Below are several items summarizing recent precipitation and stream flow:
- Images showing precipitation in Virginia and other areas of the United States, and stream flow in Virginia, over the seven-day period ending November 13, 2017 (information available as of November 14).
- An excerpt from the Virginia Drought Monitoring Task Force’s latest statewide assessment on , 2017, and a map showing the status of several drought indicators in different Virginia regions, as of November 14.
- Flooding overview maps for Virginia and nationwide, as of November 14.
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/.
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 November 13, 2017. As of that date, these data were provisional (needing to be verified for accuracy and subject to possible revision). 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. Maps for other regions are available online at https://hprcc.unl.edu/maps.php?map=ACISClimateMaps.
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 the continental U.S. 7-day precipitation map as of 7 a.m. EST on 11/14/17. Please note that UTC, the time shown on the maps at the site, is five hours ahead of Eastern Standard Time and four hours ahead of Eastern Daylight Time.
Seven-day-average Virginia stream flows at gaging stations as of November 13, 2017 are indicated in the map below, from the U.S. Geological Survey (USGS) 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. Note: Additional gaging stations (such as for reservoirs or for inactive sites) are shown on maps available at the USGS’ National Water Information System Mapper, online at https://maps.waterdata.usgs.gov/mapper/index.html.
As of about 2:30 p.m. EST on November 14, 2017, about 7 stream-gaging stations in or adjacent to Virginia were [add as necessary: either experiencing flooding or] near flood stage, according to the National Weather Service’s Advanced Hydrologic Prediction Service’s (AHPS) map of stream and river levels relative to flood stage (color-coded) for Virginia and nearby areas. The AHPS map for Virginia is shown below, along with the nationwide map as of the same time. The maps are available online at http://water.weather.gov/ahps/forecasts.php; at that site, one can select Virginia or any other state of interest.
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 November 3, 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 again on December 7, 2017.
Following is an excerpt from the November 3 report:
“During October, above-normal precipitation fell on much of the state, including southwestern Virginia, the lower (northern) Shenandoah Valley, and portions of central and eastern Virginia. However, many locations outside of these areas received substantially lower than normal rainfall. Streamflow gaging stations reported a wide range of flow conditions, with many stations across central and southern Virginia reporting below-normal flows (less than the 25th percentile).
“Most of the wells in the Virginia Climate Response network of groundwater level observation wells were reporting normal levels, except for the wells in central Virginia, which continued to report below normal levels….
“The most recent (October 19, 2017) U. S. Seasonal Drought Outlook for the period through January 31, 2018, indicated that the drought conditions in south-central Virginia may persist or even expand. However, the
Monthly Drought Outlook released on October 31, 2017 indicated a likelihood of drought removal in this region. Task Force members from the NWS and Virginia Climatology Office pointed out that the long-term (three-month) forecast for Virginia is very uncertain due to the current ENSO–La Nina forecast.
“After discussion regarding the current hydrologic conditions and existing water use restrictions in several of the drought evaluation regions, the DMTF recommended continuing the existing Drought Watches in the Northern Piedmont, Middle James, Roanoke River and Shenandoah drought evaluation regions. The next DMTF meeting was scheduled for December 7, 2017. However, if normal to above normal precipitation conditions continue throughout the Shenandoah drought evaluation region, the DMTF may meet before that time to discuss a recommendation for lifting the drought watch declaration in that region.
“The U.S. Army Corps of Engineers (USACE) Wilmington NC District reported that inflow conditions have improved somewhat at the Philpott and J. H. Kerr reservoirs in the Roanoke basin (especially Philpott). The water levels at Philpott and J. H. Kerr dams are approximately 1.5 feet and 2.5 feet below guide curve, respectively. There is some concern, however, that levels at J. H. Kerr may reach that reservoir’s winter drought warning level later this month.”
The Task Force also produces a map rating drought-status indicators. Shown below is the map for November 14, 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 groundwater in one region and stream flow in one 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.