OKLAHOMA CITY (AP) — Weather forecasters say an isolated tornado is possible as a strong storm system moves across Oklahoma.

National Weather Service meteorologist Doug Speheger said Friday that tornadic activity is not common in Oklahoma in October — but is not unheard of. Since 1950 there has been an average of about two tornadoes in October with 40 of those 60 years having none or one twister.

But there were 27 tornadoes in October 1998 — including a twister with winds estimated between 113 and 157 mph that hit central Oklahoma. And there were 19 in October 2001 that included a tornado with winds estimated between 158 and 207 mph that hit Cordell.

No fatalities were reported from either storm.

Speheger says the chance of a tornado in Oklahoma through Saturday is about 25 percent.