NWS Nashville Product Guide

The National Weather Service in Nashville, Tennessee issues a variety of products covering 39 counties in Middle Tennessee. These products are used by the media, emergency managers, and the public. The products are accessed through a variety of methods, including the NOAA Weather Wire Service (NWWS), Family of Services (FOS), the NWS AWIPS network, the Emergency Managers Weather Information Network (EMWIN), and private vendors. This guide gives a summary of the products, including necessary header information.

The listing is broken down into Severe Weather Products, Routine Public Products, Aviation Weather Products, Fire Weather Products, Hydrological Products, Climate Products, and Other General Public Products.

Severe Weather Products

Hazardous Weather Outlook
FOS/WMO Header: FLUS43 KOHX
AWIPS Header: OHXHWOOHX
The Hazardous Weather Outlook, issued at least once daily by around 5:00 AM CST/CDT and is updated as needed. The HWO highlights any expected hazardous weather conditions over the next seven days. This includes, but is not limited to, severe weather, flooding, extreme heat or cold, winter weather, and dense fog.

Tornado Warning
FOS/WMO Header: WFUS53 KOHX
AWIPS Header: OHXTOROHX
Tornado Warnings are issued for expected tornadic activity over a county, or a portion of a county. A warning may be issued based on Doppler radar indications of a tornado, reports of a funnel cloud, or observed tornado sightings. Tornado Warnings are typically valid for 45 minutes or less.

Severe Thunderstorm Warning
FOS/WMO Header: WUUS53 KOHX
AWIPS Header: OHXSVROHX
Severe Thunderstorm Warnings are issued for storms which are producing or are expected to produce winds of 58 mph or more, hail 3/4 inch or greater diameter, or both. These are issued for counties or portions of counties, and are typically an hour or less in length.

Severe Weather Statement
FOS/WMO Header: WWUS53 KOHX
AWIPS Header: OHXSVSOHX
A Severe Weather Statement is used to disseminate follow-up information on severe thunderstorm and tornado warnings. This can include actual severe weather reports, current radar information, and towns expected to be in the path of the storms. This statement is also used to cancel warnings, and to give follow-up information after a warning has expired.

Flash Flood Warning
FOS/WMO Header: WGUS53 KOHX
AWIPS Header: OHXFFWOHX
The Flash Flood Warning is issued when life or property-threatening, short-term flooding is imminent. This can include flooding due to heavy rainfall or due to a dam break. Flash Flood Warnings may be valid for up to 6 hours, and can be extended as necessary.

Flash Flood Statement
FOS/WMO Header: WGUS73 KOHX
AWIPS Header: OHXFFSOHX
The Flash Flood Statement is issued to update the status of short-term flash flood situations. It can contain information on reported rainfall, radar estimates of rain, and forecast amounts of rain in the future.

Flood Statement
FOS/WMO Header: WGUS83 KOHX
AWIPS Header: OHXFLSOHX
The Flood Statement product can be issued for a number of reasons: 1) Follow-up information on Flood Warnings, either county-based or river-based; or 2) Short-term flooding which may cause an inconvenience, but is not considered to be threatening ("urban and small stream flooding"). When issued for river flooding forecast purposes, they are issued twice daily, usually between 10:00-11:00 AM and between 8:00-9:00 PM CST/CDT.

Watch Outline Update
FOS/WMO Header: WOUS64 KWNS
AWIPS Header: MKCWOU# (# represents last digit of watch number)
The Watch Outline Update is issued by the Storm Prediction Center in Norman, OK. It is issued at the beginning and end of severe thunderstorm and tornado watches, and indicates which counties are specifically included in the watch. This product includes all NWS offices affected by a particular watch.

Local Storm Report
FOS/WMO Header: NWUS53 KOHX
AWIPS Header: OHXLSROHX
The Local Storm Report product gives a detailed listing of observed severe weather across the NWS Nashville area of responsibility. It is often issued during a severe weather event, a few reports at a time, but it is always issued after an event has ended containing a summary of all reports. Reports of significant winter weather are also transmitted in the LSR product. Data listed should be considered preliminary, as further investigation may be necessary in some cases. This product is used as input to the national Daily Severe Weather Statistics compiled by the Storm Prediction Center.

