Snowmelt Runoff Sets Streamflow Records in the Southwest

By WaterNews Network

Across the western U.S., many areas received record or near-record amounts of snowpack over the winter. With the spring and summer temperatures melting the abundant snow, a record volume of streamflow has been recorded in several basins in the southwestern U.S., providing more water for the area later into the summer than is typically seen.

Snowmelt runoff in Walker and Carson basins

The Walker and Carson basins near the California-Nevada border, for example, have reported the largest volume of streamflow for April through July that has ever been observed in roughly a century, when the records began. The ample runoff is helping fill reservoirs that have been depleted from years of drought conditions.

Weekly U.S. Drought Monitor: Cooler Northwest, Warmer Southwest

Dry conditions dominated the West and southern Plains, coupled with above-normal temperatures. Precipitation was most widespread throughout much of the upper Midwest and central Plains and into the Northeast. Almost the entire country had near- to above-normal temperatures this last week, with the greatest departures over the Southwest and central Plains where temperatures were at least 4-7 degrees above normal.

Cooler-than-normal temperatures were recorded in the Pacific Northwest with departures of 3-6 degrees below normal. At the end of the current U.S. Drought Monitor period, significant rains developed over portions of the Midwest and central Plains, and they will be accounted for in the next analysis.

U.S. Seasonal Drought Outlook

Central portions of the Intermountain West may be spared degradation, as those areas are still showing residual benefits from above normal winter snowpack leading up to the summer, in addition to periods of above normal rainfall during the last 60 to 90 days. Seasonal temperature and precipitation outlooks, ENSO, and climatology favor widespread drought improvement and removal across the central U.S. However, drought persistence is favored across the Upper Midwest, although there is the potential for localized improvements.” Read full assessment:  cpc.ncep.noaa.gov/products/expert_assessment/sdo_summary.php.

Seasonal Precipitation Outlook: November, December, January 2023-24

Colors show where total precipitation has an increased chance of being higher or lower than usual during the next three months. The darker the shading, the greater the chance for the indicated condition. White areas have equal chances for precipitation totals that are below, near, or above the long-term average (median) for the next three months.

Climate scientists base future climate outlooks on current patterns in the ocean and atmosphere. They examine projections from climate and weather models and consider recent trends. They also check historical records to see how much precipitation fell when patterns were similar in the past.

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