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Regional Drought Update Date
February 25, 2021
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Drought Status Update

Drought Update for the Intermountain West


DEWS Regions:
Update Status:

NIDIS and its partners will issue future drought updates as conditions evolve.

Below-average snowpack and a dry forecast: Potential drought impacts through spring in the Intermountain West.

 

Key Points

  • Despite recent precipitation, long-term exceptional drought conditions persist over areas of the Intermountain West U.S. (Arizona, Colorado, New Mexico, Utah).
  • Snowpack so far this season has been low, but improved from last month.
  • Dry conditions are expected to continue for the southwest
Current Conditions
U.S. Drought Monitor Conditions: Intermountain West | February 23, 2021

Current U.S. Drought Monitor map for the Intermountain West Drought Early Warning System (DEWS) region with data valid for February 23, 2021. The U.S. Drought Monitor (USDM) is updated each Thursday to show the location and intensity of drought across the country. 

Extreme (D3) to Exceptional (D4) Drought persists across much of the Intermountain West (65% of the region).

U.S. Drought Monitor Categories

The color with the hex code #ffff00 identifies:
D0 - Abnormally Dry
The color with the hex code #ffcc99 identifies:
D1 - Moderate Drought
The color with the hex code #ff6600 identifies:
D2 - Severe Drought
The color with the hex code #ff0000 identifies:
D3 - Extreme Drought
The color with the hex code #660000 identifies:
D4 - Exceptional Drought
Main Stats
85%
of Arizona is in Extreme to Exceptional (D3–D4) Drought
57%
of Colorado is in Extreme to Exceptional (D3–D4) Drought
82%
of New Mexico is in Extreme to Exceptional (D3–D4) Drought
90%
of Utah is in Extreme to Exceptional (D3–D4) Drought
23%
of Wyoming is in Extreme to Exceptional (D3–D4) Drought

Recent and Current Conditions

U.S. Drought Monitor Conditions

  • Extreme (D3) to Exceptional (D4) drought persists across much of the Intermountain West (65% of the region):
    • Arizona (85% of the state)
    • Colorado (57%)
    • New Mexico (82%)
    • Utah (90%)
    • Wyoming (23%)
  • Extreme (D3) drought conditions have been in place in this region since May 2020.

Current Snow Water Equivalent (SWE)

  • Most of the Intermountain West has experienced low SWE for this winter, so far. Recent storms (February 2021) have made large improvements to the snowpack across the west, but SWE still sits below average for this time of the season.
  • Of note, upper Colorado River basin (upper and lower) catchments are currently at 74% of the USDA Natural Resources Conservation Service 1981-2010 median.

Snow Water Equivalent in the Upper Colorado Region

A snow water equivalent time series for winter 2020-2021 for the upper Colorado River Basin. Current snow water equivalent is 86% of the historical median.
Source: USDA Natural Resources Conservation Service.

Snow Water Equivalent Percent of Median: January 21 vs. February 21

Snow water equivalent maps of the Intermountain West for January 21, 2021 (left) and February 21, 2021 (right). All basins show improvement from one month to the next.
Snow water equivalent maps of the Intermountain West for January 21, 2021 (left) and February 21, 2021 (right). Source: USDA Natural Resources Conservation Service.

February Precipitation

Precipitation through February was mixed across the Intermountain West with the region as a whole measuring near-average precipitation.  

Precipitation Conditions: January 23–February 21, 2021

Left: 30 day precipitation totals to February 23, 2021. Right: 30 day percent of normal precipitation to February 23, 2021.
Left: 30-day precipitation totals from January 23 to February 21, 2021. Right: 30-day percent of normal precipitation to from January 23 to February 21, 2021. Source: High Plains Regional Climate Center, ACIS Climate Maps.

February precipitation included region-wide (except southern Arizona) rain and snowfall from February 14–18.

72-Hour Snowfall Accumulation: February 15, 2021

 Map of the continental U.S. showing 72-hour snowfall accumulation to February 15, 2021. Most of the western and central U.S. received between 3 and 12 inches from a storm that began on the 14th.
 72-hour snowfall accumulation, February 15, 2021. Source: NOAA National Operational Hydrological Remote Sensing Center (NOHRSC).

