Here is the Virginia Water Central News Grouper’s monthly water-status report on precipitation, stream flow, and drought, as of the end of October 2017. The Virginia Water Resources Research Center thanks the agencies mentioned below for providing the data and maps used in this post. Icons for precipitation, stream flow, and drought are by George Wills of Blacksburg, Va. (https://www.etsy.com/people/BlacksburgArt). For previous monthly water status reports, please see this link: https://vawatercentralnewsgrouper.wordpress.com/?s=Water+Status.
Here are National Weather Service (NWS) preliminary (still needing verification) precipitation totals for October 2017 at 11 Virginia or near-Virginia locations, along with the “normal” (three-decade average) for this month of the year at each location. Also shown are the precipitation totals at each location for the previous 12 months and the annual precipitation normals for each location. The values are in inches.
||October 2017 Observed
||November 2016-October 2017 Observed
1 – The Bluefield location is the Mercer County, W. Va., airport, near the Va.-W.Va. state line.
2- The Bristol location Tri-Cities Airport in Tenn., about 20 miles from Bristol, Va./Tenn.
3 – The Charlottesville location is the Charlottesville-Albemarle Airport.
4 – Wallops Island is in Accomack County.
5 – Washington-Dulles Airport is in Loudoun County.
Precipitation sources: Climate pages of the following National Weather Service Forecast Offices:
Blacksburg, Va. (http://www.nws.noaa.gov/climate/index.php?wfo=rnk);
Morristown, Tenn. (http://www.weather.gov/climate/index.php?wfo=mrx;
Baltimore-Washington (http://www.nws.noaa.gov/climate/index.php?wfo=lwx); and
Wakefield, Va. (http://www.nws.noaa.gov/climate/index.php?wfo=akq).
The normal values used by the National Weather Service (NWS) in these provisional reports are based on the period from 1981 to 2010. The National Climatic Data Center released these normal values in July 2011. For information on the normal values, see the National Climatic Data Center Web page at http://www.ncdc.noaa.gov/data-access/land-based-station-data/land-based-datasets/climate-normals.
For graphs of precipitation, visit the High Plains Regional Climate Center at https://hprcc.unl.edu/maps.php?map=ACISClimateMaps), where you can find maps of total precipitation and percent of normal precipitation for the past 7, 30, 60, or 90 days for all U.S. regions; or the NWS’ Advanced Hydrologic Prediction Service at http://water.weather.gov/precip/ for a map of precipitation nationwide or by state, with capability to show county boundaries, and archives available for specific days, months, or years. Shown below are the preliminary maps of the percent-of-normal precipitation for the southeastern United States for the previous 30 days, 60 days, and 90 days, through October 31, 2017.
According to the U.S. Geological Survey WaterWatch for Virginia (online at http://waterwatch.usgs.gov/index.php?m=mv01d&r=va&w=map), monthly average stream flow values for October 2017 at 159 stream gages in Virginia and just beyond the state border were as follows, compared to the historical range for each given gage:
within the normal historial range – about 54% of gages;
below normal – about 20%;
much below normal – about 8%;
above normal – about 18%.
Shown below is the color-coded, flow-percentile map for this period, accessed online at https://waterwatch.usgs.gov/index.php?m=mv01d&r=va&w=map on 11/2/17. The color codes/percentile classes used by USGS to compared flows to historical records for the month are shown in the chart below the map.
An overall look at Virginia streamflow conditions is provided in the USGS WaterWatch summary plot of daily average streamflow conditions, compared to historical records for any given date. Below is the summary plot for 88 Virginia sites during the 45-day period ending October 31, 2017, accessed on 11/2/17 at https://waterwatch.usgs.gov/index.php?id=pa01d&sid=w__plot&r=va.
Information on current groundwater levels in Virginia monitoring wells is available from the U.S. Geological Survey’s National Water Information System, online at http://waterdata.usgs.gov/va/nwis/current/?type=gw; and from the USGS Climate Response Network, online at http://groundwaterwatch.usgs.gov/net/ogwnetwork.asp?ncd=crn (at that page, you can find a national map showing the status of groundwater monitoring wells compared to historical values).
DROUGHT IN VIRGINIA
The weekly U.S. Drought Monitor map from the University of Nebraska-Lincoln (http://droughtmonitor.unl.edu/) for October 31, 2017, categorized 41.5% of Virginia as “abnormally dry” (covering the state approximately from the Piedmont east, except for the eastern peninsulas and the Eastern Shore). The October 31 report categorized 3.8% of Virginia in “moderate drought” (covering parts of six counties along southern border, just east of Danville).
