Case Study Example 2:

Measured precipitation totals at Calgary International Airport

In this report, all temperatures are in degrees Celsius, and visibilities in kilometers.

On 13 January at 0500 LST, 2 centimeters of snow were reported on the ground. During the day, 2.0 centimeters of snowfall was officially reported, no rain, and 1.0 millimeters of total liquid equivalent precipitation. High temperature -4.6°C low temperature –19.3°C

On 14 January at 0500 LST, 2 centimeters of snow were reported on the ground. During the day, 1.0 centimeter of snowfall was officially reported, no rain, and .8 millimeters of total liquid equivalent precipitation. High temperature –12.1°C low temperature –16.8°C

On 15 January at 0500 LST, 3 centimeters of snow were reported on the ground. During the day, .4 centimeters of snowfall was officially reported, no rain, and .2 millimeters of total liquid equivalent precipitation. High temperature 2.2°C low temperature –16.4°C

On 16 January at 0500 LST, 2 centimeters of snow were reported on the ground. During the day, no precipitation was reported. High temperature 4.5°C low temperature –15.3°C

On 17 January at 0500 LST, 1 centimeter of snow was reported on the ground. During the day, no precipitation was reported. High temperature 3.0°C low temperature –11.6°C

On 18 January at 0500 LST, a trace snow was reported on the ground. During the day, a trace of rain was reported. High temperature 6.2°C low temperature –3.6°C

On 19 January, at 0500 LST, a trace snow was reported on the ground. A trace of both rain (drizzle) and snow were reported. High Temperature 8.7°C low temperature –8.2°C

On 20 January at 0500 LST, a trace snow was reported on the ground. During the day, 2.0 centimeters of snowfall was officially reported, .2 millimeters of rain, and .8 millimeters of total liquid equivalent precipitation. High temperature –8.1°C low temperature –16.7°C

On 21 January at 0500 LST, 2 centimeters of snow were reported on the ground. During the day, 3.8 centimeters of snowfall was officially reported, no rain, and .6 millimeters of total liquid equivalent precipitation. High Temperature –16.7°C low temperature –24.3°C

On 22 January at 0500 LST, 5 centimeters of snow were reported on the ground. During the day, 2.2 centimeters of snowfall was officially reported, no rain, and 1.2 millimeters of total liquid equivalent precipitation. High Temperature –19.9°C low temperature –26.9°C

Conclusions:
Snow from the 13th, 14th and 15th of January totaled 3.4 centimeters. The lowest amount of snow reported on the ground at anytime from the13th through the 22nd of January at 0500 LST was a trace on the 18th, 19th and 20th. A trace indicates less than .5 centimeters of snow on the ground. During that time, the snow likely partially melted during the day and some of the melted snow refroze as ice at night. Because at least a trace of snow was reported each morning, the snow and the water resulting from snow melt from the 16th through the 19th of January, had not completely sublimated/evaporated prior to the commencement of the precipitation event on 19 January.

Continuous precipitation fell from 2000 LST on 19 January until ending between 1300 and 1400 LST on 21 January. Temperatures were below freezing during the entire precipitation event. Snow fell on top of a thin layer of freezing drizzle, leaving a total of about five centimeters of snow on the ground by 1400LST on 21 January. It is also likely that on 21 January, that in unexposed locations, in areas where the ground is slightly depressed and liquid water can gather, some ice remained from the previous precipitation that occurred from 13 through 15 January, 2003.

The reporting station at Calgary International Airport is located at 51006’ North Latitude, 114001’ West Longitude at an elevation of 1084.1 meters. The southern end of Calgary International Airport is approximately six kilometers to the north of 503 Forego Drive in Forest Heights SE, Calgary, Alberta, while the airport terminal building is approximately nine kilometers to the north of 503 Forego Drive. It is highly likely that the weather conditions reported at Calgary International Airport would have been representative of the weather conditions at 503 Forego Drive in Forest Heights, SE, Calgary.