Last Updated on January 12, 2016 2:46 pm
*Photo: Joan Price. Information via Grandfather Mountain*
While many folks were dreaming of a white Christmas, Grandfather Mountain was experiencing the warmest holiday in the mountain’s recorded history.
According to weather data collected at the Mile High Swinging Bridge, temperatures from December 2015 shattered seven records among Grandfather’s 60 years of weather recording.
On Christmas Day, Dec. 25, the mountain recorded a high temperature of 60 degrees Fahrenheit, 8 degrees warmer than the previous record of 52 degrees from Dec. 25, 1955.
Warm temperatures became something of a broken record this past December — and in more ways than one. The mountain experienced record highs on Dec. 12, 13, 22, 23, 25, 26 and 29, the warmest day being Dec. 12, 2015, at 60.65 degrees.
These temperatures weren’t only unique to Grandfather, however. According to the State Climate Office of North Carolina, “By all measures — average high, average low and average mean temperatures — this December was the warmest on record since 1895 across North Carolina. The average statewide temperature of 53.64 (degrees Fahrenheit) was a full 3 degrees warmer than the second-warmest December in 1956.”
The climate office attributes this to a strong polar vortex in the upper atmosphere, which helped to bottle up cold air near the North Pole.
“With no cold air to spare and a persistent ridge in the jet stream over the East Coast, the eastern half of the United States experienced its warmest December on record,” the office reported.
In 2015, the mountain experienced a temperature range of 95.44 degrees. The warmest temperature of the year came on June 24, with a high of 79.08 degrees, slightly below the record high of 83.2 degrees on July 1, 2012.
2015’s lowest recorded temperature of -16.36 occurred on Feb. 19, coming in above the record low of -32 degrees on Jan. 21, 1985.
Rainfall
The weather station at the Mile High Swinging Bridge recorded 67.13 inches of precipitation in 2015, including 10.19 inches in September, the rainiest month.
That’s roughly one inch shy of Grandfather Mountain’s one-day rain record of 11.3 inches, recorded Sept. 8, 2004.
The 2015 total is about three inches more than the mountain’s 60-year average annual rainfall, 63.80 inches, and significantly higher than 2014’s sum of 50.62 inches.
Due to high winds, however, rain data collected at the bridge often amounts to lower totals than other collection areas on the mountain. In 2015, data gathered at the mountain’s Nature Museum and Entrance Gate reflected an average of 85.85 inches of rainfall.
Wind
Love was in the air on Valentine’s Day, Feb. 14, but the air just happened to be moving at 97.6 mph, which was the highest sustained gust of 2015.
The mountain’s wind record still stands at 120.7 mph, recorded in December 2012.
Winds gusted above 60 mph at least 58 days in 2015.
Weather for the Birds
While late 2015 saw many records breaking, September found one in the making.
Every fall, thousands of raptors migrate from Canada and the Eastern Seaboard along the Appalachian Mountains to Central and South America, using thermal air columns to gain lift and glide above the peaks toward their warmer destinations.
Each September, Grandfather Mountain collects data for the official Hawk Watch (www.hawkcount.org), during which trained counters record the number and type of raptors passing above, including bald eagles, golden eagles, peregrine falcons, broad-wing hawks, red-tailed hawks and others.
Grandfather is considered an ideal spot for viewing, because it sits along the eastern escarpment of the Appalachian Mountains, and its rocky peaks generate strong thermals and allow prime visibility.
On Sept. 23, however, “prime” became something of an understatement, when Grandfather Mountain Stewardship Foundation executive director Jesse Pope and company spotted 9,714 broad-wing hawks.
The largest kettle contained some 4,800 broad-wings, which “passed over in less than 30 minutes in one continuous stream of hawks,” Pope said. “At one point, the stream that formed over Beech Mountain stretched for three-quarters of a mile.”
Pope called it “by far, the best day ever recorded at Grandfather Mountain” and attributes the high volume to an unusually rainy September.
“It was certainly an unusual season for Hawk Watch this year, due to the rainy weather,” he said. “That was a huge factor in the large number of hawks we spotted that day.”
All in all, Hawk Watch volunteers logged more than 130 hours on the mountain, counting some 10,739 hawks in the process.
Grandfather and the Weather
The official U.S. National Weather Service reporting station, located near the Mile High Swinging Bridge, has been providing daily weather observations since August 1955.
The Grandfather Mountain Stewardship Foundation also works with Appalachian State University to measure weather from the bridge and top parking lot.
With rare exceptions, the temperature will be 10 to 20 degrees cooler at Grandfather Mountain than in the flatlands below. The average rate is 2.2 degrees per 1,000 feet, meaning that for each thousand feet gained, the air is 2.2 degrees cooler.
For more information on Grandfather Mountain's weather or to access current conditions, visit grandfather.com.