Special Weather Statement
FOS/WMO Header: WWUS83 KOHX
AWIPS Header: OHXSPSOHX
The Special Weather Statement is used to disseminate updated information regarding the cancellation of severe weather watches (in the future, the Watch County Notification WCN product will be used for this purpose). The SPS is more often used to augment the current forecast and highlight significant short-term weather that is not already covered in an advisory, watch, or warning product. Examples include a line of strong, but not severe, thunderstorms …or an area of moderately intense snow showers.

Routine Forecast Products

National Digital Forecast Database/Grid-Point Forecasts
FOS/WMO Header: N/A
AWIPS Header: N/A
Forecasters in todays NWS issue forecasts in gridded form via the National Digital Forecast Database (NDFD), which are updated as necessary day or night. What this means is that you can get a unique forecast for a specific point anywhere in the U.S. that offers features such as hourly temperature and precipitation forecasts. Experimental point forecasts are available for locations in the NWS Nashville area of responsibility at this website. Graphical forecasts in a map form are also available. Outside entities can use this NDFD data to view weather parameters that are important to them; an example would be a transportation company interestested in the weather along a certain Interstate. Visit the NDFD webpage for details on how you can benefit from this powerful dataset. What forecasters input into the NDFD is also used to generate our routine text products, which are described below.

Zone Forecast Product
FOS/WMO Header: FPUS53 KOHX
AWIPS Header: OHXZFPOHX
The Zone Forecast Product gives specific forecasts for out to 7 days in the 39 counties covered by the Nashville NWS office. The product is routinely issued at 4:00 AM and 4:00 PM CST/CDT, and is updated as necessary. Forecasts are broken up into "zones” or groups of counties where the forecast weather is expected to be similar. When necessary, a forecast section is headlined with a watch, warning or advisory for hazardous weather.

Area Forecast Discussion
FOS/WMO Header: FXUS63 KOHX
AWIPS Header: OHXAFDOHX
The Area Forecast Discussion is issued normally by around 3:00 AM and 3:00 PM CST/CDT, and at other times as weather changes. The forecaster gives their analysis of the current weather situation, information on the computer models, and forecast reasoning. The discussion includes a listing of non-convective watches, warnings and advisories that will be in effect, on the line following ".OHX WATCHES/WARNINGS/ADVISORIES...".

Area Forecast Matrices
FOS/WMO Header: FOUS53 KOHX
AWIPS Header: OHXAFMOHX
The Area Forecast Matrix product is a tabular listing of expected weather elements over the next several days for groups of counties. It is similar to the Model Output Statistics (MOS) guidance, but reflects forecaster input into the process. Contents include expected temperature, dew point, humidity, wind, sky condition, and precipitation chances and amounts in 3 hourly increments for the first 60 hours of the forecast, with 6 hourly increments thereafter. The AFM product is issued twice daily by around 4:00 AM and 4:00 PM CST/CDT, and is updated as necessary.

Point Forecast Matrices
FOS/WMO Header: FOUS53 KOHX
AWIPS Header: OHXPFMOHX
The Point Forecast Matrix product is a tabular listing of expected weather elements over the next several days, at specific cities in Middle Tennessee and south Central Indiana. It is similar to the Model Output Statistics (MOS) guidance, but reflects forecaster input into the process. Contents include expected temperature, dew point, humidity, wind, sky condition, and precipitation chances and amounts in 3 hourly increments for the first 60 hours of the forecast, with 6 hourly increments thereafter. The PFM is issued twice daily by around 4:00 AM and 4:00 PM CST/CDT, and is updated as necessary.

Coded Cities Forecast
FOS/WMO Header: FPUS43 KOHX
AWIPS Header: OHXCCFOHX
The Coded Cities Forecast is normally issued by around 3:30 AM and 3:30 PM CST/CDT. It contains coded forecasts of weather, temperature and precipitation chances for Nashville (BNA), Clarksville (CKV), and Crossville (CSV). The product is used as input to the national Selected Cities Summary, issued by the National Centers for Environmental Prediction (NCEP).

Short Term Forecast
FOS/WMO Header: FPUS73 KOHX
AWIPS Header: OHXNOWOHX
The Short Term Forecast is issued as needed. It covers the expected weather conditions for up to 6 hours in advance. 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.

