NIDIS Upper Colorado River
Regional Drought Early Warning System
July 22, 2014


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 majority of the UCRB was dry over the past week with less than a half an inch of precipitation being reported over much of the basin. 
  • Isolated areas of Duchesne, Uintah, and Daggett Counties picked up over half an inch of precipitation. 
  • In CO, most of Archuleta County as well as large portions of Rio Grande and Conejos Counties received over an inch of precipitation in the past week. 
  • Near the Colorado Utah border and in many of the low-lying areas west of the Continental Divide precipitation totals were below 0.25" over the past week. 
  • East of the divide, the North American Monsoon brought a very beneficial swath of moisture to much of south and southeast CO as well as the southern Front Range near the Palmer Divide. Much of the area received 1.00-2.00". 2"+ maxima can be found in El Paso, Huerfano, and Baca Counties. 
  • The northeast plains had a dry week. Most of Yuma and Logan Counties received less than 0.10" of rain in the past week. Washington, Sedgwick, Phillips, and Kit Carson Counties were all mainly under 0.25".
  • National Weather Service reports that parts of southern Lincoln County experienced over 5" of rain in the past week.

June Precipitation :

  • June was dry across much of the UCRB.  The Northern portion of the basin wasn't quite as dry with above average moisture falling across Sublette, Lincoln and Uinta counties in Wyoming.  Farther south was much below average for the month of June.  The Four Corners region saw less than 10% of normal for June.
  • Western Colorado and the headwaters of the CO river were also dry for the month with widespread areas receiving less than 70% of normal precipitation for June.
  • East of the divide, the NE plains of Colorado benefitted from convective thunderstorms.  The NE plains saw widespread above average moisture conditions for June.  The SE plains did not benefit as much as the NE plains and the rains were spottier.   The SE plains had widespread <70% of normal for the month with isolated areas in Pueblo, Kiowa, Prowers and Baca receiving above average moisture. 

Water Year Precipitation (Oct-June):

  • For the water year, Much of the UCRB remains in above average moisture since October 1 with the exception of Sweetwater county in WY and the Duchesne basin in Utah which have received <90% of normal for the water year.
  • The Four Corners area is also dry for the water year through June with lower elevations reporting <90% of normal precipitation for the water year.
  • East of the divide, the NE plains are reporting above average moisture for the water year while the SE plains remain dry at the longer time scale.  Widespread precipitation <70% of normal has been seen in SE Colorado where drought conditions persist.

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


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):

  • The short term SPI indicates slightly dry, but near normal conditions for most of the UCRB. 
  • 30 day SPIs in Mesa County have dropped to the -1 to -1.5 range.
  • The Upper Green river basin shows mostly slightly dry SPIs from 0 to -1. Some 0 to 1 SPIs show up along the Colorado in southeast Utah and just west of there in Wayne and Emery Counties. 
  • The western slopes of the Rockies show near normal SPIs, but are on the dry side of normal in the Four Corners region and near the Utah border. 
  • Most of the Front Range and Eastern Plains show above average SPIs ranging from 0 to 2. Sedgwick County appears to have been drier, but the SPI in the county, which is in the -2-2.5 range, appears to be a bit skewed by missing data. 
  • The San Luis valley is also reporting SPI's between -1 and 1 short term.
  • Southeast Colorado is showing mostly high SPIs short term. There are indices above 1.5 in Otero, Crowley, and Lincoln Counties where improvements have been and continue to be made. 

Long Term (6-month):

  • SPIs in the Upper Green River Basin are mainly dry now (between 0 and -2.5). Where the Green meets the Colorado near Moab SPIs are still in the normal range. 
  • Eastern Utah remains dry on the longer term SPIs with the driest areas in the Duchesne basin (-1 to -2.5) and around the Four Corners area where SPI's range from 0 to -2.
  • The headwaters of the Colorado are mainly wet on the longer term SPI.
  • The San Luis valley is also dry on the longer term with SPI's in the 0 to -1.5 range. 
  • The NE plains of Colorado remain mainly wet on the longer term, while the SE plains remain dry, but this has evened out some over the past month.  The SE plains are reporting SPIs between 0 and -1 with some SPIs showing between 0 and +1.  
  • The Front Range shows normal to slightly wet SPIs. 

