March 25: The day when first tornado forecast was issued in US, 73 years ago

New Delhi: It was March 25, 1948, when a tornado roared through through Tinker Air Force Base (AFB), Oklahoma which caused considerable damage, a few injuries, but no fatalities. It was Air Force Captain Robert C. Miller and Major Ernest J. Fawbush who just a few hours earlier correctly predicted that atmospheric conditions were ripe for tornadoes in the vicinity of Tinker AFB.

The tornado left $6 million dollars in damage, $4 million less than the first storm which occurred just only five days earlier.

The Events Leading Up to the Forecast

Miller and Fawbush made this historic forecast with some reservation. Until March 25, 1948, tornadoes had not been forecast and many in the science community were uncertain that storms that developed so quickly and with such force could be forecast in advance.

A key factor in the command’s decision to issue the historic forecast on that day was a fierce tornado that swept through the same area only five days earlier, March 20, 1948. The storm left significant damage and some fatalities. Some wondered if that March 20, 1948, storm could have been forecast. A board that was convened to investigate decided that “due to the nature of the storm it was not forecastable given the present state of the art” and that “it was an act of God.” The board also recommended that the meteorological community consider efforts to determine a method of alerting the public to these storms and urged base commanders to develop safety precautions to minimize personnel and property losses in violent storms.

The problem faced by the forecaster was to consider the current surface and upper air data, determine the existence of these parameters or the probability of their development, and then project the parameters in space and time in order to issue the “tornado threat area” with a reasonable degree of confidence and leadtime. The size of the threat area would cover 20-30,000 square miles. Such a detailed forecast procedure was time and labor consuming and required intensive and specialized analysis.

On the morning weather charts of March 25, 1948, Miller and Fawbush noted a great similarity between the charts of March 20 and March 25, 1948. After analyzing the surface and upper-air data, a prognostic chart was prepared for 6 p.m. local time showing the expected position of the various critical parameters. This chart resulted in the somewhat unsettling conclusion that central Oklahoma would be in the primary tornado threat area by late afternoon and early evening. General Borum was notified and shortly thereafter arrived at the weather station.

After hearing these helpful observations, the General asked what time would be the most critical. “Between 5 and 6 p.m.,” said Miller and Fawbush. General Borum decided the forecasters should issue a forecast for heavy thunderstorms during that period. He patiently explained that such a move would serve to alert the base and put in motion a brand new, and detailed, base warning system into effect. The thunderstorm warning was issued.

The squall line was fully developed by 3:30 p.m and continued to move steadily toward Oklahoma City. There had been no reports of tornadoes nor any reports of hail and high winds, as yet. Shortly after 5 p.m. the squall line passed through Will Rogers Municipal Airport, bringing a light thunderstorm, wind gusts to 26 mph and pea size hail. A little after 6 p.m. it began to thunder rather quietly and rain began. There was very little wind. Shortly thereafter, radio broadcasts were interrupted for an urgent news bulletin. A destructive tornado touched down at Tinker Field.

The base was in shambles. Poles and powerlines were down and debris was strewn everywhere. Emergency crews were busy trying to restore power, clear the streets and, in particular, to restore the main runway to operational status. General Borum’s Tornado Disaster Plan had been just as successful as the first operational tornado forecast. Miller and Fawbush became instant heroes.