NIDIS Upper Colorado River
Regional Drought Early Warning System
February 9, 2016


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.

 

Last Week Precipitation:

  • The UCRB saw a mixed week for precipitation.  This weeks precipitation maps also catch the end of the snow storm that hit the area.  The entire area was drier after the storm ended early Tuesday the 2nd.
  • The Upper Green River Basin in Wyoming saw less than 0.10 inches in the valleys of Sublette County and central Sweetwater County.  Lincoln and Uinta counties saw up to 1.00 inches last week.
  • Eastern Utah mostly saw less than 0.50 inches.  The Uintah range in Summit, Daggett and northern Duchesne counties saw up to 1.00 inch.  Central San Juan County also saw up to 1.00 inch.
  • Western Colorado saw between 0.25 - 1.00 inches in the higher elevations towards the Divide.  Western Moffat, Rio Blanco, Garfield, Mesa counties were drier seeing less than 0.25 inches.
  • The San Juan Mountains saw a good week of snowfall, with between 1.00 and 2.00 inches of liquid falling.
  • The Rio Grande Basin saw less than 0.10 inches in the valley, and up to 1.00 inches in the mountains.
  • Eastern Colorado was wet at the beginning of the 7 day period with the end of the snowstorm brining up to 1.00 inches over most of the area, and some areas seeing over an inch of liquid falling into Tuesday morning.  Most of eastern Colorado was dry from Tuesday through Sunday, with dry sunny days.  There was a nice line of precipitation through Logan, Washington, Elbert, Lincoln, El Paso, Teller and Pueblo counties that fell on the 4th.  Most of the areas saw less than 0.20 inches of liquid with this storm.

January Precipitation:

  • January, the UCRB mainly saw at or above normal precipitation for the month.
  • In the Upper Green River Basin, Sublette County was near normal, Sweetwater County saw areas with up to 200% of normal and there was an area of over 200% of normal for the month in Lincoln and Uinta counties.
  • Eastern Utah saw near to slightly above normal precipitation in the northern areas, with over 200% of normal January precipitation in the southern parts of Utah.
  • Western Colorado saw mostly near to above normal precipitation for the month.  Mesa, Delta, Montrose and parts of Gunnison counties saw areas of over 200% of normal January precipitation.
  • East of the Divide saw a month with normal to above normal precipitation from Logan County down to western Las Animas County, up to the Divide.  East of this line was drying, with much of this area seeing less than 50% of normal January precipitation.

Water Year 2016 Precipitation (Oct-Jan):

  • Most of the UCRB and eastern Colorado has seen a near to above normal start to the 2016 Water Year through January.
  • Most of the Upper Green Basin is seeing a normal start to the water year, with Lincoln and Uinta counties seeing much above normal.
  • Eastern Utah is also starting off with a normal water year through January.  Southern Utah has seen over 170% of normal precipitation through January.
  • Western Colorado is mostly normal or slightly above normal to start the water year as well.
  • Eastern Colorado has mostly seen a normal to above normal start to the water year.  Southeastern and parts northeastern Colorado is over 170%.

Additional Precipitation Links: (will take you to an outside website)
AHPS Precipitation
High Plains Regional Climate Center's ACIS Maps


The top left image shows the Natural Resources Conservation Service's SNOTEL water-year-to-date precipitation percentile rankings. The top right image shows sub-basin averaged snow water equivalent accumulations as a percent of average. 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).

SNOTEL Precipitation Percentiles:

  • SNOTEL Water Year precipitation percentiles in the Upper Green Basin are mostly below the median.  Percentiles in the northern portions of Sublette County are between the 22nd and 59th percentile.  Percentiles in Lincoln and southern Sublette counties range from the 15th to the 44th.
  • The Uintah Range is in the average range, but there is a lot of spread. SNOTEL water year to date percentiles are between 26th and 96th.
  • In the Wasatch Range there is a gradient from north to south with the northernmost percentiles being the lowest. The southern Wasatch Range and all SNOTEL precipitation percentiles in southeast Utah are well above average with one exception in Plute County.
  • The northern Rockies in Colorado extending into Wyoming percentiles are in the normal range. A few percentiles in Routt, Larimer and along the Divide in Grand counties, are above the 60th percentile. 
  • The Rockies of central Colorado have fallen a little in percentile ranking, but are still in pretty good shape. There is an anomaly in Eagle County at the 21st percentile, but the rest range from the 30th to 78th percentile. 
  • The San Juans are well above the median for the water year to date, with most above the 70th percentile. Percentiles in Mineral and Hinsdale Counties the only below the 70th, but still above the median.
  • The Sangre de Cristos are slightly above average, and range from 47-78.