Evaporative Drought Demand Index (EDDI)

4-Week EDDI for February 20, 2021

  • EDDI values have been favorable for Utah and Colorado over the past month.
  • There is high evaporation demand for this time of year across southern Arizona and New Mexico. 
4-week averaged Evaporative Demand Drought Index (EDDI) as of 20 February 2021. Areas of average to low EDDI are shown in white and blue and cover most the northern states and the central plains. Areas of high EDDI are shown in yellow and red and cover southern California, Arizona and New Mexico.
4-week Evaporative Demand Drought Index (EDDI) for February 20, 2021. Source: NOAA/Earth System Research Laboratories/Physical Sciences Laboratory.

Seasonal Outlooks: March–May 2021

Temperature Outlook

For March–May, there is a greater chance for above-normal temperatures across the Intermountain West, with the highest probabilities in southern New Mexico.

Climate Prediction Center 3-month temperature outlook, showing the probability of exceeding the median temperature for the months of March through May 2021. Odds favor below normal temperatures for the Pacifc northwest while odds favor above normal temperatures for the rest of the country with especially high odds for above normal temperatures for New Mexico and Texas.
3-month temperature outlook for the U.S., showing the probability of exceeding the median temperature for the months of March through May 2021. Source: NOAA Climate Prediction Center.

Precipitation Outlook

The Climate Prediction Center's precipitation outlook shows that below-average rainfall is the most likely outcome for March–May across the southwest, including Arizona, New Mexico, Colorado, most of Utah, and southern Wyoming.

Climate Prediction Center 3-month precipitation outlook, showing the probability of exceeding the median precipitation for the months of March through May 2021. Odds favor below normal precipitation for most of the Intermountain West while odds favor above normal precipitation for the northwest and the Great Lakes regions.
3-month precipitation outlook for the U.S., showing the probability of exceeding the median precipitation for the months of March through May 2021. Source: NOAA Climate Prediction Center.

Drought Outlook

Despite recent precipitation, drought conditions are forecast to continue at least through May across the Intermountain West.

Climate Prediction Center seasonal drought outlook, showing the probability drought conditions persisting, improving, or developing March through May 2021. Current drought conditions over the western US are forecast to persist while drought development is likely for parts of Kansas, Oklahoma, Texas, and Florida.
U.S. seasonal drought outlook, showing the probability drought conditions persisting, improving, or developing for March through May 2021. Source: NOAA Climate Prediction Center.

Climate Patterns

  • NOAA’s ENSO alert system status is currently a La Niña advisory with moderate La Niña conditions over the equatorial Pacific. 
  • There is a ~60% chance of a transition from La Niña to ENSO-Neutral during the Northern Hemisphere spring 2021 (April–June). 
  • Historically, the southwest has experienced continued dryness into spring during La Niña conditions. 

March–May Precipitation During La Niña: Increased Risk of Wet or Dry Extremes

Risk of wet or dry extremes from the historical composite of March through May La Ninas from NOAA ESRL/PSL for the continental US. Extreme dry conditions are likely for much of the Southwest and Florida.
March-April-May (MAM) rainfall pattern when averaged over historical La Niña events. Source: NOAA/Earth System Research Laboratories/Physical Sciences Laboratory.

For more information, please check out the NOAA ENSO blog and the Western Regional Climate Center info page about the La Niña impacts for the west.

State-Based Conditions and Impacts

Arizona

  • Statewide precipitation is 2.08 inches below water year average through January, making it the 14th driest water year on record so far.
    • Snowpack (SWE) in the Salt River and Upper Gila river basins are below 50% of normal.
  • Dry soil beneath the snowpack will reduce run-off and aquifer recharge.
  • Exceptionally hot and dry monsoon killed hundreds of Saguaro cacti in central and southern Arizona, largely due to extreme soil temperatures. Saguaros take decades to reach 3 feet tall and can live 150–200 years.

SNOTEL Snow Water Equivalent Percent of Normal

 Arizona snowpack. Verda System average is 81% of normal Snow Water Equivalent (SWE) and has virtually no reservoir storage. The Salt System Average is 50% of normal SWE and had the largest reservoir.
Source: USDA Natural Resources Conservation Service.

Colorado

  • A series of winter storms in mid-February provided 2–4 inches of precipitation to western Colorado.
  • Snowpack along the western slopes is currently 80%–90% of normal. Catchments east of the Divide are 90%–100% of normal.
  • 2020 was Colorado's second driest calendar year on record, leaving soils, base flows, and some reservoirs low entering 2021.

