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Tuesday, 26 November 2019

The 1993 Storm of the Century

The 1993 Storm of the Century The blizzard of March 12 to 14, 1993 remains one of the worst U.S. snowstorms since the Great Blizzard of 1888, and its no surprise, considering that the storm stretched from Cuba to Nova Scotia, Canada, affected 100 million people across 26 states, and caused $6.65 billion in damage. By the storms end, 310 fatalities had been reported, more than three times the number of lives lost during Hurricanes Andrew and Hugo combined. Storm Origin and Track On the morning of March 11, a strong ridge of high pressure sat just offshore the U.S. west coast. Its position oriented the jet stream so that it plunged south out of the Arctic, allowing unseasonably cold air to flow into the U.S. east of the Rocky Mountains. Meanwhile, a low-pressure system was developing near Brownsville, TX. Fed by a number of upper air disturbances, energy from jet stream winds, and moisture from the north-central Gulf of Mexico, the low began to rapidly strengthen. The storms center traveled near Tallahassee, FL, in the pre-dawn hours of March 13. It continued north-northeastward, centering over southern Georgia near mid-day and over New England that evening. Near midnight, the storm deepened to a central pressure of 960 mb while over the Chesapeake Bay area. Thats the equivalent pressure of a Category 3 hurricane! Storm Impacts As a result of heavy snow and high winds, most cities across the Eastern Seaboard shut down or were completely inaccessible for days. Because of such societal impacts, this storm has been assigned the highest rank of extreme on the Northeast Snowfall Impact Scale (NESIS). Along the Gulf of Mexico: The Florida panhandle received up to 4 inches (10.2 cm) of snowA squall line out ahead of the cold front caused a powerful derecho (straight-line windstorm) with gusts in excess of 100 mph (160 km/h) felt down to Havana, CubaA Supercell spawned 11 tornadoes across the Sunshine State, ranging from F0 to F2 in intensityA 12-foot (3.7 m) storm surge caused flooding along the coasts of western Florida and northern Cuba In the South: Accumulations ranged from 3-5 feet (0.9 to 1.5 m)Snow drifts of up to 15 feet (4.6 m) were reported at Mount Mitchell, NCRare convective elements such as lightning, thundersnow, and snowfall rates of 2 to 4 inches (5.1 to 10.2 cm) per hour were experiencedHundreds of thousands of residents were left without electricity for up to a week In the Northeast Canada: Accumulations ranged from 15 to 45 inches (38.1 cm to 1.1m)Syracuse, NY, broke five of its snowfall records, including 24-hr snowfall, maximum daily snowfalls for March 13 and 14, snowiest March, and snowiest seasonWith the storms passage, New Brunswick, Canada, reported a 45 F (7 C) temperature drop within 18 hours Forecasting Success National Weather Service (NWS) meteorologists first noticed signs that a fierce winter storm was brewing during the preceding week. Due to recent advances in computer forecast models (including the use of ensemble forecasts), they were able to accurately forecast and issue storm warnings two days in advance of the storms arrival. This was the first time the NWS forecasted a storm of this magnitude and did so with several days lead time. But despite warnings that a big one was on the way, public response was one of disbelief. The weather preceding the blizzard was unseasonably mild and didnt support the news that a winter storm of historic proportions was imminent. Record Numbers The Blizzard of 1993 broke dozens of records of its time, including over 60 record lows. The top fives for U.S. snowfall, temperature, and wind gusts are listed here: Snow Totals: 56 inches (142.2 cm) on Mount LeConte, TN50 inches (127 cm) on Mount Mitchell, NC44 inches (111.8 cm) at Snowshoe, WV43 inches (109.2 cm) at Syracuse, NY36 inches (91.4 cm) at Latrobe, PA Minimum Temperatures: -12 F (-24.4 Â °C) in Burlington, VT and Caribou, ME-11 F (-23.9 Â °C) in Syracuse, NY-10 F (-23.3 Â °C) on Mount LeConte, TN-5 F (-20.6 Â °C) in Elkins, WV-4 F (-20 Â °C) in Waynesville, NC and Rochester, NY Wind Gusts: 144 mph (231.7 km/h) on Mount Washington, NH109 mph (175.4 km/h) at Dry Tortugas, FL (Key West)101 mph (162.5 km/h) on Flattop Mountain, NC98 mph (157.7 km/h) at South Timbalier, LA92 mph (148.1 km/h) on South Marsh Island, LA

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