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:

  • Parts of the UCRB received over an inch of precipitation over the last week, mainly in the San Juan Mountains and in parts of northwest Colorado in Mesa, Rio Blanco, and Routt Counties. 
  • The Upper Green River basin received between 0.10 and 0.50" of precipitation. Southern Uinta County received over half an inch.
  • The Yampa and White Basins had a better week of precipitation than surrounding subbasins receiving over half an inch through much of the area, and over an inch in some spots.
  • The Duchesne Basin was mostly in the 0.25-0.50" range with higher elevation areas over half an inch. 
  • Southeast Utah was fairly dry, and mostly under a quarter of an inch for the week. 
  • Precipitation was highly variable in southwest Colorado. There was up to 2.00" in the Wolf Creek Pass area. More low-lying areas received less than half an inch. 
  • The San Luis Valley was dry, but the San Juans and Sangre de Cristos on either side of it had a good week of moisture. 
  • Northeast Colorado was a little wetter than normal along the Front Range picking up over a quarter of an inch, over half an inch in parts of Jefferson and Douglas Counties. The plains in northeast Colorado received less than a quarter of an inch of moisture in most areas.
  • Southeastern Colorado received 0.25-0.50" across much of the region. Areas farther north were generally drier. 

October Precipitation:

  • October in the Upper Colorado River Basin was a bit drier to the north and wetter to the south.
  • The Green River basin was a mixture of wet and dry. Sweetwater County was well below normal for October.  Sublette, southern Lincoln, and Uinta counties were above normal for the month.
  • The Uintah and Wasatch ranges in northern Utah saw a below average month, with the exception of Duchesne County seeing up to 200% or normal precipitation.
  • Southeastern Utah saw much above normal precipitation for the month, with most of the area above 200% of normal precipitation.
  • Northwestern Colorado in Moffat, Rio Blanco, eastern Garfield, and Routt Counties saw below normal precipitation.  Central and southwest Colorado were mostly above normal, with the exception of parts of Gunnison, Pitkin and Lake counties.
  • Eastern Colorado was above normal across much of the region. 


Water Year 2015 Precipitation (Oct-Sep):

  • As a result of a very wet Spring, Colorado east of the divide is still above average across the board for the water year to date with a few small exceptions. Isolated areas of Custer and Huerfano Counties are showing below 100% of average. 
  • The UCRB is mostly close to, but a little below normal for the water year to date. 
  • Most of the Upper Green River Basin is between 50 and 90% of normal for the water year to date. Central Sweetwater County is in great shape at over 110% of normal. 
  • Northeastern Utah is mostly between 75 and 100% of normal for the water year to date. Farther to the west over higher terrain percentages are a little lower at between 50 and 75%. 
  • Southeastern Utah has balanced out to a fairly typical water year to date. The area is between 75 and 125% of normal. 
  • AHAPS indicates a very dry band in Conejos, Rio Grande, Mineral, and southwest Saguache Counties. Here precipitation is less than 50% of average for the water year to date. Radar does tend to struggle in this area, so it may be worth taking another look at when our precipitation figures update. Most of western Colorado is just slightly dry. The area is between 75 and 110% of normal for the water year to date. 
  • The Rio Grande Basin is now showing a mixed bag of above and below normal water year to date conditions. Southern Costilla County is doing very well at over 150% of normal for the water year to date. 


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:

 SWE Timeseries Graphs:


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 across the UCRB and eastern Colorado are positive with a few readings from -1 to 0 sprinkled in. The driest area is where the Wasatch and Uintah Ranges connect to the east of Salt Lake City. 
  • The Upper Green Basin in southwest Wyoming is showing a range of -1 to +2.
  • SPIs across eastern Utah are mainly in the 0 to +1.5 range. There are some SPIs between -1 and 0 in Garfield and San Juan Counties.
  • Western Colorado is nearly all positive, up to +2 in Mesa and Rio Blanco Counties. There are two SPIs below zero in western Colorado in Grand and Gunnison Counties. 
  • The San Luis Valley is in the normal range between -1 and +1.
  • East of the divide SPIs are mostly positive, but there is a large spread in the numbers. Some areas in southeast Colorado are still a little drier than average for the last 30 days such as southern Lincoln and Otero Counties. Kit Carson County, Bent County, and even western Adams County are all showing SPIs above +2. 

Long Term (6-month):

  • 6-month SPIs are drying quite rapidly as the memory of a very wet spring is erased more week after week. 
  • SPIs in the Green River Basin are in the normal range between -1 and +1. 
  • The Yampa, White, and Duchesne River Basins are showing SPIs mainly in the normal range as well, also between -1 and +1. The northern Wasatch Range shows some SPIs between -1.5 and -1. 
  • Southeast Utah is very wet on the 6-month timescale. SPIs here range from 0 to +2.5
  • The Colorado mainstem and Upper San Juan Regions are nearly completely in the normal range between -1 and +1. Mesa County has some very wet SPIs between +1 and +2. 
  • The San Luis Valley is in the normal range with a few more SPIs on the drier side of average. 
  • 6-month SPIs in eastern Colorado are now primarily between -1 and +1.5. The driest portion of the region is in the far northeast corner of the state. There are SPI values in Sedgewick, Logan, and Washington Counties between -1.5 and -1. 


