The Skywarn program was developed by the National Weather Service (NWS) in 1971 for the purpose of fielding a network of trained weather spotters. These spotters provide real time observations of actual weather conditions at their location. This information is used by the NWS to issue highly accurate severe weather forecasts and warnings. In addition to improving warning capabilities, the information gathered by Skywarn spotters is also used by the NWS to validate the radar images generated by the NWS.

Amateur radios operators have been a mainstay of the Skywarn program since its inception. This is largely due to its ability to communicate by radio even when power outages occur and telephone service is interrupted. In Oakland County, the ARPSC is activated by the County's Homeland Security Division. ARPSC personnel initiate a Skywarn net with individual operators checking in to the net from various locations throughout the County. Severe weather reports from the spotters are radioed to the net control station where they are relayed by radio to the NWS office in White Lake.

In addition to assisting the NWS, the ARPSC works closely with the County's Homeland Security Division by providing information on such items as flooding, storm damage and damage to power and communication utilities. This information is useful in providing a quick summary of the magnitude of an event and arranging assistance to local municipalities when their resources may become overwhelmed.

More information can be found at the National Weather Service.

Skywarn Activation Criteria

Skywarn operations are activated when the National Weather Service issues one of the following Watches or Warnings. When a Watch or Warning is issued, the Homeland Security On-Call individual will contact a member of the command staff to notify them of the event and request a Skywarn Net. In most cases the net will be operated from the County's Emergency Operations Center. In some cases a severe storm may suddenly form and prompt an NWS Warning. In the case of 'pop-up' storms, a net will be conducted from the net control operator's home since the event will typically finish before an operator could arrive at the EOC.

Severe Thunderstorm Watch

A Severe Thunderstorm Watch is issued when severe thunderstorms are possible in and near the watch area. It does not mean that they will occur. It only means they are possible.

Severe Thunderstorm Warning

A Severe Thunderstorm Warning is issued when severe thunderstorms are occurring or imminent in the warning area. Storms become severe when wind speeds reach 58 mph or higher AND/OR there is hail 1 inch in diameter or larger.

Tornado Watch

A Tornado Watch is issued when severe thunderstorms and tornadoes are possible in and near the watch area. It does not mean that they will occur. It only means they are possible.

Tornado Warning

A Tornado Warning is issued when a tornado is is visually detected or indicated by radar. When a tornado warning is issued, seek safe shelter immediately.

Please note that the County's Outdoor Early Warning sirens are activated if a Tornado Warning is issued by the National Weather Service or Wind speeds in a Severe Thunderstorm reach 70 mph or above.


Estimating Hail Size:

  • Pea size: 1/4" diameter
  • Marble size: 1/2" diameter
  • Quarter size: 1" diameter
  • Golf ball size: 1 3/4" diameter
  • Baseball size: 2 3/4" diameter

Estimating Wind Speed (Miles Per Hour)

  • 25-31 Large branches in motion; whistling telephone lines
  • 32-38 Whole trees in motion; inconvenience felt walking against wind
  • 39-54 Twigs break of trees; wind generally impedes progress.
  • 55-72 Damage to chimneys and TV antennas; wind pushes over shallow rooted trees.
  • 73-113 Wind peels surface off roofs; windows broken; mobile trailers pushed or overturned; moving automobiles pushed off roads.
  • 113-157 Roofs torn off houses; weak buildings and mobile homes destroyed; large trees snapped and uprooted,
  • 158+ Severe damage. Cars lifted off the ground.

Skywarn Net Operations Protocol

A Skywarn Net is established with the issuance of a Severe Thunderstorm Watch or Warning or a Tornado Watch or Warning. Most Skywarn Nets are operated from the Communication Rooms at the County's Emergency Operations Center where Skywarn operations work side by side with Homeland Security Department personnel assigned to the Skywarn event.

The Skywarn Net will be operated under one of the following four conditions depending on the type of weather statement issued.

Checking In To The Net

When a Skywarn net is in progress, please listen for instructions from net control to determine if net check-ins are being accepted. That announcement along with the current net condition should occur on a regular basis depending on current conditions. Do not check into the net unless net control asks for check-ins or you have weather to report that meets the current conditions of the net.

