@CWCB_DNR: April 2018 #Drought Update

Here’s the update from the CWCB/DNR (Taryn Finnesey/Tracy Kosloff):

Exceptional drought has been introduced into the four corners region of Colorado as persistent precipitation deficits continue. While early April storms have helped improve conditions throughout northern Colorado, the southern half of the state remains extremely dry. Conditions are somewhat tempered by strong reservoir storage, but water providers are already seeing increased demands and implementing restrictions. Agriculture is also seeing loss of winter wheat and strong winds have fueled early fires. Water year-to-date accumulation at Mesa Verde is the lowest in its 95 year record.

  • As of April 19, exceptional drought has been introduced in southwest Colorado, covering 4 percent of the four corners region, primarily in Montezuma and La Plata County. Extreme drought, D3, covers 21 percent of the state; severe drought 29 percent and 16 percent is classified as moderate drought. An additional 15 percent of the state is currently experiencing abnormally dry conditions (see image on reverse side).
  • As of April 19, statewide snowpack at SNOTEL sites is 69 percent of average. However, there is a stark contrast between conditions in the southern half of the state and the northern half. The Gunnison basin has the lowest snowpack on record while the Southwest basins and Rio Grande have already achieved their peak snowpack and have now seen a 50 percent melt off of their snowpack.
  • Many southern basins’ year –to-date precipitation, based on SNOTEL is tracking near 2002; while other sites have the lowest in the nearly 40 year record (see image on reverse side).
  • Reservoir storage statewide is at 114 percent of normal, with all basins above average. The Arkansas basin is reporting the highest average storage at 131 percent. The Southwest basins of the San Miguel, Dolores, Animas & San Juan have the lowest storage levels in the state at 101 percent of normal. While still above average, storage levels have begun to decline from previous months.
  • The Surface Water Supply Index (SWSI) values have declined for April 1, with much of the western slope classified as extremely dry. These values are largely driven by below average streamflow forecasts. The sub- basins with the highest values are a result of large reservoirs such as Lake Granby and John Martin Reservoir (See image on reverse side).
  • Streamflow forecasts are well below average for the vast majority of the state with the South Platte the only basin with any near normal projections. The southern half of the state continues to see declines, and the southwest corner has streamflow forecasts below 50 percent of average.
  • Longterm forecasts indicate below average precipitation into May coupled with increased likelihood of above average temperatures.
  • Statewide snowpack basin-filled map April 23, 2018 via the NRCS. Note Rio Grande did not render correctly. It was at 31% of normal on April 22, 2018.

    Statewide SNOTEL water year-to-date precipitation is below average across much of the state but particularly in the south with some sites in the San Miguel, Dolores, Animas and San Juan Basins recording all time lows.

    Colorado Drought Monitor April 17, 2018.

    Southern Colorado has continued to see an expansion of drought conditions through the snow accumulation season, with exceptional conditions now present in Montezuma and La Plata counties.

    April 1 Surface Water Supply Index values are well below normal for the western half of the state, with the driest regions in the four corners area.

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