Hazardous Weather Outlook
FOS/WMO Header: FLUS43 KOHX
AWIPS Header: OHXHWOOHX
The Hazardous Weather Outlook, issued routinely at least once daily by around 5:00 AM CST/CDT and is updated as needed. The HWO highlights any expected hazardous weather conditions over the next seven days. This includes, but is not limited to, severe weather, flooding, extreme heat or cold, winter weather, and dense fog.

Non-Precipitation Weather Message
FOS/WMO Header: WWUS73 KOHX
AWIPS Header: OHXNPWOHX
The Non-Precipitation Weather Message is used to issue watches, advisories, warnings, cancellations, or updates for various weather phenomena. These include: Dense fog, high winds, excessive heat indices or wind chill, frost and freeze during the growing season which is defined locally as when daylight saving time is in effect, and blowing dust. Definitions of the various NPW products can be found here. This product is generally issued every 6 hours until the phenomena ends.

Winter Weather Message
FOS/WMO Header: WWUS43 KOHX
AWIPS Header: OHXWSWOHX
The Winter Weather Message is used to issue watches, advisories, warnings, cancellations, or updates for various winter weather phenomena. It is generally issued every 6 hours until the phenomena ends. Details on the various winter weather products can be found on our website.

Tabular State Forecast for Middle Tennessee
FOS/WMO Header: FPUS64 KOHX
AWIPS Header: OHXSFTOHX
The Tabular State Forecast for Middle Tennessee is issued twice daily, normally between 4:00 and 5:00 AM/PM central time year-round. It gives specific temperature forecasts for 39 locations in Middle Tennessee for the next 7 days, as well as a one-word summary of the weather conditions expected.

Regional Weather Summary
FOS/WMO Header: AWUS83 KOHX
AWIPS Header: OHXRWSOHX
The Weather Summary gives a brief overview of the weather across Middle Tennessee and south central Indiana over the past 12 hours, and an outlook of expected weather conditions over the Ohio Valley the next 12 to 24 hours. Expected positions of weather systems, forecasts of precipitation, and temperatures are included. The product is issued once per day; normally by around 5:00 AM CST/CDT.

State Weather Summary (Tennessee)
FOS/WMO Header: AWUS83 KOHX
AWIPS Header: OHXRWSTN
The State Weather Summary gives a brief overview of the weather across the state of Tennessee over the past 12 hours, and an outlook of expected weather conditions for the state in the next 12 to 24 hours. Expected positions of weather systems, forecasts of precipitation, and temperatures are included. The product is issued once per day; normally by around 4:30 PM CST/CDT.

Aviation Weather Products

Terminal Aerodrome Forecast (TAF)
FOS/WMO Header: FTUS43 KOHX
AWIPS Headers: OHXTAFBNA (Nashville International Airport) and OHXTAFCSV (Crossville)
These coded messages, for aviation interests, are issued routinely 4 times a day, by 0540, 1140, 1740 and 2340 UTC, and updated as necessary. The forecasts contain information related to wind, visibility, weather hazards, and cloud levels for a 24 hour period. The latest TAFs: [ KOHX ] [ KLEX ] [ KBWG ]

Fire Weather Products

Fire Weather Planning Forecast
FOS/WMO Header: FNUS53 KOHX
AWIPS Header: OHXFWFOHX
The Fire Weather Planning Forecasts are issued daily by around 5:00 AM CST/CDT. During the “fire weather seasons” a second forecast is issued by around 4:00 PM CST/CDT. A headline may be added to the top of the forecast, denoting significant weather, or for the issuance of a Red Flag Warning or Fire Weather Watch. The synopsis will briefly cover locations of fronts and systems which produce the weather. The first 36 hours of the forecast will contain specific weather elements such as temperatures, wind direction and speed, maximum and minimum relative humidity, precipitation amounts, mixing heights, and transport wind speeds and direction. The extended three to seven-day forecast is a general forecast which mentions the possibility of precipitation and high and temperatures for each day. Note that the fire weather seasons are currently defined as: February 15 through April 30, and October 1 through December 15. These dates may change depending on the severity of the fire season.

Fire Weather Station Forecasts
FOS/WMO Header: FNUS83 KOHX
AWIPS Header: OHXFWMOHX
The National Fire Danger Rating System (NFDRS) is a quantitative means for evaluating the fire danger across vast areas. This complex model of fuel and weather parameters processes daily weather observations and fuel moisture as input, and fire managers receive numeric output danger over a given area. Fire Weather Station forecasts are routinely issued during the spring and autumn fire seasons to be input into the NFDRS. The station forecast provides specific information on expected weather, temperature, humidity, maximum and minimum values, and lightning activity levels. The FWM is issued daily only during the spring and fall fire weather seasons, and is transmitted by around 3:30 PM CST/CDT. The fire weather seasons are currently defined as: February 15 through April 30, and October 1 through December 15. These dates may change depending on the severity of the fire season.

Fire Weather Watch
FOS/WMO Header: WWUS83 KOHX
AWIPS Header: OHXRFWOHX
Fire Weather Watches are used to alert users of the possible development of a Red Flag event within the next three days. A Red Flag event is defined as an event where ten-hour fuel stick moisture must be 8% or less, along with afternoon relative humidity levels 25% or below, and 20-foot winds are expected to exceed 15 mph. All three requirements must be met for at least a couple hours.

Red Flag Warning
FOS/WMO Header: WWUS83 KOHX
AWIPS Header: OHXRFWOHX
Red Flag Warnings are issued to warn an impending or ongoing Red Flag event, when rapid fire spread is likely due to favorable weather conditions. A Red Flag event is defined as an event where ten-hour fuel stick moisture must be 8% or less, along with afternoon relative humidity levels 25% or below, and 20-foot winds are expected to exceed 15 mph. All three requirements must be met for at least a couple hours.

Hydrological Products

Flood Watch
FOS/WMO Header: WGUS63 KOHX
AWIPS Header: OHXFFAOHX
The Flood Watch is issued when heavy rainfall is forecast to cause significant or widespread flooding. This is usually issued at least 6 hours in advance of the expected event, and on occasion as much as a day or two in advance in high confidence situations. Updates to an ongoing flood watch are also issued under the FFA product. If the event is still a few days away, a Hydrologic Outlook may be issued instead, to give a heads-up to the potential of heavy rainfall.

Flood Warning
FOS/WMO Header: WGUS43 KOHX
AWIPS Header: OHXFLWOHX
The Flood Warning product is issued when river levels are expected to rise to potentially damaging levels. Flood Warnings can also be used when overland flooding is expected to persist for many hours.

Flood Statement
FOS/WMO Header: WGUS83 KOHX
AWIPS Header: OHXFLSOHX
The Flood Statement product can be issued for a number of reasons: 1) Follow-up information on Flood Warnings, either county-based or river-based; or 2) Short-term flooding which may cause an inconvenience, but is not considered to be threatening ("urban and small stream flooding"). When issued for river flooding forecast purposes, they are issued twice daily, usually between 10:00-11:00 AM and between 8:00-9:00 PM CST/CDT.

Hydrologic Outlook
FOS/WMO Header: FGUS73 KOHX
AWIPS Header: OHXESFOHX
The Hydrologic Outlook is used to give an outlook of heavy rainfall and possible flooding more than 36 or 48 hours out in the forecast. In the late winter and early spring, this product can give information on the possibility of flooding due to snowmelt and expected springtime precipitation.

Hydrologic Summary
FOS/WMO Header: SRUS43 KOHX
AWIPS Header: OHXRVAOHX
The Hydrologic Summary product is issued daily around 9:30 AM CST/CDT. It contains observed river and lake levels, along with precipitation amounts across Middle Tennessee.

Climate Products

Daily Climatological Summaries:
FOS/WMO Header: CDUS43 KOHX
AWIPS Headers: OHXCLIBNA (Nashville), OHXCLICKV (Clarksville), and OHXCLICSV (Crossville)
Climatological summaries for data collected at Nashville, Clarksville, and Crossville are issued twice daily (1:30 AM CST/2:30 AM CDT, and 4:30 PM CST/CDT). These summaries contain information on temperatures, degree days, precipitation, wind, climatological normals, and records.

