The National Weather Service reports October rainfall in Pittsburgh has been pretty much average.

Just don't tell that to water-logged Western Pennsylvania high school football fans.

Rain has soaked football fields for the past four Fridays, creating sloppy playing conditions for high school teams all month long.

But as of early this week, precipitation totals in Pittsburgh were on pace for an average October.

"It just so happens that we've had our systems come on Fridays," said Alicia Smith, a National Weather Service meteorologist. "It looks like we've had a lot of rain, but it's actually normal for this time of year."

Take last week for instance -- Monday through Thursday were beautiful fall days. But, just like the sun rises in the east, storm clouds rolled in Friday morning.

Early predictions call for a 40 percent chance of rain tomorrow night.

"As far as having a dry game," Smith said, "I'm not sure when that's going to happen."

The last playoff spot in the Big East Conference will go to the winner of tomorrow's game between Kiski Area and Plum.

Both teams are 1-3 in conference play, fighting for the final playoff spot.

Plum (2-6, 1-3) will need to overcome major deficiencies if it wants to return to the playoffs after a one-year absence.

The Mustangs score an average of 11.3 points per game, the fewest in the Big East. Its defense allows an average of 31.1 points per game, the most in the conference.

Kiski Area (3-5, 1-3), which has missed out on the playoffs the past two years, will have home-field advantage in tomorrow's contest.

A late-season surge has propelled Derry to the postseason for the first time since 2000.

The Trojans clinched a playoff spot last week with a 28-14 win over Albert Gallatin.

"After a slow start, it was kind of questionable," said Derry coach Ron Polinsky.

The Trojans are 3-1 in October after going 0-4 in September, and are currently 3-2 in the Class AAA Keystone Conference.

The biggest difference? Turnovers.

Polinsky said the defense is forcing more than the offense is giving up, which wasn't the case in September.

And Polinsky said Derry's running game has been successful, which has taken a lot of pressure off quarterback Mike Kelly.

Since the fourth week of the season, Kelly is completing more than 60 percent of his passes. He had completed just 42.1 percent of his throws in the weeks prior.

Few things are certain in the Class AA Interstate Conference: undefeated Mount Pleasant is the top-seeded team, and McGuffey will join the Vikings in postseason play. Where the Highlanders are seeded, and who will join them in the playoffs, is to be determined.

Three teams -- McGuffey, Greensburg Central Catholic and Washington -- are tied for second with 6-2 conference records. Two other teams -- Jeannette and Charleroi -- are tied with 5-3 conference records.

Charleroi cannot qualify for postseason play, even if it beats Mount Pleasant tomorrow night.

Washington and Greensburg Central Catholic control their own destinies -- both teams are in if they win. But if Washington loses to McGuffey and/or Greensburg Central Catholic loses to Jeannette, things get tricky.

Jeannette needs Charleroi to lose, even though the Cougars cannot qualify for the playoffs, if the Jayhawks want to squeak into the playoffs.

Sound complicated? It's probably better for the teams to figure things out on the field and save us the arithmetic.

Wilkinsburg has been 0-for-everyone since beating Leechburg last year.

The two teams square off Saturday afternoon in a game that could finally give Wilkinsburg its 500th win in school history. Wins No. 498 and 499 came against the Blue Devils.

Both are winless in and out of Class A Eastern Conference play. Neither averages more than 10 points scored per game, and both allow an average of more than 30 points per game.

Franklin Regional took a big step toward a Class AAA Greater Allegheny Conference title last week by knocking off Hampton, 35-34.

But the best the Panthers can do is share the crown. Three teams -- the Panthers, Mars and Knoch -- are tied at 3-1 in the conference, and Mars and Knoch play one another tomorrow night. So, even if Franklin Regional beats Indiana tomorrow, the best it can do is tie for the top spot.

But the Panthers can still earn a top seed in the playoffs if Knoch beats Mars and Hampton beats Highlands.

Mike White's "High School Sports Edition" videos are featured exclusively on PG+, a members-only web site from the Pittsburgh Post-Gazette. Our introduction to PG+ gives you all the details.