,020 244,470  271,100 116% 91% 71% 344,800
Flaming Gorge 3,108,441 2,755,324  3,235,000 96% 83% 73% 3,749,000
Seminoe 740,920 393,009  827,800 90% 73% 39% 1,017,273
Boysen 619,797 300,131  714,600 87% 84% 40% 741,594
Buffalo Bill 629,853 496,326 550,000 115% 98% 77% 644,126

Figure RES-1. All reservoir content data is from June 30 of the given year. Percent of average ranges are color-coded as follows: green: >90%; light green: 60–89%; yellow: 40–59%; orange: 20–39%; red: 0–19%. (Sources: US Bureau of Reclamation and Natural Resources Conservation Service)

Basin report: Upper Colorado River Basin

Spring-summer streamflows in the Upper Colorado basin have been lowest, relative to average, in the lower Green River (Yampa, White, and Duchesne) and the Colorado Headwaters (Fraser, Blue, and Eagle), very similar to 2002 and 1977. There were slightly higher flows in the Gunnison and San Juan basins, and the best conditions—but still below-average—in the upper Green River Basin. Water-year observed (unregulated) inflows to Lake Powell for 2012 are projected to be 5.0 million acre-feet (MAF), 46% of the 1981-2010 average, the 4th lowest on record, compared to 2.64 MAF for 2002 (24% of average) (Figure UC-1).

The very low streamflows in the Upper Basin in water year 2012 are likely to cancel out all of the gains in basin-wide storage that occurred in 2011. However, no shortage declaration for the Lower Basin is possible for water year 2013. The above-average inflows to Lake Powell in 2011 triggered the equalization releases from Lake Powell that will ultimately raise the level of Lake Mead approximately 50 feet above what it would have been without the Interim Guidelines of 2007. As of June 1, Lake Mead was 44 feet above the trigger level of 1075’ (Figure UC-2). Lake Powell is currently projected to stay below the equalization trigger for 2013.

Figure UC-1. Water year inflows to Lake Powell, representing the entire Upper Colorado River Basin, comparing 2012 with 2002, 2011, and the long-term average. 2012 has been much lower than average, but was running above 2002 through May. (Data source: NOAA NWS Northwest River Forecast Center;

Figure UC-2. Surface elevations of Lake Powell (upper) and Lake Mead (lower), January 2000 through June 2012. (Data from US Bureau of Reclamation, plotted by Joseph Barsugli, NOAA ESRL Physical Science Division)

Basin Report: Wasatch Front

At four key gages representing native Wasatch Front water supply (Logan River near State Dam, Weber River near Oakley, and Provo River near Woodland, and Bear River near Utah State Line), the March-June streamflows for 2012 were between 48–68% of average for the first three, but only 28% for the Bear River. For the first three gages, 2012 flows were similar to 2002 and higher than 1992, while on the Bear 2012 was much lower than either 2002 or 1992.

As of the end of June, storage in reservoirs which serve the Wasatch Front was generally below average, with the exception of Strawberry Reservoir, Bear Lake, and East Canyon Reservoir, which were above average. Nearly all reservoirs had more storage than at the end of June 2002.



2012 Drought Impacts to Range Vegetation and Agriculture – Very early green-up, limited growth, then abrupt drying

Soil moisture was already sub-par at the beginning of the growing season in April, and was quickly depleted with the very low spring and early summer precipitation and very warm conditions causing excessive evapotranspiration (Figure ET-1). On rangelands and pastures throughout the region, there were widespread reports of no real green-up, or early green-up with limited growth and very early curing. As of June 24, poor or very poor conditions were found on 70% of Colorado’s pastures and rangelands, 66% in Wyoming, and 39% in Utah.

In early July, pasture losses reached 70–90% in some areas, such as Routt and Moffat counties in northwest Colorado, and in northeastern Colorado. Very poor forage conditions were also being reported at lower elevations throughout central and southern Utah. Dryland crops throughout the region have also suffered greatly in the hot, dry conditions. On July 3, a disaster declaration was made by the US Department of Agriculture for 62 of 64 Colorado counties due to crop and livestock production losses, following similar declarations in late June for four counties in Wyoming.

Figure ET-1. Cumulative seasonal evapotranspiration (ET) curves as calculated from meteorological observations at the Idalia CoAgMet station in northeastern Colorado. July 1, the 2012 ET curve (black) is running higher than in 2002 (red), and about 7” more than the average ET from 19922012 (dashed). This excess ET is on top of a precipitation departure of about 5” at this station from April - June. (Source: Colorado Climate Center,


Figure VG-1. eMODIS VegDRI analysis for July 8, 2012. The VegDRI is a modeled indicator of drought stress on vegetation based on satellite observations of vegetation greenness, climate-based drought indices, and biophysical land surface characteristics.(Source: USGS EROS,



2012 Wildfire Season – Large, destructive fires in all three states, much of region at very high to extreme fire danger by late June; similar to 2002

The very low spring precipitation, combined with above-average temperatures, set the stage for an early start to what has become a very active fire season. By the middle of June, and observed and modeled fuel moisture conditions had fallen to levels not seen since 2002 in much of the region, and extreme fire weather (“red flag”) conditions were occurring frequently, aided by moderate to strong winds. As of July 10, each of the states in the region had experienced one wildfire over 80,000 acres and multiple wildfires over 10,000 acres. In Colorado, three different wildfires have caused homeowner fatalities, the first in several decades, with over 600 homes destroyed in those fires. Utah has also suffered a non-firefighter fatality and dozens of homes destroyed.

Reconstructions of fire frequency and climate from tree rings indicate that the most widespread fire years in the interior West, such as 1748 and 1851, occurred when a very dry year followed a wet year which builds up the fine fuels which carry surface fire. This year fits that pattern more closely than did 2002.

