Snowpack Conditions Reflect Typical La Niña Patterns
Northern basins have received more moisture than the south. Early season storms bolstered water year to date precipitation in southern basins but a drier mid-winter has tempered forecasts. Higher latitude basins continue to benefit, with streamflow projections near or above median.
Denver, CO – March 7th, 2025 – As of March 1st statewide snow water equivalent (SWE) is at 91 percent of median, relatively consistent from February 1st. Northern water systems continue to trend near or above median, particularly: the South Platte (105%), Laramie and North Platte (102%), the Colorado Headwaters (100%) and combined Yampa-White-Little Snake (96%). The southern half of the state remains below normal with the largest decrease observed in the Arkansas (79%). The Gunnison basin is at 86 percent of median, reflective of its central geographical location on the western slope. While the Gunnison basin follows the broader north south trend, its position further north compared to other southern basins has helped mitigate more extreme deficits. In contrast, the Upper Rio Grande (63%) and the combined San Miguel-Dolores-Animas-San Juan (SMDASJ) (64%) remain drier, with some of the lowest snowpack levels recorded at this point in the season.
February storms provided some relief, with the Valentines Day storm delivering up to 3.2 inches of SWE in the La Plata Mountains, offering a much needed boost for the SMDASJ basin. "That said, February's inconsistent storm cycle has not been game changer. While northern basins benefitted the most, that mid-month surge helped slow the freefall in the southern half of the state but wasn’t quite enough to significantly impact overall snowpack conditions," noted Nagam Gill, NRCS Hydrologist.
Recent precipitation trends over the past 90 days highlight similar disparities. The Upper Rio Grande and SMDASJ are at just 44 percent of their period of record median precipitation. Northern basins, on the other hand, are sitting in a much better position heading into the peak snowmelt period. The past 30 days show precipitation at 66 percent for the Arkansas basin and 84 percent for the Gunnison basin. Winter precipitation contributes to both snowpack and overall water year precipitation. Snowpack acts as a natural reservoir, storing water at high elevations until melt out, which directly influence streamflow forecasts. While additional precipitation is expected during the summer months, particularly in southern basins during monsoon season the odds of winter driven streamflow fully catching up remain low.
Statewide reservoir storage sits at 94 percent of median, down slightly from 100 percent this time last year. With spring runoff yet to begin, storage levels are mostly unchanged from last month. Higher capacity reservoirs are generally near historical medians. While McPhee Reservoir is lower at 76 percent of median and at 55 percent capacity most major reservoirs are near to above normal and positioned to potentially further exceed medians during primary runoff. Blue Mesa Reservoir is at 96 percent of median and at 61 percent capacity. Pueblo Reservoir is at 114 percent of median and at 72 percent capacity. Lake Granby is at 101 percent of median and Dillon reservoir is at 91 percent of median.
Streamflow forecasts for March 1st closely reflect recent precipitation and snowpack trends. Statewide, the 50% exceedance streamflow remains largely unchanged from last month, currently at 88 percent of median. Of the 86 forecasts points, nearly half are projected to perform at or above 85% of median streamflow. Northern basins, which have benefited from stronger storms, continue to see near median or above median streamflow projections at the 50% exceedance probability. Meanwhile, southern basins, particularly the Upper Rio Grande and combined SMDASJ, remain well below normal. "A critical consideration when reviewing these forecasts is the full range of exceedance probabilities. In regions already experiencing sustained dry conditions, the drier exceedance forecasts (70%, 90% or 95%) may be more likely to materialize if current trends persist. Likewise, if the latter part of the season trends wetter, higher probabilities (30%, 10% or 5%) should be taken into account," notes Gill. The variability of forecasted volumes means that relying solely on the 50% exceedance forecast may not fully capture the uncertainty inherent in these projections.
In the Upper Rio Grande, one of the highest output forecast points, Rio Grande near Del Norte, is forecasted at 380 KAF for the primary period April – September (50% exceedance probability). This is below the median of 480 KAF. If drier conditions continue, the 70% exceedance probability is 320 KAF, highlighting the potential if snowpack conditions persist or in the event of earlier melt out dates.
Following suit in the Arkansas, 50% forecasts have decreased from last month to 92 percent of median. While the 50% probability is slightly below normal there is a potential for streamflow to perform near or below minimum forecasts. Recent discussions suggest that actual streamflow's in the Arkansas Basin may underperform relative to the NRCS forecast probability suite. NRCS streamflow forecasts are constrained by internal modeling thresholds and do not extend below 95% exceedance probability, meaning that exceptionally dry conditions may not be fully captured within the published forecast range.
Between March 1-7, storms have been delivering snowfall to much of the state with the southwest corner observing up to 2.5 inches of SWE at Red Mountain Pass. NOAA’s 6-10 day forecast outlook suggests increased chances for precipitation statewide, with the western slope showing slightly higher probabilities and the southwest corner expected to receive higher amounts. Temperature trends indicate cooler than average conditions on the western slope, while the central to eastern regions are projected to remain near normal, with the far eastern plains trending slightly warmer. This pattern would help extend snowpack longevity in the northern and central mountains while also offering a potential boost to moisture starved southern basins. Statewide, peak SWE is typically around April 8, meaning we still have a few weeks left to accumulate more snow.
To put 2025’s snowpack in perspective, the above graph compares March 1 snow water equivalent (SWE) percentages to similar La Niña years, including 1999, 2000, 2006 and 2018. Historically, La niña conditions favor increased snowfall in northern Colorado while the southern basins often experience drier conditions. This trend holds in 2025, with the Upper Rio Grande and SMDASJ tracking close to 2018 levels, a year that observed similar dry patterns. Meanwhile, statewide SWE trends resemble 2000.
For more details see the March 1st Water Supply Outlook Report.
Natural Resources Conservation Service
Colorado State Office
Denver Federal Center
Bldg. 56 Room 2604
PO Box 25426
Denver, CO 80225-0426
Phone: (720) 544-2852
Email: co-nrcs-snow@usda.gov
Snow Survey Supervisor
Brian Domonkos (720) 544-2852
brian.domonkos@usda.gov