A Powerball chance of a white Christmas for this year

Saturday, December 24, 2011

Indianapolis meteorologists are generally more than a little conservative in making bold forecasts before big events.

But there's some history behind that.

Their propensity for walking on eggshells around Race Days and holidays can probably be traced to the time a now-former Channel 13 weatherman predicted "a Powerball chance" of the Indianapolis 500 being run in 1998.

Bill Meck's ill-fated prediction came after a deluge had curtailed the Indianapolis 500 Festival parade the day before. But by 9 a.m. Race Day, the sun was out and it was on with the show, setting up a mad spectator dash to the track.

That's still probably why area meteorologists tend to leave the door just a bit cracked when it comes to predicting rain on Race Day or snow on Christmas. They'll call it a 10 or 20 percent change, just to save face.

But all hail WRTV, Channel 6, meteorologist Stephanie Ortmann, who joined the station in October. The Florida-born meteorologist is not afraid to make a solid prediction and stand behind it.

During her forecast the other morning, Ortmann predicted a "zero percent chance of a white Christmas" for central Indiana. So if you're dreaming of a white Christmas, you can apparently forget it.

She confirmed that Friday morning for the Banner Graphic.

"That's correct, there is a zero percent chance of a white Christmas this year for Indy and all of central Indiana," Ortmann assured.

"This year, there won't be any snow Christmas Day," she said. "It will be a completely dry with mostly sunny skies."

Even if some precipitation was to move through on Christmas, Ortmann said, "it wouldn't be cold enough for snow -- just rain."

Highs Sunday will be about 10 degrees above normal, in the mid 40s.

Meanwhile, the National Weather Service (NWS) records show that an Indianapolis area white Christmas is about a 50-50 proposition.

There are a couple of ways to define a white Christmas, the weather service says. For purposes of historical reference, the NWS defines a white Christmas as any day that has either at least a trace of snow on the ground or experiences at least a trace of snow falling that day.

In more general terms, they define a white Christmas as any Dec. 25 that central Indiana sees snow.

So what is the chance of at least a trace of snow falling on Christmas Day?

Snowfall records on Christmas Day have been kept in the Indianapolis area since 1871. And in that 140-year period, a trace of snow or more has fallen 64 times. That equates to a 46 percent chance of at least a trace of snow falling on Christmas Day.

The other possibility for a white Christmas involves at least a trace of snow already on the ground. That could be old snow from a week ago or just the day before.

The National Weather Service says snow depth records don't go quite as far back (they were started in 1896). And in that 115-year span, there has been at least a trace of snow on the ground on Christmas Day just 57 times. That's nearly a 50 percent chance of at least a trace of snow on the ground on Dec. 25.

Last Christmas five inches of snow was on the ground Christmas morning. (Remember last December was the third-snowiest on record in Indiana with 16.6 inches).

So what is the probability of having either a trace or more of snow falling, or a trace or more already on the ground on Christmas?

Since 1871, that has happened 82 times, the weather service says.

That amounts to an overall probability of just below 60 percent that Putnam County will see either some snow falling or some snow already on the ground for Christmas Day.

Just not this year. Apparently. Possibly. Maybe.

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