Wednesday morning, January 17, the SCAD Science Club hosted WSAV weekend meteorologist Lee Haywood for a lecture that focused on this month’s rare Savannah snowfall and the importance of understanding fluctuating climate conditions.
Haywood began his lecture by asking how many in the Arnold Hall classroom of students and faculty had witnessed Savannah’s January 3 snowfall.
“It was a blast,” Haywood said. “It was very, very exciting. There were areas of the city that had a couple inches of snow. How rare is that? Well, it’s very rare. It’s rare to see the type of storm that we had strengthen so rapidly and produce such intense weather up and down the eastern seaboard.”
During his presentation, Haywood referred to satellite imagery and satellite animations that showed the storm’s trajectory, including the “bomb cyclone” effect the storm had on various regions. According to Haywood, the storm formed east of Florida before it pulled up the coast.
“The storm itself developed an actual eye,” Haywood said. “It’s very unusual to see mid-latitude storms develop an eye. Everybody knows a hurricane has an eye and an eye wall. This storm itself actually developed an eye, so it’s very intense as it moves to the north.”
Haywood said the storm was referred to as a “northeaster,” because it moved up through the northeastern part of the country. The storm, according to Haywood, produced intense northeast winds, which lead to the creation of a bomb cyclone.
“What a bomb cyclone essentially is is a storm that produces a drop in air pressure of 24 millibars in 24 hours,” Haywood explained. “For those of you who aren’t familiar with pressure, that in itself is an incredible drop of pressure. Keep in mind our pressure on a day-to-day basis in Savannah . . . they only drop one millibar. That’s a whole day. Now if you get a storm system coming through, it might drop maybe a couple of millibars. But 24 millibars with a low-pressure drop is pretty significant.”
During the Savannah snow storm, Haywood said the pressure dropped 59 millibars in 24 hours, doubling the definition of a bomb cyclone. Haywood referenced the analogs he and his team used to find a Savannah storm in history that was similar to this year’s snowfall.
“Analogs are essentially looking back to what was a storm like in the past that matched this one,” Haywood said. “And if you take a look, the past comparable storm to the one we saw on the east coast the date of January 3 through the 5 was a storm that was back in 1989. Interestingly enough, it was actually on the same date, about January 4, and the pressure dropped an astounding 60 millibars in 24 hours. You essentially had about the same drop in the same area, and what we did was look at the same area because storms deepen in different parts of the ocean base at a different rate. Some storms in the Pacific deepen a little bit more than storms over the Atlantic.”
Based on weather records over the last 50 years, Haywood found that the return recurrence of these types of storms is roughly every 25 to 30 years.
“What’s even more unusual about a storm like this is to combine a storm that was a 25 to 30-year storm with one of the biggest shots of cold air Savannah has seen in potentially 20 to 30 years,” Haywood said. “Think about this. How neat to combine the extreme cold and the extreme nature of the low pressure. It meant that we were producing snowfall in our area.”
Haywood explained that usually when it gets cold in Savannah, the temperature rises and falls quickly. Because Savannah is in a subtropic region of the United States, a shot of cold air is, as Haywood calls it, progressive, meaning it passes through swiftly. With this year’s storm, the nature of the shot of arctic air was nonprogressive until it was reinforced by northern winds.
For Haywood, the storm’s most fascinating feature was its low temperatures. “The most amazing statistic is that four nights in a row, Savannah had low temperatures between 19 to 21 degrees,” Haywood said. “I have never seen that in my 18 years here, and I’ve looked back at the books, and I haven’t seen that either, and the books date back to the 1870s.”
