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 Observation guidelines – Mid-Iowa Skywarn Association

Observation guidelines – Mid-Iowa Skywarn Association

Taken from the MISA Operating Manual

Notice: The threshold for “reportable” weather may be changed by the net control station to provide more meaningful information to the NWS and make the reporting system more efficient.

Any sized hail is reportable, unless net control asks for reports above a certain threshold. In the picture above, amateur radio operators classified the hail that damaged this Toyota Prius as more than golf ball-sized hail. (Photo: Jason Smith KD0FLC/Fort Dodge Amateur Radio Association)

Skywarn spotters are strongly encouraged to take a NWS spotter training class at least every other year. These courses are offered during the spring of each year throughout the fifty-one county warning area. The schedule for spotter training (usually held mid February through Mid April) is normally posted on the Des Moines NWS web site starting in January of each year at http://www.weather.gov/dmx. The schedule is typically updated weekly throughout the spring. If you don’t see a course scheduled in your area, contact your county Homeland Security (Emergency Management) coordinator to see about scheduling a class in your county.

The spotter training class covers the subject of what is considered reportable, significant, or high priority weather. A basic definition of what is considered to be reportable is listed in the next section.

Reportable Weather

  • Tornado, funnel, wall cloud or land spout
  • Flash Flooding
  • Structural damage due to weather conditions
  • Downed power lines and tree damage (give estimated trunk/limb size diameter
  • Hail (report any hail along with size and duration) – see measurement guidelines in Appendix B)
  • Winds 30 mph or greater (measured or estimated – see the Beaufort Scale in Appendix A)
  • Rain in excess of 1 inch per hour

As stated above this is only a basic definition, and the requests for information from NWS Des Moines may include requests that would not be normally be considered “reportable or significant”.

The NWS Des Moines Amateur Radio Station (K0DMX) will advise the net control stations at the regional level of what type of information is needed. Regional net control stations and liaison stations should pass this information on to the county nets as quickly as possible. If the NWS Des Moines Station is extremely busy in another area, the regional net control station may request a brief “Do you have any ‘SEVERE’ reports, over”, this is indicative that there is trouble in another area and they are just checking with you to make sure that nothing has popped up while they have been on another frequency. The best answer is “negative, over” when you may be holding marginal or non-reportable information.

How to Report

Reports should be sent to the county or a link repeater system net control station as soon as possible. The reports should be sent in the following format:

Reporting Criteria/Keywords:

  • Tornado / Land spout
  • Funnel Cloud – Be sure of your observations!
  • Wall Cloud – Is it rotating or non-rotating? Watch for a minute or two before reporting.
  • Flooding – Blocked or washed out roads, bridges, railroads, water over banks of rivers, curb, evacuations, etc.
  • Hail – Use a coin size to report (don’t use “marble sized”). See NWS table on terms to use for reporting hail size.
  • High Winds – 30 MPH or greater. Indicate if report is estimated or measured. See NWS table to help estimate wind speed.
  • Storm Damage – Large grove of trees downed, power lines, windows blown out, major roof/building, vehicles blown over, etc.
  • Visibility – When visibility is less than ½ mile due to rain or blowing dirt.
  • Rainfall – 1/4 inch in 15 minutes, 1 inch in a short time. Rain gage reports should include start and end times.

NOTE: The NWS, or Net Control Station (NCS) may limit reports to certain conditions when a life-threatening event is imminent! Remember—Only one person can transmit and be heard at one time! If the NCS says you are a weak station, break your report into small segments to make sure the NCS is able to copy you!

Event Time: Report the time the event occurred, whether it’s occurring now or if it occurred several minutes ago.

What NOT to Report

Be very careful when sending in reports! The intention here is not to discourage reports, but to make sure that the reports that are sent are useful in nature.

For example, some of the reports that have been received at NWS offices during severe weather events that have not been useful include:

“Dark clouds,” “Heavy wind,” “Lots of lightning,” “rain” (these aren’t necessarily considered severe weather)

“Marble or ball-size hail” (Marbles and balls come in many sizes; instead give actual size or relate to a coin size such as dime, penny, nickel, quarter, etc.)

Use common sense when giving reports! Think of how the person receiving these reports will interpret them, and how useful they will be in determining the severity of the weather.