In response to the nature of risks Winter Storms present, MIS provides an Intensity-based Exposure Layer focused on identifying material risk - areas where winter storm conditions are most likely to cause operational disruption, insured loss, or claims activity.
We will deliberately avoided flagging very broad areas as impacted during winter storm events. As a result, Minimal and Low intensity assessments are not used as standard for winter storm events.
This Exposure Layer is derived from the combined behaviour of three key drivers of impact:
Temperature – measured as the lowest temperature for that area over the event
Power Outages – measured as the highest percentage of customers affected during the event
Snow Accumulation – measured as the total accumulation over the event duration
The overall intensity classification reflects how these factors distribute spatially against the thresholds below:
Intensity | Temperature (celcius)
Lowest Over Time | Power Outage
| Snow Accumulation (cm)
Total Over Event |
Minimal | > 0 | < 5% | 5 - 10 |
Low | 0 to -5 | 6 - 10 | 10 - 20 |
Moderate | -5 to -10 | 11 - 30 | 20 - 30 |
High | -10 to -20 | 31-50 | 30 - 50 |
Severe | < -20 | > 50 | > 50 |
Important considerations
If temperatures do not fall below 0°C, the intensity cannot exceed Low, regardless of snowfall or outages.
The intent of this is to highlight areas of genuine concern, rather than broadly mapping meteorological conditions that are unlikely to result in loss.