Drought watch

Yet again the rivers and streams have taken on that chocolate look among the whitecaps after another deluge.

The weekend rains swelled the 2011 rainfall total at Philadelphia International Airport to over 15 inches, or about 25 percent above normal, and the forecast the rest of the weeks is pockmarked with showers.

So why even mention drought?

The record argues that we're overdue. The drought warning issued back in September for parts of the region was the first such declaration in eight years.

That marked the longest period between drought warnings in Pennsylvania in the period of record dating to 1980. And the September drought was a quickie, washed out completely before Thanksgiving.

The run of wet weather the region has experienced in the last nine years is unprecedented.

Starting with 2002, annual precipitation in Philadelphia -- rain, snow, sleet, hail, unidentified falling objects -- has been within 95 percent of the long-term average each and every year.

That's the first such nine-year streak since the government began keeping score officially in 1874. Four of the last nine years have finished in the top 25 for wetness.

One hypothesis holds that the subtle increase in Earth's temperature is generating more water vapor and thus more rain.

Perhaps, but the long-term record would argue that it's just a matter of time before the rain stops for awhile.