Category Archives: Weather

2017 Atlantic Hurricane Season Outlook Released on May 25, 2017, Predicting 11 to 17 Named Storms

The Atlantic hurricane season (including the North Atlantic Ocean, Caribbean Sea, and Gulf of Mexico) runs from June 1 to November 30, with August to October the usual period of peak activity.   On May 25, 2017, the Climate Prediction Center of the National Oceanic and Atmospheric Administration (NOAA) released its outlook for the 2017 Atlantic hurricane season.   The news release on the forecast is available online at http://www.noaa.gov/media-release/above-normal-atlantic-hurricane-season-is-most-likely-year.  The full forecast report is available online at http://www.cpc.ncep.noaa.gov/products/outlooks/hurricane.shtml.

The outlook is a collaboration of the Climate Prediction Center, the National Hurricane Center, and the Hurricane Research Division, all within NOAA.

According to the news release, forecasters predict a 45 percent chance of an above-normal season, a 35 percent chance of a near-normal season, and only a 20 percent chance of a below-normal season.  The outlook also estimated a 70 percent likelihood of 11 to 17 named storms (winds of 39 mph or higher), of which 5 to 9 could become hurricanes (winds of 74 mph or higher), including 2 to 4 major hurricanes (Category 3, 4 or 5; winds of 111 mph or higher).  On average from 1966 through 2009, the Atlantic basin has averaged 11 named storms, of which six become hurricanes, with two major hurricanes, according to the National Hurricane Center’s “Tropical Cyclone Climatology” Web page, http://www.nhc.noaa.gov/climo/.  One named storm already occurred in 2017: Tropical Storm Arlene, in April.

NOAA’s full outlook report makes the following cautions about predicted storm numbers: The outlook is “a general guide to the expected overall nature of the upcoming hurricane season; [the outlook] is not a seasonal hurricane landfall forecast, and it does not predict levels of activity for any particular region.   Hurricane disasters can occur whether the season is active or relatively quiet.   It only takes one hurricane (or tropical storm) to cause a disaster.  Residents, businesses, and government agencies of coastal and near-coastal regions are urged to prepare for every hurricane season regardless of this, or any other, seasonal outlook.”

During the season, reports on individual storms as they occur will be available at http://www.nhc.noaa.gov/?atlc.  When storms are completed, reports on individual 2016 storms (including tracks) will be available online at http://www.nhc.noaa.gov/data/tcr/index.php?season=2017&basin=atl.

National Hurricane Center averages for the Atlantic season for the period 1981-2010 are 12 named storms, 6 hurricanes, and 3 major hurricanes. Here are the numbers for the past five years:
2016 – 15 named storms, 4 of which became hurricanes, including 3 major hurricanes;
2015 – 11 named storms, 4 of which became hurricanes, including 2 major hurricanes;
2014 – 8 named storms, 6 of which became hurricanes, including 2 major hurricanes;
2013 – 13 named storms, 2 of which became hurricanes;
2012 – 19 named storms, 10 of which became hurricanes, including 1 major hurricane.

For Water Central News Grouper posts reviewing recent Atlantic tropical storm seasons, please see the following links: 2016; 2015; 2014; 2013; 2012.

Also on May 27, 2016, NOAA issued its outlook for the Eastern Pacific and Central Pacific basins.  That report is available online at http://www.cpc.ncep.noaa.gov/products/Epac_hurr/Epac_hurricane.html.  For both basins, NOAA estimates an 80-percent chance of a near- or above-normal season.  The eastern Pacific outlook calls for a 70-percent probability of 14 to 20 named storms (6 to 11 hurricanes, including 3 to 7 major hurricanes). The central Pacific outlook calls for a 70-percent probability of 5 to 8 tropical cyclones (tropical depressions, tropical storms, and hurricanes).

Hurricane tracks 2016National Hurricane Center’s graph of the tracks of Atlantic tropical storms and hurricanes in 2016, accessed at http://www.nhc.noaa.gov/data/tcr/index.php?season=2016&basin=atl.

