The U.S. Drought Monitor from April 20th showed slight improvements in areas near Larimer and Boulder counties. Similar to last month, exceptional (D4) drought currently covers 15% of the state; extreme (D3) drought covers 17%; severe (D2) drought covers 28%; moderate (D1) drought covers 29%; and recent precipitation resulted in patches of abnormally dry (D0) areas in 10% of the state.
The 90-day Standardized Precipitation Index (SPI) values from Jan. 11 to Apr. 11 highlight continued dry conditions on the western slope. North eastern Colorado’s SPI data points reflect areas of above average precipitation after January and March snowstorms. The 12-month SPI map depicts the long-term drought conditions due to precipitation deficits in 2020 across the state, especially in the west.
The NOAA Climate Prediction Center three month outlook indicates increased chance of above normal temperatures and below normal precipitation are in the upcoming months. These forecasts are consistent with long-term temperature trends, and a strong signal in seasonal models of inordinate high pressure ridging over the West. Monsoon season remains uncertain. The current La Niña pattern continues to weaken and is expected to revert to neutral conditions in the summer. This is typical; ENSO signals are often dampened in summer. Development of a 2nd La Niña year is anticipated this fall through winter. The last two 2nd year La Niña events were water years 2012 and 2018. Both were drought years.
Water providers across the state report average to slightly below average storage levels and near normal demands. Drought management planning and potential restrictions are being discussed through multiple coordination groups. Stakeholders can follow along with state drought response actions and activities through public engagement pages for the Municipal Water Task Force and Agricultural Impact Task Force.
Colorado Public Safety presented an overview of the wildfire outlook for the coming year to the Water Availability Task Force. Many factors contribute to the extremity of a fire season including humidity, lightning or human created ignitions, rainfall during monsoon season, and winds. In the past, Colorado’s fire season began in late May through June into late August and September. More recently, this pattern has changed around the state and fires can occur during any month. The number of fires has been decreasing across the nation, but the number of acres covered by fires has increased. In 2020, 4 of the 20 largest fires in Colorado occurred, including the first, second and third largest fires in the state’s history.