Prévisions météo en montagne

The notorious atmospheric river remains aimed in the general direction of the south coast of BC, focusing mostly on Vancouver Island, the Sunshine Coast and the Sea-to-Sky with some fluctuations as a series of storms are entrained in quick succession into our region. This atmospheric river originates near Hawaii and carries abundant moisture and warm tropical air across the eastern Pacific, all the way to our shores. As it encounters our mountain ranges, the warm, moist air is forced up and condenses into rain drops which fall abundantly onto the mountains, with negligible snowfall except at the highest elevations as freezing levels remain very high. Moderate to significant melting of mountain snow is expected. Strong to extreme southerly winds will develop over the northwest ranges and extend towards the Yukon - South Klondike today, and will also prevail over the insular and south coast ranges this morning and again Tuesday morning.

The Coast Mountains will be very efficient at wringing out the abundant moisture, leaving a much drier but still warm airmass in the lee of the Range. As it makes its way across the interior, the air will eventually be lifted again upon encountering the barrier of the Columbia Ranges, producing some light precipitation, mostly in the form of rain.

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The animation above shows the upper atmosphere flow pattern, precipitation, and airmass temperature trend. We can see the persistent southwesterly flow will bring a series of storms for the next few days. The exceptionally warm air mass is indicated by the orange dashed lines spreading north into BC. Heavier precipitation is indicated by yellow to red colours over the coast today and tonight, followed by a break on Tuesday, then another period of moderate precipitation on Wednesday. The southwesterly flow will persist until mid-week maintaining warm and wet conditions. A progressive pattern change will likely begin on Thursday as a cold upper Low over the eastern Pacific slowly approaches Vancouver Island, heralding a gradual cooling trend with lighter precipitation.