When checking in please providing the following in the order they are listed.

  • Your callsign in standard ITU phonetics
  • Your Name
  • The city or township where you are located
  • The closest major crossroads to your location
  • Any severe weather conditions in your location that meet current criteria

Net control will acknowledge your check-in and any reports you may have.

Net Conditions


A net is operated in Standby mode when a Watch has been issued by the NWS but radar indicates that no severe weather is expected to enter the County for a period of at least 1 hour. During Standby mode net control may or may not accept formal check-ins from spotter personnel. Net Control will issue periodic updates on the location and severity of weather while in Standby and operators are free to call in to Net Control with questions or comments.

Depending on conditions, net control may allow general use of the repeater. If this is the case we ask that extra time be allowed between transmissions so that net control may break in if there is a need to upgrade the net to another condition.


Condition Green is used during a Severe Thunderstorm or Tornado WATCH. This condition is typically activated when there are storms in an adjacent county moving in the direction of Oakland County. This condition may continue if storms enter Oakland county but are not considered to be at severe levels. During Condition Green, net control requests check-ins from operators who are in the County and available to observe weather conditions. If any severe weather is present at your location please report it provided it meets at least one of the following criteria:

  • Clouds with rotation
  • Winds in excess of 40 miles per hour
  • Severe flooding with water over the curbs
  • Downed power lines
  • Hail 1/4 inch in size or larger
  • Funnel Clouds
  • Tornadoes


A net is placed in Condition Yellow when a Severe Thunderstorm WARNING is issued by the National Weather Service. Under Condition Yellow check-ins typically not permitted unless an operator has at least one of the following items to report.

  • Clouds with rotation
  • Winds in excess of 50 miles per hour
  • Severe flooding with water over the curbs
  • Downed power lines
  • Hail 1/2 inch in size or larger
  • Funnel Clouds
  • Tornadoes

It should be noted that, at the discretion of the net control operator, general check-ins may be allowed while the net is in Condition Yellow. This may occur when a Warning has been issued but the storm cell prompting the warning has not yet entered Oakland County. Please listen for direction from net control.


Condition Red represents the most critical net Condition. A net is placed in Condition Red when the National Weather Service has issued a Tornado WARNING. Under Condition Red general check-ins are not allowed unless the operator has at least one of the following items to report.

  • Wall Clouds with rotation
  • Winds in excess of 55 miles per hour
  • Funnel Clouds
  • Tornadoes
  • Hail 1 inch in size or larger

General Check-ins will rarely be allowed while the net is in Condition Red. The air must be kept clear to allow reports of the above items to be made without interference. Once the warning has expired or been cancelled by the National Weather Service, the net will be downgraded to either Green or Yellow with check-ins allowed.

Post Event Check-in

On occasion, severe weather can come up with little to no warning. In these cases, the net may activate in condition Yellow or Condition RED. In these cases, Net control will typically downgrade the net to Condition Green and ask for general check-ins once the severe threat has passed. This allows operators that have been on the net to be placed on the list of activated stations for the net. After all check-ins have been completed net control will formally closing the net.

SKYWARN Reporting

Accurate and concise reports of damage are the most useful products that the ARPSC can produce during and after a Skywarn activation. Our reports serve the Homeland Security Department by providing situational awareness of the location and magnitude of storm damage as it occurs. These reports are also used by the National Weather Service to issue Warnings for items that were not visible to radar. After the fact, the NWS also reviews our reports and compares actual damage to saved radar images from the time of the event. This enables forecasters to better understand the relationship between radar images and actual weather on the ground.

Damage reports should be submitted as close to the time of the damage as possible. The following outlines reporting process preferred by the ARPSC, Homeland Security and the National Weather Service.

The reporting process is best described by the acronym T - E - L, short for Time – Event – Location.


Please provide the actual time of the event you are reporting. Real time reports assist the NWS in issuing updated weather statements, Warnings and updates to existing Warnings. Your report should include denoting the time as Actual.

If you come across damage after the fact, reports are still helpful. You should attempt to determine the actual time by speaking with people in the area. If you can obtain the time of occurrence, your report should denote the time as Actual. If the time cannot be accurately determined, provide the most likely time and denote it as Estimated in your report. If the time cannot be determined, simply denote the time as Time Unknown.


