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 18Z Sat

West to southwest flow aloft continues through the period as high pressure remains over the region. Marine stratus continues to deteriorate along the coast and lower Columbia River according to satellite imagery as of 1730Z Fri. While inland terminals will keep VFR through the TAF period, there is less confidence for improvement to VFR for coastal terminals. Probabilistic guidance suggests the best chances of improvement to VFR occurring between 21Z Fri and 03Z Sat (50-70% chance of VFR CIGs). Otherwise, coastal terminals will maintain MVFR/IFR conditions through the period, with a 50-60% chance of MVFR, 40-50% chance of IFR, and 20-30% chance of LIFR. Marine stratus is expected to redevelop at the coast by 03Z Sat, giving more confidence for deteriorated conditions by then. Light northwesterly winds increase to around 5-10 kt later this afternoon for all terminals, earliest along the coast.

KPDX AND APPROACHES...VFR conditions with clear skies through period. Light northwest winds increase to around 6-8 kt this afternoon. ~12

MARINE

High pressure offshore will maintain northerly winds through the weekend and into next week. Winds are expected to remain 20 kt or less today through Saturday morning. By Sat afternoon, surface pressure gradients are expected to tighten as an inverted surface thermal trough strengthens over northern California toward the south Oregon coast. This will bring increasing chances for wind gusts up to 25 kt south of Cape Foulweather over the weekend and into early next week. Generally wind driven seas are expected to remain around 4 to 6 ft through the next week. /DH

PQR WATCHES/WARNINGS/ADVISORIES

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