Drought Monitor categories are as follows:
D0 = abnormally dry;
D1 = moderate drought;
D2 = severe drought;
D3 = extreme drought;
D4 = exceptional drought.
The Drought Monitor notes that it “focuses on broad-scale conditions [and] local conditions may vary.”
For comparison, here are Virginia ratings from previous Drought Monitors from about one month, two months, three months, and one year ago:
9/26/17 – 18/1% abnormally dry;
8/29/17 – 19.7% abnormally dry;
7/25/17 – 32.4% abnormally dry;
11/1/16 – 28.9% abnormally dry or worse; 3.4% moderate drought.
The Virginia Drought Monitoring Task Force (DMTF), a collaboration of state and federal agencies, issued its most recent (as of 10/31/17) Drought Status Report on October 11, 2017. A link to the report, along with other current drought-status information, is available online at http://www.deq.virginia.gov/Programs/Water/WaterSupplyWaterQuantity/Drought.aspx. The Task Force’s reports typically include information from some or all of the following agencies: University of Virginia Climatology Office, U.S. Geological Survey (USGS), and the Virginia departments of Agriculture and Consumer Services, Health, and Environmental Quality. The Task Force is next scheduled to meet on November 2, 2017. Following is an excerpt from the October 11 report:
“Much below normal rainfall and variable temperatures occurred across Virginia throughout September. Stream flow gaging stations reported flows that were generally below the normal range (between the 25th and 75th percentiles) with many stations across central, southern, and western Virginia reporting much below-normal flows (less than the 10th percentile). The recorded 28-day average streamflow at stations in the Shenandoah River basin were lower than the 5th percentile, indicating severe hydrologic drought. 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 DMTF discussed the continuing dry conditions, especially within the Middle James, Roanoke River and Shenandoah drought evaluation regions, and agreed to recommend the issuance of Drought Watch advisories for these regions. The DMTF also agreed to continue the existing Drought Watch in the Northern Piedmont region. The group also decided that the time period for evaluation of the precipitation indicators on the Statewide drought indicator map should be changed from the entire previous water year (October 1, 2016–September 30, 2017) to a more recent period (e.g., the previous 60 or 90 days). DEQ staff implemented this change. …
“The Virginia Department of Agriculture and Consumer Services (VDACS) reported that some growers Virginia have reported dry conditions that have negatively impacted setting of cover crops. Also, livestock producers have reported that the extended August and September dry conditions affected pastures to the extent that livestock hay use is 2-3 months ahead of normal. The U.S. Army Corps of Engineers (USACE) Wilmington NC District reported that minimal rainfall has occurred upstream of the J. H. Kerr and Philpott reservoirs in the Roanoke basin. The water levels at J. H. Kerr and Philpott dams are running 3.5 feet and 3 feet below guide curve respectively, for this time of year. USACE Norfolk Region staff reported that water levels at Lake Moomaw (Gathright Dam) on the upper James River were just above 1568 ft (approximately 3 feet above Watch level), and dropping about 0.15 feet per day.”
The Drought Monitoring Task Force also produces a map rating drought-status indicators. Shown below is the map for November 1, 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 Watch conditions for four regions in central Virginia, the groundwater emergency conditions in one region, and the streamflow warning conditions in one region. Any given day’s current map and more information on drought status in Virginia are available online at http://www.deq.virginia.gov/Programs/Water/WaterSupplyWaterQuantity/Drought/CurrentDroughtConditionsMap.aspx.
The October 31, 2017, U.S. Drought Monitor categorized 28.1% of the United States (including all or parts of 44 states) as being abnormally dry or worse. The Drought Monitor categorized 2.3% of the country (including parts of 7 states), as being in severe drought or worse (categories D2, D3, and D4). (The highest percentage in the severe-or-worse categories reported by the Drought Monitor since it began in 2000 was 38.5% of the country for the week of August 7, 2012.)
The nationwide percentages for abnormally dry or worse (categories D0-D4) and severe or worse (categories D2-D4) in the previous three months and one year ago were as follows:
9/26/17 – 31.0% abnormally dry or worse, 4.2% severe drought or worse;
8/29/17 – 25.8% abnormally dry or worse, 4.8% severe drought or worse;
7/25/17 – 33.8% abnormally dry or worse, 4.4% severe drought or worse;
11/1/16 – 45.0% abnormally dry or worse; 12.1% severe drought or worse.
90-DAY DROUGHT OUTLOOK
For a look ahead, the National Weather Service/Climate Prediction Center’s “U.S. Seasonal Drought Outlook” is available at http://www.cpc.ncep.noaa.gov/products/expert_assessment/sdo_summary.php. Shown below is the outlook map available on November 1, 2017.