Old Farmer’s Almanac predicts cold winter for the US

(www.philly.com) The new Old Farmer's Almanac is out, with weather predictions through October 2013.

Although its projection is for this winter to be generally cold and dry, snow is in the forecast for the second half of December for the Atlantic Corridor from Richmond, Va., to Boston. 

"The snowiest periods will be in mid-December, just before Christmas, and in mid- to late February," says the Region 2 Forecast.

These specifics are even given: 

Dec. 15-20: "Rain and snow, then sunny, cold." 
Dec. 21-25: "Periods of rain and snow, turning cold."
Dec. 26-29: "Snow showers, cold." 

Heck, snow is even mentioned around Election Day (Nov. 6) and right after Thanksgiving (Nov. 22). It's

"rain to snow, then sunny, cold" for Nov. 6 to 14, and "wet snow, cold" for Nov. 23 to 25.

Geography should be factored in, of course, expecting that rain's more likely toward the Virginia end, snow up toward Massachusetts, with Philadelphia in the middle.

But the publication's national forecast map even calls for a "cold, snowy" winter across much of the South, from Northern Texas to Georgia and up into Virginia.

The almanac, claiming a general accuracy rate of 80 percent, says that a year ago

"we may have been the only source to predict relatively warm winter temperatures."

It admits, however, that nobody thought last winter would be quite so warm.

The National Weather Service leans toward a warmer winter in the Northeast, with roughly average precipitation.

Average would be mean no white Christmas, since Philadelphia-area lawns have had significant snow on Dec. 25 cover only twice in the last 40 years - in 2009 and 1998. (Go to www.erh.noaa.gov/phi/xmasclimate.html.)

During an average December, Philadelphia gets about 3.3 inches of snow, half as much as in January or February, with a total of 20.5 inches for an average winter.

As for the rest of the year, the almanac foresees "warmer and drier" conditions from April through October, with

"the strongest threat of a tropical storm ... in early June," 

and even predicts rain on Halloween 2013. There are reasons, of course, to be skeptical about any predictions beyond the most general trends.

Although the science of forecasting keeps improving, meteorologists typically have trouble predicting precipitation a few days hence, let alone months from now.

The almanac explains that "we derive our weather forecasts from a secret formula that was devised by the founder of this Almanac, Robert B. Thomas, in 1792. Thomas believed that weather on Earth was influenced by sunspots, which are magnetic storms on the surface of the sun. 

"Over the years, we have refined and enhanced that formula"

to include studies of weather patterns and modern forecasting, it states.