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ARKAN Newsletter -- Page Five


The Weather Report

District L DEC Bill Smith, K1ARK

K1ARK@arrl.net Washington County EC Larry Rankin, KI5OY

lwrankin39@msn.com Washington County Assistant ECs Dan Puckett, K5FXB

danp@uark.edu University of Arkansas liason

Benton County EC Brad Clement, KJ5YD

kj5yd@arrl.net Benton County Assistant ECs Mike Engelke, KD5DGT,

W5YM University WeatherNet info from Bill Smith, K1ARK Notes from last month's presentation

Why we need spotters

One of the most important reasons we need spotters in the field are the limitations of radar. While there have been dramatic improvements in radar with the NEXRAD system, there will always be physical restrictions related to beam height and resolution. Since we do not live on a flat earth, the planet’s curvature will cause beam height to increase with distance from the antenna. The rise in beam is consistent regardless of the location. At 25 miles, the bottom of the beam is 1,200 feet above the antenna’s elevation. At 50 miles, the beam is 3,900 feet; by 75 miles, 5,000 feet; by 100 miles, 9,500 feet. As a result, the radar is not able to “see” below these heights. Another important need relates to weak tornadoes that lack well defined radar signatures.

Spotter networks versus mobile spotting

Siloam Springs Bob Kendal, K5KBK,

Digital coordinator

Carroll County EC Marshall Turner, K0ADM mturner@mynewroads.com

Madison County EC Currently vacant and seeking nominations

The topography of Washington County doesn’t lend itself to traditional open sky spotting. The road system works against mobile spotting as the connections between valleys in the rural areas make handoffs from one side of a hill line to another. This is the main reason why we have encouraged spotters at locations spread across the county.

Using the example of a late-night thunderstorm warning in early February that tracked across the mid to south parts of the county, spotter activation in front of the storm would have allowed for ground truth confirmation of the radar-indicated warning.

Call outs

The W5YM University WeatherNet activates on all warnings for Washington County, and some watches or special weather statements when needed. The best alert mechanism for our group is a NOAA weather radio equipped with Specific Area Message Encoding to limit the soundings to Washington and the nearby counties.

Over the past four years, the majority of active weather nets fall into three time frames: 8:00 p.m. to 10:30 p.m. in the evening; after 2 a.m. at night; 4:30 p.m. to 6:30 p.m. in the afternoon.

Something new from the internet:

Wind estimation and SET effect

This concept comes from the Milwaukee area SKYWARN training. Stress Excitement and Tension – SET – add to problems of spotters in the field. These pressures on the spotter make it very easy to overestimate wind speed. A strong gust of wind on a clear and sunny day will not cause concern, but the same wind during a thunderstorm is magnified by SET into a severe wind. When in doubt, rethink the wind speed estimate, if the wind is persistent, look again for the visible physical cues that will guide you on the Beaufort Scale.

Are you NIMS certified?


A quick note to all Washington County ARES members: Please update your database info as soon as possible. Folks move, change jobs, change phone numbers (in particular cell phone numbers), upgrade licenses or equipment and we need to know. If you have had a change since you filled out your ARES form, please contact one of the members of our county ARES leadership team.

Have you taken the time to become certified by the Department of Homeland Security and the National Incident Management System, or NIMS. Washington County is asking all volunteers and staff involved in emergency services to complete the on-line certification for IS 700. In the near future, DHS and FEMA will require all communications volunteers to have completed the course and taken the certification assessment.

New net controls welcome

We've had some interest in becoming the net controller for Tuesday's net, but don't be shy about other days of the week. In particular, relief net controllers are needed for the Monday weather training net during basketball season and John Robinson is seeking more controllers for the Thursday ARKAN net.

The best time to try your hand at net control is during these weekly training nets -- hence the title TRAINING net. Don't be shy.

Even if you don't foresee yourself becoming NCS in the future, you never know what an emergency might force upon you. Perfection is not required, only the willingness to read the script!

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