Here is the Virginia Water Central News Grouper’s monthly water-status report on precipitation, stream flow, and drought, as of the end of December 2015. 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: Please see this link: https://vawatercentralnewsgrouper.wordpress.com/?s=Water+Status.
Here are National Weather Service (NWS) preliminary (still needing verification) precipitation totals for December 2015 at 11 Virginia or near-Virginia locations, along with the normal 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 normal annual precipitation for each location. All values are in inches.
|Normal for Month
||Jan. 2015-Dec. 2015 Precipitation
|Normal Annual Precipitation
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 December 31, 2015. [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 December 2015 at 151 stream gages in Virginia and just beyond the state border were in the normal range at 23% of gages, below normal at 1%, above normal at 38%, and much above normal at 38%. 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 average streamflow conditions. Below is the summary plot for 87 Virginia sites during the 45-day period ending December 31, 2015, accessed at http://waterwatch.usgs.gov/index.php?id=pa07d&sid=w__plot&r=va on 1/1/16.
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 December 29, 2015, showed Virginia as essentially drought-free, with only 0.01 percent of the state rated as abnormally dry. 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:
12/1/15 – 0.01% abnormally dry;
10/27/15 – 0.01% abnormally dry;
9/29/15 – 39% abnormally dry;
12/30/14 – 16% abnormally dry.
The Virginia Drought Monitoring Task Force, a collaboration of state and federal agencies, issued its most recent Drought Status Report on December 14, 2015. 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 drought-status indicators. Shown below is daily map for January 1, 2016. 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 December 29, 2015, U.S. Drought Monitor rated 29.4% of the United States (including all or parts of 37 states, plus Puerto Rico) as being abnormally dry or worse. It rated 9.7% of the country (including all or parts of 9 states, plus Puerto Rico), as being in severe drought or worse (categories D2, D3, and D4; the highest percentage in these categories reported by the Drought Monitor since it began in 2000 was 38.5% of the country during the week of August 7, 2012).
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:
12/1/15 – 32.4% abnormally dry or worse; 12.3% severe drought or worse;
10/27/15 – 48.7% abnormally dry or worse; 14.4% severe drought or worse;
9/29/15 – 53.0% abnormally dry or worse; 16.8% severe drought or worse;
12/30/14 – 39.2% abnormally dry or worse; 14.1% severe drought or worse.
In the following states, over 50% of the state was categorized by the 12/29/15 report as being in severe-or-worse drought.
California – 88% (with 69% in extreme or exceptional drought). This is the lowest percentage of severe-or-worse drought in California since December 2013. The Golden State has had over 80% of its area categorized in severe-or-worse drought every week since June 25, 2013; over 90% in those categories from February 2014 to mid-December 2015; and 100% from May 13—July 29, 2014. California’s current drought began in late 2011 to early 2012.
Nevada – 65% (with 32% in extreme or exceptional drought). Nevada has had over 50% of its area in severe-or-worse drought since the week of March 27, 2012.
Oregon – 65% (with 61% in extreme drought). Oregon had 100% of its area categorized in severe-or-worse drought from the week of July 28, 2015, through the week of October 27, 2015.
Following are some comments from the 12/29/15 Drought Monitor on some notable conditions or events in various parts of the country, particularly as a result of a large storm system that affected much of the country during the week of December 23-29, 2015.
“A large complex storm system produced copious amounts of precipitation in the Central and Southern US during this….week. The seasonably cold air behind the system mixed with the unseasonably warm, moist air that was entrenched across the east. This produced an unstable air mass kicking off heavy rains, thunderstorms, blizzards, tornadoes and historic flooding. …The 7-day precipitation totals amounted to 800 percent of normal or greater for a large swath stretching from eastern Oklahoma, northwest Arkansas, much of Missouri, and Illinois. Portions of Alabama and Georgia also recorded far greater than normal precipitation amounts. …Average temperature departures were in the range of 20-25 degrees above normal for the…week. Temperature anomalies were as much as 20 degrees below normal in the western third of the country. The following is a list of preliminary daily and monthly temperature data records that were tied or broken during the period from December 23 – 29: 1926 highest daily maximum temperatures; 2019 highest daily minimum temperatures [including 64 degrees F at Danville, Va., 18 degrees above the previous daily record minimum for that date]; 59 highest monthly maximum temperatures; 240 highest monthly minimum temperatures.”
“As the storm moved northeastward, a mixture of rain and blizzard like conditions affected the Central region. Heaviest rain amounts were in Missouri and Illinois where much of the area received at least 5 inches or more. Historic flooding was a concern along the banks of the Mississippi. In St Louis, the river was expected to crest at 44.8 feet – its second highest level ever recorded – only behind the great flood of 1993.”
“The massive storm system brought heavy snows in New Mexico and West Texas. According to storm reports, snow totals topped out at 41” in New Mexico and 24” in Texas. Severe weather affected East Texas dumping in excess of 10 inches of rain in the region. Violent tornadoes, some rated as high as EF4, caused extensive damage and loss of life. …Oklahoma bore the brunt of the precipitation where the eastern portion of the state received as much as 11 inches of rain in a 3-day period. For some areas, the wet December bolstered the annual totals, topping the wettest calendar year on record for the state of Oklahoma.”
“The relentless flow of moisture has benefited the drought stricken areas of the Northwest and West Coast. …For December, precipitation in northwest California was 150-300 percent of normal. …[W]hile the improvements along the coast are evident, they have not been seen inland, yet. Further south, the recent storms have dried out as they moved south into the Monterey [California] area. …In Los Angeles, much like Monterey, all precipitation locations are below normal for the current water year as nearly all of the storm systems have weakened as they approach the area. Reservoirs in San Diego remained unchanged as most of the recent rains soaked into the ground. In Sacramento recent storms have helped with local precipitation totals, and are finally beginning to generate runoff, but not enough to warrant changes in the drought status.”
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 January 1, 2016.