Virginia Precipitation and Stream Flow for the 7-day Period Ending May 22, 2017, Plus an Overview of Flooding Nationwide

Below are several items summarizing recent precipitation and stream flow:

  1. Images showing precipitation in Virginia and other areas of the United States, and stream flow in Virginia, over the seven-day period ending May 22, 2017 (information available as of May 23).
  2. Flooding overview maps of Virginia and the continental United States, as of May 23.

The Virginia Water Resources Research Center thanks the agencies mentioned below for providing precipitation and stream-flow information and images.

For the current month’s other weekly reports on stream flow and precipitation, please see the News Grouper posts available at this link: https://vawatercentralnewsgrouper.wordpress.com/?s=Virginia+Precipitation.

For monthly reviews of precipitation, stream flow, and drought, please see the posts available at this link: https://vawatercentralnewsgrouper.wordpress.com/?s=Monthly+Water+Status.

For more information on current and historical surface-water and groundwater conditions in Virginia, please see the U.S. Geological Survey (USGS) Virginia Science Center’s Web site, http://va.water.usgs.gov/.

GAGE May 2017 Little River Reservoir at Radford May6 2017

May 2017 Gaging Station of the Month: Little River Reservoir near Radford on the Montgomery County/Pulaski County line, May 6, 2017.  U.S. Geological Survey information from this gage is online at https://waterdata.usgs.gov/nwis/uv?03170500.

Precipitation

The following two color-coded maps show southeastern U.S. precipitation amounts (top map) and the percent of normal precipitation compared to normal for this period of the year (bottom map) over the seven-day period ending May 22, 2017.  The maps were accessed from the National Oceanic and Atmospheric Administration’s (NOAA) Southeast Regional Climate Center, located at the University of North Carolina in Chapel Hill; online at http://www.sercc.com/climateinfo/precip_maps.  As of that date, these data were provisional (needing to be verified for accuracy and subject to possible revision).

precip May 22

precip perc May 22

Another source of precipitation data is the National Weather Service’s Advanced Hydrologic Prediction Service, online at http://water.weather.gov/precip/.  The site provides maps showing precipitation nationwide or by state for specific days, months, or years.  The site also has the capability to show county boundaries, and other map layers available include river flood forecasts and current flood/severe weather warnings.  Shown below is the continental U.S. 7-day precipitation map as of 8 a.m. EDT on 5/22/17.  Please note that UTC, the time shown on the maps at the site, is four hours ahead of Eastern Daylight Time and five hours ahead of Eastern Standard Time.

Precip US May 22

Stream Flow

Seven-day-average Virginia stream flows at gaging stations as of May 22, 2017 are indicated in the map below, from the U.S. Geological Survey (USGS) WaterWatch for Virginia, accessed online at http://waterwatch.usgs.gov/index.php?m=pa07d&r=va&w=map.  The map’s color-coded dots compare the previous week’s average stream flows to the normal flow levels for that week over the historical record for each gaging station.  The color codes/percentile classes used by USGS are as shown in the chart following the map.  Note: Additional gaging stations (such as for reservoirs or for inactive sites) area shown on maps available at the USGS’ National Water Information System Mapper, online at https://maps.waterdata.usgs.gov/mapper/index.html.

streams May22

stream codes

Flooding Overview

As of about 9:30 a.m. EDT on May 23, 2017, 15 stream-gaging stations in or adjacent to Virginia were either experiencing flooding or near flood stage.  The National Weather Service’s Advanced Hydrologic Prediction Center’s map of river levels relative to flood stage (color-coded) for Virginia and nearby areas is shown below.  Also below is the nationwide map as of the same time.  The maps are available online at http://water.weather.gov/ahps/forecasts.php; at that site, one can select Virginia or any other state of interest.
Flooding VA may23Flooding US May23

On Virginia Water Radio for 5-22-17: Here Comes Atlantic Tropical Storm Season 2017

Virginia Water Radio’s episode for the week of May 22, 2017, is “After Arlene’s April Opener, Here Comes Atlantic Tropical Storm Season 2017.”  The 3 min./56 sec. episode, available online at http://www.virginiawaterradio.org/2017/05/episode-369-5-22-17-after-arlenes-april.html, is the show’s annual preview of the upcoming tropical storm season, with preparedness information.

