Toronto under special weather statement with rain expected to melt 'much of the snowpack' - CBC

Warm rain on snowpack can trigger wet slab avalanches this winterMost people think avalanche danger comes from fresh snow, but avalanches need a weak layer in the snowpack plus a trigger. When rain falls on snow, or temperatures spike, meltwater loosens the bond between snow layers. That can release wet slab avalanches, which can break wide with little warning and run into terrain that normally feels safe.(MORE: Widespread snow blankets resorts from California to Montana)Rain triggers a wet slab avalancheA wet slab avalanche happens when water works its way down through the snowpack and weakens a layer buried below the surface. The snow above that layer, the slab, can then release all at once. Rain makes this more likely in two ways:First, it adds weight to the slab. Second, the meltwater it creates can loosen the bonds that hold snow layers together. The result is a heavy slab sitting on a weaker layer, with nothing holding it in place. Get More of Our News on GoogleSet The Weather Company as a 'Preferred Source' to get quicker access to the news you value. Wet slabs are harder to predict than many other avalanche types.

El Niño could boost Lake Mead, Lake Powell and the Sierra snowpackAfter years of diminishing winter snowpack and lowering lake levels in the West, El Niño could make this the year to recharge those reservoirs, including California’s watershed, and lakes Mead and Powell. Supercharged pipeline of moistureThe Sierra Nevada and the Rockies are likely to see a lot of help from a jet stream called the Pineapple Express. This rainmaking "firehose" is a direct movement of moisture from around Hawaii to the West Coast of the U. S. and Canada during the winter months. It is naturally occurring and is a frequent cause for flood concerns and mountain snow in California. El Niño tilts the odds toward a wetter, more active Pacific storm track. El Niño’s heat across the Pacific warms the atmosphere and allows it to hold more moisture to be transported toward North America.

Toronto and Montreal have remained above the freezing mark every day for almost six months. While frosts and even some snowflakes have intruded across parts of Ontario and Quebec in recent weeks, the two cities have yet to reach that magic number. What’s even more remarkable is that a handful of communities across the southern United States have already dipped to the freezing point--and some have even seen accumulating snowfall. DON’T MISS: Official: Canada records first -30°C reading of the seasonThe last time we saw a freezing temperature in either Toronto or Montreal was the second-to-last week of April. Toronto hit -1.3°C early on April 20, while Montreal dipped to -2.0°C the following morning. Our average first frost in both cities occurs right around the middle of October. But warmer-than-normal years can see this milestone slide several weeks past due. Montreal once had to wait 207 consecutive days for its first frost, with the city’s first subfreezing temperature in 2017 waiting until Nov. 7. The latest Toronto’s had to wait to hit the zero-degree mark was Nov. 13, 2022.