March 12, 2019 (UT, WY, CO)
- An unusually active storm track has led to continuing and nearly unprecedented gains in snowpack conditions for the region since mid-February. The region's snowpack is now similar to that in mid-March 2011 or 2017, which would have been hard to imagine two months ago. The March 1 seasonal runoff forecasts call for near-average (90-110%) or above average (110-130%) spring-summer runoff for the vast majority of forecast points, but these forecasts do not fully reflect the additional heavy snowfall since March 1. Drought conditions in the Four Corners and elsewhere have seen significant improvement.
- After a month of unrelenting storms, snowpack conditions as of March 12 are well above normal in Utah and Colorado, with most basins reporting between 120-150% of normal SWE . Wyoming has seen less improvement overall, and most basins are at 95-115% of normal SWE. Southern and central Utah, and central and southwestern Colorado, have seen SWE increases since February 1st that are 200-400% of the normal accumulation for that period. Schofield Pass SNOTEL near Aspen has added a whopping 17.2" of SWE since February 1, and many other sites have added over 10". The SNOTEL basin average for the Upper Colorado River Basin is at 133% of normal, up from 107% one month ago.
- The NRCS and NOAA RFC March 1 seasonal runoff forecasts call for near-average (90-110%) or above average (110-130%) spring-summer runoff for most forecast points in Colorado and Utah, and near-average runoff for most points in Wyoming . While these numbers are much improved over the February 1 forecasts, they don't reflect the continued anomalously wet weather into early March over Utah, western Colorado, and far-western Wyoming. For example: The March 1 forecasts for Lake Powell April-July inflows are for 102% of average (CBRFC) and 108% of average (NRCS), but the latest (March 12) CBRFC daily ESP forecast, which accounts for that recent precipitation, calls for 125% of average Lake Powell inflows.
- February was much colder than normal over the region with widespread departures of 4 to 10 deg F. Some parts of northern Wyoming were 15-20 deg F below normal. February was wetter than normal over all three states, with Wyoming and Utah cracking the 12 wettest (90th percentile) of the past 125 years. About 15 SNOTEL sites in Utah, northwestern Wyoming, and southwestern Colorado, had their wettest February on record.
- With every storm over the past month, there has been further improvement in the drought conditions over much of Utah and Colorado . The former area of exceptional drought (D4) in southeastern Utah and southwestern Colorado has improved to D1 and D2. There was some expansion of D0 conditions in north-central Wyoming.
- We have an El Niño! Sea-surface temperatures in the tropical Pacific warmed more in February and the 3-month average ONI (Oceanic Niño Index) finally crossed the magic threshold. Most forecast models call for this El Niño event to remain weak, but persist through the summer. The CPC seasonal precipitation outlooks for the March-May and April-June periods show slightly enhanced chances for above-normal precipitation for the region, with a stronger wet tendency for Colorado in the latter period.
