Hey there! The forecast for tonight through Saturday night is becoming even more complex due to the addition of smoke from wildfires in British Columbia and Alberta. This smoke will be present in the upper atmosphere.

Overall, we can expect hot temperatures tomorrow and Saturday, although they might be a bit cooler than we initially thought. As for thunderstorms, they are still likely to occur, with isolated to scattered activity in the afternoons, especially on Saturday.

There's a ridge building over the area, accompanied by an upper low located in the Gulf of Alaska. This will create a moist south-to-southwest flow into the interior Pacific Northwest, which will persist until Saturday night. This pattern will contribute to the development of a cumulus field over the mountains and central Oregon. As a result, we can expect isolated thunderstorms over the Cascades, central Oregon, and the higher terrain of the eastern mountains.

Instability this afternoon is around 500-1000 j/kg and is expected to be slightly stronger on Friday. The amount of precipitable water remains around 1 inch, which is above normal and will likely stay at this level through Saturday. Shear is relatively low, ranging from 5-10 kts today and tomorrow, which means we'll see pulse type thunderstorms that form and weaken quickly. However, on Saturday, shear will increase to around 20 kts, and instability will rise to 1000-2000 j/kg. As a result, storms on Saturday may be more organized and stronger, although severe thunderstorms are not anticipated.

In terms of rainfall, amounts in the mountains and central Oregon this afternoon and evening should be relatively light, generally not exceeding a tenth of an inch. However, thunderstorms will be slow-moving, so locally, they could drop up to a quarter of an inch.

As for tonight, the thunderstorms will come to an end this evening, and the weather should be quiet overnight and into tomorrow morning. Expect warm lows tonight, ranging from the mid-50s to lower 60s, with temperatures in the upper 40s to mid-50s in the mountains.

Stormtracker

Mike McCabe