Here is the Virginia Water Central News Grouper’s monthly water-status report on precipitation, stream flow, and drought, as of the end of August 2016. 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 August 2016 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. All values are in inches.
|Monthly Normal||September 2015-
August 2016 Precipitation
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 Southeast Regional Climate Center (Chapel Hill, N.C) at http://www.sercc.com/climateinfo/precip_maps, where you can find maps of total precipitation and percent of normal precipitation for the past 7, 30, 60, or 90 days; 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 Southeast Regional Climate Center’s preliminary maps of the percent-of-normal precipitation for the previous 30 days, 60 days, and 90 days, through August 31, 2016.
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 August 2016 at 150 stream gages in Virginia and just beyond the state border were in the normal range at about 69% of gages, above normal at about 27%, much above normal at about 2%, and below normal at about 2%. The color-coded, flow-percentile map for this period is shown below. 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 7-day average streamflow conditions. Below is the summary plot for 88 Virginia sites during the 45-day period ending August 30, 2016, accessed at http://waterwatch.usgs.gov/index.php?id=pa07d&sid=w__plot&r=va on September 1, 2016.
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 National Drought Monitor map from the University of Nebraska-Lincoln (http://droughtmonitor.unl.edu/) for August 30, 2016, showed about 5% of Virginia as “abnormally dry,” covering all or part of several counties in southeastern Virginia and on the lower Eastern Shore.
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:
7/26/16 – about 6% abnormally dry;
6/28/16 – about 3% abnormally dry;
5/31/16 – about 2% abnormally dry;
9/1/15 – about 27% abnormally dry.
The Virginia Drought Monitoring Task Force, a collaboration of state and federal agencies, issued its most recent (as of 9/1/16) Drought Status Report on July 19, 2016. 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 Drought Monitoring Task Force also produces a daily map rating drought-status indicators. Shown below is daily map for August 31, 2016. 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.” Any given day’s current map and more information on drought status in Virginia are available the Task Force Web site listed above.
The August 30, 2016, U.S. Drought Monitor rated about 37.7% of the United States (including all or parts of 46 states, plus Puerto Rico) as being abnormally dry or worse. The Drought Monitor rated about 6.1% of the country (including parts of 27 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 (D0-D4) and severe or worse (D2-D4) in the previous three months and one year ago were as follows:
7/26/16 – 46.1% abnormally dry or worse; 6.0% severe drought or worse;
6/28/16 – 40.8% abnormally dry or worse; 4.6% severe drought or worse;
5/31/16 – 29.4% abnormally dry or worse; 3.6% severe drought or worse;
9/1/15 – 52.5% abnormally dry or worse; 16.4% severe drought or worse.
In the following two states, 50 percent of more of the state was rated by the August 30 Drought Monitor as in severe-or-worse drought (that is, in Categories D2, D3, or D4):
California, 59.0% – This severe-or-worse percentage—which has been the Drought Monitor rating for California since the week of 5/31/16—is the lowest reported by the Drought Monitor for the Golden State since 53.5% for the week of June 11, 2013. California’s current drought began in late 2011 to early 2012.
Massachusetts – 77.4% – This is the highest severe-or-worse rating for Massachusetts since the Drought Monitor of March 26, 2002.
Following are some comments from the August 30, 2016, Drought Monitor on possibly record warm temperatures seen in some parts of the country in August (continuing the trend from July; see the comments in the Monthly Water Status Report for July 2016), and on the near-term outlook for California:
“…As of August 31, preliminary data suggest that New Jersey may have its fifth driest August on record. The dryness has been exasperated by extreme warmth throughout much of the region. Preliminary data also suggest that many of the Northeast states may be record warm for the month….”
“…Based on preliminary data, average temperatures for the month of August could approach record warm values for several states across the region.”
“…It is the dry season, so little to no precipitation is not surprising in California. Drought conditions there will remain status quo for the time being.”
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 September 1, 2016.