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1993 Storm of the Century

Category 5 nor'easter in the United States

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A satellite image of the 1993 Storm of the Century wreaking havoc to the Eastern United States on March 13 at 14:31 UTC.
NOAA (GOES-7), NASA · Public domain

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Through Cyclone, Canada and Atlantic Ocean

Heavy snow was first reported in highland areas as far south as Alabama and northern Georgia, with Union County, Georgia reporting up to 35 inches (89 cm) of snow. Birmingham, Alabama, reported a rare 13 in (33 cm) of snow. with hurricane-force gusts up to 145 mph (213 ft/s) (Recorded in Mount Washington, New Hampshire) and record low barometric pressures. Between Louisiana and Cuba, the hurricane-force winds produced high storm surges across the Big Bend of Florida which, in combination with scattered tornadoes, killed dozens of people.

Record cold temperatures were seen across portions of the Southern United States and Eastern United States in the wake of this storm. In the United States, the storm was responsible for the loss of electric power to more than 10 million households. An estimated 40 percent of the country's population experienced the effects of the storm and it led to a total of 208 fatalities. In all, the storm resulted in 318 deaths, and caused $5.5 billion (1993 USD) in damages.

The greatest recorded snowfall amounts were at Mount Le Conte in Tennessee, where 56 inches (140 cm) of snow fell, and Mount Mitchell in North Carolina, the tallest mountain in eastern North America, where 50 inches (130 cm) was measured to fall and 15-foot (4.6 m) snow drifts were reported.

Meteorological history

A volcanic winter is thought to have started with the 1991 eruption of Mount Pinatubo. The temperature in the stratosphere rose to several degrees higher than normal, due to the absorption of radiation by the aerosol. The stratospheric cloud from the eruption persisted in the atmosphere for three years. The eruption, while not directly responsible, may have played a part in the formation of the 1993 Storm of the Century.

During March 11 and 12, 1993, temperatures over much of the eastern United States began to drop as an arctic high pressure system built over the Midwestern United States and the Great Plains. Concurrently, an extratropical area of low pressure formed over Mexico along a stationary front draped west to east. By the afternoon of March 12, a defined airmass boundary was present along the deepening low. An initial burst of convective precipitation off the southern coast of Texas (facilitated by the transport of tropical moisture into the region) enabled initial intensification of the surface feature on March 12. Supported by a strong split-polar jet stream and a shortwave trough, the nascent system rapidly deepened. The system's central pressure fell to 991 mbar (991.0 hPa; 29.26 inHg) by 00:00 UTC on March 13. A powerful low-level jet over eastern Cuba and the Gulf of Mexico enhanced a cold front extending from the low southward to the Isthmus of Tehuantepec. Furthermore, the subtropical jet stream was displaced unusually far south, reaching into the Pacific Ocean near Central America and extending toward Honduras and Jamaica. Intense ageostrophic flow was noted over the southern United States, with winds flowing perpendicular to isobars over Louisiana.

As the area of low pressure moved through the central Gulf of Mexico, a short wave trough in the northern branch of the jet stream fused with the system in the southern stream, which further strengthened the surface low. A squall line developed along the system's cold front, which moved rapidly across the eastern Gulf of Mexico through Florida and Cuba. The cyclone's center moved into north-west Florida early on the morning of March 13, with a significant storm surge in the northwestern Florida peninsula that drowned several people. This initially caused the storm to be a blizzard but also cyclonic.

Barometric pressures recorded during the storm were low. Readings of 976 mb (976 hPa; 28.8 inHg) were recorded in Tallahassee, Florida, and even lower readings of 960 millibars (960 hPa; 28 inHg) were observed in New England. Low pressure records for March were set in areas of twelve states along the Eastern Seaboard, with all-time low pressure records set between Tallahassee and Washington, D.C. Snow began to spread over the eastern United States, and a large squall line moved from the Gulf of Mexico into Florida and Cuba. The storm system tracked up the East Coast during Saturday and into Canada by early Monday morning. In the storm's wake, unseasonably cold temperatures were recorded over the next two days in the Southeast.

Forecasting

The Storm of the Century marked a milestone in the weather forecasting of the United States. By March 8, 1993, several operational numerical weather prediction models and medium-range forecasters at the United States National Weather Service recognized the threat of a significant snowstorm. This marked the first time National Weather Service meteorologists were able to predict accurately a system's severity five days in advance. Official blizzard warnings were issued two days before the storm arrived, as shorter-range models began to confirm the predictions. Forecasters were finally confident enough of the computer-forecast models to support decisions by several northeastern states to declare a state of emergency even before the snow started to fall.

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