 SWE Timeseries Graphs:

  • All sub-basins in the UCRB are now at or above median snowpack to date.
  • The Upper Green Basin has rebounded a bit, now at 97% of median snowpack to date.
  • The Duchesne basin is at 95% of median snowpack.
  • The Yampa River Basin is at 106% of median snowpack to date.
  • The Upper Colorado River Mainstem is now at 111% of median snowpack.
  • The Gunnison Basin is at 118% of median snowpack for the season to date.
  • The San Juan Basin is at 115% or median snowpack to date.

Additional SNOTEL and Snowpack Links: (will take you to an outside website)
CBRFC Snow Conditions Map
NOHRSC Regional Snow Analyses: Central Rockies


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.

Short Term (30-day):

  • SPIs in the UCRB are mostly in the normal range (-1 to +1) over the past 30 days. 
  • The Green River Basin has one SPI in northern Subtlette County at 0 to -1 and with two gauges in Sweetwater County between 0 and +1.5.
  • Eastern Utah is showing a mix of slightly dry SPI and wet SPIs.  SPIs in the Duchesne Basin range between -1 and +1.  Southeastern Utah is showing SPIs mainly in the 0 to +1.5 range.  There is one SPI in San Juan county down to -1.
  • Western Colorado is showing mostly wet SPIs between 0 and +1.5. A station in Routt County is reporting up to +2 and a station in Mesa County is reporting up to +2.5.
  • After last weeks snowstorm, the majority of stations with SPIs are now in the 0 to +1.5 range, with a few up to +2.5.  There is still the pesky 0 to -1 SPI in Grand County.
  • The Rio Grande Basin is in the 0 to +1.5 range.
  • East of the divide, SPIs are in the wet range, mostly in the +1 to +2 SPI range.  SPIs in Larimer, Elbert, El Paso, Lincoln and Kit Carson counties are up to +3 now.  Washington, Otero and Prowers counties are still a bit drier, with an SPIs down to -1.

Long Term (6-month):

  • 6-month SPIs in the UCRB are trending a bit on the wetter side for lower elevations and a bit on the drier side for higher elevations.
  • The Upper Green River basin has been drying a bit in the long term, with stations in Carbon and Fremont counties reporting down to -1.5 SPI. 
  • Eastern Utah 6-month SPIs are mostly wet with the vast majority of SPIs between 0 and +1.5.
  • Western Colorado is still in the normal range, but now most stations are reporting above 0, with a few exceptions in Gunnison, Saguache, Rio Grande, and Mineral counties.
  • The San Luis Valley is showing 6-month SPIs in the normal range.
  • East of the divide the majority of 6-month SPIs are between -1 and +1. The northeast corner of the state is still showing some long-term dryness with SPIs down to -1.5. Some areas in Park, Summit, and Clear Creek counties are fairly dry as well. 

Additional SPI Links: (will take you to an outside website)
WestWide Drought Tracker SPI Maps
HPRCC's SPI Maps



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.

Streamflow Statistics:

  • The majority of stream gages in the UCRB are now ice-affected and not reporting. Only 40 out of 140 gages are reporting.
  • 81% of gages are reporting in the normal to much above normal range for the 7-day average streamflow.
  • 20% of gages reporting are in the below normal range.  No gages are reporting much below or lowest.
  • The Colorado River at the CO-UT state line is at 105% of normal and in the 67th percentile. 
  • The Green River at Green River, Utah is reporting at 140% of 7-day average, which corresponds to the 82nd percentile. 
  • The San Juan River near Bluff is ice affected.

Additional Streamflow and River Links: (will take you to an outside website)
USGS Streamflow Drought
CBRFC Peak Flow Forecast Conditions Map


The top left image shows VIC modeled soil moisture as a percentile ranking. The top right image shows VIC+SWE.


The above image shows last month's and this month's current volumes of the major reservoirs in the UCRB, with percent of average and percent of capacity.
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.


VIC:

  • Modeled soils moisture in the Green River Basin in Wyoming continues to be much below normal. Most of eastern Sweetwater County, soil moisture is below the 2nd percentile. All of Sweetwater, and now parts of Sublette and Uinta Counties are below the 20th percentile. 
  • Soils in eastern Utah are mostly in the normal range with a bit of a gradient from northwest to southeast. Areas farther north such as Duchesne, Uintah, and Emery Counties are indicating some dry patches of soil between the 10th and 30th percentile. Some areas farther south such as eastern San Juan and eastern Grand Counties are showing soils between the 70th and 90th percentile. 
  • Soils in western Colorado are by and large either in the normal range or a bit above normal. Areas farther south are more likely to be above normal. Some dry soils extend down into Moffat County from the north. 
  • Soils in the Upper Rio Grande part of Colorado are mostly in the normal range with some wetter soils near the Colorado-New Mexico border. 
  • Soils in northeastern Colorado are mostly in the normal range.  Jefferson, Broomfield, Adams, Boulder, and southern Weld/southeast Larimer counties are showing wet soils up to the 98th percentile.  Some areas in east-central Colorado are showing soil moisture in the 10th-30th percentile range, but most of the high plains are in the normal range. Eastern Washington County in particular is dry and is in the 10th-20th percentile range. 
  • Soils in southeast Colorado range from dry to wet. In eastern Pueblo and El Paso Counties as well as Crowley and Otero and Lincoln Counties soils are still showing up below the 30th percentile. Soils in the southeast corner of the state in Baca, Prowers, and eastern Kiowa Counties are between the 70th and 90th percentile. 

Reservoirs (based on the graphs below the map):

  • Flaming Gorge is at 104% of average. 
  • Lake Granby is at 134% of average.
  • Green Mountain is now at 71% of the December average and 44% full. 
  • Blue Mesa is at 115% of average. 
  • Navajo is at 109% of average.
  • McPhee is at 94% of average. 
  • Lake Powell is 71% of average. 

Additional Surface Water Links: (will take you to an outside website)
NLDAS Drought Monitor
Bureau of Reclamation Upper Colorado River Basin Teacup Diagrams

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 http://droughtmonitor.unl.edu/AboutUs/ClassificationScheme.aspx. 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.

Last Week Temperatures:

  • Temperatures through the UCRB and Colorado were below normal last week.
  • In southwestern Wyoming, temperatures were 0 to 6 degrees below normal.  There was an area in Sublette County that saw slightly warmer than normal temperatures.
  • Eastern Utah saw temperatures 6 to more than 15 degrees below normal.  The coldest area was along the border of Grand and Emery Counties.
  • Western Colorado also saw temperatures 6 to 15 degrees below normal.  The coldest area was from Rio Blanco County to the Four Corners area and up through the Gunnison Basin.
  • The San Luis Valley saw temperatures 0 to 6 degrees colder than normal.
  • East of the Divide in Colorado, temperatures were primarily 6 to 9 degrees below normal.  An area of 9 to 12 degrees below normal extended from Central Colorado to Lincoln County and south into Otero County.  Southeast Colorado was a little warmer, with 0 to 6 degrees cooler than normal.

January Temperatures:

  • The UCRB for January was in the normal to slightly cooler than normal range, with temperatures between 2 to -4 degrees from normal.
  • Further north in the Yampa and North Platte river basins termperatures were, on average, below normal with spots in Moffat and Jackson counties nearing 8 degrees below normal. 
  • The Upper Green River Basin in Wyoming saw temperatures mostly below normal in Uinta, Sweetwater, and Fremont counties, and at or above normal in Lincoln and Sublette counties. 
  • Eastern Utah was at or below normal for January temperatures. Eastern Carbon and northeastern Emery counties were the coolest, down to 10 degrees below average.
  • Southwest Colorado was slightly below normal for temperatures, while an area in southeast Gunnison/northwest Saguache counties was fairly far below normal at 8 degrees or colder than their January average.
  • Colorado east of the divide was at or above normal for temperatures in January. The coldest area was southern Park County at 8 degrees below normal, while most of the high plains, save for the far northeastern part of the state, were between 0 and 4 degrees above normal. 


