Products Issued
by NWS Blacksburg

Product Definitions
Severe Weather Forecast Hydrologic
Winter Weather & Non-Precipitation Climatological & Temperature-Precipitation Miscellaneous

Severe Weather Products
Tornado Warning

Issued when a Tornado is occurring or imminent in the warning area.  Updates on Tornado Warnings are transmitted under Severe Weather Statements.
 

Severe Thunderstorm Warning

Issued when a Severe Thunderstorm is occurring or imminent in the warning area.  Severe Thunderstorms are defined as having damaging winds equal to or greater than 58 mph, and hail equal to or greater than three-quarters (3/4) of an inch diameter, or penny size and larger. Updates on Severe Thunderstorm Warnings are transmitted under Severe Weather Statements.
 

Severe Weather Statement

Provides updated information on Tornado and Severe Thunderstorm Warnings that are currently in effect or recently expired.  Can include related damage reports or weather conditions and also cancel existing warnings.
 

Local Storm Report

This product contains preliminary, unofficial severe weather reports received by our office. 
 

Watch County Notification Message (WCN)

Issued by the local WFO after the Storm Prediction Center issues a Tornado Watch or Severe Thunderstorm Watch. Its purpose is to list the counties included in the watch. This product is also used to remove some of those counties from the watch as the threat for severe weather diminishes, add counties to the watch, or extend the time of the watch. It is also used to provide notification that a "Watch" has been cancelled.
 

Hazardous Weather Outlook

The Hazardous Weather Outlook, issued at least once daily by around 5 AM EST/EDT and is updated as needed. The HWO highlights any expected hazardous weather conditions over the next seven days. Included are details on the type of severe weather expected (if any), timing, and expected location of the severe weather.
 

Forecast Products

 Zone Forecast
Provides forecasts for each of our 40 counties out to seven days. This product is routinely issued by 400 AM/400 PM daily. Updates are issued on an as needed basis.   Discussion of reasoning behind forecast issued under Area Forecast Discussion.

 

Short Term Forecast (Nowcast)

Issued as needed. It covers the expected weather conditions for up to 6 hours in advance for our County Warning Area. It is meant to give very detailed, narrative information which expands on the basic foundations of the Zone Forecast, including details on timing and amounts of precipitation, or locally dense fog.
 

Area Forecast Discussion
A well-reasoned discussion of the meteorological thinking which went into the preparation of the forecast.
 

Hydrological Products

Flash Flood Warning

Flash Flood Warnings are issued when flash flooding or flooding has been reported or is imminent.  Updates are transmitted under Flash Flood Statements.  Flash Flood Warnings are 6 hours in length or less and can be issued for water washing out roads or bridges and flooding on ungaged rivers or streams.  Dam breaks may also cause a Flash Flood Warning to be issued.  
 

Flood Watch

Flood Watches are issued when flash flooding or flooding is possible in the watch area usually within 24 to 36 hours.  This is most often issued when heavy rains are expected to fall on saturated ground, but can also be posted during ice jams or possible dam breaks.  Updates on Flood Watches are transmitted under Flood Statements.
 

Flash Flood Statement

Flash Flood Statements are issued to update Flash Flood Warnings.  They can include information about the current flooding situation as well as what is expected.
 

Flood Warning

This product is issued when flooding that will significantly affect life or property is occurring or expected within 12 hours along gaged rivers or creeks yet more than six hours after that causative event (e.g., heavy rain, snow melt, or reservoir releases).  Current stages, flood stages, forecast stages and crest information are included in a tabular format.  Flood Warnings for gaged rivers are issued when stages should reach or exceed predetermined levels which may be over flood stage.    Often times the river may be out of its banks, but significant damaging or life threatening conditions are not present until the river reaches several feet above the official flood stage.  Updates of Flood Warnings for rivers are issued under Flood Statements, but Flood Warnings may also be reissued if significant changes in timing and crest levels are anticipated.  When flooding is expected along non gaged rivers or streams, Flash Flood Warnings are issued.

Flood Warnings are also issued for areal flooding of small streams, basins, urban areas, counties, parts of counties etc, when flooding does not occur along river forecast points.
 

Flood Statement

Flood Statements are issued to update, cancel, reduce in areal coverage, provide supplementary information on  Flood Warnings or Flood Watches that are already in effect.  They can also contain forecast information for gaged rivers that are currently at or expected to be between flood stage and the level at which Flood Warnings would be issued within 24 hours.  Additionally, this product may be used to inform the public of elevated stream flows or ponding of water that is not serious enough to warrant a warning. 

 

River Statement

River Statements may contain a variety of general river information, but are most often issued with forecast information for gaged rivers that are relatively high, but expected to remain below flood stage for 24 hours.

 

Hydrologic Outlook

This product can cover three different headlines.

The first is a Flood Potential Outlook. This is issued when there are good chances of widespread, significant flooding usually beyond 36 hours.  Since the event would be relatively far out in the future, the product would contain a general summary of anticipated conditions.  In shorter time frames, Flood Watches would be issued with more specific information and higher detail. 

The second is a Winter/Spring Flood Outlook. This product is issued for even longer outlook periods, for the potential of flooding during the late Winter and Spring based on current and past hydrological conditions .

