NIDIS Intermountain West
Drought Early Warning System
February 11, 2020

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. 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.

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.

San Juan County, Utah Extension Director: Above normal for snowfall and precipitation right now.  The events have been very timely and beneficial to improving conditions.

Central and Eastern UT: The general consensus is D1 is still appropriate for now.  They unfortunately have missed out on recent storm events and could be teetering on the edge of falling back into D2 if storms don't come in the next couple of weeks.

Front Range Colorado Water Managers: Very happy with above normal snowpack in the mountains and water supplies are looking good.

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: February 11, 2020

Decent precipitation fell through much of the northern and central Rockies of Colorado and along the Front Range, with this area seeing at least 0.50" of precipitation over the last week.  This is a very welcome sight for the Front Range of Colorado after a very dry January.  Other areas seeing a nice amount of precipitation in the Intermountain West was a line of 0.50" plus precipitation amounts from northwest Wyoming into northern and central Utah along the Wasatch range. 

Not showing up on our precipitation maps that end Monday morning is the additional precipitation that fell Monday along Colorado's Front Range, additional amounts up to a quarter inch, higher amounts farther south.  More impressive are the precipitation numbers coming out of the Phoenix area, with amounts up to 1.25".  New Mexico also saw beneficial precipitation from precipitation on Monday, with Albuquerque receiving a few inches of snow, translating to around a half inch of precipitation.  Other half inch amounts popped up in southern New Mexico as well.

Standardized precipitation index values (SPIs) are a mixed bag across the region and across time scales. For the Four Corners area, very dry SPIs still show up on the 6-month timescale. In the short-term 30-day timescale, dry SPIs dominated much of Utah.  Colorado is wet in the northern and central mountains and the Front Range, near normal to dry for the rest of the state.

Snowpack across the region is looking good, with the entire IMW region seeing above normal snowpack.  With the systems moving through, the region saw a nice cool down with below normal temperatures over much of the region.  This has helped with the month-to-date temperatures cool to near normal.  This will help with the evaporative demand, even while some areas remain dry.

The next 7-days starting Tuesday is showing a shot of precipitation in the mountains of Colorado, Utah and Wyoming and a nice shot of precipitation for much of New Mexico.  The 2-week outlook is hinting at chances for below normal precipitation for the western half of the IMW region and chances of above normal for the eastern half, with temperatures leaning to the cool side of normal for the region.

Recommendations: 

UCRB: Trimming of D0 in southwest Wyoming, northern Utah and northwestern Colorado along with trimming of D1 in northwestern Colorado and slightly into Utah is recommended.  Beneficial snowfall amounts the last week and in January have bumped up snowpack to better than 120% of normal for most of the region.

While Utah is looking alright, the consensus of the Utah Drought Group is that D1 is still appropriate for eastern and central Utah for the time.  They seem to miss most of the good events and are still teetering on the edge of falling back into D2 conditions.  Since they are on the edge of D1/D2, D1 is still appropriate.

The D2 of San Juan County in southern Utah and southern Colorado could be ready to be improved to D1, however, we need some cross boarder help on this improvement, so I'm throwing out the recommendation for suggestions.

Eastern Colorado: D0 improve to Dnada for El Paso and surrounding counties, catching Pueblo and D1 improved to D0 for Pueblo and Huerfano counties.  This is thanks to heavy precipitation/snow, above normal snowpack and the positive mood of water suppliers along the Front Range.