Northeast Missouri Amateur Radio Club

Serving Adair County and the Surrounding Area

Estimating Reports

Measured reports are much more desirable than estimated reports. They are generally much more accurate. Sometimes it’s hard to estimate properly under severe weather conditions. Over-estimating is as bad or worse than under-estimating storm criteria.

If you must estimate, here are some handy guidelines:

Hail Size

Pea Size 1/4″
Dime Size 1/2″ (Minimum reportable size)
Penny Size 3/4″
Nickel Size 1″
Golf Ball Size 1-3/4″ (Fore!)
Baseball Size 2-3/4″ (Get out the glove and your helmet!)

Rainfall Intensity

Light Less than 0.2″/Hr.
Moderate 0.2″ to 1.0″/Hr.
Heavy 1.1″ to 2.2″/Hr. (Minimum reportable rain)
Very heavy 2.3″ to 4.5″/Hr.
Intense 4.6″ to 7.1″/Hr.
Extreme More than 7.1″/Hr. (Anybody know how to build an arc?)

Wind Speed (Miles Per Hour)

0 Smoke rises vertically
1-3 Smoke drifts but windvanes do not move
4-7 Wind felt on face, leaves rustle
8-12 Small twigs in motion
13-18 Dust raised, loose paper raised, small branches move
19-24 Small leafy trees move, crested wavelets form on water
25-31 Large branches in motion, whistling in wires
32-38 Whole trees in motion, inconvenience felt walking against wind
39-54 Twigs break off trees
55-72 Damage to chimneys, pushes over shallow rooted trees
72-112 Peels surface off roofs, windows broken, trailer homes overturned
113-157 Roofs torn off houses, trailers destroyed, large trees snapped and uprooted
158 & Up Severe damage, cars lifted off ground (life passes before your eyes)