In Manitoba, the deadly Virden tornado got an upgraded rating because of all the damage it caused. It was classified as an EF-2 twister initially but now it's officially an EF-3. Two eighteen-year-olds lost their lives because of the storm.

Natalie Hasell, a warning preparedness meteorologist with Environment Canada, told Narcity that the new rating came after the damage was assessed more closely.

That included drone footage in particular which gave a better aerial view of things like where structures were damaged and where they landed.

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The tornado that touched down near Virden was given a preliminary EF-2 rating based on an initial damage assessment was done after the storm. 

Damage indicators like the type of buildings and structures and what tracks they left as they were uprooted by the twister are evaluated.

In this case, farm silos and grain bins are primarily what was damaged.

Then levels are given based on a bunch of different factors like if the silo was anchored or not, if it was full or not and how far it travelled.

With that, estimated wind values are given and then that correlates to a rating.

For this tornado, the estimated speed was 260 km/h which puts it in the EF-3 range.

Ratings for tornados can change because more information comes out like photos and videos received from people who witnessed the storm or closer inspection of what was found during the damage survey.

Quantifying whether a twister caused moderate, severe or devastating damage is hard to do because it was fatal and it impacts people differently.

However, based on the scale, an EF-3 has severe damage.

"We are lucky in Manitoba that we have a lot of agricultural land so storms that are probably giving winds that would be rated at EF-4 or EF-5 go through farmland," Hasell said.

So they're given lesser ratings because the damage is measured not the actual wind speed since that's not possible.

That can't be measured because instruments that do so aren't everywhere and even if they were, gusts like that could destroy them.

Hasell said there are tornados that could've gotten higher ratings on the scale because of their size, what was seen on the radar and photos or videos.

If they go through a field, they get a default EF-0 because they didn't cause damage to any sort of building or structure.

While there is still investigating being done into the data for this twister, there's a good chance that the EF-3 will be the final rating given.

Less than a week after this deadly tornado, another one touched down near Alexander just a short distance from Virden.

No damage was reported initially and no rating has been given to that twister.

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