NIDIS Intermountain West
Drought Early Warning System
October 15, 2019


The images above use daily precipitation statistics from NWS COOP, CoCoRaHS, and CoAgMet stations. From top to bottom, and left to right: most recent 7-days of accumulated precipitation in inches; current month-to-date accumulated precipitation in inches; last month's precipitation as a percent of average; water-year-to-date precipitation as a percent of average.

Standardized Precipitation Index

Standardized Precipitation Index standardizes precipitation accumulations for a specified time period into percentile rankings. Colors match the different drought categories with the U.S. Drought Monitor. 30- and 60-day SPIs focus on short-term conditions while 6- and 9-month SPIs focus on long-term conditions. SPI data provided by High Plains Regional Climate Center.


The top left image shows 7-day averaged streamflows as a percentile ranking across the UCRB. The top right image shows 7-day averaged discharge over time at three key sites around the UCRB: The Colorado River at the CO-UT state line; the Green River at Green River, UT; and the San Juan River near Bluff, UT. All streamflow data provided by United States Geological Survey.

Surface Water

The top left image shows VIC modeled soil moisture as a percentile ranking. The top right image shows satellite-derived vegetation from the VegDRI product (which updates on Mondays).

The graphs shown below are plots of reservoir volumes over the past full year and current year to date (black). The dashed line at the top of each graphic indicates the reservoir's capacity, and the background color-coded shading provides context for the range of reservoir levels observed over the past 30 years. The data are obtained from the Bureau of Reclamation. Some of the reservoir percentiles don't line up at the new year due to differences in reservoir levels at the beginning of 1985 and the end of 2014.  Dead storage has been subtracted. Note: Lake Granby data are obtained from the Colorado Division of Water Resources, and only goes back to the year 2000.

Evaporative Demand

The above images are of reference evapotranspiration (ET) from CoAgMET sites across Colorado. Reference ET assumes the amount of water that will evaporate from a well-irrigated crop. Higher ET rates occur during hot, dry, and windy conditions. Lower ET rates are more desirable for crops. See a map of locations for the above ET sites.

The above images are available courtesy of NOAA’s Evaporative Demand Drought Index (EDDI). Drought classification listed is a function of the depth of reference evapotranspiration accumulated over a given period of record with respect to a climatology of 1981-2010. The drought categories displayed are in line with the US Drought Monitor's Percentile Ranking Scheme. Data used to generate these maps come from the North American Land Data Assimilation System Phase-2 (NLDAS-2) project, which assimilates observations of temperature, wind speed, radiation, and vapor pressure deficit. The date indicates the last day of the period of record, and the week number indicates the window size for the period of record.


All images show temperature departures from average over different time periods (last 7 days on top left; month-to-date on top right; last full month on bottom). Temperature departure maps provided by HPRCC ACIS.

Condition Monitoring and Impacts

Map of current condition monitoring reports submitted to CoCoRaHS in the last week overlaid on the current U.S. Drought Monitor depiction. Specific impacts reports from local experts listed below.

Impacts in Central and East-central Utah:

Very little precipitation, mostly just wind south of Provo.  Most producers are having to haul water and hay to keep livestock fed.  There is some feed still on the rangeland, but the water isn't there to keep it going.  Producers are planning to haul hay rather than sell off livestock.


Impacts from southwest Colorado:

At the CSU Yellow Jacket Research Farm 0.30" of rain were received a few weeks ago and the dryland fall planting still didn't germinate.  It feels like we went from wet/cool spring to hot/dry all summer.  When watering alfalfa planted in August it seemed to dry out very quickly.  A farmer in Mancos said he only had 0.30: since June.  Irrigation water made it an OK year, but they observed how quickly the fields dried out after it turned hot this summer.


Eastern CO:

Seems like no precipitation has fallen since the beginning of August and heat has just hung around.  Just had to drill winter wheat, earlier planted wheat has come up with what remained of the soil moisture.  The later planted winter wheat hasn't come up yet and may not unless a good shot of precipitation comes before winter.  The other concern is pasture grasses.  Hoping for a good winter so they come back strong.
Dryland corn has been harvested and had an OK year.  Spring crops hung in well through the summer and yields were near or above average this year.


The top two images show Climate Prediction Center's Precipitation and Temperature outlooks for 8 - 14 days. The middle image shows the Weather Prediction Center's Quantitative Precipitation Forecast accumulation for seven days. The bottom left image shows the 3-month precipitation outlook from Climate Prediction Center, and the bottom right image shows the Climate Prediction Center's most recent release of the U.S. Seasonal Drought Outlook.

Summary and Recommendations

Above is the most recent release of the U.S. Drought Monitor map for the UCRB region. Below shows the proposed changes for this week, with supporting text.

Summary: October 15 2019

Last week for the Intermountain West region was dry with the exception of spotty precipitation in northern/central Wyoming, along the Front Range of northern Colorado, and southern New Mexico.  Wyoming saw up to 0.25" in most areas except for the northwest corner where counties such as Park saw up to 1.0” of precipitation and a dry spot with little to no precipitation over the southwest corner.  Northern Colorado Front Range, Larimer, Grand, and Eagle counties, received 0.26-1.00” of precipitation.  Southern New Mexico saw some spotty precipitation, with much of the area seeing 0.01 to 0.25” and Socorro county seeing over 1.00”. North New Mexico missed out on the moisture this week, along with the rest of the IMW region, receiving less than 0.10" of precipitation.

Despite the dryness, temperatures were below average for the much of the IMW region.  The exception is southern NM/AZ where some counties experienced near normal temperatures.  However, most of NM/AZ experienced cooler than average temperatures, some northern counties such as Rio Arriba in NM and Navajo in AZ saw temperature departures of 6 to 9 degrees cooler than average.  CO/UT/WY was even cooler with the entire area seeing temperature departures of at least 3 to 9 degrees below average while some areas such as western UT and northern WY were even cooler still with temperature departures of 9 to 15 degrees. This was a nice change from the past few months when the IMW experienced temperatures much above normal with Colorado and New Mexico seeing the warmest September on record.

Streamflows in the UCRB are starting to show the recent dryness with an increasing number of stream gauges showing below normal flows.  The driest of the gauges are showing up in the headwaters of the Colorado River.  The Basin as a whole is still in good shape with the key gauges seeing flows in the normal region.

Outlook is showing low precipitation probability over the whole IMW for the next couple weeks with below average temperatures in WY/CO/NM.  UT and AZ are expected to see above average temperatures.  A lack of precipitation and above average temperatures in southern UT and northern AZ is something to keep an eye on in the upcoming weeks.


UCRB: Status Quo.  While most of the area saw little to no precipitation the temperatures for the week were well below average.  Cooler temperatures have helped to offset the lack of precipitation.  Improvements were considered over southern WY.  Although SPIs look okay in the short-term, they’re still slightly negative longer-term and the area hasn’t received much moisture over the past week.  Over southwest Utah we considered possibly expanding D1 northward based on high evaporative demand and negative SPIs, but conditions didn’t worsen this past week thanks to cooler temperatures.

Eastern Colorado: Status Quo.  While most of the region east of the Front Range saw little to no precipitation the temperatures for the week were well below average. We considered expansion of D0 northeastward, towards Washington county.  EDDI shows D2-equivalent or worse on the 1 and 2-month timescales however the 1-week EDDI shows improvement over this region compared to last week so we decided to hold off.