Who Watches the Skies in Your Community
Funnel clouds were spotted in the air near West Fargo September 11. As a result, warning sirens were sounded to alert the public to the potential danger. One local weather authority dismissed the funnels as being cold air funnels which usually never reach the ground. Mark Ewens of the National Weather Service in Grand Forks was quoted as saying sounding the alarms was the right move in this circumstance. Ewens indicated when cold air funnels do reach the ground, they can cause damage consistent with a minor tornado.
But who is it that decides when to sound the warning sirens and what are the criteria? Activation of the warning system can be directed by the National Weather Service based upon their predictions of a storm's potential. The warning can also come as the result of a threatening condition reported by trained law enforcement officers or weather spotters, based upon their visual observation of a weather event. The warning system may also be used by local emergency services agencies to warn of non-weather related dangers.
The National Weather Service uses enhanced Dopler Radar and computer modeling to track storm development and potential dangerous conditions. Radar signals are sent out, rebound off of moisture in the atmosphere and return to the sending radar device. The returning signal is measured to determine conditions within the storm system. Certain patterns of returns are indicative of rain and wind potential based upon historical data. Computer modeling and the weather professional's opinion of the pattern provide an estimate of the conditions existing within the storm system. Frequently, the Weather Service will rely on trained law enforcement officials or weather spotters to confirm the existence of dangerous conditions.
During threatening weather, trained law enforcement officials and weather spotters move to pre-assigned positions to make visual observations of approaching storms. They watch for evidence of heavy rains, hail, strong winds and cloud formations related to tornado activity. The observations are reported to a central location and the Weather Service. As threatening weather approaches, an agency supervisor or the Weather Service will be updated on the current conditions. A decision is then made according to developed policy. Standard practice is all warning sirens in the Fargo-Moorhead area will be sounded for life-threatening conditions.
The Outdoor Warning Sirens in Cass and Clay Counties may be activated for any of the following conditions:
*The National Weather Service has issued a tornado warning for West Fargo, Fargo, Moorhead or Dilworth. (This would mean a tornado has been spotted on radar.)
*A trained weather observer has observed a tornado in the West Fargo, Fargo, Moorhead, or Dilworth vicinity and requested activation of the sirens.
*A Law Enforcement Officer has observed a tornado in the Cass or Clay County area, and requested siren activation.
*An on-scene Fire Department Incident Commander has requested activation of the sirens to alert the public of a hazardous materials or other life-threatening incident.
*The Incident Commander should have an evacuation plan, or other instructions such as "sheltering in-place," for the public prepared and transmitted to the Dispatch Center or the media, prior to requesting siren activation.
*The Cass or Clay County Emergency Manager has requested activation of the sirens.
*Testing and maintenance operations.
If any city in the metro area (Moorhead, Dilworth, Fargo or West Fargo) activates its warning sirens, all the other cities in the area will also activate their sirens. Whichever city decides to activate its sirens first will contact the other cities in the area and advise them of their decision.
Public Notification Process:
The RRRDC will release information to the public through the media on siren activations related to hazardous material incidents based on information supplied by the effected fire departments.
The National Weather Service will release information on siren activations related to tornado warnings based on information supplied by the RRRDC.
Both the Dispatch Center and the National Weather Service, Grand Forks will release information to the media via the use of the Emergency Alert System (EAS), media paging, and fax. This information will be released as soon as possible so the public will understand the reason for the outdoor warning siren activation.
A public information officer from one or more of the effected cities will be assigned to the Incident Command System to relay information from the scene or other safe location to the media.