Eighty-nine years ago today, Mount Washington Observatory, in its second year of existence, recorded a world-record wind speed of 231 miles per hour – a record that would stand for over 60 years.
Although a higher wind speed has since been recorded elsewhere (Tropical Cyclone Olivia, Barrow Island, Australia, April 10, 1996), the Observatory’s measurement of the “Big Wind” on April 12, 1934 still stands as the fastest wind speed ever recorded by a staffed weather station.
The ambitious weather observers atop Mount Washington had been hoping to achieve such a record, yet no one anticipated that it would occur on that particular day.
In fact, neither the Observatory team nor the consulting meteorologists at the Massachusetts Institute of Technology and Blue Hill Observatory expected the winds to reach such a historic velocity.
“We found it out as the day went on,” mentioned Observer Sal Pagliuca in his logbook. Pagliuca, with fellow observers Alex McKenzie and Wendell F. Stephenson (Steve), were only expecting a wind event of 150 mph or so – an occurrence fairly common for the mountaintop weather station. Given the somewhat typical atmospheric setup for the day, it is understandable why.
Low pressure centered north of the Great Lakes and over Connecticut paired with an area of high-pressure over the Canadian Maritimes, creating a tight pressure gradient oriented diagonally across the White Mountain region. A tight pressure gradient, or the rapid change in pressure across a horizontal distance, is a good indicator of high winds and the direction from which they will blow.
Although elevated winds were expected on Mount Washington on this day, nothing extraordinary was hinting towards a historic event. The following is a summary of Pagliuca’s log entries from the event and Alex McKenzie’s publication, World Record Wind – Measuring Gusts of 231 Miles an Hour.
The morning of April 11 began with better-than-usual conditions on the summit of Mount Washington. Good visibility, winds blowing at a mellow (for Mount Washington standards) 55 mph, and only a few cirrus clouds disrupting the sun soaked skies.
High cirrus clouds on an otherwise clear day usually indicate that unsettled weather is approaching. This is typically followed by clouds progressively becoming more dense and lowering in altitude, warning that deteriorating weather conditions are on their way.
As the summit crew took advantage of the pleasant conditions, clouds slowly began thickening and lowering while a low cumulus layer appeared in the distant east.
Mckenzie wrote, “Sal had summed up these ominous indications in the phrase ‘emissary sky,’ meaning that we were receiving messengers with bad news.”
The summit entered the fog by noon, initiating the formation of glaze ice on all surfaces. This was a surprise to the summit team, as northwest winds are typically dry, steady, and result in rime ice. On this day, however, glaze ice indicated chaotic winds of varying speeds and directions with very high moisture content in the air around them.
Just a couple hours later, winds had accelerated to 103 mph and shifted southeast, an atypical direction for the summit weather station. After an otherwise normal winter day on Mount Washington, the summit team went off to bed on the evening of April 11, unsuspecting of the magnitude of the meteorological event that was about to unfold.
McKenzie took on the night shift alone, wanting to maintain hourly radio signal measurements until at least 2 a.m. The lone observer recalled that the stage office shook more heavily than usual and the doors rattled louder than is typical, but it otherwise seemed like a normal night. After retiring to rest around 1:30 a.m., McKenzie handed over his duties to Stephenson.
Alex McKenzie, in front, works with Joe Dodge in the radio room in the 1930s.
Periodically dozing off during his watch, Stephenson was abruptly awakened by a strong gust of wind on the morning of April 12. Upon checking the wind speed, he noticed that the instruments were reading much lower than he thought was true. This meant it was necessary for him to go outside and deice the anemometer in what he believed to be the fastest winds he had ever experienced on the mountain. After making the treacherous climb to deice the anemometer, winds were registering about 150 mph from the southeast.
At left, a weather observer climbs to the anemometer. The original Mount Washington Observatory was located in the Stage Office of the Mount Washington Summit Road Company. The Observatory's anemometer is shown at right.
Even though conditions were dangerous, the observation team took their jobs seriously and normal Observatory operations continued. This included walking outside to collect precipitation cans, periodically clearing the anemometer of ice, and various other tasks.
As the morning wore on, prevailing winds of 150 mph or so were holding steady. At this time, the method for measuring wind speed involved linking the anemometer to a telegraph sounder. A stopwatch was used to measure the time that had elapsed after three clicks of the telegraph sounder. After performing a calculation and applying corrections, this could then be translated into a wind speed.
Exhausted after several hours of 150 mph winds, McKenzie, Pagliuca, and Stephenson longed for either a decrease in wind speeds or stronger gusts worth measuring. The telegraph sounder was kept on due to the significance of the storm, and the monotony of constant ticking wore down on their nerves.
Pagliuca joked, “We are conducting a psychological experiment,” after Stephenson suggested that they turn it off. Nevertheless, the device remained on throughout the event and the team passed the test.
By the early afternoon, Stephenson reported an average wind speed of 173 mph with gusts of 220+ mph. His fellow observers could not believe this, insisting that they time the gusts themselves. When Pagliuca began measuring with the stopwatch, the telegraph clicks suddenly increased in frequency. Timing the next three clicks only took 1.17 seconds. Although the calculation to translate this into a wind speed had not been done yet, Pagliuca recalls knowing immediately that it was a record.
After a brief lull in the wind, Pagliuca heard the telegraph clicks increase in frequency once again, and timed three clicks in 1.17 seconds another time. Upon performing the calculation, the summit team was astonished at what they had just witnessed – two wind gusts of 231 mph.
“We had measured by means of an anemometer the highest natural wind velocity ever recorded officially anywhere in the world,” he wrote in his logbook.
A page from Sal Pagliuca's logbook entry about the recording of the Big Wind.