textproduct: Portland

SYNOPSIS

Warming trend continues through the weekend as high pressure peaks on Sunday, with periods of offshore flow and early morning fog within sheltered valleys. Temperatures moderate but remain above normal as dry weather persists through much of the workweek. More seasonable conditions with increased chances for rain may return late in the week.

LONG TERM...Monday through Friday

By the beginning of the workweek, there remains good agreement that the upper-level ridge will shift inland over the Rockies while its amplitude decreases, resulting in nearly zonal flow over the Pacific Northwest. This pattern shift will allow onshore flow to return, supporting moderating but still above normal temperatures Monday through Thursday. The broad ridge continues to support high confidence in further dry weather. Late in the week, there is increasing agreement that upper troughing will return to the Gulf of Alaska, bringing renewed rain chances to the region from Friday into the weekend. While details in timing and amounts remain low confidence, some 60% of long-range ensemble members favor rain at some point from Friday through the weekend. -36

AVIATION...Through 06Z Sunday

Satellite imagery and terminal observations as of late Friday evening depicts low marine stratus along the coast bringing LIFR CIGs and IFR/LIFR VIS to KAST and KONP. High confidence that these trends continue through 16-17z Sat with 1/2SM fog at KONP. High pressure aloft is building, which is resulting in the marine layer being pushed lower to the surface. For Willamette Valley terminals, VFR conditions prevail through the TAF period with high clouds. There is a 15-30% chance for MVFR stratus at any given hour between 10-17z Sat, but due to low confidence, MVFR conditions were not included in the TAFs. Northerly to northwesterly winds across the region generally under 10 kt. Easterly winds increase through the Columbia River Gorge and far east Portland Metro (KTTD), but remain light.

KPDX AND APPROACHES...VFR with high clouds through the TAF period. 10-20% chance for MVFR stratus at any given hour between 11-16z Sat. Northwesterly winds 2-6 kt. -10

MARINE

Persistent high pressure offshore will see northerly winds prevail through much of the next week, with speeds reaching diurnal peaks each afternoon. Chances for peak wind gusts of 20-25 kt generally increase daily through Wednesday, though the duration and coverage stronger gusts may not be sufficient to support Small Craft Advisories each day. High pressure building aloft through this weekend will also support areas of dense fog developing nightly as cloud bases are compressed down to the surface. A Dense Fog Advisory therefore remains in effect through noon Saturday for widespread visibility of 1 SM or less, especially within 40 NM of the coast. Strengthening northerly flow will see largely wind- driven seas continue at 4-6 ft through much of the week, with a modest west-northwest swell at 8-9 seconds lengthening to 10-12 seconds early in the workweek.

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 and chances for rain return to the region Friday into next weekend. -36

PQR WATCHES/WARNINGS/ADVISORIES

OR...Dense Fog Advisory until 10 AM PDT this morning for ORZ101>103.

WA...Dense Fog Advisory until 10 AM PDT this morning for WAZ201.

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