The Event portion of your report identifies the nature of the report. Items typically reported include one or more of the following:

  • High Winds
  • Wall Clouds
  • Hail
  • Tornados
  • Flooding
  • Tree Damage
  • Clouds With Rotation
  • Power Lines Down
  • Funnel Clouds
  • Damage To Structures

High Winds are winds in excess of 40 mph. The chart on the Skywarn home page can be useful in estimating wind speed. If you have an anemometer please use that to determine wind speed. When you provide a wind report please indicate whether it is Estimated or Measured.

Hail of 1/2 inch diameter or larger can be reported. Please use the chart on the Skywarn home page to determine hail size.

Flooding should be reported when water reaches a level that covers a roadway from curb to curb.

Clouds With Rotation is an observation possible only in daylight hours. The rotation is clearly defined around the center of a rotating circle.

Wall Clouds frequently precede tornadoes and funnel clouds. Please visit the National Weather Service website for a detailed description and photographs of wall clouds.

Funnel Clouds are rotating cone shaped formations descending from clouds. Many times these are incorrectly reported as tornadoes. While similar in structure, a funnel cloud only becomes a tornado when the funnel reaches and makes contact with the ground. When reporting a funnel cloud you should also include its direction of travel.

Tornadoes are rotating cone shaped formations descending from a cloud and making contact with the ground. Depending on the strength of the tornado, a debris cloud may be visible. When reporting a tornado please indicate it direction of travel.

Tree Damage includes any damage caused by wind. Reports should begin with tree limbs being broken from trees. The diameter of the broken branch should be estimated and included in your report. With stronger winds the trunk of a tree may be completely broken off. In your report please indicate that the trunk was snapped and provided the estimated diameter of the trunk where it was broken. The final form of tree damage is the complete uprooting of the tree. This is evidenced by the tree's root ball being pulled from the ground and completely visible. When reporting please submit this damage as an "Uprooted Tree" along with an estimate of the trunk diameter near the base of the tree.

Power Lines/Utility Poles Down all power line down incidents should be reported to net control. Additionally, any utility pole damaged during a storm should also be reported to net control.

Damage To structures should be reported for any incident where shingles have blown from the roof to major structural damage. Samples would include; shingles blown off roof, garage roof blown off with damage to walls, etc.


The final component to the report is the location of the event. An accurate location provides the information necessary for the NWS to enhance its forecast capability and provide additional weather statements in the case of an imminent threat to a specific well defined area. As a service to Homeland Security an accurate location provides the building blocks to develop a picture of the area affected, the magnitude of the event and, when coupled with GIS data, the population within the damage area. When a potential threat is moving, the direction of its movement becomes an additional component to the report.

The location of an event should describe the location as close as possible. This would include an address (which is not always practical), the closest major cross roads and the direction from that point and the city or township where it is located. Latitude and Longitude Coordinates will also be accepted if available.

Reporting Examples:

"At 1540 hours – clouds with rotation just north of 14 Mile and Orchard Lake Rd in West Bloomfield moving east northeast"

"At 2015 hours – power lines down and arcing with the utility pole broken on the west side of Coolidge just south of Long Rd in Troy."

"Time unknown – 4 trees down, 2 uprooted, 2 snapped trunks – trunk diameter of 18 inches on the west side of Milford Rd south of General Motors Rd in Milford."

"At 1842 hours – winds in excess of 40 mph, estimated on Rochester Rd north of Wattles in Troy."

"At 1933 hours – winds in excess of 55 mph estimated, multiple trees uprooted or trunks snapped, estimated trunk diameter of 30 inches, garage roof blown off with damage to the walls at 5729 Cherry Crest Dr, just southwest of Walnut Lk Rd and Orchard Lk Rd in West Bloomfield."

"At 1417 hours – 3/4 inch size hail accumulating 4 inches in 10 minutes at Troy Fire Training Center, east side of John R south of Long Lk Rd in Troy."

"Right now...right in front of me...huge TWISTER!!! AAAAHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH" (end of transmission)