Alpine weather forecast

A snowy start and rainy end?

Despite our incredibly snowy start to April, things are finally turning more spring like with a few showers in our forecast and unfortunately some considerable rain for Sunday. But we will also see some sun.

A rather mild southwesterly flow will prevail both Wednesday and Thursday. Moisture embedded within the flow will maintain overcast skies with the odd spit of rain Wednesday. The warm southwest winds will help drive temperatures and freezing levels upwards with a high near +5C Wednesday and +7C Thursday with no overnight refreeze in between. The showers will become more organized Thursday with 5-10 mm expected and a freezing level soaring up to 2300 metres, the snowpack will inevitably begin to shrink. Also worth mentioning will be the chance of Thunderstorms Thursday night which could produce locally heavy downpours. Needless to say, with the warmth and the rain, rivers will be on the rise.

The flow weakens on Friday and an upper ridge of high pressure begins to slowly build in from the west. We can therefore look for a very gradual clearing and a shift to moderate northwest winds. Despite the change in wind direction, temperatures will remain mild near +6C in the alpine under cloudy skies Friday. We will have to wait until Saturday for the ridge to draw closer and the sun to shine. Worth remembering that a mid-April sun has the same punch as mid-August. We can therefore expect all aspects and elevations to soften and the melt to continue. You will want to take advantage of some spring corn skiing before thing turn ugly on Sunday.

Models are in relatively good agreement to bring a deep, well-organized Colorado low up towards Hudson’s Bay on Sunday. This trajectory will place the Chic-Chocs in a very mild and very strong (90-110 km/h) southerly flow that will drive alpine temperatures up past to +7C under rainy skies. The rain will steadily increase through the day before the passing of a vigorous looking cold front Sunday evening. After 5-10 mm of rain, winds will abruptly swing to the NW with the passage of the front, driving temperatures down to -8C by Monday morning and switching the precip over to snow. This will be a classic setup for a dust-on-new-rain-crust with 5-10 cm of wet snow set to fall on the freshly established rain crust by midday Monday. Worth monitoring will be the SW winds Sunday night as they could cause localized power outages.

Looking further out, additional flurries seem likely through most of next week as temperatures return to below seasonal values with highs near -2C and occasional moderate SW winds. We may have to wait until the very end of April for the sun to return so slap on the zinc and get out to enjoy it this weekend!

Forecast Confidence :

Generally good confidence overall. The amount of sunshine on Friday is somewhat uncertain as some models have the cloud clearing out sooner. Sunday night’s cold front looks rather violent so be sure to follow Environment Canada alerts for possible wind and/or flash freeze.