May 26

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SkyWarn Spotter Reporting Criteria

It’s that time of the year again, when we start the transition from winter to spring and spring into the full-fledged heat of summertime in Southeast Tennessee.

And while the springtime was more forgiving to our immediate area this season, we’ve still got quite a way to go with plenty of potential for strong or severe summertime storms which could bring about the need for SkyWarn spotter activation by the National Weather Service.

While many of you have attended SkyWarn training by the NWS in the recent past…some of you might be unofficially spotting (which is always welcome, too)!  The more “eyes on the storm” the better, really.  And as an Amateur Radio operator it’s part of our public service duties to lookout for the well-being of the general public and our fellow neighbors.

First and foremost, remember to spot safely!  NEVER put yourself in harm’s way while spotting a storm.  While “storm chasing” might be fun, remember that a storm can turn ugly…QUICK!  We highly recommend leaving those action-filled storm chase scenes from the movie “Twister” to the Hollywood stunt guys!  As a spotter, you’re more valuable to the spotter community ALIVE than dead. Spot safely!

Reporting criteria is another element to SkyWarn spotting that’s important to keep in mind while filing your reports either to the NWS directly, online, or via a SkyWarn or weather net over the air.  Below is the NWS and SkyWarn accepted reporting criteria as of 2012 along with some “Do’s” and “Don’ts” of reporting…

Reporting Criteria:

1. Wall Cloud
2. Tornado
3. Funnel Clouds
4. Cloud Rotation
5. Damaging Winds (58 MPH or greater measured)
6. Hail 1″ or larger
7. Flooding – Any stream out of its banks or water covering a roadway (do not report minor stream flooding & overflowing ditches)
8. Rainfall 1 inch or more per hour

What NOT to report:
1. Anything not seen personally.
2. Information from Internet, TV, or radar, or traffic from scanners or media broadcasting to the Net Control Station while a formal net is in progress.
3. Frivolously Reports such as “It’s getting really windy cloudy here”, “We are experiencing a lot of lightning and heavy rain”, or “We still have sunshine at my location” are not valid reports.

Common Hail Sizes:
Pea – 0.25″
Penny – 0.75″
Nickel – 0.88″
Quarter – 1.00″
Golf ball – 1.75″
Tennis – 2.50″
Baseball – 2.75″
Softball – 4.25″

Wind Speed Estimator:  MPH
39-54: Twigs break off of trees; wind impedes walking.
55-72: (Severe) Damage to chimneys, pushes over shallow rooted trees.
73-112: Peals surface off roofs, Pushes autos off the road.
113-157: Roofs torn off houses, weak buildings destroyed. Large trees snapped and uprooted.
158+: Severe Damage. Cars lifted off ground.


Keep these things in mind while making your spotter reports this year…and remember, just because spring is almost over and summertime is here — some of our heaviest storms and tornadic activity has occurred outside of spring time.


Logan, W4QXL

Permanent link to this article: https://kd4atw.org/2012/05/26/skywarn-spotter-reporting-criteria/

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