How Are PSAI Hail Swaths Calculated?
PSAI storm swaths are based on data from the National Weather Service RADAR network, which is supplemented with further data from:
- Reports on social media
- Trained weather spotters
- Information from the National Weather Service
What Does the Hail Size on a Swath Mean?
Each PSAI storm swath is labeled by a given hail size, the color of which corresponds to the legend at the far right of the map. You can also hover over any swath to see the hail size and the home count, as shown in the example below (1.75" hail over 252 homes).
So what exactly does the hail size indicated here mean?
Each hail swath reflects the maximum size of hail expected at that location. So, for example, if a storm produced a lot of quarter-sized hail but just one or two golfballs, the swath would still be labeled as 1.75" (golfball) because that is the maximum detected or reported.
Maximum hail size is often the most important metric from an insured loss perspective.
Does a Swath with Large Hail Guarantee Roof Damage in That Area?
No. While we are very confident in the accuracy of the PSAI weather map, there is no guarantee that all or even a majority of the homes within the swath will have experienced damage at the roof level. This is because there are many factors beyond size that determine whether or not hail will cause damage to a roof.
These factors include:
- Angle of impact of individual hailstones
- Density of hailstones (slushy and loose vs. hard and dense)
- Accompanying wind speed and direction
It is not uncommon for penny-sized hail combined with significant winds to completely obliterate a roof. In other cases, larger hail of up to 2" may not do any appreciable damage at the roof level.
How Can I Check Whether a Certain Hail Swath Is Worth a Large Campaign Spend?
If you would like to target a specific hail storm with a significant investment of time, travel, money, or other expenditures, please contact PSAI support before you commit to the campaign. We want your outreach efforts to be successful and would be happy to have our PhD climatologist review the storm data to evaluate the potential ROI for that specific hail storm.
Please fill out a support ticket for the quickest assistance.