Like watching weather radar? Here's why you won't see much for a few months

A photograph of Carvel Weather Radar Station located near Beach Corner, Alta. (Source: Jeff Adam)

EDMONTON — Edmonton is getting its biggest weather tech update in decades. The radar at Carvel (35 km west of Edmonton) went Doppler in 1991 and is now going “Dual Pol”.

Once the work at the Carvel radar is done, radar coverage of Edmonton and surrounding areas will get significantly better. Dual-Polarization radars are a massive improvement over the technology currently being used. But, until then, it’ll be tougher to track precipitation coming into the Edmonton area (particularly from the west and northwest).

The area won’t be completely without radar coverage, though. Environment & Climate Change Canada has the ability to switch it back on in the event of severe weather (but only up until late September. After that, it’ll be offline for good.) ECCC has also extended the range of nearby radars from 240 km to 400 km.

However, because of the way radar works, rain (or snow in the coming months) that falls from low clouds likely won’t be detected or show up on radar maps. The tilt of the radar beam from far-off radar sites will simply be “too high” above the city.

Think of holding a flashlight tilted slightly upwards. The light may only be a few feet off the ground in your hand, but the beam is much higher above the ground 10, 20 or 30 feet away. That’s what we’ll be dealing with in regards to radar coverage.

That short-term “pain” will pave the way for a BIG long-term gain.

Dual-Polarization radars scan the atmosphere both horizontally and vertically. Among the many benefits of this, dual-polarization allows for better “precip-typing” (figuring out what’s snow and what’s rain). The upgrade will also improve our ability to determine the size of hail and will make it easier to eliminate non-precipitation echoes (birds, bugs, dust etc) from the radar images.

This is all part of a nationwide project to modernize Canada’s 31 radar sites and to add a new radar near Fort McMurray. The project began with the radar near Radisson, SK in 2017 and will wrap up in 2023. So far, 21 radars across the country have gone “Dual Pol”.