A Look Back at The Great Appalachian Storm of November 1950 Nov 24, 2017

[Photo credit from Cleveland News, Richard J. Misch via NOAA]

From NOAA NCEI

The Great Appalachian Storm from November 22 to 30, 1950, was a slow-moving, powerful storm system dumped heavy snow across much of the central Appalachians. Known as “The Great Appalachian Storm of 1950,” the storm blanketed areas from western Pennsylvania southward deep into West Virginia with over 30 inches of snow. Several locations even received more than 50 inches of snow. Coburn Creek, West Virginia, reported the greatest snowfall total—a staggering 62 inches.

Frigid Cold, Fierce Winds, and Far-Reaching Floods

Frigid cold also stretched from the Northeast into the Ohio Valley and all the way down into the far Southeast. Temperatures fell to 22°F in Pensacola, Florida, 5°F in Birmingham, Alabama, 3°F in Atlanta, Georgia, and 1°F in Asheville, North Carolina. And, this record cold led to widespread crop damage, particularly in Georgia and South Carolina.

Further north, intense winds associated with the storm caused extensive tree damage, power outages, and coastal flooding in New England. In New Hampshire, Mount Washington observed gusts as high as 160 mph. And, onshore winds along the coast caused extreme high tides and flooding in New Jersey and Connecticut.

After the storm, the eastern half of the country saw above normal temperatures during the first week of December. This led to a fast snowmelt, which flooded several tributaries and major rivers.The Ohio River reached 28.5 feet, 4 feet above flood stage, in Pittsburgh. In Cincinnati, it reached 56 feet, 4 feet above flood stage.

[Surface weather map from November 25, 1950. From NOAA]

At the time, the Great Appalachian Storm of 1950 was one of the costliest storms on record, and it contributed to at least 160 deaths. Overall, on our Regional Snowfall Index, or RSI, this powerful storm ranked as a Category 5—the worst category—for the Ohio Valley and a Category 4 for the Northeast.

Comparing this Storm to Others in the Ohio Valley

The Great Appalachian Storm snowstorm currently ranks as the worst storm to impact the Ohio Valley of the 212 storms our scientists have analyzed for the region. The RSI value of 34.7 securely cements its first place rank above the second worst storm in March 1993, which has an RSI value of 24.6. Only four Category 5 storms have impacted the Ohio Valley since 1900.

During the storm, Pittsburgh, Pennsylvania, received 30.2 inches of snow, and both Erie, Pennsylvania, and Youngstown, Ohio, received more than 28 inches of snow. Across the region, over 18 inches of snow affected more than 6.1 million people. Such high snowfall totals affecting so many people largely contributed to the storm’s high ranking on the RSI scale.

Comparing this Storm to Others in the Northeast

In the Northeast, the Great Appalachian Storm ranks as the ninth worst storm to impact the region of the 203 analyzed. Over 30 inches of snow affecting 1.3 million people in the region largely contributed to the storm’s RSI value of 14.5. With that value, it ranks just behind the more recent February 2003, February 2010, and January 2016 storms.

The late February snowstorm of 1969 remains the strongest storm to hit the Northeast, with an RSI value of 34.0 making it a Category 5 or “Extreme” event. The March 1993 “Storm of the Century” remains the second strongest snowstorm to hit the Northeast, with an RSI value of 22.1 also making it a Category 5 event.

[Surface weather map from November 28, 1950. From NOAA]

The Science Behind the Regional Snowfall Index

To calculate these RSI values, our scientists use a formula that takes into account the snowfall amount within the region’s borders, the spatial extent of the storm, and the relationship of these elements to the area’s population. Then, they categorize the snowstorm’s impacts on a scale from 1 to 5, similar to the Enhanced Fujita scale for tornadoes or the Saffir–Simpson scale for hurricanes.

Because our scientists produce separate indices for six climate regions in the eastern two-thirds of the United States, they can account for both regional variations in snowfall patterns and how the amount of snow disrupts areas of the country differently. For example, 10 inches of snow would have much less of an impact in the Northeast than it would in the Southeast. And, the RSI values and rankings for each storm reflect that for each region that’s affected.

NCEI scientists have also calculated RSI values for nearly 600 snowstorms, going as far back as 1900. And, they add new storms each year as they occur. So, the RSI not only helps local officials better understand the impacts of each major snowstorm, but it also provides a historical perspective that allows them to better prepare for future storms.

Edited for WeatherNation by Meteorologist Mace Michaels

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