NIDIS Intermountain West
Drought Early Warning System
June 25, 2019

Precipitation


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. -1.0 to -1.5 is equivalent to a D1 to D2. -1.5 to -2.0 is equivalent to a D2 to D3. -2.0 and worse is equivalent to a D3 to D4. 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.

Snotel and Snowpack

The above image shows SNOTEL snowpack percentiles for each SNOTEL site in the Intermountain West. The images below show accumulated snow water equivalent in inches (green) compared to average (blue) and last year (red) for several different sub-basins across the UCRB (and were created by the Colorado Basin River Forecast Center).

Streamflow





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 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.

Temperature

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.

Troy Huse with Utah USDA- Sanpete County, "starting to get hotter and drying out a little.  Lingering effects of the 2018 drought, still havent hit peak run off yet."

Chuck Hanagan with Colorado USDA- Rocky Ford- "Scatter showers bringing everyone in the area precipitation.  However, localized storms mean some received 0.02 while other received 1.50 of precipitation.  Good reports of grass and crops.  Most ditches full."

Dawna Weirich with Colorado USDA Kiowa County- "FSA report of 12.00 on 6/18, roads washed out.  Wheat is beginning to turn and needs to dry out a little before cutting."  Verification of 12.00 in progress. 

Outlook


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.
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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: June 25, 2019

After a large snowpack year, and a cold, wet May, the Intermountain West has finally said "goodbye" to most of its seasonal snowpack below treeline. The view from an airplane reveals no shortage of snow still above 11,000 ft. Streamflows are running above average, and reservoirs continue to fill. Both the Colorado River near the CO-UT state line, and the San Juan River near Bluff, UT recently crested at about 90th percentile peak flows. Cumulative water year streamflows, which started out low, have rebounded to average on the San Juan, and are above average on the Colorado and Green Rivers. Lake Powell water storage is rising, but will not recover to normal in one season; not even this one.

The Intermountain West was subjected to a seasonal June precipitation pattern this last week; dry in the southwest portions and wet in the northeast portions. North-central Colorado was anomalously wet. A large swath of 2+" of precipitation fell from Meeker to Wellington. With much thanks to an unseasonably strong cold front that came through on Thursday, it was a cooler than average week for most of the Intermountain West as well. This week was one of many cooler than normal offerings over the last two months. The month of June to date has been cooler than normal for most of the Intermountain West. These cooler temperatures have been a welcome change from last year. At this time last year, fire season was in full swing. The fire situation now is much less serious (knock on wood).

The coming week looks to be the warmest and driest weather the IMW has experienced in some time. Temperatures will be mostly above normal. Some 90 degree days are possible in the valleys with 100+ weather on tap or the southwest portions of the region. Precipitation amounts will be mostly light save for the occasional scattered thunderstorm, and will be mostly confined to the southern Rockies. The 8-14 day outlook shows increased chances of below normal precipitation for the western IMW, and increased chances of above normal precipitation for the eastern IMW.

Recommendations:  

IMW: Status quo. Parts of the south and west IMW were dry, but this is normal for this time of year. Short and medium-term SPIs are still mostly normal or above normal. With the cooler temperatures recently as well, there's no need to reintroduce D0 anywhere this week. We'll defer to our colleagues in NM on their official drought amelioration commentary. Given it was dry in their neck of the woods, it's probably not an opportune week for improvements.