Here is the Virginia Water Central News Grouper’s monthly water status report on precipitation, stream flow, and drought, as of the end of July 2015. 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 July 2015 at 11 Virginia or near-Virginia locations, along with the normal 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 normal annual precipitation for each location. All values are in inches.
|Normal for Month||Aug. 2014-July 2015 Precipitation
|Normal Annual Precipitation|
|Bluefield (Merc. Co. airport, near Va.-W.Va. state line)||5.14||4.17||43.20||39.63|
|Bristol (Tri-Cities Airport in Tenn., about 20 miles from Bristol, Va.-Tenn.)||5.79||4.69||40.45||41.01|
|Charlottesville (Char.-Albemarle Airport)||4.01||4.32||39.4||42.71|
|Wallops Island (Accomack County)||4.41||4.09||43.33||40.84|
|Washington-Dulles Airport (Loudoun County)||4.89||3.67||41.20||41.54|
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 provisional (still needing verification) maps of the percent-of-normal precipitation for the previous 30 days, 60 days, and 90 days, through August 3, 2015.
According to the U.S. Geological Survey WaterWatch for Virginia (online at http://waterwatch.usgs.gov/classic.php?m=mv01d&r=va&w=real%2Cmap), monthly average stream flow values for July 2015 at 150 stream gages in Virginia and just beyond the state border were in the normal range at about 40% of gages, below normal at about 5%, above normal at about 34%, and much above normal at about 21%. 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.
The weekly National Drought Monitor map from the University of Nebraska-Lincoln (http://droughtmonitor.unl.edu/) for July 28, 2015, showed Virginia as being drought-free, which has been the case since the Drought Monitor report for July 7, 2015. The Drought Monitor notes that it “focuses on broad-scale conditions [and] local conditions may vary.”
Drought Monitor categories are as follows:
D0 = abnormally dry;
D1 = moderate drought;
D2 = severe drought;
D3 = extreme drought;
D4 = exceptional drought.
For comparison, here are Virginia ratings from previous Drought Monitors from about one month, two months, three months, and one year ago:
6/30/15 – 13% abnormally dry;
5/26/15 – 32% abnormally dry;
4/28/15 – drought-free;
7/29/14 – 27%abnormally dry.
The Virginia Drought Monitoring Task Force, a collaboration of state and federal agencies, issued its most recent Drought Status Report on July 16, 2015. 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 next report is scheduled for September 2015. 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.
Following is an excerpt from the beginning of the July 16, 2015, report, summarizing statewide conditions at that time: “The typical summer pattern of scattered thunderstorms produced normal to above normal rainfall across Virginia over the past month. As a result, stream discharge rates have been normal to above normal depending upon local rainfall amounts. Groundwater levels in some of the Climate Response Network observation wells have continued a normal summer decline, while others, particularly in the eastern half of Virginia, have rebounded. Maps of precipitation as a percent of normal rainfall illustrate that most of Virginia has received normal or above-normal rainfall during the past 30, 60 and 90 days. A large area in southern Virginia within the upper portions of the New River and Roanoke River basins has received less than normal rainfall for the current water year (since October 1, 2014). Note that precipitation estimates based on radar in parts of northwestern Virginia along the Virginia-West Virginia border and on the boundary between the Upper James and Shenandoah drought-evaluation regions are generally considered to be underestimated due to that area’s distance from radar stations.”
The Drought Monitoring Task Force also produces a daily map rating drought-status indicators. Shown below is the July 31, 2015. 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.
MORE ON GROUNDWATER LEVELS
More 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).
The July 28, 2015, Drought Monitor rated 44.2% of the United States (including all or parts of 38 states, plus Puerto Rico) as being abnormally dry or worse, and it rated 14.4% of the country (including all or parts of 15 states, plus Puerto Rico), as being in severe drought or worse (categories D2, D3, and D4). The abnormally dry or worse percentage increased sharply from just a week earlier—39.4% on 7/21/15—largely because during Alaska’s abnormally dry percentage increased from 57% to 71%.
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:
6/30/15 – 41.7% abnormally dry or worse; 13.0% severe drought or worse;
5/26/15 – 46.4% abnormally dry or worse; 11.9% severe drought or worse;
4/28/15 – 48.5% abnormally dry or worse; 16.7% severe drought or worse;
7/29/14 – 39.8% abnormally dry or worse; 19.0% severe drought or worse.
In the following states, over 50% of the state was categorized by the July 28 report as being in severe-or-worse drought.
California – 95% (with 71% in extreme or exceptional drought). California has had over 80% of its area categorized in severe-or-worse drought every week since June 25, 2013, and the Golden State had 100% in those categories from May 13—July 29, 2014. California’s current drought began in late 2011 to early 2012.
Idaho – 52% (with 22% in extreme drought).
Nevada – 76% (with 40% in extreme or exceptional drought).
Oregon – 100% (with 48% in extreme drought).
Washington – almost 100% (with 32% in extreme drought).
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.html. Shown below is the outlook map available on August 5, 2015.