Dec 18, 2011 06:57PM ● Published by Anonymous
Until recently, the Blizzard of ’96, or the Great Furlough Storm, was the big one most Marylanders talked about. Congress had just cleared a budget impasse and furloughed federal employees were prevented from returning to work when the region was hit with as much as 24 inches of snow. Just a few days later, an Alberta Clipper brought another 3–5 inches of snow, only to be followed within the week with another 4–6 inches. By the end of the week, 1–4 feet had fallen across Maryland.
Then, of course, there was PDII (Presidents’ Day II) or the Blizzard of 2003, which dropped as much as 40 inches of snow and brought down the roof of the B&O Railroad Museum, damaging many of the historic trains inside.
Even our founding fathers had their legendary storms. The Washington and Jefferson snowstorm (so named because each of their diaries recorded the 1772 event) piled the snow so deep that neither George Washington nor Thomas Jefferson could get out their front doors. But the winter of 2009–2010 was the year we coined the term “Snowmageddon.”
Winter Storms in the Mid-Atlantic
The biggest storms to impact the Chesapeake Bay region occur when moisture from the Atlantic Ocean meets a cold air mass descending from the Arctic Circle. According to Janice Stillman, editor of The Old Farmer’s Almanac which is known for its longrange weather forecasts, cold winds typically blow around the North Pole in a tight pattern. “Sometimes, however, the winds loosen up and get sloppy,” Stillman says. “The cold wind slows and pulls down and away from the North Pole. The slower rotation sort of sets it free. Our prevailing winds are from north to east. As this cold air loosens, it comes down and hooks up with the jet stream and meets up with the warm, humid air of the mid-Atlantic. At that point it comes down to what wins out, the cold front or the warm front.”
Combine a storm track that drives storms up the East Coast, picking up moisture over the Atlantic Ocean, with arctic winds descending from the north, and it’s time to break out the shovels.
Predicting the Big One
While some may base their winter weather predictions in the bands of a Woolly Bear, the changing color of a goose bone, or the thickness of a pig’s spleen, modern science has lead us to other methods to predict the weather. However, long-range forecasting is still a game of chance.
Mike Halpert, deputy director for NOAA Climate Prediction Center, said that although we can make short-term predictions about the amount of snow that might fall, long-range predictions are expressed in terms of climate patterns in relation to the norm. The “norm” is based on a 30-year period that resets every 10 years. This past summer, “norms” were adjusted for a new 30-year period ranging from 1981–2011. Long-range predictions attempt to foresee temperatures which are above normal, below normal or normal in reference to this 30-year period. However, it’s not an exact science.
“While the weather forecast might be able to tell you what the weather will be like about one week in advance, long-range climate forecasts are probabilistic. They basically tell you what is likely to happen,” Halpert says. “With climate prediction, we’re looking at a shift in the odds. It’s like Vegas. If you load the dice, you tilt the odds, but it’s still a game of chance.”
Halpert says a highly confident forecast might reach a prediction of 60 percent probability, but he could probably count the number of times the NOAA Climate Prediction Center issued a 60 percent probability on one hand.
According to Halpert, the temperature of the oceans can have a big impact on our winter weather. “The best tool we have is the La Nina/El Nino trend. That gives us the biggest thing to grasp when looking at the forecast. It has the biggest affect on seasonal impact,” he says.
La Nina and El Nino conditions represent warming and cooling patterns in the Pacific. La Nina is a cooling pattern, which tends to result in milder winters. An El Nino pattern means warmer waters and a storm track that hugs the coast, resulting in more moisture in the air and bigger storms.
El Nino patterns tend to last nine months to a year, and La Nina patterns can last a little longer. Halpert pointed out that during the winter of 2009–2010, we had an El Nino which favors a storm track that impacts the mid-Atlantic. The cold air and El Nino came together, and snow lovers got what they wanted.
Halpert adds that last year we had the cold but we didn’t have the storm track to bring snow. “A 200–250-mile difference to the north, and you’re looking at 50-plus inches of snow compared to less than a foot in the D.C. area,” Halpert says.
At the time of writing this article, it was too early to know if El Nino or La Nina patterns would affect the Chesapeake this winter, but Halpert suspected a La Nina pattern to continue. “It would not surprise me to see a weaker La Nina, which may impact our winter. All that means though is a shift in probability. Although La Nina can decrease the chance of snow, that doesn’t mean that snow won’t happen.”
Look to the Sun
Stillman says that unlike most forecasting services, The Old Farmer’s Almanac factors in solar activity when making his longrange predictions. “We look at sunspot activity and then look back over time to find comparable periods in history,” Stillman says. “Most weather scientists seldom mention the sun.
