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 majority of the UCRB had a quiet week in terms of precipitation.  The highest amounts fell around the Four Corners and in the San Juan Mountains of Colorado where 0.11-1.00" was reported.  The northern portion of the basin only received 0-0.25" with isolated areas up to 1.00" in Lincoln county, WY. 
  • While the valley area of the San Luis valley was dry, the Sangre de Cristo mountains between Costilla and Las Animas counties received 0.11-1.40".
  • East of the divide was also dry only receiving 0-0.10" for the week.

September Precipitation :

  • The majority of the UCRB had a well above average September for precipitation. The headwaters of the Green River saw widespread areas of above 300% of average precip for the month. Some of these areas include parts of Uintah, and Grand Counties in Utah as well as Uintah, Sublette, and Lincoln Counties in Wyoming. 
  • East of the CO-UT state line precipitation totals were closer to normal for the month on average. 
  • The Four Corners area was generally between 100% and 200% of normal for the month. A small portion of Dolores County was below normal.
  • Precipitation was in the normal range for the northwest portion of the state with spotty areas receiving as much as 200% of normal. 
  • The San Luis Valley was mostly below normal for the month (between 50 and 90% of average). Some portions of Conejos and Saguache Counties reported as little as 30% of average precipitation for the month. 
  • East of the divide there is a large gradient in the percentage of average precipitation for the month of September right along the Palmer Divide. Areas just north of the Palmer Divide experienced well above average precipitation for the month. Douglas, Elbert, Arapahoe, Washington, and Yuma Counties show widespread areas above 200% of average. 
  • South of the Palmer Divide in El Paso, Fremont, and Lincoln Counties precipitation totals were between 30 and 50% of average. 
  • The northeastern CO counties saw much above average precipitation, mainly 150% to 100% of average precipitation for August.
  • The northern Front Range had an average month with precipitation totals between 70 and 130% of average. 
  • In the extreme southeast portion of the state there is a large gradient where precipitation totals were as much as 200% of average right at the corner of the state, but as little as 50% of average in large areas of Bent, Prowers, Otero and Las Animas Counties. 

Water Year Precipitation:

  • Much of the UCRB is now near or above average for the Water Year through August, with spotty areas below average.
  • Most of the northern portion of the basin in Wyoming is above average, with portions of Lincoln, Uinta, and southern Sublette counties 200% to 250% of average.  
  • Much of eastern UT is now near average, with no widespread areas clearly above or below normal. The distinction between above areas with above and below a normal water year here is very spotty. 
  • Western Colorado is a bit spottier than Utah with precipitation as a percent of average, however much of the area is near average for the Water Year.  Most of the western slopes are between 70 and 110% of average for the water year. Some spotty areas including parts of San Miguel, Mineral, and Mesa Counties were over 200% of average for the water year. 
  • The northern portion of the Colorado River headwaters area is still much above average, mainly greater than 130% of average.
  • East of the Divide a north-sound gradient exists in water year precipitation as a % of average. The north-south gradients in soil moisture and vegetative health echo this gradient quite clearly. 
  • Almost all of the northeastern plains were above average for the 2014 water year. Percents of average were between 90 and 150. 
  • Most of the Front Range was between 90 and 130% of average for the water year. 
  • Southeastern CO has improved, but still came in below normal for the 2014 water year across the majority of the region. Totals were mainly between 70 and 110% of average. 
  • A strip in the southern Colorado Rockies extending through Costilla, Huerfano, and Custer Counties had an above average water year. Totals were between 150 and 250% 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.

Short Term (30-day):

  • Much of the UCRB is reporting positive SPI's on the short time scale.  A few areas are reporting slightly dry conditions in northern Sweetwater county, WY, Rio Blanco county, CO as well as 2 sites in SE Utah west of the Colorado River.  The rest of the area has SPI's ranging from 0 to +2.  The wettest areas are along the Wasatch Range in Utah.
  • East of the divide is also showing the majority of stations in the wet SPI categories.  A few sites are reporting between 0 and -1 in Yuma and Lincoln counties.  The rest of the area is reporting between 0 and +2 with the wettest areas in Washington and El Paso counties.  The -1.5 in Sedwick county is quite suspicious and suspected to be driven by several days of missing data.

