AccuWeather.com's forecast: Colder and snowier
The folks at AccuWeather.com have issued their preliminary winter forecast for Baltimore, and they'll calling for "one of the coldest winters in several years across much of the East."
At first glance that sounds pretty foreboding. But I spoke Wednesday with Ken Reeves, who co-authored the forecast with Joe Bastardi, and it turns out that what they're really expecting is a more nearly normal winter, compared with the easy ones we've seen in recent years.
"We're keeping in mind what it's going to feel like to people in your area, given what it was this past season," Reeves said. Last winter was mild. In fact, winter temperatures at BWI have averaged 2 to 3 degrees above normal since the winter of 2003-2004. Better still, at least for snow-haters, we clocked only 8.5 inches of snow - almost all of it in December. Average winter snowfall for BWI is about 18 inches.
This year, Bastardi and Reeves say the meteorological set-up has changed. We're looking at a more nearly "normal" - that is to say, a more nearly average - winter. And that, Reeves said, means people around these parts (at least those with short memories or thin blood) are in for "a shock."
With colder temperatures and higher prices for electricity and heating fuels, this may also portend a more financially painful winter than we've seen in some time. And it could begin sooner rather than later.
"We think we're going to get off to a roaring start in December, then ease back in January, before getting cold again in February," Reeves said.
He and Bastardi arrived at their conclusions by looking at several indicators. One, of course, is the state of the tropical Pacific Ocean's ENSO cycle, or El Nino Southern Oscillation. Last winter we were in a La Nina phase of the ENSO cycle - with cooler sea surface temperatures than average in the eastern and central tropical Pacific. That typically means mild winters in our part of the world. This time, Reeves noted, we're in a "neutral phase" of the cycle.
Combining a neutral ENSO with other factors, including this year's active hurricane season in the Gulf of Mexico, the AccuWeather.com forecasters concluded that weather patterns over the continental U.S. will shift eastward. That will bring a high pressure ridge - similar to one that produced colder weather to Iowa and eastern Nebraska last winter - farther east into Indiana, Illinois and Ohio. And that, they say, will increase the opportunities for cold Canadian air to flow south into the eastern third of the nation, including Maryland.
When they looked for "analogs" - past years when similar patterns were in place - they found several. And in those years, Baltimore and its environs recorded average to just-blow-average winter temperatures.
When I asked Reeves about snow, he wisely hesitated. Seasonal snow forecasts are "tricky," he said. "If it's colder, you do stand a greater chance of more snowfall. That makes sense. But it does depend somewhat on when the cold air arrives."
To make snow, you need both cold AND moisture. And they have to meet up at the same time. But this is Baltimore, and I couldn't let him get away without some kind of snow forecast for the coming winter. Baltimoreans demand snow omens at this time of year. So I leaned on him a little more.
"The thinking is the season will certainly be a snowier season than last year," Reeves ventured. That shouldn't be hard. I mean, we got 8.5 inches. But he took the bait. "Probably somewhere in the mid- to upper-teens. Maybe around 20 inches," he said, with an early "rude slap" coming in December. (Sounds like a lot, especially if it all fell at once. But remember, 18 inches of snow in Baltimore is about average for the season.)
With luck that wintery "slap" will come on Dec. 5 and bring snow. BWI has recorded at least a little snow on Dec. 5 in five of the last six years:
2007: 4.7 inches
2005: 1.4 inches
2003: 0.85 inch
2002: 7.4 inches
For the record, the U.S. Climate Prediction Center forecast for December thorugh February calls for warmer-than-average temperatures here with no clear trend either way on precipitation.