The first day of winter will be warm in Schuylkill County but residents shouldn't get used to it.
John LaCorte, a meteorologist with the National Weather Service, State College, said today would be wet with a slight chance of snow, temperatures will be "average" for Dec. 21 - about 41 degrees - but cooler temperatures may be on the horizon.
Meanwhile, some forecasters said this winter in Schuylkill County may not be as warm as last year's unusual season.
"The Northeast U.S. is under an 'equal chances' area for both precipitation and temperature, which means that we do not expect that conditions will be as warm as they were last year. In the long run, we would expect a more seasonable winter, but that doesn't mean that things will always be normal," David Unger, a meteorologist with the NOAA/National Weather Service Climate Prediction Center, College Park, Md., said Thursday.
"Our seasonal forecast for January, February and March kind of has you in an area where there's no strong preference for above- or below-normal temperatures or precipitation. Your best strategy would be to look at normal temperatures and precipitation for that time," said Ed O'Lenic, chief of the Climate Operations Branch at the Climate Prediction Center.
Trying to predict the weather for an entire season may require a crystal ball, Unger said.
"There is no way to predict how long the cool and unsettled conditions will last. Weather prediction is only possible out to around seven to 14 days," Unger said.
LaCorte concurred.
"We are dealing with today through day seven. As far as the long-range, seasonal forecast, well, a lot of people like to have fun and guess at it," LaCorte said.
However, some news organizations have made predictions.
"Above-normal snow is forecast for the I-95 cities, including Boston, New York City, Philadelphia and Washington, D.C., this winter with an active coastal storm track expected," according to accuweather.com.
"Precipitation is always less predictable than temperatures, since individual storms - think Superstorm Sandy - which are unpredictable beyond seven to 10 days or so, can give an substantial portion of an entire season's worth of precipitation in one or two days," Unger said.
The Old Farmer's Almanac offers its "2012-2013 U.S. Weather Highlights" on its website at almanac.com.
"The 2013 Almanac says that temperatures will be much colder this winter from the East Coast westward to a line from the Dakotas to Texas," according to the website.
Forecasters can get ideas of what to expect by examining data from a number of sources. They include factors like Lezak's Recurring Cycle, The Arctic Oscillation, The El Niño Southern Oscillation, the North Atlantic Oscillation, the PNA and the MJO.
"The models are telling us that sometimes the cooler air will win out on average, and we will finish the winter averaging cool, sometimes the warmer air wins, and we finish the winter averaging warm, and sometimes we have a mix and the winter finishes out as 'near normal' temperatures. We call this 'equal chances' in our forecast terminology," Unger said.
"The climate model that we run here at the National Centers for Environmental Prediction suggests that the Pennsylvania area seasonal mean temperatures this winter will be on the boundary between above-normal temperatures favored for the southern part of the U.S. and below-normal temperatures that are most probable to the northwest, north of U.S./Canadian border. So far in December, we have been on the warm side of this boundary, with the cold air trapped in western and central Canada. That is about to change, at least for a while, with the short and extended-range weather forecast predicting a circulation that will allow the cold air to spill into the U.S. and bring below-normal temperatures for the last part of December and into early January. It looks like we will see ample precipitation as well, with the storm track expected near your area," Unger said.
In the winter of 2011-12, the average temperatures in Schuylkill County had been higher than normal.
For example, at the National Weather Service Cooperative Observer Program site in Mahanoy City, established in 2000, the normal temperature for January has been 27.8. This year, it was 28 degrees, LaCorte said.
In February, the normal average is 27.8 degrees. This year, it was 32.2.
In March, the normal average is 36.7. This year, it was 45.3, according to LaCorte.
Meanwhile, snowfall in the winter of 2012 was below-average.
Since 2000, the average seasonal snowfall in Schuylkill County had been 43.2 inches. The winter with the most snow in that cluster was the winter of 2002-03, when there was 85.2 inches. The winter with the least snow in that cluster was the winter of 2001-02, when there was only 18 inches. The winter of 2011-12 was the second-least with 20.1, the National Weather Service said previously.
Temperature statistics from recent months suggest that colder weather is on the way.
In September, the normal average is 62.8. This year, it was 60.7. In October, the normal average is 49.2. This year, it was 51.2, and in November, the normal average is 41.3. This year, it was 36.5, according to LaCorte.
Patrick Caulfield, executive director of the Schuylkill County Municipal Authority, said he's hoping for a "normal" winter.
The authority manages six reservoirs that contain a total of 1.68 billion gallons.
"As of Dec. 15, our total reservoir capacity was at 91 percent. This would be pretty typical for this time of year. Generally speaking, we would be well within the normal capacity expectations for early winter, with the anticipation of reaching full 100 percent capacity in the wet spring season," Caulfield said Thursday.
"However, the lack of snow and corresponding spring melt brought us into the summer with a marginally lower capacity. At this point, we hope for a typical Pennsylvania winter season. Major variations, either way, cause concern on all levels," Caulfield said.