NIDIS Upper Colorado River
Regional Drought Early Warning System
March 4, 2014
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:
- Larger precipitation accumulations were mainly confined to the higher elevations in the UCRB last week
- The majority of the mountainous areas of the basin saw 0.51- 2.00" with isolated areas in the Upper Green, Wasatch, and San Juan's seeing 2 - 4" over the past week.
- The western valleys saw small amounts of precipitation ranging from 0.26"-0.50". Sweetwater county in Wyoming was dry with less than 0.10" over the week.
- The four corners area picked up much needed moisture in the range of 0.26" up to 2" in isolated areas.
- East of the divide in Colorado was dry with most areas of the plains seeing less than 0.25" over the week. SE Wyoming saw more moisture which also made it into Larimer county in Co. Those amounts totalled 0.26" up to 2" in some locations.
- The Upper Green River basin and Wasatch mountains saw much above normal precipitation in February. Large areas of 300% or more are present in Western Wyoming and NE Utah.
- The lower Yampa basin and eastern Utah saw below normal precipitation in February.
- The northern, central and southern mountains in Colorado saw near normal to above normal precipitation in February.
- The four corners area was dry in February receiving less than 70% of normal precipitation for the month.
- East of the divide saw above normal precipitation for February farther east (SE Wyoming and NE Colorado were >300% of normal) on the plains while areas closer to the Front Range saw below average moisture in February.
- The Crowley/Otero area saw near normal to above normal moisture in February, which was very much needed. That moisture also made it farther east into Cheyenne, Kiowa, Bent and Powers counties bringing normal to above conditions in February.
- The I-25 corridor was dry for February, but February is normally dry along the Front Range.
- The San Luis Valley saw below normal moisture through much of the valley bottom in February.
Water Year Precipitation (Oct-Feb):
- Much of the UCRB is showing normal to above conditions for the water year through February.
- The driest areas are present in eastern Utah and the four corners area. Those areas saw less than 90% of normal.
- Much of the mountainous areas of the UCRB are reporting above normal conditions, particularly in the Green River basin.
- Much of the state of Wyoming has seen normal to above normal precipitation since the start of the water year.
- East of the divide in CO, conditions for the water year are above normal over the NE plains and deteriorate to the South, particularly south of I-70 and east of I-25.
- Las Animas and Baca counties saw less than 50% of their normal water year precipitation through February. Below normal water year precipitation predominates much of the lower Arkansas valley.
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 most of the higher elevations of the UCRB are showing wet indicators
- The Wasatch range in central UT is showing SPIs between 0 and +2.5
- Western WY SPIs are mostly between 0 and +2.5 with slightly drier SPIs (between -1 and +2.5) to the east along the Wind River range
- Most of northern, central, and eastern CO are showing wet indicators, with SPIs between -2.5 and +2. The lowest SPI is in Las Animas county near Trinidad.
- The Four Corners region improved on the short term with recent moisture. Those SPI's are now in the -1 to +1 range.
Long Term (6-month):
- Most of the UCRB shows wetter long-term SPIs with the exception of the Wastach and Four Corners areas.
- The driest area of the UCRB on the longer term is northern Utah near the Wasatch range where SPIs range from -1 to +2.
- The Four Corners area is still slightly dry on the longer term with SPI's from -1 to +1.5.
- The rest of the UCRB indicates wet conditions, with SPIs ranging from 0 to +3
- The driest areas on the plains remain in the lower Arkansas valley from Pueblo to Otero county.
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 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.
- Most of the UCRB is showing near average to wet soil moisture conditions.
- Soil moisture across most of western CO and parts of eastern UT are between the 70th and 95th percentiles.
- Some spots of southern WY and northern UT are slightly drier, with soil moisture percentiles between the 5th and 30th percentiles.
- Most of eastern WY is showing wet soil moisture.
- The lower Arkansas valley, east of the divide, is reporting dry soil moisture conditions with percentiles in the 2nd to 30th percentile range. The driest area is centered over Otero county.
- Adding in SWE for total moisture storage, conditions are even wetter for western CO and even drier for northern UT with the below normal snowpack conditions.
- All of the major northern reservoirs in the UCRB are near to above their March averages, ranging between 94% (Lake Granby) and 109% (Green Mountain) of average
- The southern reservoirs are below average, ranging between 56% (Powell) and 98% (Blue Mesa) of average
- Green Mtn and Granby have seen slight decreases since the end of last month while the remaining reservoirs have remained at the same level.
Additional Surface Water Links: (will take you to an outside website)
NLDAS Drought Monitor
Bureau of Reclamation Upper
Colorado River Basin Teacup Diagrams
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 near normal to above normal temperatures over the past week between 0 to 15 degrees above normal.
- The Wasatch range was the warmest area of the UCRB with temperatures 10-15 degrees above normal.
- East of the divide was much colder with temperatures ranging 0 to 20 degrees below normal with the coldest areas in eastern Wyoming and the NE corner of Colorado.
Last Month Temperatures:
- The UCRB mainly saw above normal temperatures in February ranging from near normal along the divide to 10 degrees above normal.
- The warmest areas were in Utah and SW Wyoming with temperatures near normal to 10 degrees above normal for the month.
- Western Colorado was mainly in the 2-4 degrees above normal range for February.
- The Rio Grande basin was also warm with temperatures 2-8 degrees above normal.
- East of the divide was a completely opposite situtation with temperatures ranging from near normal at the divide to more than ten degrees below normal farther to the east. The effects of these cold temperatures on the plains winter wheat crop can only be assessed once it emerges from dormancy.
- The coldest areas were in north central and eastern Wyoming as well as the NE corner of Colorado. Temperature departures moderated slightly on the SE plains of Colorado but remained 2 to 8 degrees below the February normal.
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
- A fast moving system will bring an additional 4-10 inches of snowfall to eastern Utah and Western Colorado mountains through tonight. The best chance for precipitation will be above 8,000 feet from the Wyoming border to Rabbit Ears Pass and Vail Pass.
- Valley areas could see 2-5 inches as mixed precipitation and potential for isolated thunderstorms.
- This system has potential to spill over to the eastern plains and bring rain this afternoon transitioning to snow overnight. Snow amounts are forecast to be a Trace up to 5" on the plains with the heaviest amounts over NE Colorado.
- Conditions will improve from NW to SE overnight with dryer and warmer conditions Wed-Thurs.
- Another system is forecast to pass through the area Fri-Sat with potential for significant snowfall over portions of Colorado.
- The 8-14 day precipitation outlook shows higher probability of below normal precipitation across the UCRB with more normal conditions east of the divide.
- The CPC 3-month outlook shows equal chances for wet, dry, or near normal conditions across the entire basin for March-April-May
- The seasonal drought outlook shows a probability of drought persisting across the western portion of the basin and across southeast CO and northern UT
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: March 4, 2014
The Four Corners and San Juan mountains picked up very beneficial moisture over the past week. That area is still being closely monitored as it was very dry previous to this recent storm. The area is forecast to continue to pick up moisture over the next week as is much of the UCRB and eastern plains of Colorado.
In light of the current conditions and forecast precipitation over the region, status quo is recommended this week. There is potential for some improvements next week, particularly in parts of western Colorado and Wyoming if the forecast verifies.
UCRB: Status quo is recommended this week.
Eastern Colorado: Status quo is recommended this week.
**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