Below are images showing precipitation in Virginia and other areas of the southeastern United States, and stream flow in Virginia, over the seven-day period ending April 16, 2017 (information available as of April 17). Also below is a national flooding overview map, as of April 17, and the Virginia Drought Monitoring Task Force’s daily map showing the status of several drought indicators in different Virginia regions, as of April 16. The Virginia Water Resources Research Center thanks the agencies mentioned below for providing precipitation and stream-flow information and images. For the current month’s other weekly reports on stream flow and precipitation, please see the News Grouper posts available at this link: https://vawatercentralnewsgrouper.wordpress.com/?s=Virginia+Precipitation. For monthly reviews of precipitation, stream flow, and drought, please see the posts available at this link: https://vawatercentralnewsgrouper.wordpress.com/?s=Monthly+Water+Status. For more information on current and historical surface-water and groundwater conditions in Virginia, please see the U.S. Geological Survey (USGS) Virginia Science Center’s Web site, http://va.water.usgs.gov/.
April 2017 Gaging Station of the Month: North Fork Shenandoah River, at Mt. Jackson (Shenandoah County), June 26, 2007.
The following two color-coded maps show southeastern U.S. precipitation amounts (top map) and the percent of normal precipitation compared to normal for this period of the year (bottom map) over the seven-day period ending April 16, 2017. The maps were accessed from the National Oceanic and Atmospheric Administration’s (NOAA) Southeast Regional Climate Center, located at the University of North Carolina in Chapel Hill; online at http://www.sercc.com/climateinfo/precip_maps. As of that date, these data were provisional (needing to be verified for accuracy and subject to possible revision).
Another source of precipitation data is the National Weather Service’s Advanced Hydrologic Prediction Service, online at http://water.weather.gov/precip/. The site provides maps showing precipitation nationwide or by state for specific days, months, or years. The site also has the capability to show county boundaries, and other map layers available include river flood forecasts and current flood/severe weather warnings. Shown below is a screen shot of the continental U.S. 7-day precipitation map as of 8 a.m. EDT on 4/17/17. Please note that UTC, the time shown on the maps at the site, is four hours ahead of Eastern Daylight Time and five hours ahead of Eastern Standard Time.
Seven-day-average Virginia stream flows at gaging stations as of April 16, 2017 are indicated in the map below, from the U.S. Geological Survey WaterWatch for Virginia, accessed online at http://waterwatch.usgs.gov/index.php?m=pa07d&r=va&w=map. The map’s color-coded dots compare the previous week’s average stream flows to the normal flow levels for that week over the historical record for each gaging station. The color codes/percentile classes used by USGS are as shown in the chart following the map.
Flooding Overview Nationwide
The National Weather Service’s Advanced Hydrologic Prediction Center’s map of river levels relative to flood stage (color-coded) is available online at http://water.weather.gov/ahps/forecasts.php; at that site, one can zoom in to show Virginia or any other state of interest. Shown below is a screenshot of the map available online at that site as of 2:30 p.m. on 4/17/17.
Mid-month Drought Status Update
The Virginia Drought Monitoring Task Force (DMTF), a collaboration of state and federal agencies, issued its latest Virginia drought-status report on March 20, 2017. The report is available at the DMTF Web site, http://www.deq.virginia.gov/Programs/Water/WaterSupplyWaterQuantity/Drought.aspx. The Task Force was scheduled to meet and report again in April 2017.
The Task Force also produces a daily map rating drought-status indicators. Shown below is the map for April 16, 2017. The status-indicator abbreviations on that map are as follows: GW = groundwater levels, Prcp = precipitation deficits, Res = reservoir storage, and Flow = stream flow conditions. For each region of Virginia, the indicators are color coded for “normal,” “watch,” “warning,” or “emergency conditions.” Note the emergency-conditions code (in red) for streamflow and groundwater in parts of the northern and central Piedmont, the warning code (in orange) for precipitation in those areas, and the warning code for groundwater in the Shenandoah Valley region. Any given day’s current map and more information on drought status in Virginia are available the Task Force Web site, http://www.deq.virginia.gov/Programs/Water/WaterSupplyWaterQuantity/Drought.aspx.