Rains at the end of June and in early July moderated the fire danger across the region, especially in eastern and central Colorado. Even so, high and very high fire danger were still prevalent throughout the region as of July 10 (Figure WF-1), with the worst conditions in southern Wyoming, central Utah, and northwest Colorado. Two new fires on July 10 in western Colorado demonstrate the persistence of the wildfire risk.

Figure WF-1. Observed Fire Danger Class for June 26, 2012 (top); July 10, 2012 (bottom left), and July 10, 2002 (bottom right). June 26 was the day that the Waldo Canyon Fire surged into Colorado Springs, and other large fires started in the region. The Fire Danger Rating level takes into account current and antecedent weather, fuel types, and both live and dead fuel moisture. (Source: U.S. Forest Service Wildfire Assessment System;

Further amelioration of fire danger in Colorado and southern Utah was expected as the typical monsoonal moisture comes into the region, as reflected in the monthly and seasonal outlooks for significant wildland fire potential (Figures WF-2 and WF-3). Significant fire potential was expected to remain above normal through the summer in far northwestern Colorado, most of Wyoming, and central Utah.

Figure WF-2. Significant Wildland Fire Potential Outlook for July 2012. (Source: National Interagency Fire Coordination Center;

Figure WF-3. Significant Wildland Fire Potential Outlook for AugustOctober 2012.(Source: National Interagency Fire Coordination Center;


Outlook for Drought Persistence – emerging El Niño points to increased chances of wet conditions through fall for most of the region

Despite the significant rains in Colorado in early July, drought conditions still persist there, and across the region. Given the magnitude of the precipitation departure and water supply deficit, drought impacts will likely persist for months to come. The emergence of El Niño conditions does raise the prospect of improved moisture over the next several months, as El Niño is historically correlated with above-average late summer and fall precipitation in the region. The correlation is strongest in eastern Wyoming and Colorado in the summer, and in Utah and Colorado in the fall.

While NOAA has not yet officially declared an El Niño event, it has hoisted an "El Niño Watch," indicating that sea surface temperatures in key areas in the tropical Pacific averaged over a 3-month period are nearing the thresholds for declaring an event (Figure EN-1). The latest (May-June) values for the Multivariate ENSO Index (MEI), which uses a broader set of ENSO indicators, have already risen into the "borderline moderate" El Niño category. The emergence of El Niño and its persistence into the winter season is also projected by the majority of models collated by CPC and IRI in mid-June, with the dynamical models almost unanimous in calling for El Niño development and persistence.

Figure EN-1. Figure EN-1. Time-longitude map of observed SST anomalies (upper) in the Pacific Ocean between 80°W–120°E and 5°N–5°S, over the period August 2011 (top) to early July 2012 (bottom). The yellow and orange shading at the bottom right shows the emergence of warmer conditions in the past several months, progressively extending to the west. The blue box shows conditions since mid-June over the Niño 3.4 region, which is used as a key indicator for monitoring and forecasting ENSO conditions. (Source: NOAA Climate Prediction Center)

Figure EN-2. Forecasts made by dynamical and statistical models for sea surface temperatures (SST) in the Niño 3.4 region for nine overlapping 3-month periods from June–August 2012 to February–April 2013 (released June 20, 2012). (Source: International Research Institute (IRI) for Climate and Society)

The Seasonal Drought Outlook from the NOAA Climate Prediction Center issued July 5 has not integrated the likely prospect of El Niño conditions this summer and fall, and calls for persistence of drought conditions through September across the region, except in far southeastern Utah and southwestern Colorado, where the southwestern monsoon is expected to produce wet conditions extending northward from Arizona and New Mexico (Figure DO-1). The Seasonal Drought Outlook is based on the CPC seasonal outlooks for precipitation and temperature (Figures PPT-1 and TEMP-1).


Figure DO-1. Seasonal Drought Outlook for July 5, 2012–September 2012. (Source: NOAA Climate Prediction Center)



Figure TEMP-1. Long-lead national temperature outlook for July–September 2012. (Source: NOAA Climate Prediction Center)


Figure PPT-1. Long-lead national precipitation forecast for July–September 2012. (Source: NOAA Climate Prediction Center)


Other selected resources for drought monitoring

US Drought Portal (NIDIS)

Colorado Drought Portal

Wyoming Drought Portal

Utah Drought Portal

Upper Colorado River Basin Portal

Colorado Climate Center -
Drought status webinars (Colorado and Upper Colorado River Basin)

Wyoming State Climate Office - Drought Page

Utah Climate Center (monthly climate updates at lower left on home page)

NOAA Colorado Basin River Forecast Center - Water Supply Map-

Colorado Water Conservation Board - Drought Status and Monitoring

High Plains Regional Climate Center - Current Climate Maps



The Intermountain West Climate Summary is published six times annually by the Western Water Assessment (WWA). WWA is a program of the University of Colorado Cooperative Institute for Research in Environmental Sciences (CIRES), funded as a Regional Integrated Sciences and Assessments (RISA) program by the National Oceanic and Atmospheric Administration (NOAA) Climate Program Office, and hosted by the NOAA Earth System Research Laboratory (ESRL) in Boulder, CO.

Disclaimer: This product is designed for the provision of experimental climate services. While we attempt to verify this information, we do not warrant the accuracy of any of these materials. The user assumes the entire risk related to the use of this data. WWA disclaims any and all warranties, whether expressed or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose. This publication was prepared by CIRES/WWA with support in part from the U.S. Department of Commerce/NOAA, under cooperative agreement NA17RJ1229 and other grants. The statements, findings, conclusions, and recommendations are those of the author(s) and do not necessarily reflect the views of NOAA.


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