Photo 2 Arlene from NASA
An early starter for the 2017 Atlantic tropical storm season: Tropical Storm Arlene in the mid-Atlantic on April 21, 2017, 7:45 a.m. EDT.  Puerto Rico is visible in the lower left corner of the photo.  Photo from the GOES-East satellite, NASA/NOAA GOES Project, in “NASA Satellite Animation Shows Tropical Storm Arlene “Eaten” By Weather System,” 4/22/17, online at https://www.nasa.gov/feature/goddard/2017/td1-atlantic-ocean.


Virginia Water Radio’s is a weekly broadcast/podcast produced by the Virginia Water Resources Research Center.  The home page is http://www.virginiawaterradio.org.  Have a listen or two!

National Hurricane Preparedness Week was May 7-13, 2017; Atlantic Tropical Storm Season Runs Officially on June 1-Nov. 30

The Atlantic tropical storm season (for the North Atlantic Ocean, Caribbean Sea, and Gulf of Mexico) runs officially from June 1 to November 30.  But once again in 2017, nature didn’t follow the official rules, because Tropical Storm Arlene formed in the mid-Atlantic in April.  (In 2016, Hurricane Alex formed in the mid-Atlantic in January.)

You may have missed Arlene, but the bulk of the Atlantic tropical storm season is coming, and mid-May is a good time to get ready.  The National Oceanic and Atmospheric Administration (NOAA) designated May 7-13, 2017, as National Hurricane Preparedness Week.  The agency identified seven areas of preparedness, one for each day of the week: Determine your risk;
Develop and evacuation plan;
Assemble disaster supplies;
Secure an insurance check-up;
Strengthen your home;
Check on your neighbor; and
Complete your written hurricane plan.
Information on these areas and lots of other information resources are available online at http://www.nws.noaa.gov/com/weatherreadynation/hurricane_preparedness.html.

Here are some additional online resources for staying informed during the Atlantic tropical storm season:
National Hurricane Center Web site for current advisories, tracks, etc.: http://www.nhc.noaa.gov/index.shtml.

Two-day outlook for photos of all active systems in the Atlantic basin, online at http://www.nhc.noaa.gov/gtwo.php?basin=atlc&fdays=2; and five-day graphical outlook, online at http://www.nhc.noaa.gov/gtwo.php?basin=atlc&fdays=5.

Information on storms missed: Advisory archive for 2017, online at http://www.nhc.noaa.gov/archive/2017/; and links to graphs and other data for 2017 storms, online at http://www.nhc.noaa.gov/data/tcr/index.php?season=2017&basin=atl.

National Hurricane Center videos on You Tube: https://www.youtube.com/user/nwsnhc.

Virginia Precipitation and Stream Flow for the 7-day Period Ending May 15, 2017, Plus a Mid-Month Drought Assessment

Below are images showing precipitation in Virginia and other areas of the southeastern United States, and stream flow in Virginia, over the seven-day period ending May 15, 2017 (information available as of May 16); a national flooding overview map and a map of flooding in the region around Virginia, as of May 16; and the Virginia Drought Monitoring Task Force’s daily map showing the status of several drought indicators in different Virginia regions, as of May 16.  The Virginia Water Resources Research Center thanks the agencies mentioned below for providing precipitation and stream-flow information and images.  For the current month’s other weekly reports on stream flow and precipitation, please see the News Grouper posts available at this link: https://vawatercentralnewsgrouper.wordpress.com/?s=Virginia+Precipitation.

For monthly reviews of precipitation, stream flow, and drought, please see the posts available at this link: https://vawatercentralnewsgrouper.wordpress.com/?s=Monthly+Water+Status.

For more information on current and historical surface-water and groundwater conditions in Virginia, please see the U.S. Geological Survey (USGS) Virginia Science Center’s Web site, http://va.water.usgs.gov/.

GAGE May 2017 Little River Reservoir at Radford May6 2017 May 2017 Gaging Station of the Month: Little River Reservoir near Radford on the Montgomery County/Pulaski County line, May 6, 2017.  U.S. Geological Survey information from this gage is online at https://waterdata.usgs.gov/nwis/uv?03170500.

