textproduct: Portland

SYNOPSIS

Unseasonably warm and dry weather persists through Thursday with areas of early morning valley and coastal fog. Weak offshore flow will bring slightly warmer temperatures Wednesday and Thursday, before a trough brings a return to cooler temperatures with chances for light rain Friday into Saturday. Cool nights will bring chances for morning frost in rural valleys away from urban cores this weekend into next week.

LONG TERM...Friday through Monday

A strong ensemble consensus continues to support upper-level troughing returning to the region from Friday through this weekend. The large majority of members bring rain into the Oregon and Washington coasts late Friday morning or early Friday afternoon, reaching inland to the I-5 corridor by Friday mid- afternoon. Chances for light rain showers persist into Saturday as the trough elongates and ultimately looks to pinch off into a closed low which drifts south over California. Mean 48-hour rainfall totals from Friday through Saturday night are generally less than 0.1 inches, higher to the north and on western slopes of terrain, and lower to the south and on eastern slopes. There is a 10% chance of up to 0.2-0.4 inches of rain at low elevations, and higher amounts in excess of 0.5 inches in areas of terrain.

As the core of cold air within the upper trough moves overhead this weekend, temperatures will fall to much more seasonable levels with afternoon highs largely in the 60s. Morning lows will similarly cool, yielding increasing chances for frosty temperatures in the low to mid 30s from Friday night through Monday night. Frost may occur as early as Friday night in the Upper Hood River Valley, with 30-40% chances of falling to 36F or lower near Parkdale and Dee. Saturday and Sunday nights look to be the coldest, with nearly 10% chances for frost in Hood River proper, 50% near Odell, and 90% in Parkdale and Dee. Elsewhere, frost chances reach 15-35% in north Oregon Coast Range valleys, the central and southern Willamette Valley away from urban cores, and the Cascade foothills from Cowlitz County south to Lane County on Sunday night. Chances for a true freeze peak Sunday night at 50-60% near Parkdale and Dee and 15-20% near Odell in the Upper Hood River Valley, and at 20-35% along the OR-58 corridor between Eugene and Oakridge. Those with agricultural interests or home growers with sensitive outdoor plants should continue to monitor the forecast this week.

As the closed upper low then drifts to the south, rising heights aloft in the Pacific Northwest could again favor a drying and warming trend early next week. -36

AVIATION...Through 18z Wednesday

The widespread stratus that formed through inland valleys and along the coast Tuesday morning is beginning to dissipate fairly rapidly as of 1745z Tue. Most inland and coastal terminals with MVFR/IFR/LIFR conditions are expected to improve to VFR by 18-20z. Winds increase and turn north to northwesterly this afternoon, up to 5-10 kts inland and 10-15 kts along the coast with gusts up to 20 kts. Winds decrease by 03-06z Wed, turning more east to northeasterly along the western Cascades, Coast Range, and into the coast into Wednesday morning. These easterly winds should limit the amount of marine air able to infiltrate the coast and inland, likely preventing another round of widespread stratus and fog Wednesday morning. There are pockets of 10-20% chances of MVFR/IFR conditions along the coast near KNOP and in the Portland metro area, with 20-40% chances in the SW Washington lowlands including KSPB, mainly after 13z Wed for inland areas.

KPDX AND APPROACHES...VFR conditions have returned and are expected to prevail through the TAF period. There's a low (10-20%) chance of stratus returning MVFR conditions 13-18z Wed. Northwest winds 5-7 kts today, becoming light after 03z Wed. -03

MARINE

High pressure offshore will continue to maintain diurnal northerly winds through the week with peak afternoon and evening wind gusts of 20-25 kt today through Thursday. Small Craft Advisories are now in effect across the waters from 2 PM PDT this afternoon into tonight. Expect largely wind-driven seas around 4-6 ft through midweek, with a west-northwest swell of 3-4 ft at 10-12 seconds. High pressure aloft will also support areas of dense fog developing nightly through the morning hours as cloud bases are compressed down to the surface. Dense Fog Advisories for visibility of 1 NM or less also remain in effect across the waters until noon PDT today.

More active marine conditions are likely in the latter half of the week as troughing over the Gulf of Alaska generates a building northwest swell. Seas will increase to 7-10 ft Wednesday into Thursday, with the longer-period swell also supporting a moderate risk for sneaker waves at the coast. Chances for rain return to the region Friday into the weekend, though rain amounts are not expected to be impactful. -36/03

CLIMATE

Daily record high temperatures for October 8

LocationValue (Year)

Astoria81 (1951, 1971) Portland Int'l87 (2022) Vancouver, WA89 (1891) Hillsboro89 (2022) McMinnville88 (2022) Salem84 (1971, 2022) Eugene83 (1934, 1943)

PQR WATCHES/WARNINGS/ADVISORIES

OR...None.

WA...None.

PZ...Dense Fog Advisory until noon PDT today for PZZ210-251>253- 271>273.

Small Craft Advisory from 2 PM this afternoon to 2 AM PDT Wednesday for PZZ210.

Small Craft Advisory until 2 AM PDT Wednesday for PZZ251>253.

Small Craft Advisory until 5 AM PDT Wednesday for PZZ271>273.