Long Term (6-month):

  • For the longer term, much of the UCRB continues to report wet SPIs.  There are a few dry areas reported around the Four Corners and in Gunnison county.  These are between 0 and -1.  The rest of the area is reporting SPIs between 0 and +2.  The wettest areas are along the Wasatch in NE Utah and Mesa and Routt counties in Colorado. 
  • The San Luis valley in Colorado is fairly dry with the majority of valley stations reporting SPIs between 0 and -1. 
  • East of the divide, a north/south gradient still remains.  The Arkansas basin is reporting drier SPIs along with a few wetter SPIs between -1 and +1.  The NE plains are wetter with the majority of stations reporting between 0 and +2.  The dry SPI in Sedgwick still exists and is again thought to be erroneous due to missing data.

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:

  • 6% of gages in the UCRB are reporting 7 day average streamflow in the below to much below average category.  These gages are mainly located along the San Juan drainage.
  • 43% of the gages are in the normal category (25th-75th percentiles).
  • 51% of gages are above to much above normal and 1% are reporting record high flows for the the 7 day period.
  • Streamflow on the Colorado River near the CO-UT state line is above average, reporting in the 80th percentile (128% of average).
  • The Green River at Green River, UT is also reporting above average, in the 60th percentile (104% of average) but has dropped off quickly over the past week.
  • The San Juan River near Bluff, UT has held steady this week reporting in the 41st percentile at 52% of average. 

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:

  • VIC modeled soil moisture totals in the UCRB are generally at or above the normal range. 
  • Sweetwater County, WY still shows dry soils between the 10th and 30th percentile, with a few pockets showing up down to the 10th percentile, however this area is always quick to dry out in the VIC product.
  • Soil moisture is in the normal range in the Four Corners area.
  • The San Luis valley is showing normal soil moisture conditions.
  • East of the divide, the northern plains are showing moist soil conditions from the 30th to 95th percentile. The foothills west of Denver are also very wet with soil moisture percentiles between the 90th and 98th.
  • The southern plains have improved thanks to recent precipitation.  Most of the area is now showing normal soil moisture.  There are still dry soils showing up in southern Lincoln County.

VegDRI:

  • The VegDRI is showing healthy vegetation over southwestern Wyoming, eastern Utah and NW Colorado over the past few weeks.  Parts of Sweetwater and Sublette counties in Wyoming are showing poorer vegetation in the pre- to moderate drought condition category.  The Wasatch and Uintah Ranges in NE Utah are also seeing pre- to moderate drought conditions.
  • The Four Corners area is still indicating dry vegetation conditions from San Juan county, UT east into the San Luis valley.  These areas are mainly in the pre- to moderate drought category.
  • The San Luis Valley is indicating drier conditions than areas farther west.  This index gets down into the severe drought classification in the valley. 
  • The Front Range is showing vegetative health conditions in the normal range. 
  • East of the divide there is a north-south gradient.  The northern plains are doing good in terms of vegetation health and the dry area in Sedgwick County is likely not valid based on ground reports (likely SPI driven). 
  • Farther south on the eastern plains is showing a mixed bag of conditions.  Irrigated areas along the Arkansas river are showing wet conditions while the surrounding areas are mainly reporting in the pre- to moderate drought classification.  Some areas in Pueblo, Lincoln, Las Animas and Baca have spotty areas of severe drought classified by VegDRI.

Reservoirs:

  • Many of the reservoirs in the UCRB are holding steady (Flaming Gorge and McPhee) or rising (Powell, Granby, Dillon and Navajo) and just a few are seeing normal volume decreases (Green Mtn and Blue Mesa)
  • Flaming Gorge is 103% of the October average.
  • Green Mtn is 86% of October average.
  • Lake Granby is 127% of October average.
  • Lake Dillon is at 108% of the October average.
  • Blue Mesa is 93% of the October average.
  • Navajo is 81% of the October average.
  • McPhee is 69% of the October average. 
  • Lake Powell is 63% of average and 51% full.

