On March 26, 2015, with Virginia’s and the Northern Hemisphere’s spring equinox just a few days gone by, here’s a look back at what happened with rainfall in the southeastern United States and stream flow in Virginia in winter 2014-25. The Virginia Water Resources Research Center thanks the agencies mentioned above for their work to providing these valuable assessment products.
The following maps, from the National Oceanic and Atmospheric Administration’s (NOAA) Southeast Regional Climate Center (SRCC), located at the University of North Carolina in Chapel Hill (http://www.sercc.com/climateinfo/precip_maps, accessed 3/26/15), show southeastern U.S. precipitation between December 26, 2014, and March 25, 2015 (first map), and how this rainfall compared to historical normal values for that period (second map). These data are provisional. (For perspective, Virginia’s statewide average annual rainfall since 1895 has been about 43 inches, according to the SRCC’s “Monthly and Seasonal Climate Information” Web page at http://www.sercc.com/climateinfo/monthly_seasonal.)
In the second map, note the brown and red areas—indicating precipitation at least 10 percent below normal for the period—in a swath of Virginia from the southwest to the center of the state. These levels have helped cause the occurrence of “abnormally dry” conditions in about 20 percent of Virginia as of March 24, 2015, according to the report of the U.S. Drought Monitor for that date. (The Drought Monitor is produced by the University of Nebraska-Lincoln and is available online at http://droughtmonitor.unl.edu/.) Virginia has had some areas rated as abnormally dry since the April 22, 2014, Drought Monitor report.
Outside of Virginia, note the large swath of below-normal precipitation from Virginia south to the Gulf Coast. The March 24, 2015, Drought Monitor rated about 25 percent of the southeastern United States as abnormally dry.
For another color-coded map of precipitation in Virginia or any other state of your choosing, see the National Weather Service’s Advanced Hydrologic Prediction Service’s nationwide map of precipitation, with daily, monthly, and yearly archives; online at http://water.weather.gov/precip/.
The first graph below, from the U.S. Geological Survey’s (USGS) “WaterWatch—Current Water Resources Conditions” Web site (http://waterwatch.usgs.gov/new/index.php?id=pa01d&sid=w__plot&r=va), accessed 3/26/15), compares average daily stream flow to historical records for the 45-day period of Feb.7—Mar. 25, 2014. The second graph covers the period since January 2001. The data in the graphs come from 88 sites that have at least 30 years of records. Each graph uses a “stream flow index,” which measures how a site’s average stream flow over 24 hours compares to the historical average stream flow for that same site and date. The graphs shows a further average: the stream flow index averaged statewide over the 88 sites.
Other Water Status Posts on the Water Central News Grouper
Previous seasonal look-backs are at this link: https://vawatercentralnewsgrouper.wordpress.com/?s=Seasonal+Look-back.
Monthly water-status updates are at this link: https://vawatercentralnewsgrouper.wordpress.com/?s=Virginia+Water+Status.