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Frequently Asked Questions
Q. What is the mission of the National Weather Service ?
A. The mission of the National Weather Service (NWS) is to protect the life and property
of our citizens from natural disasters by issuing warnings and forecasts for all manners of severe or
extreme weather, and to enhance the national economy. This mission is carried out by weather offices
and national centers located throughout the U.S. and its territories, along with a highly trained staff
of dedicated men and women.
Q. What is the organizational structure the National Weather Service ?
A. The National Weather Service (NWS) is an agency under the National Oceanic and Atmospheric
Administration (NOAA), and under the Department of Commerce (DOC).
Q. What is the history behind the National Weather Service ?
A. The National Weather Service (NWS) is a federal agency that has been in existence since 1870. The
"original" NWS began under the direction of the Signal Corps until it was transferred to the Department
of Agriculture in 1890. This was part of the "Organic Act" that defines the responsibilities of the
agency. The Weather Bureau remained under the Department of Agriculture until 1940 when it was
transferred to the Department of Commerce...where it remains today.
The Weather Bureau was renamed the National Weather Service and, in 1970, was placed under the newly
created National Oceanic and Atmospheric Administration (NOAA) which remains under the Department of
The National Weather Service provides weather, hydrologic, and climate forecasts and warnings for
the United States, its territories, adjacent waters and ocean areas, for the protection of life
and property and the enhancement of the national economy. NWS data and products form a national
information database and infrastructure which can be used by other governmental agencies, the
private sector, the public, and the global community.
This mission is accomplished by providing warnings and forecast of hazardous weather, including
thunderstorms, flooding, hurricanes, tornadoes, winter weather, tsunamis, and climate events. The
NWS is the sole United States OFFICIAL voice for issuing warnings during life-threatening weather
Q. How can I contact the National Weather Service in Raleigh ?
A. Our contact information is shown below …
1005 Capability Drive, Suite 300
Raleigh, North Carolina 27606
(919) 515-8209 (Monday – Friday, 8:00 AM – 430 PM)
(919) 515-8225 Recorded forecast for the Raleigh-Durham Metro Area
Q. What is the difference between a Watch, Warning, and Advisory ?
A. Explanation shown below...
A Watch is a product issued by the NWS indicating that a particular hazard is possible, i.e., conditions are
more favorable than usual for its occurrence. A watch is a recommendation for planning, preparation,
and increased awareness (i.e., to be alert for changing weather, listen for further information,
and think about what to do if the danger materializes).
A Warning is a product issued by the NWS indicating that a particular weather hazard is
either imminent or has been reported. A warning indicates the need to take action to protect life
and property. The type of hazard is reflected in the type of warning (e.g., tornado warning, blizzard
warning). See short-fuse warning.
An Advisory is a product issued by the NWS that highlights special weather conditions
that are less serious than a warning. They are for events that may cause significant inconvenience,
and if caution is not exercised, it could lead to situations that may threaten life and/or property.
Q. What are the criteria for the issuance of a Watch, Warning, and Advisory ?
Q. I had really bad thunderstorm and a warning wasn’t issued, why ?
A. The National Weather has criteria for the issuance of watches, warnings and advisories. These criteria
are used both by forecasters when deciding whether to issue a watch, warning or advisory and after the
event when verification statistics are computed.
The criteria of the majority of hazardous weather situations are standardized across the country. For
example, the criteria for a Severe Thunderstorm Warning is a wind in excess of 58 MPH (50 knots) or
hail greater than ¾ of an inch in diameter. Some of the criteria are modified based on regional and
climatic differences (Winter Storm Warnings are issued for 12 hour snowfalls of 4 inches or more across
central North Carolina but 7 inches or more across upstate New York).
NWS Watch, Warning, and Advisory criteria
Q. What is the National Digital Forecast Database (NDFD) ?
A. The NWS is currently making available a limited number of forecast grids of sensible weather
elements (e.g., cloud cover, maximum temperature) in what is being called the NWS National Digital
Forecast Database (NDFD). In addition a set of national graphics produced from these grids will be
available, such as temperature and probability of precipitation.
The NDFD contains a seamless mosaic of NWS digital forecasts from NWS field offices working in
collaboration with NWS National Centers for Environmental Prediction (NCEP). The database will
be made available to all customers and partners–public and private– and will allow those customers
and partners to create a wide range of text, graphic, and image products of their own. With time,
a wider array of forecast elements will be available in the database as will a larger set of
The NDFD web site contains additional information on the NDFD including information on what new grids,
products, and capabilities are coming on line. The NDFD web site can be accessed at the link below...
Experimental graphical products of the National Digital Forecast Database can be accessed at the link below...
Q. Where can I find historical weather data ?
A. Historical data can sometimes be difficult to find because there is so much
of it and finding exactly what you want can be time consuming. Four sources
are shown below…
1) The National Weather Service in Raleigh has climate data on line, especially data from recent
days, months and years. The climate page can be accessed at the web site shown below …
2) The State Climate Office of North Carolina (SCO) has access to a great deal of climate data. They
can be contacted the phone number and web site shown below …
3) Another resource is the Southeast Regional Climate Center (SERCC). They are located in Columbia South Carolina.
They can be contacted at the phone number and web site shown below …
(866) 845-1553 (toll free)
4) Nearly all of the weather data gathered by the National Weather Service can retrieved from
NOAA's National Climatic Data Center (NCDC) in Asheville, NC. You can contact NCDC at the phone
number and web site shown below …
Q. For what period of record do normal temperature and precipitation data come from ?
A. Normal temperature and precipitation data are typically based on average values during the 30 year period from
1971 to 2000. The values are based on 30 years of data and are recomputed every 30 years. In the year 2010
they will again be recalculated based on the period 1981-2010.
Q. What is NOAA Weather Radio and what is its purpose ?
A. NOAA Weather Radio is a service of the National Oceanic and Atmospheric Administration, broadcasting on
seven VHF Band frequencies ranging from 162.400 MHz to 162.550 MHz. These frequencies are outside the normal
AM or FM broadcast bands, and are therefore not found on the average home radio.
These broadcasts originate from National Weather Service Offices across the Unites States and its territories.
As the Voice of the National Weather Service, more than 400 FM transmitter sites provide continuous broadcasts
of the latest and up-to-date weather information.
NOAA Weather Radio broadcasts can be heard as far away as 40 miles from the antenna site. The effective range
depends on many factors, particularly the terrain, the quality of the receiver, and current weather conditions.
The broadcast schedule consists of recorded messages which are repeated every three to five minutes and are routinely
revised to provide the latest and up-to-date information. The broadcasts on NOAA Weather Radio are tailored to the
weather needs of the people within the receiving area, and include a variety of programming subjects.
During severe weather, our forecasters may interrupt the routine weather broadcast to substitute live warning messages,
in which the regularly scheduled programming will be suspended. Special receivers can also be activated, sounding an
alarm indicating that important information soon follows. This alerts the user to turn the receiver up to an audible
volume. Tests of the warning alarm are conducted by the National Weather Service every Wednesday between 1100 AM and
Noon local time.
In extreme cases, NOAA Weather Radio will be used to alert the public of non-weather related emergencies, such as
earthquakes, toxic or chemical spills, other civil emergencies, national attacks, or nuclear blasts.
Much more information on NOAA Weather Radio is available at the NOAA Weather Radio section of
the NWS Raleigh web site which can be accessed at the link below ...
Q. There used to be several different voices recorded on NOAA Weather Radio broadcasts. Now it is always the same
person. Why did that change ?
A. A program to automate NOAA Weather Radio has been ongoing for several years. The NOAA Weather Radio program is
produced by a set of computers called the Console Replacement System (CRS). The CRS is a new, computer-based
broadcasting console, installed at each NWS office, which automatically translates and schedules written National
Weather Service forecasts and warnings into synthesized voice broadcasts over NOAA Weather Radio.
The automatic weather broadcast consoles will provide a more efficient means of disseminating severe weather watches,
warnings and emergency information over NOAA weather radio.
Q. What is Skywarn and is there an internet site where I can get information about Skywarn and the services offered ?
A. Skywarn is the National Weather Service (NWS) program of trained volunteer severe weather spotters. Skywarn spotters
support their local community and government by providing the NWS with timely and
accurate severe weather reports. These reports, when integrated with modern NWS technology, are used to inform communities
of the proper actions to take as severe weather threatens. Additional details are available at the NWS Raleigh Skywarn
Q. What is “GMT”, “Zulu (Z)”, or “UTC” time?
Q. I often see "GMT”, “UTC”, or “Z" on weather maps, satellite
photos or radar images, but I don't know what it means. What is it ?
A. GMT stands for Greenwich Mean Time and UTC stands for Coordinated Universal Time. GMT, Z and UTC refer to the
same time, which is a standard used around the world by a variety of agencies and industries who have to deal
with issues across several time zones. It can also be thought of as the time at the Prime Meridian.
To convert “GMT”, “Zulu (Z)”, or “UTC” to Eastern Standard Time (EST), subtract 5 hours from the “GMT”, “Zulu (Z)”, or “UTC” time.
To convert “GMT”, “Zulu (Z)”, or “UTC” to Eastern Daylight Time (EDT), subtract 4 hours from the “GMT”, “Zulu (Z)”, or “UTC” time.
The current “GMT”, “Zulu (Z)”, or “UTC” time is available at the link below ...
Q. What are "degree days?"
A. Heating and cooling degree days are calculated by using the average temperature for the day (the high temperature
added to the low temperature and the sum divided by two) and then subtracting the average temperature from the
number 65 for heating degree days or subtracting 65 from the average temperature for cooling degree days. The
number 65 is used as the base number because most buildings and homes would be most comfortable and energy
efficient at our around 65 degrees.
Example: On a summer day the high was 90 degrees and the low was 70 degrees. The average temperature was
80 degrees (90 + 70 = 160 / 2 = 80). The average temperature of 80 minus the base temperature of 65 yields
15 cooling degree days (80 – 65 = 15). Cooling degree days can be used to calculate the amount of energy
needed to cool their homes or businesses.
Example: On a winter day the high was 40 degrees and the low was 20 degrees. The average temperature was
30 degrees (40 + 20 = 60 / 2 = 30). The base temperature of 65 minus the average temperature of 20 yields
45 heating degree days (65 – 20 = 40). Heating degree days can be used to calculate the amount of energy
needed to heat their homes or businesses.
Q. What employment opportunities are available with the National Weather Service, and what would
be the best kind of college courses to take for these jobs ?
A. Most occupations with the National Weather Service (NWS) are for those trained in meteorology,
atmospheric sciences, climatology, hydrology or related fields. The National Weather Service is an agency
within the National Oceanic and Atmospheric Administration (NOAA).
The links below are to websites that are related to a career in weather and atmospheric sciences...
How to Become a Meteorologist
NWS Student Employment Programs
Human Resources Office
National Oceanic Atmospheric Administration Diversity