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:

  • 87% of the gages in the UCRB are reporting above the 25th percentile (normal and above) for 7-day average streamflow.
  • The lowest streamflows are in the headwaters of the Duchesne, White Rocks, and Big Rush Rivers, which all feed into the Green River in Utah. 
  • The headwaters of the Colorado River are flowing very strongly with many gages in the area above the 90th percentile. 
  • Flows on all three key gages around the basin have peaked.
  • Streamflow on the Colorado River near the CO-UT state line remains in the normal range and reporting in the 69th percentile.
  • The Green River at Green River, UT is reporting in the 33rd percentile, which is on the low side of the normal range.
  • The San Juan River near Bluff, UT has recovered into the normal range and is reporting at the 33rd percentile running at 906 cfs. 

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 modeled soil moisture combined with SWE as a percentile ranking.


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.

VIC:

  • Soil moisture throughout northeast UT and southern WY are between the 0 and 30th percentiles with the driest area in the Duchesne basin just south of the Uintah Mountains. This area is now reading below the 2nd percentile.
  • Sweetwater and Carbon Counties in WY also show well below-average soil moisture below the 30th percentile. A good chunk of Sweetwater County is now showing up below the 2nd percentile in soil moisture. 
  • The northern and central mountains in CO are reporting a mix of normal soil moisture conditions with conditions above the 70th percentile. 
  • The Four Corners region is reporting soil moisture between the 10th and 20th percentiles.
  • Huerfano, Costilla, and western Las Animas Counties are now showing soil moisture above the 70th percentile. 
  • East of the basin, soils are showing up wetter than the 70th percentile across most of the Front Range. The wettest areas are Jefferson and northern Weld Counties. 
  • Eastern Colorado from north to south along the Nebraska and Kansas borders is showing soil conditions in the normal range. 
  • With the exception of extreme southeast Lincoln County the VIC model shows soil conditions in the normal range to slightly above normal for southeast Colorado. Soils are as dry as the 10th percentile in Lincoln County. 

VegDRI:

  • The VegDri product is showing very dry soils in Duchesne County and western Uintah County. 
  • VegDri's classification of Montezuma and La Plata Counties would be "severe drought." 
  • Conditions in Summit and Clear Creek Counties are shown as well above average. 
  • East of the divide, the SE plains continue to see dry vegetation conditions, particularly in western Cheyenne and Kiowa Counties. Las Animas and Baca counties also point to very dry vegetation conditions. 
  • VegDri conditions are shown as above average in Huefano, Custer, and eastern Saguache Counties. 

Reservoirs:

  • Most northern reservoirs seem to have reached their peaks for the season. 
  • Flaming Gorge is 101% of the July average.
  • Green Mtn is 106% of July average.
  • Lake Granby is 117% of July average, but has shown decreases since last month. 
  • Lake Dillon is 103% of July average.
  • Blue Mesa is 95% of the July average and has begun showing decreases.
  • Navajo is 81% of average and showing volume decreases.
  • McPhee is 78% of average and showing volume decreases.

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 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.

Reference Evapotranspiration:

  • Olathe: ET is tracking slightly above normal for the growing season.
  • Cortez: ET has been tracking consistently slightly below average for the growing season for the last few weeks. 
  • Center: ET has ramped up and is now tracking well above normal for the season since the beginning of June. 
  • Avondale: ET has been tracking just slightly above normal since mid-June.
  • Idalia: ET is tracking below average for the growing season as of the last week due to a monsoonal surge.
  • Holyoke: ET rates dropped off over the past week, and ET is now below average for the growing season.
  • Lucerne: ET rates are tracking along the seasonal average this growing season.


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:

  • The UCRB mostly saw temperatures 0-4 degrees above average over the past week. Areas west of the Green and Colorado Rivers in UT tended to be between 2 and 4 degrees above average. In Western CO and Sweetwater County, WY temperatures were 0-2 degrees above average. 
  • East of the divide also saw mainly below average temperatures, especially out on the plains towards the CO-KS and CO-NE borders. Eastern border counties as well as Crowley and Morgan Counties were 6-8 degrees below average. 
  • The Front Range and high country were mainly 2-4 degrees below average. 

 

Last Month Temperatures:

  • Temperatures in the southern part of the UCRB basin were slightly above normal and temperatures in the northern and eastern parts of the basin were slightly cooler than normal. 
  • East of the basin temperatures did not stray far from seasonal normals either. South WY and northeast CO show mainly between 0 and 2 degrees below normal.
  • South and southeastern CO saw the warmest June temperatures. Most of Huerfano, Las Animas, and Pueblo Counties showed temperatures 2 to 4 degrees above normal. 
  • Most of southeastern CO recorded temperatures 0 to 4 degrees above normal for the month of June. Otero and Bent Counties were the most above normal in the region. 


