Here is the Virginia Water Central News Grouper’s monthly water-status report, as of the end of April 2013.
First, in precipitation: Here are National Weather Service (NWS) preliminary precipitation totals for April 2013 at 10 Virginia locations, with the amount above (+) or below (-) normal for this month of the year historically in parentheses. All values are in inches, rounded to the nearest 1/10 inch from NWS values.
Blacksburg: 3.6 (+0.1)
Bristol: 4.1 (+0.8) (Tri-Cities Airport in Tenn., about 20 miles from Bristol)
Charlottesville: 3.0 (-0.3)
Danville: 3.0 (-0.4)
Dulles Airport: 2.3 (-1.2) (Loudoun County)
Lynchburg: 3.4 (+0.1)
Norfolk: 3.2 (-0.2)
Richmond: 2.9 (-0.4)
Roanoke: 2.9 (-0.4)
Wallops Island: 3.8 (+0.7) (Accomack 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 1981-2010 period. The National Climatic Data Center released these normal values in July 2011. For information on the normals, 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 daily map of precipitation nationwide or by state, with capability to show county boundaries, and archives available for specific days, months, or years. Shown below is the Southeast Regional Climate Center’s 30-day percent-of-normal precipitation map for April 1—30, 2013.
Next, in stream flow: According to the U.S. Geological Survey WaterWatch for Virginia, average streamflows for April 2013 were in the normal range at about 77 percent of stream gages in Virginia and just beyond the state border; above normal at about 13 percent; and below normal at about 10 percent. The color-coded, flow-percentile map for April 2013 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 The National Drought Monitor map from the University of Nebraska-Lincoln (http://droughtmonitor.unl.edu/) on April 30, 2013, showed Virginia being drought-free. This has been the case since the March 12, 2013, Drought Monitor, when Virginia was rated as drought-free for the first time since the December 6, 2011, report.
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 one month, two months, three months, and one year ago:
2/26/13: 14 percent abnormally dry;
1/29/13: 25 percent abnormally dry;
5/1/12: 61 percent abnormally dry; 10 percent in moderate drought.
Meanwhile, looking beyond Virginia, the April 30 Drought Monitor rated 54.8 percent of the United States as being abnormally dry and 29.5 percent, in 20 states, as being in severe drought or worse (categories D2, D3, and D4). This continues the run of 25 percent or more of the country rated in severe drought or worse since the report of June 26, 2012. (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.) This nationwide severe-or-worse percentages in the previous three months and one year ago were as follows:
4/2/13: 29.5 percent;
2/26/13: 30.4 percent;
1/29/13: 34.0 percent;
5/1/12: 17.1 percent.
In the following states, severe-or-worse drought covered over 50 percent of the state in the April 30 report:
New Mexico (98%);
South Dakota (66%);
Here are some key comments from the April 30 report:|
Mid-Atlantic and Northeast: “Much of the northern Mid-Atlantic and Northeast is dealing with increasingly dry conditions, and will need to be monitored over the upcoming weeks for potential impacts.”
Northern Plains and Upper Midwest: “Despite the general consensus that conditions continue to improve, long-term indicators…show underlying, long-term drought persists in the core D1 and D2 areas of the Upper Midwest.”
Western U.S.: “The largely disappointing water year neared an end, with many areas of the west ending the season with bleak spring runoff prospects and increasing drought concerns…. In New Mexico, the past 36 months (Apr 2010 – Mar 2013) have been the 4th driest period on record for the state, the driest since the 1950s.”
Click these links for previous News Grouper monthly status reports during the past 12 months: