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Storm-Based Warning FAQ Page

  1. Question: Will my NOAA Weather Radio still work?

    Answer:   Yes. The county codes (called UGC or FIPS codes) will still be used to alarm NOAA Weather Radios and the Emergency Alert System (EAS).

  2. Question: What type of warnings will be storm based?

    Answer: The following warnings are storm-based and include a polygon for areal coverage:  Tornado (TOR), Severe Thunderstorm (SVR), Special Marine (SMW), Convective Flash Flood (FFW), Extreme Wind (EWW), and Areal Flood (FLW) Warnings. The following statements are also storm-based and include a polygon: Severe Weather Statements (SVS), Convective Flash Flood Statements (FFS), Areal Flood Advisories and Areal Flood Statements (FLS), and the Marine Weather Statements (MWS).

  3. Question: I’ve heard about sub-county codes that can be used by NOAA Weather Radio to alert smaller areas. Will these codes by used?

    Answer:  Not during the initial implementation. There will be no change in the NOAA Weather Radio coding and dissemination of warnings with the implementation of storm-based warnings.  Long-term there may be limited use of the partial county codes, but that is at least a year away.

  4. Question: Will the polygons always have four vertices?

    Answer: No. A polygon can have several vertices. An example would be for a line of thunderstorms. There would typically be three or more points to identify the location of the line at the time the warning is issued, and another three or more points to identify the forecast location of the line at the end of the valid period of the warning.

  5. Question: I live near a county line, and I know the adjacent county receives their warnings from a different National Weather Service office. Will I continue to get warnings from the NWS office currently serving my county, the adjoining counties warning office, or from either office?

    Answer: For now, warnings will be issued by the same office with warnings truncated at the boundary of our county warning areas (CWA). In the upcoming year we will test having a few offices coordinate the issuance of warnings across their CWA boundaries. If the test is successful, the answer to this question will change to either office.

  6. Question:  I live near the center of my county, if hear a tornado warning is for the northern part of the county, what should I do?

    Answer: Take Cover Immediately! If you get the information over the radio, don’t try to guess whether you are in the warning, assume that you are in the warning and take action.

  7. Question: Are there any changes to the format of the warnings?

    Answer: Yes, one minor change. Information on tracking information that will follow the LAT…LON that lists the vertices of the polygon. This will begin with TIME...MOT...LOC followed by the time tracking begins (in GMT), the direction and speed of the feature (kts), and the location of the feature (LAT/LON). In the case of a line of storms there may be more than one LAT/LON.

  8. Question: When will see the addition of the tracking information?

    Answer: The addition of the TIME...MOT...LOC at the end of these warnings were gradually added in August and September on an office by office schedule. All offices will include this line of tracking information by the October 1, 2007 implementation date.

  9. Question: If a Severe Thunderstorm Warning (SVR) is upgraded to a Tornado Warning (TOR), and the exact same polygon is used, is the Severe Thunderstorm Warning technically canceled even though a cancellation (CAN) is not sent out?

    Answer: Yes, the Tornado Warning (TOR) supersedes the Severe Thunderstorm Warning (SVR). The concern is that cancellation of the SVR may cause confusion to the public threatened by a tornado.

  10. Question: If a Severe Thunderstorm Warning (SVR) is upgraded to a Tornado Warning (TOR), and the polygon is slightly different, does the SVR stay in effect?  If so, is the SVR in effect only for the area outside of the new TOR?

    Answer: Yes, the part of the SVR not in the TOR stays in effect. As in the previous case, the TOR takes precedence in the area where it overlaps an existing SVR. The follow-up Severe Weather Statement (SVS) should reference the existing SVR include a headline stating a TOR is in effect for the overlapping area.

  11. Question: Can a Severe Weather Statement (SVS) update a warning with a different polygon? If so, can the updated warning contain fewer counties that the original warning?

    Answer: Yes, on both questions. A warning can shrink in size (it can not become larger). If a county is removed, the warning would be segmented with a continue (CON) section for the valid counties, and a cancelled (CAN) section for those counties removed.   If it is smaller and a county is not removed, it will be reflected in the LAT...LON section, but not in the county codes (VTEC/UGC) section. We do recommend the forecaster include reasoning for partial cancellation and/or new information in the continuing segment.

Department of Commerce
National Oceanic & Atmospheric Administration
National Weather Service
Office of Climate, Water, and Weather Services
Warning Decision Training Branch
120 David L. Boren Blvd.
Norman, OK 73072
Page Author: WDTB Webmaster
Page last modified: October 21, 2009 13:37

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