Here is the Virginia Water Central News Grouper’s monthly water-status report, as of the end of December 2014. The Virginia Water Resources Research Center thanks the agencies mentioned below for providing the data and maps used in this post.
Here are National Weather Service (NWS) preliminary precipitation totals for December 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)||2.4||-0.5|
|Bristol (Tri-Cities Airport in Tenn., about 20 miles from Bristol, Va.-Tenn.)||3.0||-0.3|
|Dulles Airport (Loudoun County)||3.3||+0.3|
|Wallops Island (Accomack County)||3.2||-0.1|
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/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 December 31, 2014.
According to the U.S. Geological Survey WaterWatch for Virginia, average stream flow values for December 2014 at about 150 stream gages in Virginia and just beyond the state border were in the normal range at about 83 percent of gages; below normal at about 12 percent; and above normal at about 5 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:
The weekly National Drought Monitor map from the University of Nebraska-Lincoln (http://droughtmonitor.unl.edu/) on December 30, 2014, categorized about 16 percent of Virginia as being abnormally dry. That area the middle and lower parts of the Rappahannock River basin; some of the non-tidal York River basin; all or parts of several counties around or near Danville, Lynchburg, Martinsville, and Roanoke; and most of the Eastern Shore.
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:
11/25/14 – 38 percent abnormally dry;
10/28/14 – 23 percent abnormally dry;
9/30/14 – 48 percent abnormally dry;
12/31/13 – 0.2 percent abnormally dry.
The Virginia Drought Monitoring Task Force, a collaboration of state and federal agencies, issued its most recent Drought Status Report on December 16, 2014. 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 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 January 1, 2015, 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 December 30, 2014, U.S. Drought Monitor rated 39.2 percent of the United States (including all or parts of 38 states) as being abnormally dry or worse, and it rated 14.1 percent of the country (including all or parts of 12 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:
11/25/14 – 39.5 percent abnormally dry or worse; 14.0 percent severe drought or worse;
10/28/14 – 36.4 percent abnormally dry or worse; 15.1 percent severe drought or worse;
9/30/14 – 40.1 percent abnormally dry or worse; 15.6 percent severe drought or worse;
12/31/13 – 45.8 percent abnormally dry or worse; 14.0 percent severe drought or worse;
In the following states, over 50 percent of the state was categorized by the December 30 report as being in severe-or-worse drought:
California – 94% (with 78% in extreme or exceptional drought; California has had over 90 percent of its area categorized in severe-or-worse drought every week since February 11, 2014, and the Golden State had 100 percent in those categories from May 13—July 29, 2014).
Nevada – 68% (with 48% in extreme or exceptional drought).
Following are some comments from the December 30, 2014, Drought Monitor on some notable events or situations around the country.
Southeast: “Several tornadoes struck the South on December 23, resulting in four fatalities in Mississippi. It was the nation’s deadliest tornado outbreak since July 8, when four people perished in Madison County, New York.”
Northern Plains and Upper Midwest: “Outside of [the] area of abnormal dryness, Sioux City, Iowa, received enough precipitation during the monitoring period to secure its wettest year on record. Through December 29, the total of 41.36 inches (149 percent of normal) in Sioux City surpassed its 1903 annual standard of 41.10 inches.”
Central and Southern Plains: “[One example of the] long-term impacts of the multi-year drought on water supplies [is that] reservoirs in Texas were five-eighths (62.6 percent) full at the end of 2014, compared to 64.3 percent at the end of 2013. Historically, reservoirs in Texas are collectively about 80 percent full in late December.”
The West: “December 25 became the snowiest Christmas Day on record in Wyoming locations such as Lander (9.6 inches) and Cheyenne (6.8 inches). … Since October 1, season-to-date precipitation in the Cascades has generally averaged 105 to 125 percent of normal. However, with an unusual amount of the precipitation falling as rain, the late-December snowpack contained only about one-third to one-half of its typical amount of water for this time of year…. This discrepancy—overall wet conditions but meager snowpack—has led to some mixed drought indicators, such as favorable rangeland, pasture, and winter grain growth and improved soil moisture, while concerns persist with respect to the possibility of limited runoff into streams and reservoirs during the upcoming spring snow-melt season. Many of the same concerns persisted in California, especially given the return of drier weather during the last one-third of December.”
For a look ahead, the National Weather Service/Climate Prediction Center’s “U.S. Seasonal Drought Outlook” for the next 90 days is available at http://www.cpc.ncep.noaa.gov/products/expert_assessment/sdo_summary.html. Shown below is the outlook map available on Jan. 8, 2015.
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