The top two images show Climate Prediction Center's Precipitation and Temperature outlooks for 8 - 14 days. The middle image shows the 3 months Precipitation outlook. The bottom left image shows the Hydrologic Prediction Center's Quantitative Precipitation Forecast accumulation for the five days between Tuesday 12Z and ending Sunday 12Z. The bottom right image shows the Climate Prediction Center's most recent release of the U.S. Seasonal Drought Outlook.

Short Term: (2/9)

  • This week will be dominated by high pressure and warmer than average temperatures across the UCRB and eastern Colorado. The area east of the divide will have the highest temperature anomalies.
  • Temperature anomalies will peak in the UCRB a little later than east of the divide on Thursday/Friday rather than Wednesday. 
  • A weak, shortwave disturbance will cool off temperatures in the northern portion of the UCRB on Friday and Saturday, but then the ridge is expected to rebuild. 

Longer Term:

  • The 8-14 day precipitation outlook shows increased chances for below average precipitation for the southern portion of the UCRB. Northeastern Colorado and the Upper Green River Basin will have increased chances for above average precipitation.
  • The  temperature outlook shows increased chances for above average temperature for the entirety of the UCRB and eastern Colorado. These chances are lowest in the western portion of the basin and highest east of the divide. 
  • The Climate Prediction Center February through April precipitation outlook shows increased chances for above average precipitation for all but the far northwest end of the UCRB and all of eastern Colorado. These odds maximize in southeast Colorado. 
  • The seasonal drought outlook for February through April indicates that no drought development is likely in the UCRB or eastern Colorado. 


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 9, 2016

The last week saw precipitation to a majority of the Upper Colorado River Basin, with much of the Green River Basin missing out, seeing less than 0.10 inches over a large area in Wyoming, Colorado and Utah.  Most of what fell throughout the UCRB was a result of the winter storm on February 1st, mostly ending early on the 2nd.  Little precipitation fell the remainder of the week.  As a result of the recent precipitation, most short term SPIs are on the wet side of the SPI scale, with the exception of a few 0 to -1 SPIs in Wyoming and eastern Utah.  All basins in the Upper Colorado River Basin now have near normal or above normal snowpack for this time of the year. 

In eastern Colorado, the winter storm dropped at least 0.50" of liquid to much of the area.  Most of this precipitation fell on Monday, February 1st, before the start to this week's drought monitor week.  Up to 0.25 inches fell in Teller and El Paso counties from precipitation on Tuesday, February 2nd and another shot of snow on the 4th.  The precipitation helped the short term SPIs quite a bit, with most of the area showing greater than +1 SPI.  There is still some dry SPIs and dry soils in Washington and Otero counties where we have D0.  The D0 in central Colorado and in Yuma and Kit Carson counties might be ready to be removed this week after the recent precipitation. 

Recommendations:

UCRB: Status quo.  Even with the precipitation last week, areas that are in D0 are still showing dry soils and missed out on most of the precipitation from the last week.

Eastern Colorado: We are recommending the D0 in Chaffee, Park, Fremont, Teller and El Paso counties be removed.  With the recent snowstorm, SPIs on 30 and 90-day time scales are positive (wet) and soils are not showing any dryness.  Also, some trimming of the D0 in northeastern Colorado is recommended.  This area also is showing positive SPIs and good soil moisture.

**Disclaimer: The above recommendations are recommendations only, based on data, impacts, and input from local experts. These recommendations are sent to the U.S. Drought Monitor author on Tuesdays. The USDM author has sole discretion on final changes made in the region and can accept, reject, or modify the above recommendations and may have additional modifications. Additionally, any recommendations discussed during the NIDIS webinars that are agreed upon by the local experts and USDM author are still subject to change. Changes are final and official as of Thursday morning, and can be viewed on the official U.S. Drought Monitor website.

Additional Drought Index Links: (will take you to an outside website)
Palmer Drought Severity Index for Climate Divisions Updated Weekly
WestWide Drought Tracker's PDSI Updated Monthly
Surface Water Supply Index

When available, maps and text are updated Tuesday afternoons.

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