ACARES Monthly Meeting -- June 8th 7:00pm -- CCSD ESC 4700 S. Yosemite St. Greenwood Village, CO

Arapahoe County Amateur Radio Emergency Service is dedicated to public service and support of our served agencies. One of the primary functions in this area is participation as weather spotters. Note that this is the only emergency where self-activation is permitted. Once you hear of severe weather in your area, you should monitor 146.640. If you observe severe weather meeting the criteria below, inquire on this frequency if there is a net control taking weather reports. If not and the criteria meets the NWS criteria, contact local law enforcement, advise them that you are a trained weather spotter with Arapahoe County ARES and ask them to report this information to Emergency Management. Otherwise, give your report to NCS.

The most important requirement of weather spotting and reporting is SPEED, ACCURACY and VERIFICATION. needed to offer ample warning time to areas in the path of an impending severe storm. Reporting visual sightings as quickly as possible allows the NWS to expedite the warning process.

With the advancement of the more sophisticated radar, complemented by the visual information of trained SKYWARN spotters, lives and property can be saved not only in your community but also in other counties and communities in the storm's path. important because the equipment and information available to the NWS are not always sufficient to determine the on site conditions of severe weather. NWS personnel depend on trained local observers (spotters) to identify, report, and verify conditions in their area. needed after the weather event has passed. Spotters are trained to report any visual items that meet severe storm damage criteria for verification of the NWS warnings. It's no wonder why the NWS refers to amateur radio weather spotters as "the eyes of the National Weather Service".

Note that our mission is slightly different that the mission of SKYWARN. The National Weather Service only wants to have reported:

Although reporting criteria may vary slightly depending on the spotter network and local needs, these are the events the National Weather Service would like to know about as soon as possible:

TORNADO Always Call - ALSO CALL 911 Tornado Warning Issued. Look for debris on the ground
FUNNEL CLOUD/WALL CLOUD Always Call Look for organized persistent sustained rotation
HAIL Call if Half-inch size or larger** Severe thunderstorm Warning Issued: 1 inch diameter or larger. Always report he largest size hailstone
WIND GUSTS Call if 50 mph or higher Severe Thunderstorm Warning Issued: Sustained 40 mph. gusts to 58 mph or greater. Specify esitmate or measurement
HEAVY RAIN/FLOODING 1.0” rain/hr or greater for urban areas. 1.5” rain/hr or greater for rural areas. Also call 911 for flooding Flash Flood Warning issued: Flooding that impacts roads homes or businesses.
STORM DAMAGE Always Call Damage to structures (roof siding windows etc). Damage to vehicles (from hail or wind). Trees or large limbs down. Power/telephone poles or lines down. Damage to farm equipment machinery. Or any other significant damage.

      ** Quarter size hail (1.00 inch) is considered as severe weather hail.


     - Roll Clouds (indicates strong straight-line winds)
     - Wall Cloud, with or without rotation
     - Rotating Funnel Shaped Clouds
     - Roar and debris
2. TORNADO (funnel cloud touching ground or debris field with rotation above in clouds)
     - Pea size (1/4") or larger
     - Is hail impeding traffic?
     - Is the ground covered or not (intensity)?
4. WINDS OVER 40 MPH (Unless directed otherwise)
     - When ESTIMATING wind speed use the Guide at the end of this page and say "estimated" in the report.
     - If MEASURED by wind instruments (e.g., Weatherstation or handheld anemometer) say "measured" in report
     - Streams out of banks
     - Ponding of water in streets (including depth)
     - Water standing curb-to-curb)
     - Immediate: 1" or more within 1 hour
     - After Event: Total measured for that storm Be sure to empty your rain gauge before the storm
     - Damage to buildings, trees and utility poles, any limbs down, the diameter of the limbs/trees and the direction they fell


     - Lightning (all severe storms contain lightning and it is not possible to warn for lightning)
     - Blue Sky Reports ("I have blue sky over my house in Aurora ". This just ties up the frequency with unnecessary reports)
     - Activation/Non-Activation of Warning Sirens
     - Information overheard on Public Safety Radios (e.g. police, fire, sheriff - unless specifically requested)
     - Power outages (unless specifically requested)
     - Traffic Accidents (unless you witness the accident. Then stay and render aid until authorities arrive. Notify NCS that you are are of service and why)