The top two images show Climate Prediction Center's Precipitation outlooks for 8 - 14 days (top left) and 3 months (top right). 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:

  • An upper-level high pressure system is currently dominating the region's weather. Areas that have been dry, particularly Eastern Utah will be hot for the next few days. Some thunderstorms over the higher terrain are possible.
  • The next chance for a good monsoonal surge will be this weekend into Monday and Tuesday as the ridge axis moves to the south and east. The primary beneficiaries of this moisture are expected to be south-central Colorado, the San Juans, and some of the high terrain west of the continental divide. 
  • Along the Front Range and Eastern Plains some high-base thunderstorms are possible, but moisture amounts will likely be low. There will be lack of low-level upslope, and the best precipitable water values are not expected to extend north of the Palmer Divide. 
  • Eastern Utah and southwest Wyoming are forecast to miss out on precipitation almost entirely over the next week with hot, dry weather persisting. 

Longer Term:

  • The 8-14 day precipitation outlook shows equal chances of above and below average precipitation for the UCRB. 
  • The 8-14 day temperature outlook (not pictured) shows increased chances for above average temperatures over the Green and Duchesne river basins, and along the Colorado River west of the Colorado Utah state line. Slightly below average temperatures are forecast for this time frame for eastern Colorado and the Front Range. 
  • The CPC 3-month outlook shows higher chances for wetter than normal conditions over the UCRB in Utah, Colorado, and Wyoming for the late July-mid October time period.
  • The seasonal drought outlook indicates no areas in the UT, WY, or CO where drought is anticipated to develop or intensify. Drought conditions are likely to improve in UT due to the combination of El Nino development and the North American Monsoon. In drought-stricken SE-CO drought is likely to continue, but improve. 
  • Drought in the Four Corners region is anticipated to continue, but improve. 


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: July 22, 2014 

The UCRB had a hot, dry week. Hopefully this is the time of year where it will see a shift to wetter, and hopefully a little cooler pattern.  Climatologically, rain should start to increase in this area over the next few weeks, and El Nino could potentially help enhance this effect.  If not, conditions will degrade further. Areas of concern such as Sweetwater, Duchesne, and Uintah have stayed very dry, and conditions are deteriorating in the Four Corners region especially, but along much of the CO-UT border. 

East of the divide monsoonal flow has continued to improve conditions in southeast Colorado. However this rain has been primarily convective and have lead to more runoff than desired where rains have been heaviest. This is well-reflected by streamflow statistics along the Arkansas River. 

Drier conditions have returned to the northeastern plains with most of the area picking up less than a quarter of an inch of precipitation over the past week. This is not a major concern as of yet due to recent slugs of moisture in the area and below average temperature conditions. Reference ET in this area is tracking below normal for the season. 

Important moisture has fallen over the past week in the Upper Rio Grande and San Juan River basins as well as Las Animas and Huerfano Counties in southern CO. Flows in the San Juan River have returned to the normal range. 

Recommendations**

UCRB

Conditions along the Green River in western Carbon and Uintah Counties have been hot and dry, and indices in Duchesne County continue to tell a sad story. Based primarily on SPIs in Duchesne County and the way soil and vegetative health models show the area just to the east of Duchesne in comparison a one-category degradation is recommended in the area. This would involve extending D1 into extreme northeastern Emery County, eastern Carbon County, and central Uintah County. Conditions look the worst in Duchesne and western Uintah Counties, so western Uintah would be degraded to D2 and the D3 over southern Duchesne could be pushed to the county line. 

Another area to watch for possible degradation based on recent dry conditions would be the CO-UT state line, primarily around Grand Junction. Based primarily on wet 90 day SPIs the recommendation is status quo for now.

Eastern Colorado:

Recent monsoonal moisture and below average temperatures have brought improvements to southern and southeastern Colorado. Looking back at 6 and 9 month SPIs there doesn't appear to be justification for keeping the D3 in southern Las Animas and Baca Counties. This justification would have to come from data of 12+ month time series. It is recommended that this region be improved to D2. 

Huerfano, eastern Pueblo, south Lincoln, western Otero, and western Crowley Counties all came out with a good week of moisture. Vegetation and soil health is shown by models to be improving in the area as well. A one-category improvement is recommended for much of this region. No improvements are justified east of Lincoln County's border with Cheyenne County, so these boundaries would take on more of a southerly slope. 

 

 

**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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