Frost Situation Update – September 17, 2012
Synopsis:
Last week below normal temperatures saw frost developing across most of the agricultural areas of
the province. Several stations recorded temperatures below -5C.
Frost Areas September10 to September 11 2012-See map
Frost Areas September15 to September 16 2012-See map
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Province wide, cooler than normal temperatures over the past week have brought frosts to most
areas.
Generally, two episodes of frost were seen. One spanned the two nights from September 11 and
12, and struck several locations across southern Alberta, with the coldest temperatures recorded
at Blackie AGCM (-8.4 C) south of Calgary and at Manyberries AGCM (-7.4 C) south of the
Cypress Hills.
A second major episode of frost occurred between September 15 and 16th, with many areas
north of Red Deer seeing temperatures dip below -2 C. During this time the coldest temperatures
recorded at the La Glace AGCM station (-5.5C) in the central Peace Region, followed by Dapp
AGCM station (-4.8C), just northwest of the town of Westlock.
It is likely that some low lying areas will have experienced temperatures even lower that what is
represented on the attached maps.
Perspective:
Frosts of this magnitude, this early in the season are generally quite rare. The following are
estimated probabilities that each of the following stations will have a frost down to -5 C on or before
September 15:
• La Glace AGCM ......................... once in 16 years
• Dapp AGDM ............................... once in 50 years
• Blackie AGCM ............................ once in 20 years
• Mossleigh ACGM ........................once in 50 years
• Manyberries AGCM ..................... once in 50 years
Additional Maps can be found at www.agriculture.alberta.ca/maps
Near-real-time hourly station data can be viewed/downloaded at
www.agriculture.alberta.ca/stations
Note: Data has about a two hour lag and is displayed in MST (add one hour for daylight savings time)
Ralph Wright
Soil Moisture Specialist
Head, Agrometeorology Applications and Modelling Section, ARD