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 2017. 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 2017 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. The values are in inches.
|Location||July 2017 Observed
|Monthly Normal||August 2016-
July 2017 Observed
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 July 31, 2017.
According to the U.S. Geological Survey WaterWatch for Virginia, average stream flows for the 28-day period ending July 31, 2017, at 159 stream gages in Virginia and just beyond the state border measured as follows, compared to the historical range for each given gage:
*in the normal historical range: about 65% of gages;
*below normal: about 18%;
*much below normal: about 4%;
*above normal: about 6%;
*much above normal: about 7%.
Shown below is the color-coded, flow-percentile map for this period, accessed online at https://waterwatch.usgs.gov/index.php?m=pa28d&r=va&w=map on 8/1/17. 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 daily average streamflow conditions, compared to historical records for any given date. Below is the summary plot for 88 Virginia sites during the 45-day period ending July 29, 2017, accessed on 8/1/17 at https://waterwatch.usgs.gov/index.php?id=pa01d&sid=w__plot&r=va.
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 U.S. Drought Monitor map from the University of Nebraska-Lincoln (http://droughtmonitor.unl.edu/) for July 25, 2017, categorized 32.4% of Virginia as “abnormally dry.” This was the highest abnormally dry rating for Virginia since the week of April 25, 2017.
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.”
For comparison, here are Virginia ratings from previous Drought Monitors from about one month, two months, three months, and one year ago:
6/27/17 – 0.9% abnormally;
5/30/17 – drought-free;
4/25/17 – 46.4% abnormally dry or worse, 16.0% moderate drought;
7/26/16 – 5.5% abnormally dry.
Here are some comments on Virginia conditions from the July 25, 2017, Drought Monitor:
…[P]ersistent dryness over the last 1-2 months, low streamflow, and growing agricultural impacts resulted in the expansion of D0 in much of Virginia, where the percent of the state experiencing short or very short (dry or very dry) topsoil moisture rose from 42% last week to 59% this week. A fourth (26%) of Virginia’s pasture and range land was rated in poor to very poor condition by the U.S. Department of Agriculture (USDA) as of July 23.”
The Virginia Drought Monitoring Task Force (DMTF), a collaboration of state and federal agencies, issued its most recent (as of 8/1/17) Drought Status Report on July 17, 2017. 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 July 17 report:
“Above normal temperatures prevailed across much of Virginia during the first half of July, but precipitation varied considerably across the Commonwealth. July rainfall has been well below normal in southwestern and central Virginia. Stream flow gaging stations across the Commonwealth are reporting widely varying flows, with the lowest occurring in the James River basin. Most of the wells in the Virginia Climate Response network of groundwater level observation wells are reporting normal to above-normal levels, except for the wells in central Virginia, which continue to report below-normal levels. The DMTF agreed to recommend continuing the existing Drought Watch in the Northern Piedmont region, based upon the continued low groundwater levels and consequent low base flows between storm events.
“For the current water year (October 1, 2016–July13, 2017) precipitation totals are below the July drought watch indicator level for precipitation (85% of normal) for one of Virginia’s thirteen drought-evaluation regions: the Northern Piedmont region has received 77% of normal precipitation for the current water year.…
“The Virginia Department of Forestry noted that in some areas of Virginia, Keetch-Byram Drought Index values are approaching levels where prescribed burning is suspended due to dry conditions. …
“As of July 2017, one waterworks is implementing voluntary water-use restrictions in Virginia: The Town of Strasburg [in Shenandoah County]…implemented voluntary restrictions based on the 7-day running average of stream flows in North Fork Shenandoah River on July 7th. The running average was measured at 142 cubic feet per second (cfs), which is below the 175 cfs voluntary restriction trigger set by DEQ. However, the reservoir is full and source capacity is not currently affected. The Town serves a population of approximately 6,489 people.”
The July 25, 2017, U.S. Drought Monitor categorized 33.8% of the United States (including all or parts of 36 states plus Puerto Rico) as being abnormally dry or worse. The Drought Monitor categorized 4.4% of the country (including parts of 11 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.)
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:
6/27/17 – 23.2% abnormally dry or worse, 2.7% severe drought or worse;
5/30/17 – 20.7% abnormally dry or worse, 0.9% severe drought or worse;
4/25/17 – 23.6% abnormally dry or worse, 0.9% severe drought or worse;
7/26/16 – 46.1% abnormally dry or worse; 6.0% severe drought or worse.
The following states had 50% or more categorized by the July 25 Drought Monitor in severe-or-worse drought:
North Dakota – 61%;
South Dakota – 54%.
Following are some more comments from the July 25 Drought Monitor on conditions in several parts of the country:
…[T]the drought areas that needed the rain received below-normal to no precipitation. D2 was added to Iowa, D0-D1 expanded in Iowa, and D0 expanded in much of Missouri and parts of Illinois in response to dryness and heat that has persisted over the last 2 to 2 months. The state climatologists of Iowa, Illinois, and Missouri noted that significant agricultural impacts were developing.”
…“D0-D2 expanded in parts of Texas and Oklahoma, reflecting dryness and heat of the last 2 months….”
“Half an inch or more of rain fell across parts of the Dakotas this week, but the rain did little to improve drought conditions, only holding off drought expansion or intensification. ….But expansion occurred in other parts of the region. Much of Montana and parts of the Dakotas, Nebraska, and Kansas had no rain this week; some areas have been drier than normal for the last 2 to 3 months; and some drought indicators reflect dryness for the last 12 months. …Governors provided much-needed response to the dire drought impacts. Montana Gov. Steve Bullock issued an executive order declaring a drought disaster in 28 counties and five Indian reservations in the eastern part of the state. Nebraska Gov. Pete Ricketts issued an emergency proclamation, allowing the state Emergency Management Agency to address unmet drought needs, particularly those related to wildfires. …According to media reports, as of July 25th, the Lodgepole Complex wildfire in Montana was the largest wildfire in the [continental United States].”
“In the Southwest, several inches of rain fell with monsoon showers and thunderstorms in much of Arizona and parts of New Mexico, with 1-2 inches common across parts of western Colorado. …No rain fell this week across most of the Northwest and northern Rockies, with only a tenth of an inch or two tenths recorded at coastal stations in Oregon and Washington, and at a few stations in the Rockies. The continued dryness further eroded soil moisture…. A fifth of the pasture and rangeland was rated in poor to very poor condition in Washington (22%) and Oregon (20%). …Numerous large wildfires have broken out in this area….”
Hawaii and Alaska
“Reports of worsening drought conditions have been received by the National Weather Service in Hawaii. The Department of Water Supply put Upcountry Maui into a Stage 1 water shortage last week, which requests conservation of public water use. …Agricultural impacts were worsening on the Big Island, including impacts to sweet potato farmers on the windward side and poor condition of pastures and vegetation in the interior. …In Alaska, Nome had its wettest July day on record on the 23rd, with 1.74 inches of rain. The previous record had been 1.68 inches on July 21, 1920, and July 19, 1953….”
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 August 1, 2017.