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Home > Severe Weather > Criteria

Criteria

Severe Weather Watch

There is moderate confidence that specified severe weather event may occur within the time frame specified.

Severe Weather Warning

There is high confidence that the specified severe weather event is imminent or occuring.

A severe weather watch or warning will usually be issued when one or more of the following weather conditions are possible:

• Heavy, disruptive rainfall
• Heavy, disruptive snowfall
• Widespread wind gusts in excess of 70 mph
• Large hail over 15 mm diameter
• Tornadoes / funnel clouds not associated with a thunderstorm

PDS* Severe Weather Warning

There is high confidence that extreme weather conditions are imminent or occuring, and that these conditions pose a significant threat to life, property, travel, and / or infrastructure.

A PDS Severe Weather Warning may be issued when one or more of the following conditions are expected:

• Extreme snowfall
• Extreme rainfall leading to widespread flooding
• Frequent wind gusts in excess of 80 mph

Severe Thunderstorm Watch

There is moderate confidence of severe thunderstorms occuring within the timeframe specified

Severe Thunderstorm Warning

There is high confidence that severe thunderstorms are imminent or occuring.

A severe thunderstorm watch or warning will usually be issued when thunderstorms accompanied by one or more of the following conditions are possible:

• Wind gusts over 55 mph
• Hail over 20 mm diameter
• Tornadoes and / or funnel clouds

PDS* Severe Thunderstorm Warning

There is high confidence that extremely violent thunderstorms are imminent or occuring, and that these storms pose a significant threat to life, property, travel, and / or infrastructure.

A PDS Severe Thunderstorm Warning may be issued when one or more of the following conditions are expected:

• Potentially damaging tornadoes of at least T2 intensity
• Extremely large hail of at least 50 mm diameter
• Non-tornadic wind gusts in excess of 80 mph
• Frequent CG lightning

*PDS = Potentially Dangerous Situation

Our Icons Explained

Rain / Flooding
	Heavy rain and flooding not expected
	Moderate risk of heavy rain, local flooding
	High risk of disruptive rain, severe flash flooding
Wind
	High winds not expected
	Moderate risk of high winds
	High risk of damaging winds
Winter Weather
	Severe winter weather not expected
	Moderate risk of severe winter weather
	Severe, disruptive winter weather likely
Thunderstorms
	Severe thunderstorms not expected
	Scattered, locally severe thunderstorms possible
	Severe, violent thunderstorms likely