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SKYWARN

SKYWARN® Nets 

SKYWARN nets serve the National Weather Service by providing real time ground truth related to hazardous weather events. Ground truth is defined as observations of hazardous weather precursors, elements, and their impacts, made by spotters, and used by the National Weather Service (NWS) to make warning decisions, supplement radar observations, and verify forecasts.

Safety

Throughout any weather net, safety is a primary concern. The responsibility for a spotter’s safety and property lies with each individual spotter. If at any time, a spotter feels unsafe because of approaching weather or any other condition, they are encouraged to move to safety and report their status to the NCS when practical. 

    • Spotters must think safety, especially at night, and plan escape routes should destructive weather move toward their location. 
    • Spotters are expected to obey all laws and avoid creating a safety hazard to other people. 
    • Mobile spotters are urged to avoid distractions such as computers and other devices while driving. 
    • A partner is strongly encouraged and recommended for mobile operations. 
    • It is recommended that spotters carry a cell phone to report situations that fall outside of net guidelines (for example, power lines down, lightning strikes, and automobile accidents.) 
    • Spotters must stay alert to unusual hazards such as slippery roads due to hail or flooded roadways after heavy rain. 
    • Flash flooding is extremely dangerous, and spotters are urged to never risk driving through water covering a roadway. 
    • Lightning is a deadly hazard, and mobile spotters should stay inside their vehicles as much as possible. 
    • APRS is not required to participate in a weather net, but spotters are asked to turn it on if available for safety reasons, and are encouraged to consider including it in their mobile equipment.

 Three Stage System Leading to a Weather Net

The severe weather forecast system often, but not always, will progress through a three stage process leading up to a severe weather event. The three stages and their approximate lead times before the event are: outlook (6-72 hours), watch (2-6 hours), and warning (0-1 hour). In each stage, spotters should increase their state of readiness.

Outlook Stage: Severe weather is in the Storm Prediction Center (SPC) Convective Outlooks or NWS Hazardous Weather Outlook. Spotters should be aware of these statements and should prepare radio equipment, batteries, and ready kits. Spotters should listen for updates including the NWS Hazardous Weather Outlook and watch issuance. In some cases, information will be sent via the Collin County ARES email reflector or updates will be communicated on the repeater.

Watch Stage: SPC issues a weather watch box that includes Collin County. The NCS-on-call sets the “A” (Morse dit dah) alert tag on the repeater. Spotters should make final personal preparations for a net and be sure that pagers are turned on to receive activation messages. When severe weather is imminent, likely to move into the county, or activation is requested by the NWS, the NCS changes repeater tone to “N” tag, and initiates the net.

Warning Stage: A weather net is activated on the primary repeater frequency, 147.18 [+] PL 107.2 (**Pages may be sent to indicate a change of repeater, which becomes the primary) and indicated by the “N” tag (dah dit) on the repeater. Spotters should listen and follow the instructions of the NCS. The NCS will position spotters and direct the net through a series of “conditions” as detailed below. The watch and warning stages are the most active and are detailed in the following sections.

Because of the uncertainties in weather, not all severe weather events will fit into these guidelines. It is possible, for example, for a severe storm to develop rapidly within the county before any watch or warning has been issued and that spotter reports actually initiate the warning. When necessary, the NCS shows the best adaptability possible to meet the needs of the situation, keeping in mind that the purpose of the net is to pass accurate and relevant ground truth observations to the NWS.

Net Conditions

A SKYWARN net normally starts in condition 4 and progresses to condition 3 and condition 2 as necessary. Throughout the net, the NCS will periodically announce the net condition, station identification, and any minimum reporting criteria, according to good amateur practice.

Condition 4: is an informal, informational mode that allows check-ins and any weather-related traffic. The NCS directs the net, but there are no minimum reporting criteria.

Condition 3: When the NCS needs to reduce and discipline the net traffic, the condition will change to 3 and the NCS will announce minimum reporting criteria. Those criteria will typically include ¼” diameter hail or greater, 50 mph winds or greater, wall clouds, funnels, tornadoes, and other key rotation signatures (rear flank downdraft clear slot during daylight or power flashes not associated with lightning at night.) Note that rainfall rates are not normally needed and spotters are asked to refrain from reporting rainfall or lightning strikes, unless specifically requested by the NCS.

Condition 2: A rotating wall cloud, funnel, or tornado will prompt the NCS to move the net to condition 2 and take only reports relating to the rotating “hot spot” and its movement. At this point, it is especially important for spotters to listen to the NCS and stay off of the air unless they have a report related to the established criteria.

Condition 1: is a standby/staging mode that may be used after a destructive weather event in which communications have been disrupted and amateur radio assistance is requested by one of its served agencies. In this case, the EC will give instructions.

Net Check-In 

The NCS will prepare a log for station check-ins and will generally begin by asking for stations in the part of the county that may be affected by the weather first. Spotters wishing to check-in should listen to the instructions from the NCS and check–in with their call sign spoken slowly, using ITU phonetics (pg. 37) and their location. Locations should be reported as major intersections and city, and if they are fixed or mobile.

