April 10, 2017
- Very warm and dry conditions the first three weeks of March caused unusually early snowmelt across the region, with significant or complete meltout at low and middle elevations in many basins, and substantial SWE losses at some high-elevation sites. A return to an active storm pattern put accumulation back on track so that as of April 7th, SWE in most basins was still well above normal .
- With the large snowpacks and early snowmelt, daily streamflows in northern Utah and western Wyoming rivers are at high (>90th percentile) or record-high values, including the Provo, Weber, Ogden, Logan, Bear, upper Green, Snake, Wind, Bighorn, and Yellowstone. There is an elevated risk of flooding in these basins as spring runoff progresses.
- The April 1 NRCS spring-summer runoff forecasts came in lower than the March 1 forecasts at most points, though the regional picture is still dominated by above-average runoff . Forecast points in northern Utah and western Wyoming are expected to have >150% of average runoff, while points in Colorado, southern Utah, and eastern Wyoming, are split between the below-average (70-89%), near-average (90-109%), and above-average (110-129%; 130-149%) categories. Forecasted Lake Powell inflows have slipped to 130% of average, per both NRCS and NOAA CBRFC.
- With the boost from storms late in the month, central and western Wyoming, much of Utah, and far eastern Colorado ended up with well-above-normal precipitation. Northwestern and southern Utah, northeastern and south-central Wyoming, and western and north-central Colorado stayed well on the dry side . Statewide, Wyoming was yet again very wet, in the 89th percentile for precipitation, with Utah in the 65th percentile and Colorado in the 34th percentile.
- Like February, March ended up as very warm across the region, with temperature departures of +2°F to +10°F . Colorado had its warmest March on record, 6.4°F above normal, while Utah saw its 2nd-warmest March, and Wyoming, its 4th-warmest March.
- Drought conditions have improved in central Utah and areas of eastern Colorado since early March, but deteriorated in other areas of eastern Colorado . D1 or D2 conditions now cover 22% of Colorado (down from 37%), 9% of Wyoming, and 0% of Utah.
- The tropical Pacific remains in ENSO-neutral conditions, though with warming sea-surface temperatures off the Peruvian coast in the Niño 1+2 region . The ENSO forecast models call for neutral conditions to continue through spring, with in increasing chance of El Niño conditions by fall .
