Here is the Virginia Water Central News Grouper’s monthly water-status report on precipitation, stream flow, and drought, as of the end of September 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 September 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||Oct. 2014-Sept. 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 September 30, 2015.
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 September 2015 at 150 stream gages in Virginia and just beyond the state border were in the normal range at about 68% of gages, below normal at about 8%, above normal at about 19%, and much above normal at about 5%. 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.
The weekly National Drought Monitor map from the University of Nebraska-Lincoln (http://droughtmonitor.unl.edu/) for October 6, 2015, showed Virginia as essentially drought-free, with only 0.01 percent of the state rated as abnormally dry. Two weeks earlier, however, the 9/22/15 report rated about 80 percent of the Commonwealth as abnormally dry, before the heavy rains that took place during the last week of September and the first week of October.
The Drought Monitor notes that it “focuses on broad-scale conditions [and] local conditions may vary.” 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:
9/8/15 – 59% abnormally dry;
8/4/15 – drought-free;
7/7/15 – drought-free;
10/7/14 – 48% abnormally dry.
The Virginia Drought Monitoring Task Force, a collaboration of state and federal agencies, issued its most recent Drought Status Report on September 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 next report is scheduled for October 2015. 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 the October 8, 2015. 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.
MORE ON GROUNDWATER LEVELS
More 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).
The October 6, 2015, U.S. Drought Monitor rated 46.9% of the United States (including all or parts of 47 states, plus Puerto Rico) as being abnormally dry or worse. It rated 18.0% of the country (including all or parts of 14 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:
9/8/15 – 52.0% abnormally dry or worse; 16.4% severe drought or worse;
8/4/15 – 47.0% abnormally dry or worse; 14.6% severe drought or worse;
7/7/15 – 40.5% abnormally dry or worse; 14.4% severe drought or worse;
10/7/14 – 39.4% abnormally dry or worse; 15.6% severe drought or worse.
In the following states, over 50% of the state was categorized by the 10/8/15 report as being in severe-or-worse drought.
California – 92% (with 71% in extreme or exceptional drought).
California has had over 80% of its area categorized in severe-or-worse drought every week since June 25, 2013, and the Golden State had 100% in those categories from May 13—July 29, 2014. California’s current drought began in late 2011 to early 2012.
Nevada – 76% (with 38% 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 – 100% (with 67% in extreme drought).
Washington – 100% (with 63% in extreme drought).
Oregon and Washington have had essentially 100% of their area in severe-or-worse drought since the week of July 28, 2015 (the percentage in Washington was 99.99% from July 28 through September 15).
Following are some comments from the 10/6/15 Drought Monitor on some notable conditions or events in various parts of the country.
“Record rains and flooding inundated much of eastern and central South Carolina and extreme southeastern North Carolina as a very slow moving upper-air low over the Southeast funneled tropical moisture from Hurricane Joaquin (stalled over the central Bahamas) into the southern Atlantic Coast region for several days. More than 10 inches of rain fell on the eastern half of South Carolina, and well over 20 inches drenched east-central sections of the state. During the first 6 days of October, maximum Carolina storm amounts totaled 26.88 inches at Mt. Pleasant, S.C., and 22.25 inches at Calabash, N.C. … The Southeast was a tale of (historical) haves and have nots as a stalled upper-air pattern locked the weather conditions in place, leading to copious rains and flooding (in the Carolinas) versus persistent dryness and growing drought (in Mississippi and western Alabama).”
“In Alaska, another week of wet weather across most of the state punctuated a wet September, with the wettest September on record at Anchorage (7.71 inches) and the wettest September at Fairbanks (3.74 inches) since 1925. Both Denali National Park HQ and Juneau had the wettest July-September of record. An exception was found at Kodiak where fish processors were asked by the city to limit water usage due to low water supply behind the dam due in part to the driest June-September at Kodiak since 1956 and the warmest since 1979.”
Lower Mississippi Valley and Southern Plains
“…[The] remnants of Pacific Hurricane Marty…brought 0.5 to 2 inches of rain to extreme southwestern and western Texas and the Oklahoma Panhandle… In Texas, Muenster (Cooke County) recorded 41.67 inches during April 1-June 30, 4.40 inches July 1-September 30, and only 1.91 inches since July 9. At the USHCN station Blanco (Blanco County), 8.55 inches fell on May 24, but only 0.48 inches since July 1 – so it seems likely that Blanco received as much rain in 14 minutes on May 24 as in the most recent 140,000 minutes (97 days). In Arkansas, several stations established new record lows (Minden 0.02”; Pine Bluff 0.03”; Shreveport 0.07”; and Little Rock 0.12”) for the driest September ever.”
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 October 7, 2015.