When severe weather threatens, Environment Canada issues alerts that notify those in affected areas in British Columbia so that they can take steps to protect themselves and their property from harm. The type of alert issued depends on the severity and timing of the event. Special statements: issued to highlight significant weather or express uncertainty. Watches: alert you about weather conditions that are favourable for a storm or severe weather, which could cause safety concerns. Warning: an urgent message that severe weather is either occurring or will occur. Warnings are usually issued six to 24 hours in advance, although some severe weather (such as thunderstorms and tornadoes) can occur rapidly, with less than a half hours' notice.