"There are unusually volatile trends in consumer spending and weather patterns, and the tax issue is clouding everything," she said.

It is a matriarchal society with an unusually volatile gas.

Some oil experts contend that the current oil markets are unusually volatile, and price swings like those yesterday have much more to do with emotion than fundamentals.

The bid revived interest in takeover issues and ended an unusually volatile month in the equities markets on a positive note.

Undoubtedly, the moderate La Nina pattern set the stage for the unusually volatile weather conditions across the U.S.

The market has been unusually volatile in recent weeks, reflecting concerns that the Fed might raise short-term interest rates again when it meets next month.

Golden cites "unusually volatile" markets as the cause for the steep decline.

Prices could prove unusually volatile today, traders cautioned, because it is a so-called triple-witching session, when stock options, index options and index futures contracts all expire.

The trader may also use other factors, such as whether the period was unusually volatile, or if there are going to be unusual events in the near future, to adjust his forecast.

"The market is unusually volatile," said Andrew Lebow, of E.d.F. Man Energy.