A significant weather advisory, is issued when doppler weather radar indicates a strong thunderstorm is producing small hail or high winds whose strength does not reach severe thunderstorm criteria. It does not necessarily account for lightning or flooding.
Contents |
This forecast product was created in the early 2000s, and is sometimes a precursor to a severe thunderstorm warning. Many versions of the First Warning broadcast weather alert system have begun including significant weather alert into their systems, however, these systems usually classify such an advisory under the terms "Heavy T-Storms", "Heavy Storms" or "Strong T-Storms".
The National Weather Service issues a significant weather advisory if hail size in a thunderstorm is less than 1 inch in diameter, and/or winds less than 58 miles per hour (90 km/h). These are mainly used in the NWS's southern region headquarters (SRH).[1] Many NWS offices do not use the Significant Weather Advisory title and instead just use no warning text, though.
This product is not an official product, instead it is issued as a special weather statement. Special weather statements are also used for any type of weather approaching watch/warning/advisory level. Many offices do not use significant weather advisories, instead issue normal special weather statements mentioning much of the same text used in a significant weather alert.
The following example of a significant weather advisory was issued by the Norman, Oklahoma National Weather Service on July 14, 2011.[2]
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE NORMAN OK 1251 AM CDT THU JUL 14 2011 OKZ015-140600- DEWEY OK- 1251 AM CDT THU JUL 14 2011 ...SIGNIFICANT WEATHER ADVISORY... THIS SIGNIFICANT WEATHER ADVISORY IS FOR DEWEY COUNTY. AT 1251 AM CDT...A STRONG THUNDERSTORM WAS LOCATED OVER CAMARGO... MOVING EAST AT 15 MPH. HAZARDS INCLUDE... HAIL UP TO ONE-HALF INCH... WIND GUSTS TO 50 MPH... MINOR FLOODING IN AREAS OF POOR DRAINAGE... SEVERE WEATHER IS NOT EXPECTED AND NO WARNINGS ARE ANTICIPATED AT THIS TIME. LAT...LON 3613 9899 3593 9900 3595 9934 3613 9933 $$ WR
If severe weather is detected, alerts (Severe Thunderstorm Warning or Tornado Warning) are issued by the National Weather Service, and the Emergency Alert System may activate and broadcast the alert. EAS alerts begin with a SAME header, which sounds as three digital busts and automatically activates the EAS, a 1050 Hz attention signal, the alert as processed by text-to-speech software, then the SAME End of Message tone to end the alert broadcast. Also, sirens may be activated to warn the public who are not listening to media to take cover.
Severe weather terminology (United States)
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||