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:

  • There are only 77 stream gages in the UCRB that are still reporting out of about 140 gages.
  • 89% of gages are reporting in the normal to much above normal range for the 7-day average streamflow, with 1% reporting record high 7-day average streamflow for the last 7 days.
  • 11% of gages are below normal and no gages in the basin are much below normal.
  • The Colorado River at the CO-UT state line is at 101% of average and in the 59th percentile. 
  • The Green River near Green River, UT is at 133% of average and in the 81st percentile.
  • The San Juan River near Bluff has been up and down for much of the late summer and fall in particular.  It is now reporting at 68% of average, which corresponds to the 30th percentile. 


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 belo 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.


  • The Green River Basin in Wyoming continues to be much below normal in Sweetwater county, below the 2nd percentile in the eastern portion of the county.   Dry soils, in the 10th to 30th range, are also starting to sneak north into Sublette and Uintah Counties.
  • The Yampa, White, and Duchesne Basins are mostly in the normal range with some drier soils (20-30th percentile) in the Duchesne Basin, and some wetter soils (70-80th percentile) mostly in the White Basin. 
  • The Colorado Mainstem is either in the normal range or above normal. Soils are as wet as the 95th percentile in western Mesa County according to the VIC. There is a dry spot in eastern Emery County near where the Colorado River meets the Green River. Here Soils range from the 2nd to 30th percentile. 
  • The San Juan Basin is showing mostly west soils between the 70th and 90th percentile. 
  • 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 eastern Colorado are mostly in the normal range. There is a wet spot ranging from the 70th to 90th percentile in Jefferson, Broomfield, Adams, Boulder, and southern Weld Counties. There is another wet spot from the 70th to 90th percentile along most of the Colorado-Kansas border. Some dry soils remain in eastern Pueblo, southeast El Paso, southern Lincoln and Otero and Crowley Counties. Here Soil moisture is in the 5th-30th percentile range. 



  • Flaming Gorge is at 106% of the November average.
  • Lake Granby is at 122% of the November average.
  • Green Mountain is now down to 68% of the November average. 
  • Blue Mesa is at 112% of November average. 
  • Navajo is at 102% of November average, 81% full.   
  • McPhee is at 89% of its November average.
  • Lake Powell percent of average is missing, but 73% of average for the year (not just November). 


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..

Reference Evapotranspiration:

  • Olathe finished the growing season with cumulative ETs below the previous all-time low year of 1999. 
  • Cortez saw ETs following roughly the low year of 1995, if not a little above, since summer, and has ended well below normal. 
  • Center began seeing an increase in ET since mid-July, but has still ended the growing season below average. 
  • Avondale tracked along a normal rate for the growing season, save for a dip from early to late May, and thus has ended slightly below normal.
  • Idalia ET was tracking at roughly the low year of 2009 for almost the entire growing season until late August, when ETs started to increase substantially. Cumulatively, however, Idalia has ended below normal. 
  • Holyoke ET started around normal and dropped below normal since the second week of May. It continued to track at a normal rate through the growing season. 
  • Lucerne had been tracking lower than the previous record low year in 2009 since the second week of May. It has completed the growing season at nearly the same cumulative ET as 2009. 


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:

  • Most of the UCRB experienced below average temperatures over the last week, but there was still some warm anomalies, especially in western Colorado. 
  • The Green River Basin was cooler than normal with temperatures anywhere from 3 to 9 degrees below average. 
  • Northeastern Utah was mostly 0-6 degrees below normal for the week. There was a part of Uintah and Duchesne Counties that was 0-6 degrees above normal. A similar feature was present last week, and it looks like it may be unphysical, so we'll keep an eye on this. 
  • Temperatures in southeast Utah were within 3 degrees of normal on either side. 
  • Temperatures in northwestern Colorado fluctuated anywhere from 6 degrees above normal to 6 degrees below normal. The coolest areas were in the extreme northwest corner of the state. Western Eagle County and far east Garfield County were 6-9 degrees above normal.
  • Southwestern Colorado saw temperatures 0 to 9 degrees above normal.
  • Eastern Colorado was cooler than normal. The Front Range was the most consistently cool area at 3-6 degrees below normal. Farther east on the plains temperatures were more in the neighborhood of 0-3 degrees below normal. 

