By FRANK LEWIS
PDT Staff Writer
Have you been wondering why forecasters have been calling for snow, only to wake up and find out it never materialized? Have you asked why forecasters have said it is going to rain, and you take you umbrella to work, only to find out you don’t need it? Meteorologists say there is a very good reason.
“It’s a virga, which means (precipitation) is evaporating before it reaches the ground,” meteorologist Myron Padgett said. “It may look like precipitation showing up on the radar, but most of it is aloft and it’s not now reaching the ground.”
In meteorology, virga is an observable streak or shaft of precipitation that falls from a cloud but evaporates before reaching the ground. At high altitudes the precipitation falls mainly as ice crystals before melting and finally evaporating; this is usually due to compressional heating, because the air pressure increases closer to the ground.
Last week, some forecasts had predicted 2 to 3 inches of snow, but that snow did not come far enough north to reach this area. The U.S. Weather service at Wilmington did not make that prediction until Saturday. Even then it didn’t arrive.
“Our forecast is based a lot on computer models and 50 miles can make a big difference,” Padgett said. “So it’s difficult to tell sometimes in the near-term especially two or three days out. Fifty or a hundred miles can make a big difference in what you get. Temperatures have been too warm for some of the snow to be produced. Some places have had some snowfall, but a lot of it has been melting as it reached the ground.”
According to officials of the Scioto County Emergency Management Agency, it looked as if a recent storm stopped at the Ohio River and made a turn eastward.
“This past storm had a very abrupt northern cutoff,” Scioto County EMA Director Kim Carver said. “And they were not sure how far north that cutoff would go. It was very difficult with this last storm particularly to forecast where the snow line would be. Everybody was talking about how difficult it was to forecast this last storm. The computer models that guide their forecast were all over the place during this last storm. One day they would show a significant snow dump further north. The next day it would be a more southern track.”
Carver said there is no way to be completely sure of what the weather will be.
“As far as we have come with the science, it still seems that there are difficulties in 100 percent accuracy in forecasting,” Carver said. “We’ve made leaps and bounds in technology. Still that is a hard thing to do.”
Carver said there will be two opportunities for local weather enthusiasts to learn more about meteorology and how they can help their communities in times of severe weather coming up this spring. Carver said there will be training April 23 for a new program known as COCORAHS (Community Collaborative Rain, Hail and Snow Network) that uses volunteers to identify precipitation in a given area. March 15, the NWS will hold its annual Weather Spotter Training Program that provides information on local weather patterns and how to identify and report specific types of weather occurring locally to the weather office at Wilmington.
April 23 training will be from 6:30 to 7:30 p.m., while the March 15 training will be from 4 to 6 p.m., both at Southern Ohio Medical Center East Campus in the Gibson Building meeting room on the main floor. That building is at 2201 25th St., Portsmouth.
Frank Lewis may be reached at 740-353-3101, ext. 232, or at firstname.lastname@example.org.