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.

 

Last Week Precipitation:

  • The northern portion of the UCRB in Sublette and Lincoln counties in WY received between 0.25 - 0.50" with a few areas in Sublette County receiving just over 0.50".
  • Sweetwater and Uinta counties in Wyoming largely missed out on the moisture reporting <0.25" over the week.
  • Northwestern CO and northeastern UT saw some beneficial precipitation over the last week, with most of the area receiving over 0.25" with areas over 0.50". Parts of Duchesne and Uintah counties in UT saw some drier areas of less than 0.25".
  • The southern counties in the UCRB, in the San Juan Mountains and Four Corners area greatly benefited from last weeks monsoonal flow, receiving over 1.00" over much of the area.
  • The east portion of the basin along the Divide were drier, especially in Gunnison and Grand Counties and part of Eagle County, receiving less than 0.25" over the last week.
  • The San Luis Valley was also dry reporting less than 0.25".
  • East of the divide saw spotty moisture over the week.  The best moisture fell in Morgan and Washington counties in northeastern CO, and Park and Teller counties in central CO, receiving 2.00" with a few areas over 2.00".
  • The driest areas on the plains were Otero, Bent, Kiowa and Prowers counties in southeastern CO and Larimer, Weld counties and into the Denver Metro area where less than 0.25" fell.

July Precipitation :

  • July was a well above average month for precipitation across much of the drought monitor region. 
  • In the UCRB most of Eastern Utah experienced above average precipitation with areas of 300+ percent of average in Wayne and Emery Counties and north of the Salt Lake metro area. 
  • A little farther to the east, the Western slopes of Colorado extending up into Sweetwater County, WY saw the lowest percents of average precipitation for the month of July. Areas of Moffat and Rio Blanco Counties were as low as 31-50% of average. 
  • Western Colorado and the headwaters were mostly well above average, which has manifest in increased streamflows over the past few weeks. Most areas are above 110% of average. 
  • East of the divide, the NE plains of Colorado dried out quite a bit over the month of July with the majority of Sedgwick, Phillips, Yuma, and Kit Carson Counties seeing below average precipitation. 
  • Further to the south the North American Monsoon was very generous to areas of SE CO that have been in extreme, or even exceptional drought over recent months past. The whole SE portion of the state with a small exception in Baca County received above average precipitation for the month of July. Areas of Otero, Crowley, Kiowa, Huerfano, and Custer Counties received as much as 300+% of average precipitation. 
  • The Front Range also saw well above average precipitation as a result of the monsoon, but conditions were drier not far to the east.

Water Year Precipitation (Oct-June):

  • For the water year, fairly equal portions of the UCRB show above and below average precipitation. The parts of the UCRB that have been most above normal are near the headwaters in Uinta and Lincoln County, WY as well as Emery County, UT. Duchesne, Uintah, and Sweetwater Counties have been dry. 
  • The Four Corners area is still showing up below average for the water year. Parts of Dolores County have only seen 31-50% of their average precipitation by this point in the water year with surrounding areas in Montezuma, and La Plata Counties also below average. 
  • Some areas in the southern portion of CO west of the I25 corridor have been well above average. Custer, Huerfano, and Costilla County are all above normal for the water year, in some areas receiving as much as 200% of average precipitation.
  • 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.  Most of SE CO has recovered to at least 70% of average for the water year with the Pueblo, Otero, and Crowley County area back to normal. 
  • Most of the Front Range has had 110-150% of average precipitation for the water year. 

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.

Short Term (30-day):

  • After a few weeks of beneficial precipitation, much of the UCRB in in the 0 to 1.5 SPI range, with a few wetter SPIs in Mesa County, CO, Grand County, UT and in the Wasatch Range in northern UT.
  • The drier SPIs show up near the divide in Grand, Gunnison and Hinsdale counties in CO.
  • The Front Range foothills are also reporting wet SPI's on the short time scale between 0 to +1.5.
  • Farther east on the plains of Colorado is more variable with SPI's ranging from -2 to +1.5.  The driest areas are in Sedgwick, southern Yuma, Kit Carson and central Lincoln counties on the short time scale.

Long Term (6-month):

  • The longer time scale is drier for the UCRB.  The Green River basin is reporting SPI's between +1 to -1.5 on the 6 month time scale. 
  • Eastern Utah also indicated drier conditions with SPI's between +1.5 to -1.5.  The driest area is along the Duchesne in northeast UT.
  • The headwaters of the UCRB in Colorado are mainly wet with SPI's reporting from +1.5 to -1.  The drier areas are in Grand and Gunnison counties.
  • The 4 corners is also drier with SPI's ranging from 0 to -1.
  • The Rio Grande basin is drier on the west side and wetter on the east side with SPI's ranging from +1 on the eastern mountains of the basin, to -2 through the valley and into the western mountains. 
  • East of the divide is a mix of wet and dry SPI's.  The plains range from +1 to -1.5 with the driest values in Lincoln and Crowley counties. 

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.

Streamflow Statistics:

  • 89% of the gages in the UCRB are reporting above the 25th percentile (normal and above) for 7-day average streamflow.
  • 11% of the gages are reporting in the below normal (10th-25th percentile) range. 
  • Streamflow on the Colorado River near the CO-UT state line is in the average range, reporting in the 73rd percentile (118% of average).
  • The Green River at Green River, UT is reporting in the 45th percentile (79% of average).
  • The San Juan River near Bluff, UT has rebounded once again into normal range and is reporting in the 64th percentile (90% of average) after an increase from monsoonal moisture. 