90-Day Standardized Precipitation Index (SPI): January 23, 2020–February 20, 2021

This map of Colorado shows which rainfall stations are experiencing a high or low Standardised Precipitation Index (SPI) for the 90 day to 20 February 2021. This shows low to very low SPI values across western Colorado
90-day Standardized Precipitation Index (SPI) for Colorado, valid February 20, 2021. Source: High Plains Regional Climate Center, ACIS.

New Mexico

  • Snowpack in the Upper Gila, Upper Pecos, and Rio Grande-Mimbres regions is still below 50% for this time of the season.
  • Precipitation for February-to-date has been below average, overall, for the state.
  • Long-term drought shows up clearly in surface water levels in the Rio Grande and Pecos Basins. For example, Elephant Butte storage is 9% of capacity.
Storages on the Rio Grande and Pecos River Basins. Elephant Butte is at 9% full, Caballo is at 14%, Sumner is at 52%, Brantly is at 32% and Avalon is at 55%.
Rio Grande and Pecos River Basin storage as of February 23, 2021. Source: U.S. Bureau of Reclamation.

Utah

  • All but the northern Wasatch Range is in a deepened drought situation that is twice as bad as a year before (from December 1, 2020 through February 22, 2021), as shown in the first figure of soil moisture deficit map below based on GRACE data. Southwest Utah remains the worst hit.
  • The weekly time series of the GRACE data averaged over Utah shows a continual decline in groundwater despite the recent precipitation events, as shown in the second figure. This suggests the “sponge effect” of a very-dry subsurface in absorbing the large precipitation that otherwise would have eased the drought. This is evident in the depression of surface soil moisture after the recent storms.
  • Recent snowfall has helped snowpack conditions, as shown by the third graphic of SNOTEL change in snow water equivalent observations between February 1 and February 23. Supporting the evidence that while snowfall has occurred, soil moisture is still significantly outside of historical boundaries, as shown in the yearly comparison of statewide soil moisture conditions in the final figure.

Rootzone Soil Moisture Deficit: Dec. 1, 2020–Feb. 22, 2021 Compared to One Year Ago

Map of the western US showing rootzone soil moisture percentiles between 1 December 2020 to 22 February 2021 compared to the same period one year ago. The data shows a drop by 35 to 75 percentiles for most of the western US.
Rootzone soil moisture percentiles between December 1, 2020 to February 22, 2021 compared to the same period one year ago.

Utah Groundwater Conditions

A weekly time series of the GRACE data averaged over Utah shows a continual decline in groundwater from January 2020 through February 2021.
Weekly time series of GRACE data averaged over Utah. 

Utah Change in Snow Water Equivalent Values: February 1–23, 2021

Change in SNOTEL observed snow water equivalent values between February 1 and February 23.
Change in SNOTEL observed snow water equivalent values between February 1 and February 23. Northern Utah has benefited the most while much of the state has seen impactful snowfall. Southern Utah has fared the worst this month.

Utah Soil Moisture Conditions

Period of record comparison for statewide soil moisture observed by the SNOTEL/SCAN network. The black line represents the 2021 water year while the historical range of observations over all observed years is shown with the rainbow color scale.
 Period of record comparison for Utah soil moisture observed by the SNOTEL/SCAN network. Source: USDA Natural Resources Conservation Service.

For More Information

More local information is available from the following resources:

Prepared By

Joel Lisonbee
NOAA/National Integrated Drought Information System (NIDIS)

Nancy J. Selover
Arizona State Climatologist/Arizona State University

Simon Wang and Jon Meyer
Utah Climate Center/Utah State University

Dave DuBois
New Mexico Climate Center/New Mexico State University

Peter Goble
Colorado Climate Center/Colorado State University

Special Thanks

This Drought Early Warning Update is issued in partnership between the National Oceanic and Atmospheric Administration (NOAA), and the offices of the state climatologist for Arizona, Colorado, New Mexico, Utah, and Wyoming. The purpose of the update is to communicate a potential area of concern for drought expansion and/or development within the Intermountain West based on recent conditions and the upcoming forecast. NIDIS and its partners will issue future drought updates as conditions evolve.