“Historically, a quiet sun has a cooling affect on earth’s atmosphere and an active sun will warm the atmosphere. A lot of our weather comes from the temperature of our oceans which are impacted by a warm or cool atmosphere. Warm water equals higher humidity. Colder water equates to lower humidity. Warmer oceans will result in more hurricanes and winter storms.”
Stillman says that on average, sunspots follow an 11-year cycle. “We are currently in a quiet solar year and we expect it to continue, meaning an extended cooler than normal period,” she says. Like the NOAA climate prediction center, The Old Farmer’s Almanac issues its forecasts in the form of deviations from the 30- year averages or norms.
According to The Old Farmer’s Almanac website, its exact predictions are based on a secret formula devised in 1792 by Robert B. Thomas, founder of the Almanac, which is kept in a black box at their Dublin, New Hampshire offices. Stillman says that today, however, they rely mostly on meteorologist Michael Steinberg, who’s been helping them with their long-range forecasts since 1995.
“The Old Farmer’s Almanac is traditionally 80 percent accurate. Although we won’t tell you the temperature or how much snow we’ll get, we will tell you the average deviation from the norm,” Stillman says. That said, The Old Farmer’s Almanac correctly called the Presidents’ Day Storm of 2010 within a few days when it predicted a heavy snowfall for the second week of February 2010.
Preparing for the Storm
City, state, and county municipalities start preparing for winter storms long before winter arrives. The process of arranging snow removal contractors starts as early as July, and winter storm preparation is a never-ending process.
“This is a serious business for us,” says Greg Africa, deputy director of Bureau of Highways for Anne Arundel County. “It’s like preparing for battle. We don’t prepare for winter only when it’s winter. We are preparing year-round.”
Anne Arundel County owns approximately 150 pieces of snow removal equipment. They then supplement their snow removal workforce through private contractors. Annual needs are based partially on long-range climate and weather forecasts. “We look at long-range predictions from a number of sources and use that information to prepare contracts starting in July,” Africa says. “It’s important to lock them in early because we are competing with private entities such as shopping malls and business parks.”
Those predictions include both public sources such as the NOAA Climate Prediction Center and private, contracted meteorologists specializing in long-range forecasting. Africa says that along with daily weather forecasts, he participates in a number of webinars and other information sessions specializing in longrange forecasts.
Africa says that once all equipment is in order and contractors are in place and ready to go, an announcement is made, usually around Thanksgiving, that they are ready for the snow. “In a Norman Schwarzkopf sort of way, you have to have your forces ready and make sure everyone is prepared for the situation,” Africa explains.
Africa adds, “When it comes to preparing for battle, we can usually prepare for specific storms about a week out. The difficult thing is knowing how much equipment to call in.” Fail to call in enough equipment and the county can’t dig out. Call in too much and it becomes a budget situation. “The moment you don’t react properly, you’re dead,” Africa says.
He said the county’s mission is to be able to respond to emergency services such as fire and ambulance service and get them where they need to go. Once emergency services are functioning, the main roads are cleared. From there they move to the neighborhood collectors, and finally the smaller roads and cul-de sacs. When it comes to the intersections of county and state roads, Africa says that they have a “gentlemen’s agreement” that whoever gets there first clears the connection. Africa pointed out that Anne Arundel County has specific snow removal goals based on the amount of snow that falls. From 0-6 inches, main and collector roads should be plowed to bare pavement up to 24 hours after the end of the storm and residential streets will be passable up to 36 hours after the storm. With a big storm of 22 inches or more, the county tries to clear the thru lanes to bare pavement up to 36-60 hours after the end of the storm. Residential streets should be passable up to 4-6 days after the storm.
“Poorly parked cars are one of the biggest problems we run into when clearing the roads, and cul-de-sacs can be a nightmare,” Africa says. “Often, we find cars parked in driveways with the back ends sticking out. Then we have to send out a smaller piece of equipment such as a front loader to clear the snow. What a waste of time and resources when cars are parked improperly. We’ve got the machine there to do the job and it can’t because cars are in the way. It’s a lose/lose situation for everyone.”
Stock the Shelves
Although the line at the local grocery store (milk, bread, and toilet paper) may be one of the best predictors of snow, Africa points out that it is important to personally plan for the storm. “When snow is coming, prepare for it. Get medication in advance. Stock up on any groceries you may need and make sure you’ve got enough heating oil.”
He says he finds it amazing how many times the County Bureau of Highways receives requests for priority snow removal due to a need for medication or oil. He says he often wonders what people think when they watch the weather forecasts and fail to prepare. “This is serious stuff and it’s important to assume a level of personal responsibility,” he says.
As long as you have prepared properly, stocked the shelves and maybe rented a few movies, riding out a winter storm can be a fun break from the norm. Or as Stillman puts it, “No matter what the forecast, the best weather is always found in bed.”