October Temperatures:

  • The UCRB and Colorado saw much above normal temperatures through the entire region for October.
  • The Green River basin was 6 to 8 degrees above normal, with a pocket in Lincoln County that was up to 10 degrees warmer than normal.
  • Northeastern Utah was mostly 4 to 6 degree above normal, and areas in the western Wasatch Range and Duchesne County 6 to 8 degrees warmer than normal.
  • Southeastern Utah was also 4 to 6 degrees warmer than normal, with San Juan County 2 to 4 degrees above normal.
  • Western Colorado was in the 4 to 6 degrees above normal range, with Moffat and Rio Blanco counties seeing 6 to 8 degrees warmer than normal.
  • Eastern Colorado saw mostly 4 to 6 degrees warmer than normal.  Morgan, Weld, Pueblo and El Paso counties saw areas between 6 to 10 degrees warmer than 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: (11/24)

  • This fall has been more mild than average thus far with a few cooler airmasses traversing the region over the past few weeks. The coldest air of the fall thus far is baring down on the UCRB and eastern Colorado for the middle of the week this week. High temperatures Friday are forecast to be as much as 35 degrees cooler Friday than today across the Front Range. The coldest day for the western end of the UCRB will be Thursday. 
  • Mild temperatures will be removed first from the Upper Green River Basin and then from northwest to southeast starting early afternoon on Wednesday. 
  • On Friday most of the moisture and primary forcing for precipitation exits the region to the east. Some light snow remains in southeast Colorado.
  • On Saturday another surface low builds in from the southwest bringing more light, persistent snow to western Colorado working its way up into Wyoming and the Uintah Range. 
  • The upper-level low is forecast to hang around into at least early next week, so similar situations with cooler temperatures and light to moderate snow can be expected. 
  • By Friday evening most of the region is forecast at least a tenth of an inch of precipitation. The driest regions will be southern Utah and northeast Colorado. Areas that can expect the highest precipitation totals by this time are the San Juans, Sange de Cristos, Uintah Range, and Rockies in Wyoming. All these areas could see 0.50-1.00" of precipitation over this time frame. 
  • Over the weekend it continues to be southwest Colorado that sees the highest odds of precipitation. The San Juan Range could receive another half an inch over this time frame. 
  • Early next week precipitation totals are forecast to be light, but the western slopes of the Rockies and the northeast corner of Colorado are currently forecast some precipitation, mostly under a tenth of an inch, for Monday into Tuesday. 

Longer Term:

  • The 8-14 day precipitation outlook shows increased chances for below normal precipitation across the entirety of the UCRB and Colorado east of the divide. These chances are highest in the Upper Green River Basin to the far northwest. 
  • The 8-14 day temperature outlook shows increased chances for below normal temperatures across the entirety of the UCRB and eastern Colorado. These chances increase in magnitude from southeast to northwest. 
  • The Climate Prediction Center December through February precipitation outlook shows increased chances for above average precipitation the south end of the UCRB. In the Upper Green River Basin and the northern portion of the Yampa River Basin precipitation is expected to be below normal. Most of Colorado east of the divide is forecast increased chances of above average precipitation, particularly towards the southeast corner of the state. The northern Front Range is forecast equal chances of above and below normal precipitation. 
  • The seasonal drought outlook for December through February indicates that drought improvement and removal are likely for the southwest portion of the UCRB by the end of January, but drought is likely to persist or intensify where it exists in the northern Wasatch and Uintah Ranges. 


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: December 1, 2015

Last week arctic air brought cooler temperatures to the northern UCRB and Colorado east of the divide. The whole of the UCRB and eastern Colorado benefitted from at least some precipitation with the biggest winners being the San Juan and Sangre de Cristo Mountain Ranges. The Yampa and Duchesne river basins also made out pretty well for precipitation over the last week, but are lingering a bit below average for snowpack to start the year. 

Weather is currently breezy across northeast Colorado as the last of the airmass that produced last week's snow exits the region to give way to some warmer, drier conditions over the next week. Some fine-tuning to the drought monitor will be recommended for this week before the warmer, drier air sets in over the next week that is likely to leave us with status quo recommendations for next week. 


UCRB: Removal of D0 is recommended for the central Rockies in eastern Grand, eastern Summit, northeast Lake, and northwest Park Counties. Following this week's snow the SNOTEL precipitation percentiles for the water year to date in this area are looking much better than areas to the immediate north or south. It's still early in the year for utilizing snowpack data, but snowpack east of the divide and along the Colorado mainstem is off to a promising start. 

Removal of D0 is recommended for eastern and central Uintah County and central Grand County in Utah with an outcropping of D0 left in place near the county line. This area received above average precipitation last week, and soil moisture appears to be back in the normal range. SPIs are positive on all timescales. This line was drawn making heavy use of the Evaporative Demand Drought Index, and not making improvements where drying is still indicated over the last 12 weeks. 

It is recommended that the appendage of D1 be downgraded to D0 over the Uintah Mountain Range. Following the moisture last week this area appears to be in good shape to start the water year. 

Western Sevier, southern San Pete, and extreme eastern Millard County in the southern Wasatch Range mostly fall just outside our jurisdiction for recommendations, so feel free to interpret this as a personal plight and leave it alone. This area had another good week of precipitation and looks much better than the Wasatch Range farther north to start the water year based on SNOTEL precipitation percentiles. Even at six months there is a SPI gradient from north to south with the zero line going through central San Pete County. This is a region that has been very gradually healing from a severe drought, but the more I study data from this area the more I just don't buy that it'll be in better condition that it is now over 90+ percent of the time. Please consider an upgrade to D1. 

Eastern Colorado: Status quo. In spite of the moisture in southeast Colorado soils remain dry over the area currently classified as D0.