Your severe weather report should be detailed but concise, and should address the following questions:
     - WHAT did you see?
     - WHERE did you see it? Report the location/approximate location of the event. Be sure to distinguish clearly between where you are and where the event is thought to be happening (“I'm 5 miles north of Mayberry. The tornado looks to be about 5 miles to my northwest”).
     - WHEN did you see it?   Be sure that reports that are relayed through multiple sources carry the time of the event, NOT the report time.
Any other details that are important - How long did it last? Direction of travel? Was there damage? etc.
If you are unsure whether to report or not to report, GO AHEAD AND REPORT IT

Spotters Rules and Clues

     - Always have a safe place nearby to protect yourself from wind or hail. Cars can be safe places in case of lightning, but not in the case of tornadoes or high winds.
     - Overshooting tops are an indicator of a very strong storm.
     - The first gust of wind to reach you from a thunderstorm is frequently the strongest.
     - A rain-free base denotes the storm's updraft area... a place to watch closely.
     - Large hail often falls just in advance of a tornado, especially large tornadoes.
     - Wall clouds form from the rain-free base often 15-20 minutes before a tornado occurs. Watch these clouds closely for 1 to 2 minutes to determine if there is any
rotation in the wall cloud.
     - Tornadoes generally move toward the northeast at 25 to 35 MPH when associated with fronts and squall lines, but can travel up to 70 MPH. Go to a substantial building instead of trying to outrun an approaching tornado.
     - Look carefully, Spotters may not be able to see a tornado due to it being wrapped in a curtain of rain.
     - Moving water is very powerful. It only takes a slight current to push a car off a road.
     - Do not drive vehicles through roads covered by moving water!

Guide to Estimating Wind Speeds (modified Beaufort Scale)

MPH   Wind Speed Evaluation Chart
0         Smoke rises vertically
1-3      Direction of wind shown by smoke drift but not by wind vanes.
4-7      Wind felt on face, leaves rustle, ordinary wind vane moved by wind.
8-12     Leaves and small twigs in motion, light flags extended,
13-18   Dust raised, loose paper raised, small branches move.
19-24   Small leafy trees sway, crested wavelets form on lakes and ponds.
25-31   Large branches in motion, whistling in telephone wires or link fences.
32-38   Whole trees in motion, inconvenience felt walking against wind.
40+      Report Any Winds 40 MPH or Greater (Unless otherwise requested)
39-46   Twigs and small branches break off trees, impedes progress walking.
47-54   Slight structural damage; chimneys have bricks loosened, shingles blow off.
58+      Winds Are Defined As Severe By NWS
55-63   Trees uprooted, widespread structural damage, mainly roofs.
64-72   Damage to structures major and wide spread. Many roofs & windows damaged
72-112 Peels surface off of roofs, windows broken, moving autos pushed off roads, some mobile homes overturned.
112+   Cows spotted in the air

Conversion Tables

      KTS to MPH
5 Knots = 5.8 MPH
10 Knots = 11.5 MPH
15 Knots = 17.3 MPH
20 Knots = 23.0 MPH
25 Knots = 28.8 MPH
30 Knots = 34.6 MPH
35 Knots = 40.3 MPH
40 Knots = 46.1 MPH
45 Knots = 51.8 MPH
50 Knots = 57.6 MPH
55 Knots = 63.4 MPH
60 Knots = 69.1 MPH
65 Knots = 74.9 MPH
70 Knots = 80.6 MPH
75 Knots = 86.4 MPH
80 Knots = 92.2 MPH
85 Knots = 97.9 MPH
90 Knots = 103.7 MPH
95 Knots = 109.4 MPH
100 Knots = 115.2 MPH
105 Knots = 121.0 MPH
110 Knots = 126.7 MPH
115 Knots = 132.5 MPH
120 Knots = 138.2 MPH
125 Knots = 144.0 MPH
130 Knots = 149.8 MPH
135 Knots = 155.5 MPH
140 Knots = 161.3 MPH
145 Knots = 167.0 MPH
150 Knots = 172.8 MPH

Some commonly used hail sizes

Pea .25 inch Golf Ball 1.75 inch
Half-inch .50 inch Hen Egg 2.00 inch
Dime .75 inch Tennis Ball 2.50 inch
Nickel .88 inch Baseball 2.75 inch
Quarter 1.00 inch Tea Cup 3.00 inch
Half Dollar  1.25 inch Grapefruit 4.00 inch
Ping Pong Ball 1.50 inch Softball 4.50 inch