“The Snowstorm of the Century” The Snow Just Kept On Falling from March 3 to 5, 1971
Commemorative Report of the Snowstorm of March 3–5, 1971 Part of a Series on Extreme Weather in Quebec March 2001
Series on Extreme Weather in Quebec CES-Q99-02
Perrier R. and M. Slivitzky (1999), Overview of Heavy Rainfall events in Quebec, Scientific Report, in collaboration with Environment Canada, Quebec Region, 48 pp.
CES-Q99-01
Milton J. and A. Bourque (1999), A Climatological Account of the January 1998 Ice Storm in Quebec, 2nd edition, Atmospheric Sciences and Environmental Issues, Environment Canada, Quebec Region, 87 pp.
CES-Q98-01
Milton J. and A. Bourque (1998), A Climatological Account of the January 1998 Ice Storm in Quebec, 2nd edition, Atmospheric Sciences and Environmental Issues, Environment Canada, Quebec Region, 87 pp.
Other reports/studies on extreme weather in Quebec ENVIRONMENT CANADA (1998), Characterization of Rainfalls of November 7-10, 1996, over southern Quebec, Scientific Services Division, Quebec Region, 69 pp. ENVIRONMENT CANADA (1997), Torrential rains of July 18 to 21 1996, in the province of Quebec: Analysis and interpretation of meteorological and climatological data, Scientific Services Division, Quebec Region, September 9, 1997, 103 pp. ENVIRONMENT CANADA (1987), Les pluies du 14 juillet 1987 dans la région de Montréal/July 14th 1987 rainstorm in the Montreal area, Expert Report, Environment Canada, Scientific Services Division, 52 pp.
For more information: Centre de Ressources en Impacts et Adaptation au Climat et à ses Changements - CRIACC Place Bonaventure, Portail Nord-Est, 800, rue de la Gauchetière Ouest, suite 7810 Montréal (Québec), Canada H5A 1L9 E-mail :
[email protected] Internet address: www.criacc.qc.ca Aussi disponible en français
‘The Snowstorm of the Century,’ March 3–5, 1971 Some called the March 1971 storm the “storm of the century.” Thirty years after the event and now that we are in the 21st century, did that turn out to be true? This brief report describes the weather conditions in Montreal at the time of the famous snowstorm and compares it to three other significant snowstorms recorded at the Montreal-Dorval station since the early 1940s. The three other storms, classified by snowfall amount, occurred on December 26–28, 1969, February 16–17, 1954, and March 26–27, 1955 (Appendix A). Each of these storms clearly had significant impacts, which were related to the socio-economic conditions of the time. However, the most notable characteristic of the March 1971 storm was not necessarily the amount of snowfall (fourth among the four storms), but rather the combination of three other factors: snowfall intensity, wind speed, and depth of snow on the ground at the beginning of the storm. Synoptic description The storm was caused by a coastal low-pressure system from the Carolinas that intensified rapidly after 00:00 GMT on March 4, 1971, (19:00 EST on March 3, 1971) as it passed over Virginia. The low was located in New York State at 966 mb on March 4 at 12:00 GMT, after deepening 33 mb in 12 hours. It continued its northeasterly course while slowly filling, moving into New Brunswick on March 5 at 12:00 GMT. At that time, it had a central pressure of 974 mb. Progression of the storm Figures 2 and 3 show the hourly progression of wind speed and visibility at the MontrealDorval International Airport and Quebec City Airport. Visibility at Dorval diminished gradually as the snow began to fall, dropping dramatically in the evening of March 3 as the wind intensity increased. Visibility was reduced to less than 1 km due to moderate snow and blowing snow for at least 17 hours. It was also during this period that Dorval recorded wind speeds of 70–75 km/h with gusts to nearly 110 km/h. Conditions in Quebec City were similar but deteriorated much more rapidly after the snow began to fall. The average winds associated with this storm were stronger at this station and contributed to the rapid reduction in visibility after the snow started falling. There was a lag of nearly 18 hours between the onset of the storm at these two stations. The storm progressed in a similar manner in other parts of the province. Snowfall associated with moderate to strong winds quickly reduced visibility to less than 0.5 km for periods of up to 24 hours (Appendix B).
March 6, 2001
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Storm of March 3–5, 1971, at Montreal-Dorval Int'l 80.0
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Figure 1: Wind speed and hourly visibility at Dorval-Montreal Int’l airport, from March 3, 1971, 00:00 EST to March 4, 1971, 22:00 EST Storm of March 3–5, 1971, at Quebec City A 45
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Figure 2: Wind speed and hourly visibility at Quebec City Airport, from March 4, 1971, 00:00 EST to March 5, 1971, 12:00 EST
March 6, 2001
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Comparison of the storms Table 1 shows specific meteorological and climatological parameters measured during the four heaviest snowstorms at Montreal-Dorval. The following observations can be made from the data: 1. The average daily temperatures were relatively similar (with the exception of February 1954) for all storms; 2. Of the four storms, the March 1971 storm at Montreal-Dorval had the least amount of snowfall; 3. The depth of snow on the ground, an important factor at the start of a storm, was 56 cm; 4. The average wind speed for March 4, 1971 as well as the maximum hourly wind speed were the strongest recorded; 5. The maximum wind gusts recorded on March 4 were severe, reaching up to 108 km/h; 6. The combination of strong to severe winds, significant depth of snow on the ground and amount of snowfall all contributed to aggravate the effects of the storm of March 3–4, 1971, at Montreal. Montreal-Dorval Station Average temperature (°C) Snowfall (cm) Total storm snowfall Snow on the ground (cm) (08:00 EST)
Average hourly winds (km/h) Maximum hourly wind (km/h) Maximum wind gust (km/h)
March 1971 Storm 4 3 -8.1 -5 3.8 43.2 47 56 66 17.3 43.1 31 74 43 108
December 1969 Storm 26 27 -9.5 -5 15 37.8 5 36.2 61 77
30 24.3 40 72
28 -5.3 6.1 58.9 53 21 26