Precipitation

The following two color-coded maps show southeastern U.S. precipitation amounts (top map) and the percent of normal precipitation compared to normal for this period of the year (bottom map) over the seven-day period ending May 15, 2017.  The maps were accessed from the National Oceanic and Atmospheric Administration’s (NOAA) Southeast Regional Climate Center, located at the University of North Carolina in Chapel Hill; online at http://www.sercc.com/climateinfo/precip_maps.  As of that date, these data were provisional (needing to be verified for accuracy and subject to possible revision).
Precip May 15
Precip Perc May 15

Another source of precipitation data is the National Weather Service’s Advanced Hydrologic Prediction Service, online at http://water.weather.gov/precip/.  The site provides maps showing precipitation nationwide or by state for specific days, months, or years.  The site also has the capability to show county boundaries, and other map layers available include river flood forecasts and current flood/severe weather warnings.  Shown below is the continental U.S. 7-day precipitation map as of 8 a.m. EDT on 5/16/17.  Please note that UTC, the time shown on the maps at the site, is four hours ahead of Eastern Daylight Time and five hours ahead of Eastern Standard Time.

Precip US May 16

Stream Flow

Seven-day-average Virginia stream flows at gaging stations as of May 15, 2017 are indicated in the map below, from the U.S. Geological Survey (USGS) WaterWatch for Virginia, accessed online at http://waterwatch.usgs.gov/index.php?m=pa07d&r=va&w=map.  The map’s color-coded dots compare the previous week’s average stream flows to the normal flow levels for that week over the historical record for each gaging station.  The color codes/percentile classes used by USGS are as shown in the chart following the map.  Note: Additional gaging stations (such as for reservoirs or for inactive sites) area shown on maps available at the USGS’ National Water Information System Mapper, online at https://maps.waterdata.usgs.gov/mapper/index.html.

Streams May 15

stream codes

Flooding Overview

As of about 2 p.m. EDT on May 16, 2017, one stream-gaging stations near Virginia was near flood stage.  The National Weather Service’s Advanced Hydrologic Prediction Center’s map of river levels relative to flood stage (color-coded) is available online at http://water.weather.gov/ahps/forecasts.php; at that site, one can select Virginia or any other state of interest.  Shown below are the U.S. and Virginia-region maps as of approximately 2 p.m. EDT.

Flooding US May 16

Flood VA May 16

Mid-month Drought Status Update

The Virginia Drought Monitoring Task Force (DMTF), a collaboration of state and federal agencies, issued its latest Virginia drought-status report on May 12, 2017.  The report is available at the DMTF Web site, http://www.deq.virginia.gov/Programs/Water/WaterSupplyWaterQuantity/Drought.aspx.  The Task Force was scheduled to meet and report again on June 8, 2017.

The Task Force also produces a daily map rating drought-status indicators.  Shown below is the map for May 16, 2017.  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.”  Note the emergency-conditions code (in red) for  groundwater in the Shenandoah Valley and north-central Piedmont areas, Virginia, and the warning code (in orange) for in the northern region.  Any given day’s current map and more information on drought status in Virginia are available the Task Force Web site, http://www.deq.virginia.gov/Programs/Water/WaterSupplyWaterQuantity/Drought.aspx.Drought VA May 16

 

Virginia Precipitation and Stream Flow for the 7-day Period Ending May 8, 2017; Plus an Overview of Flooding Nationwide

Below are images showing precipitation in Virginia and other areas of the southeastern United States, and stream flow in Virginia, over the seven-day period ending May 8, 2017 (information available as of May 9).  Also below is a national flooding overview map and a map of flooding status in Virginia, as of May 9.  The Virginia Water Resources Research Center thanks the agencies mentioned below for providing precipitation and stream-flow information and images.

For the current month’s other weekly reports on stream flow and precipitation, please see the News Grouper posts available at this link: https://vawatercentralnewsgrouper.wordpress.com/?s=Virginia+Precipitation.

For monthly reviews of precipitation, stream flow, and drought, please see the posts available at this link: https://vawatercentralnewsgrouper.wordpress.com/?s=Monthly+Water+Status.

For more information on current and historical surface-water and groundwater conditions in Virginia, please see the U.S. Geological Survey (USGS) Virginia Science Center’s Web site, http://va.water.usgs.gov/.

