Weather Spotting

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 146.880. 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.

SPEED...is 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.

ACCURACY..is 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.

VERIFICATION...is 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:

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:

**Quarter size hail (1.00 inch) is considered as severe weather hail.
Again, reports should provide as much detail as possible to describe the where, when, how, etc of the event

WHAT TO REPORT TO EMERGENCY MANAGEMENT

1. CLOUD FORMATIONS

Roll Clouds (indicates strong straight-line winds)

Wall Cloud, with or without rotation

Rotating Funnel Shaped Clouds

Roar and debris

TORNADO (funnel cloud touching ground or debris field with rotation above in clouds)

2. HAIL

Pea size (1/4") or larger

Is hail impeding traffic

Is the ground covered or not (intensity)

3. 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

4. FLASH FLOODING

Streams out of banks

Ponding of water in streets (including depth)

Water standing curb-to-curb)

5. RAIN GAUGE REPORTS

Immediate: 1" or more within 1 hour

After Event: Total measured for that storm Be sure to empty your rain gauge before the storm

6. DAMAGE REPORTS

Damage to buildings, trees and utility poles, any limbs down, the diameter of the limbs/trees and the direction they fell

DO NOT REPORT

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)

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)

Convertion Tables

Some commonly used hail sizes