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Technical Note (National Research Council of Canada. Division of Building Research), 1960-07-01
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Discussions with Dr. T. Zingg on the Weather Forecast Required for Avalanche Hazard Forecast
Schaerer, P. A.
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DIVISION OF BUILDING RESEARCH
NATIONAL RESEARCH COUNCIL OF CANADA
.
-TEClHIN ][CAlL
NOT FOR PUBLICATION
NOTlE
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FOR INTERNAL USE
PREPARED BY Po Schaerer CHECKED BY L. W. G. APPROVED BY
July 1960
PREPARED FOR Record purposes
SUBJECT
Discussions with
Dr.
T. Zingg on the Weather Forecast Required for Avalanche Hazard Forecast.In January 1960 the author visited the Federal Institute for Research on Snow and Avalanches at Weissfluhjoch-Davos, Switzer-land to discuss various topics of avalanche defence with members of that Institute. This note describes the discussions with Dro
T. Zingg, January 26, on weather forecasting for the avalanche warning,service.
Dro ｚｩｮｧｧｾ the meteorologist for the ｉｮｳｾｩｴｵｴ･Ｌ is also
the assistant director. He is in charge of the snow cover studies including the related climatological observations. In addition, he is head of the group that issues the avalanche warning bulletin based on the snow and weather observations collected from 50 special observers in the ｾｴ｡ｩｮ regions of Switzerland.
Dr.
Zingg waswith the Meteorological Service in Zurich before he joined the staff of the Institute.
The regular avalanche warning bulletin, covering all mountain regions in Switzerland, is issued every Friday. Special bulletins are issued during the week, including weekends, when the avalanche conditions warrant it. The bulletins are broadcast
over the radio along with the weather forecast and the news and they are published in the newspapers. Although the bulletins are nqrmally prepared for skiers and mountain climbers, at times of
high hazard they will include a warning of avalanches which may reach roads and inhabited areas. Since avalanches are intimately related to the ｷ･｡ｴｨ･ｲｾ a good weather forecast is essential in the pre-paration of the avalanche bulletin.
2
-During the first years of its operation the Avalanche Research Institute found that it could not issue a satisfactory avalanche warning bulletin based on the public weather forecast from the Meteorological Service. It was only after a meteorologist
(Dr.
Zingg) was transferred from the Meteorological Service to the Institute that a satisfactory avalanche hazard forecast was obtained.Before the preparation of each bulletin,
Dr.
Zingg contacts the weather bureau in Zurich by telephone and discusses the weather situation with the forecaster. From this discussion and his own lmowledgeDr.
Zingg is then able to judge how the weather willinfluence th'e avalanche hazard. Since the weather forecast obtained from Zurich is not always satisfactory,
Dr.
Zingg sometimes pre-pares his own forecast, using the weather map, the observations from meteorological stations which are transmitted to the Institute and the observations received from the avalanche observation stations. The Institute finds that the present system is satisfactory.Dr. Zingg mentioned the organization of the avalanche warn-ing service in Austria. For some years the weather bureau in Vienna has issued an avalanche hazard fOrecast for the mountain regions. As the weather bureau does not know the local snow conditions, this forecast is not accurate and is normally useless. To overcome this situation the Sand (Province) Vorarlberg, the most western province of Austria, close to the Swiss border, decided to organize its own avalanche warning service. A station in Bregenz issues an avalanche warning bulletin for this area based on daily ｾｮｯｷ observations
received from six observers in the province and also the snow and weather observations from Switzerland. There is close co-operation between the station in Bregenz and the Swiss Avalanche Research
Institute. The Sand TYrol is giving consideration to the establish-ment of a similar service.
The situation at Glacier in British Columbia was outlined to
Dr.
Zingg and he was asked to comment on the weather forecast that would be required by the avalanche warning service in such an area. He thought it impossible for the weather bureau in Vancouvel' to forecast the weather in the Glacier area accurately enough ｦｯｾＧthe avalanche hazard forecast. The ideal situation would be for a meteorologist to live at Glacier during the winter at least. He would receive all the observations from the weather stations, plot
the weather map, make his own observations and forecast the weather for the area. It is important that the meteorologist have a real interest in this special work and be willing to carry out the required observations in such a semi-isolated area.
3
-Dr.
Zingg suggested also that the avalanche service at Glacier might organize special observations. The majority of the avalanches occur as a result of snowfalls and most of the storms causing snowfalls at Rogers Bass approach from the Pacific Coast. It m1gb:t be possible to obtain useful correlations between the precipitation at Glacier and partioular observations on thedevelopment of the weather from the coast inland if stations were available at which these observations could be made.
As
an example of the correlations which might be useful,Dr.
Zingg has foundthat for the conditions on the north side of the Alps, an increase in the rate of change of barometric pressure is a good indication of possible precipitation. If the rate of change of barometrio pressure is decreasing no precipitation is found to ocour.
