Foehn wind environment with strong and gusty winds. Explanations of the foehn warming and drying effect in popular literature or on the web often single out just one causal mechanism (#1 - Condensation and Precipitation - in the below), but there are in fact four known causes (illustrated in the schematic at top right of this page). These mechanisms often act together, with their contributions varying depending on the size and shape of the mountain barrier and on the meteorological conditions, for example the upstream wind speed, temperature and humidity. 1) Condensation and precipitation: When air is forced upwards over elevated terrain,
Weather warning [increasing] significantly, but its occurrence, location, and/or timing is still uncertain"" and a warning as ""hazardous weather or hydrologic event [that] is occurring, is imminent, or has a very high probability of occurring"" . Additionally, the NWS breaks down weather warnings and watches based upon the specific type of hazardous weather. These warnings and watches include, but are not limited to, flooding, severe local storms, tropical cyclones, and winter storms. In Canada, governmental weather warnings and watches are issued by the Environment Canada. Non-governmental alerts, not watches or warnings, such as a "rotation detected" or "tornado reported" are issued by