Monthly Climatological Summaries:
FOS/WMO Header: CXUS53 KOHX
AWIPS Header: OHXCLMBNA (Nashville)
Preliminary climatological summaries for the past month are issued on the 1st of each month, normally before 12:00 PM CST/CDT, for Nashville. The summaries include average temperature and maximum observed values, degree days, precipitation, and comparisons to normal.

Record Report
FOS/WMO Header: SXUS73 KOHX
AWIPS Headers: OHXRERBNA (for Nashville specific records) and OHXRERCSV (for Crossville specific records)
The Record Report is issued when record conditions have been observed from Middle Tennessee and south central Indiana official observing sites.

Regional Temperature and Precipitation Table
FOS/WMO Header: ASUS63 KOHX
AWIPS Header: OHXRTPOHX
The Regional Temperature and Precipitation Table is issued twice daily: between 9:00 and 10:00 AM CST (10:00 and 11:00 AM CDT), and again between 7:30 and 8:30 PM CST (8:30 and 9:30 PM CDT). It contains basic climate information from around Middle Tennessee from airport observation sites and cooperative observers. The data primarily consists of high and low temperatures, and measured precipitation, including snow depth if applicable.

Tennessee Temperature and Precipitation Roundup
FOS/WMO Header: ASUS63 KOHX
AWIPS Header: OHXRTPTN
The State Temperature and Precipitation Table is issued twice daily no later than 7:30 AM/PM CST (8:30 AM/PM CDT). It lists the maximum and minimum temperatures along with precipitation and snow depth (if applicable) for select cities across Tennessee.

General Public Products

Hourly Weather Roundup (Tennessee)
FOS/WMO Header: ASUS43 KOHX
AWIPS Header: OHXRWRTN
The hourly weather roundup provides the most recent hourly weather observations at selected locations across Tennessee. Due to occasional delays in data transmission, the roundup is issued twice an hour; directly at the top of the hour, and again at eight minutes past the hour. Present weather, temperature, dew point, relative humidity, wind direction and speed, atmospheric pressure, and pressure tendency are included. The remarks section will include additional information such as the heat index, wind chill, and any obstructions to visibility.

Nashville Air Quality Index
FOS/WMO Header: AEUS73 KOHX
AWIPS Header: OHXAQIOHX
The Metropolitan Nashville Air Pollution Control District monitors air quality at various locations around Nashville, Tennessee. At minimum four times each weekday, the Air Quality Index is issued by NWS Nashville which includes the current air quality, the elevated pollutant, the current pollution category, and a short-term forecast for the pollution index. In the case of dangerous pollutants, health advisories or alerts would be included at the end of the product.

Public Information Statement
FOS/WMO Header: NOUS43 KOHX
AWIPS Header: OHXPNSOHX
The Public Information Statement is used for a variety of purposes. They include notifications of winter storm accumulations of snow and/or ice, storm damage surveys, severe weather safety rules, media advisories, and NOAA All Hazards Weather Radio outages.

Civil Emergency Message
FOS/WMO Header: WOUS43 KOHX
AWIPS Header: OHXCEMOHX
Civil Emergency Messages are used to inform the public of a non-weather related, hazardous emergency. An example would be a chemical spill where hazardous vapors are being released. The product is issued at the request of an official agency, such as local government officials or state emergency management.

Earthquake Report
FOS/WMO Header: SEUS63 KOHX
AWIPS Header: OHXEQROHX
An Earthquake Report is issued upon occurrence of an earthquake being felt or causing damage in Middle Tennessee. The information is relayed to the U.S. Geological Survey, who establishes the official Richter Scale reading for the quake.

Aircraft Accident Report
FOS/WMO Header: NOUS53 KOHX
AWIPS Header: OHXOAVOHX
The Aircraft Accident Report includes weather details around the time that a significant aircraft incident occurs in Middle Tennessee.

Radar Outage Notification
FOS/WMO Header: NOUS63 KOHX
AWIPS Header: OHXFTMOHX
This message is to inform NWS offices, vendors, and users of WSR-88D data that the radar at Old Hickory (KOHX) has experienced an outage (either planned or unexpected). It includes reasons for the outage if known, expected outage time, and a statement of which surrounding radars can be used for radar information in Middle Tennessee.