Prévisions météo en montagne

The unusually strong-for-late-September ridge will continue to give summer-like conditions to southern BC today and Wednesday with daytime highs reaching 5 to 8 degrees above the 30 year averages. The Fort Nelson area and the BC Peace will also see a continuation of mostly sunny skies and mild daytime temperatures.

Elsewhere, the rain that drenched Haida Gwaii, Prince Rupert, Kitimat-Terrace and Bulkley Valley to Prince George corridor over the last two days will finally end today as a warm front lifts north to the Alaska Panhandle. A little sun may finally poke through the clouds in these areas later today and Wednesday.

Now why where was there a hint of uncertainty expressed in today's blog headline? Because of the likelihood that some wildfire smoke will return to our fair province beginning Wednesday and "ruining" another ridge of high pressure. Smoke transport models are currently forecasting relatively low concentrations of PM 2.5 moving up from California and reaching Vancouver Island Wednesday morning ( see day 2 tab), continuing to spread northwards and reaching all the way to the Alaska Panhandle by Thursday morning. Models are forecasting smoke concentrations about 10-20 times less than the mid-September smoke event, so it will hopefully be more of a haze issue than a serious respiratory hazard. Stay tuned to the blog and keep an eye on weather.gc.ca and @ECCCWeatherBC for the latest information on the wildfire smoke.

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The 500 mb animation shows the upper ridge sharpening up today and shearing the front draped from Haida Gwaii to Prince George into two sections; one piece heads up to the Panhandle and another fragment goes down the Rockies. The ridge axis continues to sharpen and moves to interior BC on Wednesday while the next (weak) front approaches the Haida Gwaii. The problem/risk in our present situation with the sharpening ridge is the resulting southerly flow on the coastal side of the ridge that will advect California wildfire smoke all the way up the BC coast by Wednesday afternoon.

On Thursday the ridge flattens ever so slightly and the upper flow becomes more westerly, allowing the north coast front to spread some mid-high cloud across BC. Smoke and haze may also spread across the interior Thursday.

The ridge ridge rebuilds over BC Friday as yet another weak front brings rain to Haida Gwaii and the north coast.