textproduct: Portland

SYNOPSIS

Onshore flow continues over the next week. Near zonal flow aloft is expected through Sunday will slowly become southwesterly by the start of the week as high pressure starts to build over the Great Basin through the weekend. This pattern will bring warmer temperatures and a good deal of sunshine during peak heating hours each day. Most inland valleys will warm into the low to mid 80s each day, with the warmest day looking to occur on Monday. Onshore flow will keep the coast cooler with highs in the 60s.

DISCUSSION...Today through Thursday

Minimal changes in the overall pattern expected through the weekend and into the middle of next week. Our CWA will be sandwiched in-between an exiting upper level trough within Canada and a slowly building upper level high over the Great Basin. This synoptic pattern is resulting in zonal flow over the region. The Great Basin high will slowly become more dominant through the latter part of the weekend and into the start of next week. However, even as the Great Basin high develops, onshore flow will persist and that will help to maintain normal to slightly warmer than normal daytime highs across the forecast area. Of note, normals for this time of year are typically in the upper 70s to mid 80s, with cooler temperatures, within the aforementioned range along the coast.

Ensemble guidance is in agreement that ridging building over the Great Basin will push slightly northwest into NW OR and SW WA by Monday. This will result in Monday looking to be the warmest day of the upcoming week with daytime highs in the mid to upper 80s for the interior lowlands with a 10-35% chance of temperatures reaching 90 degrees between Vancouver, WA and Eugene, OR. Daytime highs along the coast are expected to be about 10-15 degrees cooler (upper 60s to mid 70s) along with daytime highs for the Cascades about 5-10 degrees cooler (mid 70s to mid 80s).

As Tuesday approaches, the region in for another pattern chance as ensemble guidance remains in agreement that a broad, Alaskan low will slowly move east into British Columbia. This will unseat the Great Basin high, thus bringing daytime highs much closer to seasonal normals across the CWA. Temperatures are slated to remain in the low 80s from Tuesday, with cooler temperatures along the coast, through the end of next week with less than 5% chance of temperatures reaching 90 degrees.

It is important to remember that while temperatures will be warming up for the holiday weekend and next week, many local lakes and rivers remain very cold and can cause cold water shock. Also, rivers may still have swift currents in some areas, which can quickly sweep you away. Please practice water safety by wearing life jackets, visiting with a buddy, and always being aware of your surroundings. /42-03

AVIATION

Satellite imagery and terminal observations show widespread marine stratus along the coast bringing MVFR to LIFR conditions. Meanwhile, inland locations are maintaining VFR conditions between FL035 to FL050, with a 10-30% chance of MVFR conditions from 13Z-17Z Friday. Coastal locations are expected to maintain MVFR to LIFR conditions improving towards VFR around 18Z-20Z Friday. Inland locations are expected to improve with CIGs expected to lift above FL050 around 18Z-20Z Friday.

Marine stratus is expected to return towards 04Z-08Z Saturday and will bring another round of IFR/LIFR conditions to the coast and VFR conditions between FL035 to FL050 for inland locations once again. Light and variable winds under 5 kt through 15Z-18Z Friday at any given terminal, becoming northwesterly in the afternoon and remaining under 10 kt.

KPDX AND APPROACHES...VFR conditions between FL035 to FL050 expected, with CIGs lifting above FL050 around 18Z Friday. Light and variable winds under 5 kt through 15Z-18Z Friday at any given terminal, becoming northwesterly in the afternoon and remaining under 10 kt.

MARINE

Current seas of 4 to 6 ft and northerly winds around 5 to 10 kt will continue through today. North/northwesterly winds increase this afternoon to around 10 to 15 kt, strongest to the south of Cape Foulweather where gusts up to 20 kt are expected late in the day.

Saturday and Sunday, a thermally induced surface trough develops along the coast, which will result in northerly winds increasing northward, impacting all waters with gusts up to 30 kt. In addition seas will also react to the increasing winds thus building towards 5 to 8 ft by Saturday night/Sunday. In response to expected gusty winds, Small Craft Advisories have been issued across all waters as gusts are expected to build towards 25-30 kt with highest wind gusts expected in zones PZZ253 and PZZ273. Small Craft Conditions are expected to persist through the weekend and likely into the start of next week. By mid-week conditions are expected to subside below Small Craft Advisory levels. /42

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...Small Craft Advisory from 11 PM Saturday to 8 PM PDT Sunday for PZZ251-271.

Small Craft Advisory from 8 PM Saturday to 8 PM PDT Sunday for PZZ252-272.

Small Craft Advisory from 2 PM Saturday to 8 PM PDT Sunday for PZZ253-273.