Here is the Virginia Water Central News Grouper’s monthly water-status report on precipitation, stream flow, and drought, as of the end of November 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 November 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.
|Location||November 2016 Precipitation
|Monthly Normal||December 2015-November 2016 Precipitation||Annual Normal|
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 November 30, 2016. Please note that the scale is different for the 30-day map.
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 November 2016 at about 153 stream gages in Virginia and just beyond the state border were in the normal range at about 37% of gages, below normal at about 43%, and much below normal at about 20%. 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 November 29, 2016, accessed at http://waterwatch.usgs.gov/index.php?id=pa07d&sid=w__plot&r=va on December 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 November 29, 2016, showed about 69% of Virginia as “abnormally dry,” covering the western and central two-thirds of the state. The November 1 report also showed about 28% of Virginia in “moderate drought” or worse, from the New River basin westward, plus parts of the northern and central Piedmont; about 5% in “severe drought” or worse, in all or parts of six far southwestern counties; and about 0.9% in “extreme drought,” in Lee County. The Drought Monitor indication of severe drought began in the week of November 8, 2016; that was the first severe drought indication in Virginia since the Drought Monitor of September 4, 2012. The Drought Monitor indication of extreme drought began in the week of November 15, 2016; that was the first extreme drought indication in Virginia since the Drought Monitor of September 28, 2010.
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.”
Please note that the Drought Monitor assessment for November 29, 2016, did not incorporate the significant rainfalls received in Virginia during the first week of December 2016.
For comparison, here are Virginia ratings from previous Drought Monitors from about one month, two months, three months, and one year ago:
11/1/16 – about 29% abnormally dry or worse; about 3% in moderate drought;
9/27/16 – about 85% abnormally dry or worse; about 0.8% in moderate drought;
8/30/16 – about 5% abnormally dry;
12/1/15 – about 0.01% abnormally dry.
The Virginia Drought Monitoring Task Force, a collaboration of state and federal agencies, issued its most recent (as of 12/6/16) Drought Status Report on December 2, 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. Following is an excerpt from the December 2 report:
“The Virginia Drought Monitoring Task Force (DMTF) met on Monday, November 28, 2016 to discuss the status of drought monitoring and weather forecasts across the Commonwealth of Virginia. Based upon the current three-month precipitation forecast (see below), the DMTF agreed to closely monitor conditions during December and meet again in early January, 2017. If the current dry conditions have not abated and the three-month precipitation outlook has not improved, the Task Force plans to prepare and distribute a message to water users across Virginia to raise awareness of the long-term water-supply impact of dry winter conditions. Dry conditions caused by below normal rainfall continued across all of the western two-thirds of Virginia. Extreme southwestern Virginia continued to be the driest portion of the Commonwealth, with abnormally dry conditions extending northeastward to northern Virginia. For the current water year (October 1, 2016–November 30, 2016) precipitation totals have so far been below 85% of normal for 9 of the 13 drought-evaluation regions. The Northern Piedmont, Northern Virginia and Shenandoah drought-evaluation regions received less than 50% of normal precipitation. Since December 1, 2015, however, all 13 drought-evaluation regions have received 85% or more of normal precipitation.”
The Drought Monitoring Task Force also produces a daily map rating drought-status indicators. Shown below are daily maps for December 1 and December 6, 2016, showing an improvement in conditions in parts of the Commonwealth from rainfall between those dates. 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 November 29, 2016, U.S. Drought Monitor rated about 48.6% of the United States (including all or parts of 46 states) as being abnormally dry or worse. The Drought Monitor rated about 13.9% of the country (including parts of 38 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.) In the November 29 report, areas of severe-or-worse drought stretched from eastern Texas and Oklahoma to southwestern Virginia, and from eastern Pennsylvania to Maine.
The nationwide percentages for abnormally dry or worse (categories D0-D4) and severe or worse (categories D2-D4) in the previous three months and one year ago were as follows:
11/1/16 – 41.6% abnormally dry or worse; 9.2% severe drought or worse;
9/27/16 – 38.8% abnormally dry or worse; 6.8% severe drought or worse;
8/30/16 – 37.7% abnormally dry or worse; 6.1% severe drought or worse;
12/1/15 – 32.4% abnormally dry or worse; 12.3% severe drought or worse.
In the following states, 50 percent of more of the state was rated by the November 29 Drought Monitor as in severe-or-worse drought:
Alabama, 100%. This severe-or-worse rating is the highest for the Yellowhammer State since 100% in the Drought Monitor of December 12, 2000 (although the state had near 100% ratings in June 2007).
California, 60%. California’s current drought began in late 2011 to early 2012.
Georgia, 75%. This severe-or-worse rating was the highest for the Peach State since 79% in the Drought Monitor of February 5, 2013. In the November 29 report, the Atlanta metropolitan region was in an area of extreme-to-exceptional drought (categories D3 and D4) that stretched from Louisiana to far southwestern Virginia.
Mississippi, 100%. This severe-or-worse rating, which was the case for Mississippi since the report for November 22, 2016, is the highest for the Magnolia State since 100% in the Drought Monitor of November 14, 2000.
New Hampshire, 57%.
Tennessee, 99%. This severe-or-worse rating, which was the case for Tennessee since the report for November 22, 2016, is the highest for the Volunteer State since 100% in the Drought Monitor of October 16, 2007.
Following are some comments from the November 29, 2016, Drought Monitor on some of the conditions current in the Northeast, Mid-Atlantic, Southeast and lower Mississippi Valley, and Far West:
Northeast and Mid-Atlantic
“…Long-term precipitation deficits ranged from 4 to 8 inches over the last 90 days to more than 12 inches over the last 12 months across southern New England, with 20-inch deficits evident for the last 24 months. …. Record low to much-below-normal streamflows continued across much of southern New England to eastern Pennsylvania. According to November 27 USDA reports, topsoil moisture was rated short to very short (dry to very dry) across 85% of Connecticut, 66% of New Hampshire and Virginia, 55% of West Virginia, 46% of Massachusetts, 38% of Pennsylvania, and 34% of Maine….”
Southeast, and Lower Mississippi Valley
“…Severe drought impacts continued to mount in this region and included parched soils, record to near-record low streamflows, and drying stock ponds. …November 27 USDA reports indicated that 81% of topsoil moisture in Tennessee was rated short or very short, with such ratings at 76% in Kentucky and Mississippi, 74% in Louisiana, 59% in Florida, 57% in South Carolina, and 43% in North Carolina. Subsoil moisture was rated short to very short in 80% of Tennessee, 79% of Mississippi, 75% of Kentucky, 70% of Louisiana, 53% of Florida, 49% of South Carolina, and 35% of North Carolina….”
…The Rockies and Far West
“…The precipitation [Nov. 22-28, 2016] increased high elevation SNOTEL station snow depth almost everywhere across the West, but SWE (snow water content) values continued to be lower than average across the Pacific Northwest and most of the Rockies. …This was still early in the snow season… Reservoirs in [part of New Mexico] continued below 30+ year average levels, but this is due to long-term conditions mostly upstream in the basin out of state; in arid regions like New Mexico, it may take many years for some of these reservoirs to refill to these long-term average levels. …”
On the brighter side of the November 29 report: Puerto Rico was drought-free for the first time since the report of November 19, 2013.
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 December 1, 2016.