Mobile spotters should turn on their APRS equipment, if available. APRS will be integrated at the discretion of the NCS but it is not intended to be used for managing the positioning of spotters. It may, for example, be used to help locate a spotter who is not responding to calls from the NCS. APRS is not required to participate in a net and spotters are asked to refrain from requesting APRS signal checks during a net.

As the net progresses and more spotter reports are made, the NCS must strike a balance between taking reports and checking in spotters for good coverage. There may be a time when the NCS chooses to stop check-ins to keep up with weather reports. It is important for spotters to remember that their presence is appreciated, even if they do not have a report nor cannot check-in, and that they may be given an opportunity to be recognized by the NCS before the net shuts down.

Positioning of Spotters

During the course of a net, the NCS may establish spotter positions as defined by the location and expected movement of storms. Positioning is not done to place a Spotter in harm’s way, but to get them in an area that may provide an opportunity to be more effective in their observation. If at any time a Spotter feels they are in an unsafe situation, they should move to a safer location immediately and then advise Net Control that they have done so.

Typically, two “picket lines” are formed perpendicular to the storm movement. A general west to east movement would call for a north-south line of spotters along Preston Road, and another along US Hwy. 75 and possibly along SH78.

The NCS will direct the net and call for stations to check out (“secure”) at the appropriate time. 

Reporting Criteria

The NCS will establish and periodically update reporting criteria for each situation. Spotters are expected to listen and understand these criteria and report only within these criteria. Positions are reported as a major road or highway intersection and the city (“Preston Road and FM 720 in Frisco”). CCARES does not use MapscoTM or other like reference.

Below is a guide to help format your report.

Hail
      • Your time and location. 
      • Diameter in inches, or similar object? (Do not use quarters) 
      • Estimated or measured? 
      • Duration of hail fall?

 Wall Clouds

      • Your time and location. 
      • Direction, and distance to the wall cloud. 
      • Is it persistent (period of minutes) and organized? 
      • Is there organized, persistent rotation? 
      • Is there a funnel? 
      • Is there a visible clear slot?

 Tornado

      • Your time and location. 
      • Direction, and distance to the tornado. 
      • Is there a visible condensation funnel connected to cloud base? 
      • Is airborne debris visible near the ground? 
      • Are there consistent ground flashes not associated with lightning (night)? 
      • Not all power flashes are associated with tornadoes.)

Wind

      • Your time and location.               Direction From?
      • Speed in miles per hour?           Inflow or Outflow?
      • Estimated or measured?            Damage Observed?

Flash Flooding (to be reportable, water must cover the road)

      • Your time and location. 
      • The road and closest intersection affected. 
      • Is water covering the entire road (not just covering curb)? 
      • Is the water visually flowing? 
      • Are there people, cars, homes, or buildings affected?
Reporting Example:

Spotter:   “Net control, this is KD5JEO.”

NCS:   “KD5JEO, Net Control, go ahead.”

Spotter:   “I am near the intersection of Highways 289 and 380 in Prosper. I have a wall cloud approximately 3 miles to my northwest. It appears well organized with visible rotation and there is a visible clear slot. KD5JEO.”

NCS:   “Thank you. This is N5BYL, Net Control, taking the net to Condition 2. We are focusing our attention on a wall cloud near Prosper. Do I have any other stations in that area that can verify? All other stations please stand by.”

Flash Flood Warnings

A special class of weather warning that will occasionally affect the county is the Flash Flood Warning. The Flash Flood Warning is issued by the NWS when a rapid and life-threatening water rise is occurring or imminent. This is not to be confused with other flood statements which indicate a longer term potential or extended hazard. When a Flash Flood Warning is issued for the county, a Morse code “F” (di-di-dah-dit) tag is activated on the repeater to alert all amateur radio operators that a flood hazard exists. These may occur during heavy rain events or during severe weather events in which torrential rain has fallen over a small area in short period of time. Although spotters are normally not sent to observe flash flooding, they are encouraged to make reports if they see life-threatening floods occurring, such as moving water over a road. If there is no organized net or NCS available, spotters should alert local law enforcement, if barricades or personnel are not already on site. Flash flooding is extremely dangerous, and spotters are urged to never risk driving through water covering a roadway.

Net Check-Out

All spotters are asked to make every effort to monitor the net until the NCS permits check-outs. This will permit an accounting of all spotters in the event that a spotter has lost communications and needs help.

Post-Net Reports 

Some spotters may have reports of significant weather or damage that did not fit the minimum reporting criteria at the time it occurred. Spotters are encouraged to make a note of the observation time and description and then pass this information to the NCS when the net moves back to condition 4. You may also be asked to submit via e-mail to the NWS AEC. We encourage photographic evidence of your observations.

NWS Position Regarding Severe Weather

Effective January 4th, 2010, the National Weather Service nationwide has adopted the following criteria for issuing Severe Thunderstorm Warnings:
    • 1” Hail (Quarter Size) and/or 58 mph wind
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