GAGE May 2017 Little River Reservoir at Radford May6 2017May 2017 Gaging Station of the Month: Little River Reservoir near Radford on the Montgomery County/Pulaski County line, May 6, 2017.  U.S. Geological Survey information from this gage is online at https://waterdata.usgs.gov/nwis/uv?03170500.

Precipitation

The following two color-coded maps show southeastern U.S. precipitation amounts (top map) and the percent of normal precipitation compared to normal for this period of the year (bottom map) over the seven-day period ending May 8, 2017.  The maps were accessed from the National Oceanic and Atmospheric Administration’s (NOAA) Southeast Regional Climate Center, located at the University of North Carolina in Chapel Hill; online at http://www.sercc.com/climateinfo/precip_maps.  As of that date, these data were provisional (needing to be verified for accuracy and subject to possible revision).
Precip May 8Precip perc May8

Another source of precipitation data is the National Weather Service’s Advanced Hydrologic Prediction Service, online at http://water.weather.gov/precip/.  The site provides maps showing precipitation nationwide or by state for specific days, months, or years.  The site also has the capability to show county boundaries, and other map layers available include river flood forecasts and current flood/severe weather warnings.  Shown below is the continental U.S. 7-day precipitation map as of 8 a.m. EDT on 5/9/17.  Please note that UTC, the time shown on the maps at the site, is four hours ahead of Eastern Daylight Time and five hours ahead of Eastern Standard Time.

Precip US May 9

Stream Flow

Seven-day-average Virginia stream flows at gaging stations as of May 8, 2017 are indicated in the map below, from the U.S. Geological Survey (USGS) WaterWatch for Virginia, accessed online at http://waterwatch.usgs.gov/index.php?m=pa07d&r=va&w=map.  The map’s color-coded dots compare the previous week’s average stream flows to the normal flow levels for that week over the historical record for each gaging station.  The color codes/percentile classes used by USGS are as shown in the chart following the map.  Note: Additional gaging stations (such as for reservoirs or for inactive sites) area shown on maps available at the USGS’ National Water Information System Mapper, online at https://maps.waterdata.usgs.gov/mapper/index.html.

Streams May 8

stream codes
Flooding Overview

As of about 1:50 p.m. EDT on May 9, 2017, four stream-gaging stations in Virginia were near flood stage [or experiencing…add as necessary.  The National Weather Service’s Advanced Hydrologic Prediction Center’s map of river levels relative to flood stage (color-coded) is available online at http://water.weather.gov/ahps/forecasts.php; at that site, one can select Virginia or any other state of interest.  Shown below are the U.S. map and the Virginia regional map as of 1:51 p.m. EDT.

US Flooding May 9

Va flooding May 9

Virginia Water Status Report as of the End of April 2017, Plus a Look at Drought Nationally

Here is the Virginia Water Central News Grouper’s monthly water-status report on precipitation, stream flow, and drought, as of the end of April 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.

01 Icon Precip

Here are National Weather Service (NWS) preliminary (still needing verification) precipitation totals for March 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.  All values are in inches.

Location April 2017 Observed

 

Monthly Normal May 2016-

April 2017 Observed

Annual Normal
Blacksburg 5.92 3.48 45.42 40.89

 

Bluefield1

 

4.59 3.34 40.35 39.63
Bristol2

 

5.16 3.33 38.16 41.01
Charlottesville3

 

2.80 3.36 31.37 42.71
Danville

 

7.54 3.46 49.81 44.41
Lynchburg

 

4.18 3.31 40.95 41.57
Norfolk

 

3.58 3.41 65.01 46.53
Richmond

 

2.28 3.27 52.87 43.60
Roanoke

 

5.92 3.37 47.54 41.25
Wallops Island4

 

2.31 3.07 57.58 40.84
Washington-Dulles Airport5 3.04 3.47 34.34 41.54

Location notes
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 April 30, 2017.

Precipperc30 AprilPrecipperc60 AprPrecipperc90 Apr 

02 Icon Streamflow
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 April 2017 at 156 stream gages in Virginia and just beyond the state border were in the normal historical range at about 65% of gages, below normal at about 3%, above normal at about 18%, and much above normal at about 14%.  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.