The third is the Drought and Water Resources Statement. This product is issued whenever our hydrologic service area's average precipitation falls to 85% or less of normal for the most recent six month period.
 

Daily River & Lake Summary
Issued once per day in the morning to provide a summary of river and lake stages along with forecasts for specific points along the rivers.
 

Winter Weather Watches, Warnings, & Advisories
Non-Precipitation Watches, Warnings & Advisories

Winter Weather Watches, Warnings and Advisories

All of the following winter weather products would be issued under this header WSW, and titled "Winter Weather Message".  Updates of these products will be issued under the same header.

  • Winter Storm Watch (One of the following warning or advisory conditions are expected in the next day or so)
    • Blizzard Warning (Sustained wind or frequent gusts to at least 35 mph and blowing snow reducing visibilities to a quarter mile or less for 3 hours or longer)
    • Winter Storm Warning (Issued when events that pose a direct threat to life or property such as heavy snow or an ice storm are imminent or occurring.
    • Heavy Snow Warning (when 4 to 6 inches of snow is expected)
    •  Ice Storm Warning (Damaging accumulations of ice usually of 1/4 inch or greater)
    • Winter Weather Advisory/Snow Advisory/Freezing Rain/Drizzle Advisory (Issued for less serious winter weather conditions (snow, blowing/drifting snow, freezing rain/drizzle) that cause significant inconvenience and if caution is not exercised, could lead to situations that may threaten life and/or property.).
  • Wind Chill Watch (One of the following warning or advisory conditions are expected in the next day or so)
    • Wind Chill Warning (Sustained wind of 5 mph or greater combined with very cold temperatures to produce wind chills of 20 degrees below zero or colder).
    • Wind Chill Advisory (Sustained wind of 5 mph or greater combined with very cold temperatures to produce wind chills from 5 to 19 degrees below zero)

Non-Precipitation Watches, Warnings and Advisories

All of the following non-precipitation products would be issued under this header, NPW, and titled "Weather Message".  Updates of these products will also be issued under the same header.

  • Freeze Warning (Issued in conjunction with forecast low temperatures of <=32°F (with or without frost) across half or more of the county. Sufficient to end the growing season in fall, or delay it in the spring. Generally not issued between mid November and mid April).
  • Frost Advisory (Whenever the minimum temperature is forecast to be 33-36F in the next 12 to 36 hours during the freeze/frost season, on nights with light wind and good radiational cooling)
  • High Wind Watch (Wind warning conditions are expected in a day or so).
  • High Wind Warning (Non-thunderstorm winds sustained at 40 mph for an hour or more, or 58 mph or more for any duration)
  • Wind Advisory (Sustained winds of 31-39 mph or greater for 1 hour or longer, or gusts to 46-57 mph or greater for any duration)
  • Excessive Heat Watch (Heat Warning conditions are expected in a day or so)
  • Excessive Heat Warning (Widespread Heat Index of 110°F for 3 hours or more).
  • Heat Advisory (Widespread Heat Index of 105°F to 109°F for 3 hours or more).
  • Dense Fog Advisory (Widespread visibilities of 1/4 mile or less)

Climatological & other Temperature/Precipitation Products

Daily Climatological Data
(Blacksburg, Roanoke, Lynchburg, Danville and Bluefield)

This product contains daily temperature, precipitation, wind, degree day and astronomical data.  This includes Blacksburg, Roanoke, Lynchburg, Danville, and Bluefield. Preliminary data is normally sent by 530 pm with complete and final data by 530 am. 

Monthly Climatological Data
(Blacksburg, Roanoke, Lynchburg, Danville and Bluefield)

This product contains monthly temperature, precipitation, wind, degree day, and cloud cover data for Blacksburg, Roanoke, Lynchburg, Danville, and Bluefield. It is usually issued on the first day of the following month.
 

Hydrologic Summary/Cooperative Observer Data

This product contains high and low temperature information as well as 24 hour precipitation amounts from cooperative observation sites across the forecast area.  It is usually transmitted by 900 am local time
 

Record Event Report

This product is issued as needed when record weather phenomena are officially recorded within the Blacksburg National Weather Service county warning area.
 

Miscellaneous Products

Air Quality Index

The National Weather Service is Blacksburg will issue an air quality forecast (AQI) that is created by the Virginia Division of Environmental Quality (VDEQ). This product will be issued around 4:30 pm daily. The content of this message covers the Roanoke Area only, for particle pollutants or ground level ozone.
 

Civil Emergency Message
This product is disseminated upon request of federal, state, county or local government officials.  Information or appropriate actions necessitated by nuclear incidents, hazardous material releases, unstable explosive materials or other occurrences is relayed.
 

Special Weather Statement

This product is issued for weather hazards that do NOT meet or exceed advisory or warning thresholds. Examples

  • A thunderstorm that is causing gusts to 45 mph and small hail.
  • Patchy dense fog
  • Locally heavy rain creating ponding of water on highways
     

Regional Weather Summary

Broken into two sections, this product contains recent past weather (up to 24 hours in the past), present weather and the second section contains forecast information about what will soon occur region-wide.
 

Public Information Statement

This is a generic product that can contain many different kinds of information.  It can distribute information regarding hydrometeorological events; public education; National Weather Service (NWS) service changes, limitations or interruptions; and special guidelines for interpreting NWS data.