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 February 19, 2018 (information available as of February 20).
- An excerpt from the Virginia Drought Monitoring Task Force’s latest statewide assessment on February 1 and a map showing the status of several drought indicators in different Virginia regions, as of February 19.
- Flooding overview maps for Virginia and nationwide, as of February 20.
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 and West Virginia Science Center’s Web site, https://www.usgs.gov/centers/va-wv-water.
February 2018 Gaging Station of the Month: Goose Creek near Leesburg (Loudoun County), January 20, 2018. U.S. Geological Survey information from this gage is online at https://waterdata.usgs.gov/va/nwis/inventory/?site_no=01644000. For the Virginia map of gaging sites, see https://waterdata.usgs.gov/va/nwis/rt.
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 February 19, 2018. 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 High Plains Regional Climate Center, located at the University of Nebraska in Lincoln, 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 February 20, 2018. 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 stream flows at Virginia gaging stations as of February 19, 2018, 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 11:30 a.m. EST on February 20, 2018, 2 stream-gaging stations in Virginia or in nearby areas of adjacent states were [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 as of February 1, 2018. 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 March 8, 2018.
Following is an excerpt from the February 2018 report (a map of Virginia’s Drought Evaluation Regions follows this excerpt):
“Recorded precipitation during January was variable across the Commonwealth, with generally above normal amounts in eastern Virginia and continued below normal amounts across most of the central and western regions. The majority of streamflow gaging stations continue to report below-normal seven-day average flows. Wells in the Virginia Climate Response network of groundwater level observation wells located in central Virginia also continued to report below normal to much-below-normal levels.
“…The National Weather Service Monthly Drought Outlook released on January 31, 2018 indicated a likelihood of continuing drought across central Virginia through February. The current U. S. Seasonal Drought Outlook for the period through April 30, 2018 (released January 18, 2018) also indicated drought persistence across the same region.
“The DMTF discussed the continuing drought conditions throughout the central half of the state, as well as the abnormally dry conditions in the southwest. The Task Force decided to recommend that a Drought Watch Advisory should be issued for the Upper James drought evaluation region based upon below normal groundwater levels, stream flows and subsequent below-normal reservoir levels. The group also agreed that the existing Drought Watch Advisories in six regions (Chowan, Middle James, Northern Piedmont, Northern Virginia, Roanoke River and Shenandoah) should continue. If the pattern of below-normal precipitation during the winter “leaf-off” period continues through February, most of the state will have experienced a second consecutive winter season with low recharge to the groundwater system. These conditions may have serious impacts upon water availability during the next growing season due to low water table levels and subsequent low base flow in streams.”
The Task Force also produces a map rating drought-status indicators. Shown below is the map for February 19, 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.” [ADD as called for: 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.