Streams map Aprilstream codes
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 April 29, 2017, accessed on May 1 at https://waterwatch.usgs.gov/index.php?id=pa01d&sid=w__plot&r=va.

Stream plot April

03 Icon Groundwater

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).

04 Icon Drought DROUGHT IN VIRGINIA

The weekly National Drought Monitor map from the University of Nebraska-Lincoln (http://droughtmonitor.unl.edu/) for April 25, 2017, showed about 46.4% of Virginia as “abnormally dry” worse; and about 16.0% in “moderate drought.”

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:
3/28/17 – 61.0% abnormally dry or worse, 41.0% moderate drought or worse, 2.2% in severe drought;
2/28/17 – 80.5% abnormally dry or worse, 17.1% moderate drought or worse, 2.9% in severe drought;
1/31/17 – 30.0% abnormally dry or worse, 0.5% moderate drought;
4/26/16 – 95.1% abnormally dry or worse; 4.1% moderate drought.

The Virginia Drought Monitoring Task Force, a collaboration of state and federal agencies, issued its most recent (as of 5/1/17) Drought Status Report on April 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.  The Task Force is next scheduled to meet on May 11, 2017.  Following is an excerpt from the April 17 report:

“Although precipitation in early April increased streamflow rates, it was not enough to offset dry conditions that extend over most of central Virginia due to below-normal winter precipitation.  Portions of Northern Virginia, especially those areas within the Northern Virginia and Northern Piedmont drought evaluation regions, continue to experience the driest conditions.  The Virginia Department of Environmental Quality (DEQ) issued a drought watch for these two regions on March 22.  Recognizing that dry conditions also exist within other drought evaluation regions extending southward through central Virginia, DEQ distributed a message to water users in those areas to raise awareness of the long-term water supply impact of the dry winter conditions.  The task force discussed the possibility of recommending issuance of a drought watch for some of these regions, particularly the Middle James drought evaluation region, but agreed to continue to closely monitor conditions for now.  …For the current water year (October 1, 2016–April, 13, 2017) precipitation totals have so far been below the April drought watch indicator level for precipitation (81.5% of normal) for nine of Virginia’s thirteen drought evaluation regions.  The Northern Virginia and Northern Piedmont regions have received just 66% and 59% of normal precipitation, respectively.  The Shenandoah and Roanoke regions have received 72% and 74% of normal precipitation, respectively.  …The Virginia Department of Game and Inland Fisheries (VDGIF) reported no low water level issues with the Department’s fish stocking program.  However, there have been a few complaints regarding recreational water access due to low water.  The Virginia Department of Forestry (VDOF) reported that we are nearing the end of the spring wildfire season.  VDOF does not have any current concerns regarding drought related fires or insect/disease issues.”

The Drought Monitoring Task Force also produces a map rating drought-status indicators.  Shown below is the map for April 29, 2017.  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.

 

VA Drought Apr29
DROUGHT ELSEWHERE

The April 25, 2017, U.S. Drought Monitor rated about 23.6% of the United States (including all or parts of 39 states) as being abnormally dry or worse; this was the lowest nationwide percentage of abnormally dry-or-worse conditions since the week of November 17, 2009.  The Drought Monitor rated 0.92% of the country (including parts of 8 states), as being in severe drought or worse (categories D2, D3, and D4); this was the lowest nationwide percentage of severe-or-worse drought since the Drought Monitor began on January 4, 2000.  (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:
3/28/17 – 34.9% abnormally dry or worse, 2.4% severe drought or worse;
2/28/17 – 34.0% abnormally dry or worse, 3.1% severe drought or worse;
1/31/17 – 28.3% abnormally dry or worse, 3.2% severe drought or worse;
4/26/16 – 37.0% abnormally dry or worse; 5.0% severe drought or worse.

No state had 50% or more rated by the April 25 Drought Monitor in severe-or-worse drought.  The highest percentage of those categories was in Florida, at about 33%.

In California, just over 1% of the state was rated on 4/25/17 as being in severe-or-worse drought.  This severe-or-worse rating, in effect since the week of March 14, 2017, was the lowest for the Golden State since the week of February 14, 2012.  Most of California is out of the drought that began in late 2011 to early 2012 and continued into early 2017.

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 May 1, 2017.
Drought Outlook US Apr20