Heat advisory to take effect Wednesday for much of Pacific Northwest

PORTLAND, Ore. (KPTV) - The Pacific Northwest is gearing up for another heat wave with temperatures expected to climb into the upper 90s on Wednesday and Thursday.

On Monday, the metro area briefly 90 degrees at PDX, and it looks like the area experience a similar day Tuesday. The only difference will be some patchy morning clouds surging up the Columbia River. Those clouds shouldn’t stick around too long. Expect to see mostly sunny skies between the late morning and the afternoon. Highs will range between the upper 80s and low 90s.

High pressure will really start to expand across the western United States between Tuesday night and Thursday, bringing some pretty intense heat to the region. A Heat Advisory will be in effect starting midday Wednesday and lasting through Thursday evening. Temperatures will soar into the upper 90s both afternoons, with overnight lows in the mid to upper 60s.

Some monsoonal moisture will also move in from the south between Wednesday evening and Thursday, bringing a bit more cloud cover and isolated chances for thunderstorms. The greater chance of storms will be in the Cascades and central Oregon, but one or two could sneak over the Willamette Valley. Thursday will feel a bit more muggy with dew points rising into the upper 50s. This probably means the heat index values will briefly jump into the triple digits.

Onshore flow strengthens quite a bit between Thursday night and Friday, bringing a nice push of marine air and low clouds. Due to the gradual clearing of skies, highs will only make it into the low to mid 80s. This weekend still looks pretty warm though with highs in the mid to upper 80s. But that sure beats highs in the 90s.

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