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 has dropped off since the middle of August and has finished the growing season below average. 
  • Cortez: ET tracked below normal all growing season and finished the season slightly below normal. 
  • Center: ET has continued to track above normal since early June, but is still finished the growing season well lower than its high year in 2002.
  • Avondale: ET is tracking just slightly below the growing season average, and has dropped farther below normal since the start of September. ET has finished the growing season below normal.
  • Idalia: ET dropped in mid-July with monsoonal moisture coming into the area.  In the start of September ET fell even lower and finished the growing season well below normal.
  • Holyoke: ET dropped off in mid-July and has tracked even lower since then. ET at the end of the growing season is well below average.
  • Lucerne: ET rates are tracking slightly below average for the growing season since the end of July. ET rates began to fall even lower at the beginning half of September, but rebounded in the latter half of the month. ET for the growing season finished just below normal.


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 above average temperatures last week in the range of 0-6 deg above normal, with the vast majority of the area falling in the 0-3 deg above average range. 
  • The San Luis valley was 3-6 deg above average for the week.
  • East of the divide saw similar departures with much of the plains 0-3 deg above normal for the week.  Isolated areas reached 3-6 deg above normal over Pueblo, El Paso, Larimer and Weld counties.

Last Month Temperatures:

  • September temperatures in the UCRB, Wyoming and much of Colorado were mostly above average. 
  • The Upper Green River basin in WY was mostly 1 to 3 degrees above average, with southern Lincoln County, WY was 3-5 degrees above average.
  • Eastern UT saw temperatures mainly 3 degrees above average with a few areas 4 degrees warmer than average.
  • Northwestern CO saw temperatures 1-3 degrees above average, while temperatures farther south were 3-4 degrees above average, with pockets near the Four Corners area up to 5 degrees above average.
  • East of the divide most of the Front Range was between 1 and 2 degrees below average for September with Larimer County being near average. 
  • The eastern plains saw 1 to 2 degrees above average for the month.
  • The San Luis Valley saw temperatures greater than 4 degrees above average.  These warm temperatures saw their way east in to Las Animas 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:

  • UCRB has a chance of showers today through Wednesday as a low pressure trough moves over the area bringing a few inches of snow above 10,000 feet.  The area dries out again Wed - Sat as high pressure again builds over the area.  The weekend will bring dry condidtions and above average temperatures.
  • A second disturbance is forecast to move into the UCRB region Sun-Mon bringing unsettled weather.
  • East of the divide has a chance of thunderstorms and shower activity tonight and into Wednesday along with cooler temperatures.  Thurs-Sat will bring a drying trend with warmer temperatures.

Longer Term:

  • The 8-14 day precipitation outlook shows increased chances for below normal precipitation over southern Colorado and chances for above average moisture in northern Utah, Colorado and all of Wyoming.
  • The 8-14 day temperature outlook (not pictured) shows chances for above normal temperatures over much of the entire U.S. and much of the UCRB and eastern plains.  The exception would be northern Wyoming where normal temperatures are forecast.
  • The CPC 3-month outlook shows equal chances for wetter or drier than normal conditions over the UCRB in Utah, Colorado, and Wyoming, with chances of above average precipitation over southern UT and CO.
  • The seasonal drought outlook indicates that drought is expected to stay away or be removed northeast Utah and southwest Wyoming. 
  • Drought in the Four Corners region is anticipated to continue, but improve with some removal likely. 
  • Drought in the southeast CO is anticipated to continue, but improve. Little to no removal is likely. 

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 October 21, 2014: 

Much of the precipitation for the week was confined to the Four Corners region and San Juan mountains as well as the Sangre de Cristo mountains.

Recommendations:

UCRB:

Given recent improvements over the past few weeks in SW Colorado, and the fact that streamflow volumes on the San Juan river and reservoir levels are still below average, status quo is recommended for the UCRB.

 

Eastern CO:

Major improvements have taken place across SE Colorado over the past few weeks by removing the most severe drought categories, however the area is still facing long term deficits and impacts from several years of drought.  The past week was dry and warm over the region, therefore status quo is recommended for this week.