textproduct: Portland

SYNOPSIS

Warm and dry conditions continue today, but temperatures are expected to gradually moderate toward August norms by Sunday, continuing into early next week. Renewed onshore flow will keep smoke east of the Cascades. Precipitation is not expected during the next week across the area.

DISCUSSION...Today through Thursday

Satellite imagery and surface observations as of early Friday afternoon depicts mostly sunny skies across interior locations with marine clouds dissipating along the coast. Clouds should continue breaking up along the coast and lead to some brief afternoon sunshine. Can't rule out some clouds hugging the immediate coastline as we maintain moist onshore flow. This onshore flow, where winds come from the west/northwest, is what's clearing western Oregon and Washington from all the smoke and haze these last several days. Expect these winds from the west/northwest to keep pushing smoke eastward as we head into the weekend.

High pressure will maintain dry and warm conditions today through the weekend, afternoon highs forecast in the upper 80s to low 90s today. A shortwave trough approaching the coast tonight into early Saturday morning will strengthen onshore flow and likely deepen the marine layer enough to push clouds inland up the Lower Columbia River Valley into the Portland/Vancouver Metro. Afternoon sun should allow temps to warm again into the mid to upper 80s across the interior lowlands Saturday afternoon. While winds from the west/northwest generally remain around 15 mph or weaker across most areas, the breeziest locations will be along the Central Columbia River Gorge and portions of the Upper Hood River Valley where gap winds are forecast to gust up to 30-35 mph, with a 20-30% chance for gusts exceeding 40 mph. Combined with low relative humidity and dry fuels, these conditions would be favorable for rapid fire spread. NWS Pendleton has issued a Red Flag Warning for the Central Gorge and portions of Eastern Hood River County, in effect from 11 AM today through 11 PM Saturday. Elsewhere across northwest Oregon and southwest Washington, higher relative humidity and weaker winds will not be favorable for rapid fire spread.

There is high confidence temperatures trend into the low to mid 80s Sunday through early next week as a more zonal flow pattern emerges. Majority of ensemble members show a weak trough approaching the Pacific Northwest middle of next week, however, it appears to be a dry trough with no precipitation chances expected. -10

AVIATION...Through 06Z Sun

West to southwest flow aloft continues through the period as high pressure remains over the region. At 04z Sat, marine stratus is reforming along the coast and is forecast to produce MVFR/IFR/LIFR cigs along the entire NW OR and SW WA coast by 06-08z Sat. Guidance indicates stratus will dissipate with conditions improving to VFR by 18-21z Sat, dissipating from the north to south. VFR conditions are expected over the next 24 hours for inland terminals, though a stronger marine push could allow stratus and mid-level clouds to push east through the Columbia River to around KKLS.

Northwesterly winds will weaken below 6 kts by 06-08z Sat at all terminals then increase again to 6-11 kt after 18-22z Sat. KONP may see gusts up to 20 kt tomorrow after 18Z Sat as winds over the waters strengthen, decreasing by 04-06z Sun.

KPDX AND APPROACHES...VFR conditions through period. Mid to high level clouds expected to develop after 12z Sat, clearing by 18-20z Sun. Northwest winds around 6-8 kt this afternoon will become light and variable after 06-08z Sat, then increase once again to 7-9 kt after 22z Sat. -03

MARINE

High pressure offshore will maintain northerly winds through the weekend and into next week. Winds will remain 20 kt or less through Saturday morning. Surface pressure gradients will then tighten Saturday afternoon, bringing increased chances for wind gusts up to 25 kt south of Cape Foulweather through the weekend and into early next week. Specifically, there is a 40% chance for small craft wind gusts on Saturday south of Cape Foulweather, then increased chances of 50-70% on Sunday. Wind driven seas are expected to remain around 4 to 6 ft through the next week. ~12/DH

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...None.