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Ice accumulation index may help Oklahomans prepare

by Bryan Painter Modified: December 21, 2009 at 4:09 am •  Published: December 21, 2009
Is it time to sweat another winter?

Today is the official first day of winter, and although we’ve already had some hard freezes, it’s the severe ice storms that have made many Oklahomans sweat the last several winters.

Of 62 declared disasters in Oklahoma since 1955, eight were for "ice storms” or "severe winter storms.” Each has come since December 2000, according to the state Department of Emergency Management.

Although they work in two different professions, Sid Sperry, director of public relations, communications and research at the Oklahoma Association of Electric Cooperatives in Oklahoma City, and Steve Piltz, meteorologist in charge at the Tulsa National Weather Service forecast office, have been among those bearing beads of perspiration as precipitation turned to ice that eventually led to power outages and property damage.

So they decided to wipe their collective brow and designed the "Sperry-Piltz Ice Accumulation Index” with assistance from the Oklahoma Climatological Survey.

The purpose of the index is to measure an oncoming ice storm’s severity, Sperry said.

This may be helpful for electric and communication utilities with overhead lines and equipment, but also for other disaster preparedness agencies, including Oklahoma Emergency Management.

Using this index, damage potential is categorized in five levels and is gauged by ice accumulation, wind speed and temperatures. Knowit: Severe weather

by Bryan Painter
Assistant Local Editor
Bryan Painter, assistant local editor, has 31 years’ experience in journalism, including 22 years with the state's largest newspaper, The Oklahoman. In that time he has covered such events as the April 19, 1995 bombing of the Alfred P. Murrah...
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Sperry-Piltz Ice Index

The Sperry-Piltz Ice Accumulation Index takes into account the ice amount, the wind speed and damage and impact description.

The levels
Level 3 — Numerous utility interruptions with some damage to main feeder lines and equipment expected. Tree limb damage is excessive. Outages lasting one to five days.

Level 4 — Prolonged and widespread utility interruptions with extensive damage to main distribution feeder lines and some high voltage transmission lines/structures. Outages lasting up to 10 days.

Level 5 — Catastrophic damage to entire exposed utility systems, including both distribution and transmission networks. Outages could last several weeks in some areas. Shelters needed.

Dec. 25-27, 2000, southeastern Oklahoma (Level 4)

Jan. 28-30, 2002, central and northern Oklahoma (Level 5)

Dec. 3, 2002, central and northern Oklahoma (Level 5)

Dec. 18-20, 28-29, 2006, Oklahoma Panhandle (Level 5)

Jan. 12-15, 2007, eastern Oklahoma (Level 5)

Dec. 8-11, 2007, central and northeastern Oklahoma (Level 5)

Jan. 26-29, 2009, eastern Oklahoma (Level 4*)

March 27-29, 2009, northwestern and northern Oklahoma (Level 3)

*This was a Level 5 ice storm in northern Arkansas, southern Missouri and Kentucky.


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