NIDIS Upper Colorado River
Regional Drought Early Warning System
November 24, 2015
When available, maps and text are updated Tuesday afternoons.
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 mix of precipitation last week.
- The Upper Green River basin saw between 0.25 and 1.00" of precipitation in Sublette, Lincoln and Uinta counties. Sweetwater County saw less than 0.25" in the eastern portion of the county, and less than 0.10" in the western portion.
- In Utah, the Wasatch and Uintah ranges received between 0.25" to 1.00". Eastern and southern Utah saw less than 0.25".
- In western Colorado, the lower elevation saw less than 0.25", with much of northwestern CO seeing less than 0.10". The higher elevations saw greater than 0.50", with some areas seeing better than 2.00".
- The San Juan Mountains saw between 0.50" in the lower elevations, up to 2.00" in the higher elevations.
- The Rio Grande basin was dry in the valley with less than 0.25", but saw up to 2.00" in the mountains.
- East of the Divide, most areas saw some precipitation. Weld and eastern Larimer counties along with the Arkansas River valley saw less than 0.25", while the rest of eastern Colorado received greater than 0.25".
- Southeastern Colorado, including Las Animas, Baca, southern Bent, Prowers and eastern Kiowa counties saw up to 3.00". Just east and southeast of the Denver area also received up to 2.00" for the week.
- 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.
Additional Precipitation Links: (will take you to an outside website)
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):
- SPIs across the UCRB are all positive in the short term, with the exception of the western portion of the basin.
- The Upper Green Basin in southwest Wyoming is showing a range of -1.5 to +1.
- The Wasatch range in northern Utah is showing mostly dry SPIs on the 30-day time scale, between 0 and -2. The southern Uintah range and the rest of eastern Utah is showing mostly wet SPI, between 0 and +2. The wettest show up in Grand County.
- Western Colorado is all positive, up to +2 in Mesa, Delta, and Summit counties.
- East of the divide is mostly positive, with the exception of the Arkansas River from eastern Fremont County to Otero County, which is in the 0 to -1 range. The wetest areas in eastern Colorado is around the Denver metro area and northeastern CO, with SPIs up to +2, and Prowers County, with an SPI up to +2.5.
- With the recent wettness, the 90-day SPIs are starting to recover, however it is still showing the dry late August and September.
Long Term (6-month):
- Long term SPIs are still being influenced by the wet spring, but are increasingly showing influence by the dry late August and September.
- The Green River basin is still positive at all stations, in the 0 to +1 range.
- Eastern Utah is, for the most part, still positive. The southwest portion of the state has been very wet for the long term. One station in eastern Wayne County is still at near +3 SPI. Stations in the Wasatch Range in central UT are still holding on to slightly negative SPI values, however.
- SPIs in the headwaters of the UCRB are showing plenty of -1's with SPIs increasing substantially further downstream into Mesa County. The Four Corners area has been very wet on the long term, with SPIs up the +2.5.
- The western portion of the Upper Rio Grande Valley is showing SPIs between 0 and -1.
- Eastern Colorado is also starting to dry out on the long term, losing the wet spring influence. Larimer County and northeastern Colorado is showing SPIs in the 0 to -1 range. Yuma and Sedgwick counties are still wet on the 6 month time scale. Southeastern Colorado is mostly in the near normal range.
Additional SPI Links: (will take you to an outside website)
Drought Tracker SPI Maps
HPRCC's SPI Maps
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.
- There hasn't been much change in the soil moisture over the past week.
- 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 County.
- Eastern Utah is showing mostly normal to wet soils, especially in the Four Corners area, with soils up to the 90th percentile. There is a dry swath in western Duchesne, Carbon and Emery counties.
- Western Colorado is showing some very wet soils along the border counties, up to the 95th percentile in Mesa County. Normal soils are showing closer to the divide.
- Most of eastern Colorado is normal to slightly wet soils. El Paso and Pueblo counties are showing some drier soils down to the 10th percentile.
- 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.
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..
- 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:
- Temperatures through the basin were a mix of above and below normal.
- The Green River Basin saw temperatures 0 to 2 degrees below normal in Sublette and western Sweetwater counties and 0 to 2 degrees above normal in the rest of Sweetwater County, southern Lincoln County and Uinta County.
- Northeastern Utah in the Uintah Range saw temperatures 0 to 8 degrees above normal, with the warmest bulls eye in Duchesne County. The rest of Utah saw below normal temperatures.
- Northwestern Colorado in Moffat, Rio Blanco, Garfield, Eagle counties and into northern Gunnison Counties saw mostly 0 to 2 degree normal temperatures, with some areas up to 4 and 6 degrees warmer than normal.
- Southwestern Colorado saw temperatures 0 to 4 degrees below normal.
- Eastern Colorado also saw a mix. Warm temperatures popped up in El Paso and Pueblo counties and from Otero up to souther Yuma counties. Most temperatures were 0 to 2 degrees warmer than normal, with a few areas up to 4 degrees above normal.
- The rest of Colorado saw mostly 0 to 2 degrees below normal. Southern Colorado was cooler, down to 4 degrees below normal.
- 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
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.
- 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.
the proposed changes for this week, with supporting text.
Summary: November 24, 2015
Last week in the Upper Colorado River Basin brought beneficial snow to the mountains with less precipitation to the lower elevations. The snow helped to increase the mountain snowpack to above normal for many of the basins. The Upper Green, northern Utah ranges and Yampa basin are still less than 90% of the snowpack to date. It is still early in the snowpack accumulation season, so the basins could still turn around with a few good storms. Precipitation this month in the basin has been over 1.00" in most areas, with the San Juan Mountains and along the Divide seeing up to 5.00". The Upper Green River Basin has been drier, mainly in Sweetwater and southern Sublette Counties.
East of the Continental Divide, the South Platte and Arkansas Basins are showing much above normal snowpack. November precipitation has been weak in much of the Arkansas Basin, with Fremont, Pueblo, El Paso and Lincoln counties receiving less than 0.25" so far this month. Elsewhere in eastern Colorado, precipitation totals are over 1.00" through most of the area, with a few areas seeing between a half to 1.00 inch.
Through much of the area, the UCRB and Colorado, most 30-day SPIs have turned positive (wet), with a few dry areas. There are still a lot of 90-day SPIs that show up dry, especially where there is already D0, however. Those wet 6-month SPIs are starting to turn to the dry side, as well.
UCRB: Status quo, with watchful eyes for some improvements in the Central Colorado Mountains.
Eastern Colorado: The Drought Monitor Author has already planned some deletion of D0 in Yuma County to blend with improvements in Nebraska and Kansas, we are in agreement of this, although we are recommending a little more improvement to catch the northwestern corner of Yuma County and a +2 30-day SPI. All SPIs in this D0 area are positive on the 30-day time, however they are still dry on the 90-day time. We will hold off on improving those areas.
**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
Friendly Version of current Drought and Water Assessment
PDF of current Drought and Water Assessment