STERLING, Va. -- Residents of Howard County got a scare yesterday when forecasters in Virginia issued a tornado warning after at least one funnel cloud appeared near Columbia in advance of a severe thunderstorm.
No wind damage was reported and there was no sign that a tornado touched down. But the broadcast warnings rattled television and radio audiences and, combined with heavy rains just before 3 p.m., prompted some school officials to delay dismissals.
The events demonstrated how the National Weather Service's Skywarn observer network and new Doppler radar technology can act in minutes -- from 60 miles away -- to warn Baltimore-area residents of a weather emergency that could threaten lives and property.
Closure of the weather service office at Baltimore-Washington International Airport earlier this year has not diminished the accuracy or timeliness of such warnings, according to James P. Travers. He is meteorologist-in-charge at the forecast office in Sterling, Va. -- the office that now issues forecasts and warnings for the Baltimore region.
"The fact is, with all the high-tech equipment available today, we are in a better position to issue short-term forecasts and warnings than we ever have been in the past," Travers said.
Howard schools spokeswoman Patti Caplan said five classrooms Howard High School in Ellicott City were heavily flooded by the storm. The school's second floor also suffered water damage. No damage estimate was available, but the school expected to open on time today.
The Elkridge, Phelps Luck and Rockburn elementary schools -- all in eastern Howard County -- kept students indoors and delayed school buses for up to a half-hour to protect children from the storm, Caplan said. Local radio and television stations advised parents of the delay.
Yesterday's tornado warnings came barely five weeks after a powerful tornado struck parts of Carroll County.
Hours before yesterday's alert, thunderstorms drifted east across Central Maryland, producing up to 2 inches of rain in eastern Montgomery, central Howard, southeastern Carroll, and western Baltimore counties. Street flooding was reported in Eldersburg, in Carroll County, after 2: 30 p.m.
More than 1,800 Baltimore Gas and Electric Co. customers, most in Baltimore City and Howard and Anne Arundel counties, lost electricity after lightning blew out electric fuses, according to Darcel Guy, a BGE spokeswoman. Most power outages were brief, Guy said, and about 200 customers were without electricity at sunset.
The forecast office at Sterling received two reports of ominous developments near Columbia, from a police officer and a trained member of the weather service's 1,500-member Skywarn weather spotter program.
Skywarn observers are taught by the weather service how to identify severe storms and report them to weather authorities. Many also are amateur radio operators who assist in gathering and disseminating information during weather emergencies.
"They actually saw a funnel cloud rotating," said Dr. Alan Nierow, meteorologist at the Sterling center.
The cloud was first reported two miles southwest of Columbia, moving east at 25 mph. Funnel clouds -- the same one or others, it's not clear -- also were reported along Route 29, near Route 103, and near Route 100.
At Sterling, near Dulles International Airport in Northern Virginia, weather officials checked their Doppler radar screens.
Doppler radar is a major advance in weather forecasting. Where older weather radar systems noted the density of rain in a storm cloud, Doppler can discern fine details in the movement of wind and water within a 125-mile radius of the radar dome.
When tornadoes begin to form, color patterns on the Doppler's computer displays can clearly show the characteristic rotation of winds within the thunderstorm -- called a mesocyclone.
When the Doppler operators in the computer-filled control room in Sterling looked yesterday, said Nierow, they saw only "marginal tornadic activity." "This was not a major system," he said. "The cells were very strong, and the atmosphere was very unstable. But there was not much wind to support a large area of tornadoes."
The Doppler data, however, combined with the credible reports from several trained eyewitnesses at the scene, was enough to tip the balance. "We had to issue a warning," Nierow said.
At 2: 54 p.m., the Sterling office asked broadcasters to activate the Emergency Alert System (formerly the Emergency Broadcast System), with warnings for central and eastern Howard County, including the communities of Columbia, Guilford, Jonestown, Ellicott City, Pfeiffer Corners, Ilchester and Harwood Park.
WTOP News Radio in Washington interrupted its regular programming with a high-pitched tone before the warning was delivered.
WBAL Radio in Baltimore does not routinely activate the EAS system, opting instead to announce the warning as part of its regular news-talk programming. Yesterday, it broadcast the warning on the 3 p.m. newscast. News Director Mark Miller said the warning was repeated at least five times before it expired at 3: 30 p.m.
From 1950 through 1995, 172 tornadoes have been recorded in Maryland -- an average of 3.8 per year. But meteorologists have long believed that barely a third of all the tornadoes that form were actually spotted.
Doppler radar, and the expansion of the Skywarn spotter system in recent years, may prove that hunch to be conservative.
Since 1992, after the installation of Doppler equipment at Sterling, 64 tornadoes have been recorded in Maryland -- an average of 16 per year through 1995.
The annual counts have set and reset records, with 13 in 1992, 21 in 1994 and 24 in 1995.
So far in 1996, the weather service has confirmed 15 tornadoes in Maryland.
Even so, the powerful tornadoes seen in other parts of the country are still rare here. Eighty percent of the state's tornadoes are Force 0 or Force 1 storms, with winds less than 115 mph.
The "Gamber Tornado" that struck July 19 in Carroll County was an exception. That was a Force 3 storm, with winds of 175-200 mph. It left a three-mile path of destruction up to 400 yards wide, damaged 67 homes and hurled two young boys from their second-floor bedroom. Neither they nor anyone else was seriously hurt.
Pub Date: 8/28/96