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 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:

  • The driest region of the UCRB from the modeled soil moisture product extends from Sweetwater County in Wyoming SE into the Duchesne basin in Utah.  That area shows widespread soil moisture below the 30th percentile.  Central Sweetwater County is the driest with much fo the area reporting soil moisture below the 5th percentile with an area below the 2nd percentile.
  • The Four Corners area is reporting soil moisture from the 10th-30th percentile, with some improvements from the last week.
  • East of the divide shows wet soils on the NE plains and near normal soil moisture farther to the south.  Southern Lincoln county is reporting soil moisture mainly between the 10th and 30th percentiles and is the driest area on the plains according to the VIC model. 

VegDRI:

  • The VegDri product is showing very dry vegetation in the Upper Green river basin in Wyoming and the Duchesne river basin in Utah, similar to many other products.  This area ranges from moderate to severe as depicted by VegDRI
  • The Four Corners area is very dry and reporting vegetation conditions in the moderate to severe drought categories.
  • Much of the high country in Colorado is showing near normal vegetation conditions.
  • The east side of the Rio Grande basin is showing moist vegetation conditions, but that dries out rapidly on the west side fo the basin. 
  • East of the divide shows slightly above normal conditions along the Front Range and foothills, but dries out farther east.
  • The area east of Lincoln county is reporting vegetation in the pre- to moderate drought categories.  
  • Central Kiowa County now shows some areas of above average vegetative health. 
  • Sedgwick County is indicating moderate drought conditions, however this is not really in agreement with ground reports in the area and high wheat yields. 

Reservoirs:

  • Most of the reservoirs have seen decreasing volumes, which is normal to see this time of year.
  • Flaming Gorge is 101% of the August average.
  • Green Mtn is 111% of August average.
  • Lake Granby is 121% of August average.
  • Lake Dillon is 104% of August average and has still seen a slight volume increase.
  • Blue Mesa is 95% of the August average.
  • Navajo is 80% of the August average.
  • McPhee is 74% of the August average. 
  • Lake Powell (not reporting on graphic) is currently reporting 67% of average and is 92 feet below full pool.

EVAPOTRANSPIRATION



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 right along normal for the growing season.
  • Cortez: ET had been tracking slightly below average for the growing season but has come back to normal.
  • Center: ET has been slightly above normal since early June.
  • Avondale: ET is tracking just slightly below the growing season average. 
  • Idalia: ET dropped in mid-July with monsoonal moisture coming into the area.  ET has tracked slightly below the normal since then.
  • Holyoke: Similar to Idalia, ET dropped off in mid-July and continues to track below average for the growing season.
  • Lucerne: ET rates are tracking slightly below average for the growing season over the last two weeks. 


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.

Last Week Temperatures:

  • The UCRB saw mostly near average temperatures over the last week, between 2 degrees above normal to 2 degrees below average. 
  • The northern portion of the basin in WY saw temperatures 2 degrees above normal, while eastern UT and parts of western CO saw temperatures slightly cooler, 2 degrees below normal.
  • Emery County in UT, was much warmer, up to 8 degrees above normal.
  • In the Four Corners area, southwestern CO was 2 degrees warmer than normal, while southeastern UT was 2-4 degrees cooler than normal.
  • East of the divide was near normal for the week, with a few areas 2 degrees warmer and a few areas 2 degrees cooler.

 

Last Month Temperatures:

  • July temperatures in the UCRB were unanimously above normal despite a cool last week to the month. The entire UCRB ranged from 0-4 degrees above normal. 
  • Areas that were warmer (2-4 degrees above normal) included Uintah County, UT, and Montezuma, San Miguel, Dolores, and Montrose Counties in CO.
  • East of the divide temperatures were generally slightly below average. Most of the Front Range was between 0 and 2 degrees below average for July. 
  • Most of the eastern plains were also 0 to 2 degrees below normal, but some regions were 0 to 2 degrees above. This includes most of Lincoln County, central Kiowa County, and western Cheyenne County. 

FORECAST AND OUTLOOK

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:

  • Monsoonal flow will continue in the UCRB through Tuesday, with rainfall amounts possibly exceeding 1 inch. 
  • The remainder of the week into the weekend will see some thunderstorm development each day through the basin.
  • East of the divide, the monsoonal moisture will hit the area Wednesday, with drier air on Thursday.
  • Late week into the weekend will see an increase in thunderstorm activity with the best chances in the high country.

Longer Term:

  • The 8-14 day precipitation outlook shows chances for normal conditions over the UCRB with above average chances for eastern CO.
  • The 8-14 day temperature outlook (not pictured) shows increased chances for below average temperatures across the entire UCRB, CO and WY.
  • 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 other than the far northwest corner of UT. This being said, the anticipated El Nino has died off in the west Pacific with current indicators now showing very mild La Nina, which may impact this forecast in the weeks to come. 
  • Drought in the Four Corners region is anticipated to continue, but improve. 
  • Drought in the southeast CO is anticipated to continue, but improve. 

U.S. DROUGHT MONITOR

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 for August 19, 2014: 

Monsoonal flow continued to bring moisture into the UCRB, mainly in the Four Corners area, extending into eastern UT and western CO.  Precipitation on the eastern portion of the UCRB was spottier.  Even with the moisture in the Four Corners area, precipitation totals are still below normal.

East of the divide also saw spotty convective storms.  Areas not in drought conditions saw the most precipitation. What fell in the areas still in drought, did not benefit enough for improvements.

 

Recommendations

UCRB:

Status Quo for the UCRB.  Even with the precipitation in the Four Corners area, it has been too dry to justify improvements.

Eastern Plains:

With recent improvements the last few weeks and little precipitation this week in eastern CO status quo is recommended.