Here is the Virginia Water Central News Grouper’s monthly water-status report, as of the end of July 2014. The Virginia Water Resources Research Center thanks the agencies mentioned below for providing the data and maps used in this post.
First, in precipitation: Here are National Weather Service (NWS) preliminary precipitation totals for July 2014 at 11 Virginia or near-Virginia locations, with the amount above (+) or below (-) normal for this month of the year historically. All values are in inches, rounded to the nearest 0.1 inch from NWS values.
|Location||Observed Precipitation(inches)||Above (+) or Below (-) Normal (inches)|
|Bluefield (Va.-W.Va. state line)||3.0||-1.2|
|Bristol (Tri-Cities Airport in Tenn., about 20 miles from Bristol, Va.-Tenn.)||5.3||+0.6|
|Dulles Airport (Loudoun County)||2.1||-1.6|
|Wallops Island (Accomack County)||3.4||-0.7|
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 1981-2010 period. 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/oa/climate/normals/usnormals.html.
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 precipitation and percent-of-normal precipitation for the 30-day period of July 2 to July 31, 2014.
Next, in stream flow: According to the U.S. Geological Survey WaterWatch for Virginia, average stream flow values for the 28-day period ending July 31, 2014, at 146 stream gages in Virginia and just beyond the state border (that is, the monthly average of stream flow readings taken at each gage) were as folows:
normal range at about 68 percent of gages;
below normal at about 21 percent;
much below normal at about 3 percent;
above normal at about 7 percent;
and much above normal at about 1 percent.
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 as follows:
Red and maroon dots: Below 10th percentile = much below normal to record low;
Yellow dots: 10th to 24th percentile = below normal;
Green dots: 25th to 75th percentile = normal;
Light blue dots: 76th to 90th percentile = above normal;
Dark blue and black dots: Above 90th percentile = much above normal to record high.
Finally, our drought watch:
The weekly National Drought Monitor map from the University of Nebraska-Lincoln (http://droughtmonitor.unl.edu/) on July 29, 2014, categorized about 27 percent of Virginia as being abnormally dry. The areas included were the Alleghany Highlands; all of southwestern Virginia, from Roanoke west, excluding the four westernmost coalfield counties; the Danville/Martinsville area; the upper Chowan River basin, from Dinwiddie County to the North Carolina border; and northern Accomack County.
The Drought Monitor notes that it “focuses on broad-scale conditions [and] local conditions may vary.” The 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:
7/1/14 – 10 percent abnormally dry; 2 percent in moderate drought;
6/3/14 – 9 percent abnormally dry;
4/29/14 – 0.1 percent abnormally dry;
7/30/13 – drought-free.
The Virginia Drought Monitoring Task Force, a collaboration of state and federal agencies, issued its most recent Drought Status Report on July 11, 2014. That report is online (as PDF) at http://www.deq.virginia.gov/Portals/0/DEQ/Water/WaterResources/VirginiaDroughtStatus/CurrentDroughtTaskForceReport.pdf; 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 also produces a daily map rating groundwater levels (GW), precipitation deficits (Prcp), reservoir storage (Res), and stream flow (Flow) conditions across the Commonwealth. In each area, a color code indicates “normal,” “watch,” “warning,” or “emergency conditions.” The July 30, 2014, map is shown below. The current map and more information on the ratings are available the Task Force Web site listed above.
Looking beyond Virginia: The July 29, 2014, U.S. Drought Monitor rated 39.8 percent of the United States (including all or parts of 42 states) as being abnormally dry or worse, and it rated 19.0 percent of the country (including all or parts of 14 states), as being in severe drought or worse (categories D2, D3, and D4). (On August 7, 2012, 38.5 percent of the country was in the three worst categories; that was the highest percentage in these categories reported by the Drought Monitor since it began in 2000.) 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:
7/1/14 – 37.2 percent abnormally dry or worse; 20.9 percent severe drought or worse;
6/3/14 – 43.6 percent abnormally dry or worse; 22.8 percent severe drought or worse;
4/29/14 – 41.3 percent abnormally dry or worse; 22.4 percent severe drought or worse;
7/30/13 – 56.6 percent abnormally dry or worse; 27.4 percent severe drought or worse.
In 6 states, over 50 percent of the state was categorized by the July 29 report as being in severe-or-worse drought:
Arizona – 68% (with 17% in extreme drought);
California – 100% (with 82% in extreme or exceptional drought; this level of extreme/exceptional drought is the highest percentage in California since at least January 2000, the start of the Drought Monitor’s records shown online);
Nevada – 87% (with 55% in extreme or exceptional drought);
New Mexico – 54% (with 18% in extreme drought);
Oklahoma – 60% (with 23% in extreme or exceptional drought);
Oregon – 56% (with 20% in extreme drought).
Here are some excerpts from the July 29, 2014, Drought Monitor:
On the southeast, including Virginia: “Despite periods of very cool weather, dryness has begun to take a toll on Southeastern pastures. On July 27, USDA [U.S. Department of Agriculture] reported 45% of the pastures were rated in very poor to poor condition in South Carolina, along with 23% in Virginia and 20% in Kentucky. By the morning of July 30, in the midst of the latest cool spell, daily-record low temperatures were established in Southeastern locations such as Blacksburg, Virginia (49°F); Jackson, Kentucky (52°F); Muscle Shoals, Alabama (55°F); and Meridian, Mississippi (56°F).”
On the southwest, particularly the Colorado River basin in Arizona and Nevada: “Lake Mead—above Hoover Dam—which serves multiple states, recently fell to its lowest level since being filled during the 1930s.”
On California: “For California’s 154 intrastate reservoirs, storage at the end of June stood at 60% of the historical average. Although this is not a record for this time of year—the standard remains 41% of average on June 30, 1977—storage has fallen to 17.3 million acre-feet. As a result, California is short more than one year’s worth of reservoir water, or 11.6 million acre-feet, for this time of year. The historical average warm-season drawdown of California’s 154 reservoirs totals 8.2 million acre-feet, but usage during the first 2 years of the drought, in 2012 and 2013, averaged 11.5 million acre-feet.”
For previous News Grouper monthly water status reports during the past 12 months, please click these links: