PORTLAND, Ore. (KOIN) — The final weekend of summer came to a close on Sunday, with mostly sunny skies and temperatures in the 70s.
As we look ahead to Monday and the coming week, a ridge of high pressure will be nearby and will divert any storm systems well to the north. However, with this pattern will come very little mixing of the atmosphere, leading to the development of overnight and early morning fog and low clouds from the coast through the valley.
Late in the week a trough of low pressure will approach the coast from the Gulf of Alaska, increasing the chances for showers. Exact timing and amount of late-week rainfall is still in doubt so we will broad-brush the forecast for now until later model guidance brings this into clarity.
Expect temperatures to cool to slightly below average for this time of the year, which continues the trend of cooler than average temperatures during the month of September…