textproduct: Portland

SYNOPSIS

Onshore flow continues over the next week. Near zonal flow aloft today through Sunday will become southwesterly early next week, with surface high pressure building this 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, except 70s today. Onshore flow will keep the coast cooler with highs in the 60s.

DISCUSSION...Thursday afternoon through Thursday

A very slight pattern change occurs today into Friday as the upper level trough situated over the West Coast begins flattening out into more zonal flow. Ensemble guidance is in very good agreement that generally zonal flow will remain over the area into Sunday. Although general onshore flow remains in this pattern, there will be less of a push inland, so stratus cover that forms in the mornings will mostly break up by midday, allowing for more sunshine and warmer temperatures. Some locations along the coast may remain socked in by stratus while others might clear out. Expect interior lowland temperatures in the low to mid 70s today, increasing into the low 80s for tomorrow through the holiday weekend. Northwest winds will become locally breezy along the Columbia River, the central Gorge, and downwind of the Coast Range gaps each afternoon and evening. Expect wind gusts of 15-25 mph, except up to 25-30 mph in the Gorge.

Ensemble guidance is in agreement that ridging building over the central US pushes slightly northwest into NW OR and SW WA on Monday. Daytime temperatures will peak for the week on Monday, warming into the mid to upper 80s for the interior lowlands with a 10-30% chance of temperatures reaching 90 degrees between Vancouver and Salem. Then a strong low pressure system will slowly move east into British Columbia Tuesday into late next week, pushing the ridging out of the PacNW and lowering heights over the PacNW. Temperatures are slated to remain in the low 80s Tuesday through the rest of next week with less than 5-10% 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. -03

AVIATION

Currently as of 21Z Thu, widespread VFR with high level clouds throughout the airspace. Coastal terminals will continue to bounce between VFR and MVFR this afternoon, then trend towards at least IFR conditions by 01-03Z Fri, expected to persist until around 16Z Fri. Additionally, there is a 30-50% chance of LIFR conditions between 05-14Z Fri, earliest chances at KONP. Coastal terminals will return to MVFR CIGs by 17-18Z Fri. As for inland terminals, models continue to suggest VFR conditions through at least 12Z Fri, then a 20-40% chance of MVFR CIGs between 12-19Z Fri. Expect generally northerly to northwesterly winds at or below 8 kt for all terminals, with the exception of southwesterly winds at KAST.

KPDX AND APPROACHES...VFR through at least 12Z Fri, then a 20-35% chance of MVFR CIGs between 12-19Z Fri. Expect north to northwesterly winds under 8 kt through the TAF period. ~12

MARINE

Current seas of 3 to 5 ft and northerly winds around 5 to 10 kt will continue through Friday morning. Winds will then increase Friday afternoon and evening 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. This will help increase seas by a foot or two, but conditions are expected to remain below small craft advisory criteria.

Saturday and Sunday, a thermally induced surface trough will build northward up the Oregon coast, bringing northerly wind gusts up 20-25 kt. Although significant wave heights are not expected to increase much, increasing to at most 8 ft by Sunday, the increasing winds will result in choppier seas. In response to expected gusty winds, Small Craft Advisories have been issued for the inner and outer waters south of Cape Falcon OR from Saturday afternoon to early Sunday morning. Seas and northerly winds then gradually ease early next week.~12/23

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...Small Craft Advisory from 8 PM Saturday to 5 AM PDT Sunday for PZZ252-272.

Small Craft Advisory from 2 PM Saturday to 5 AM PDT Sunday for PZZ253-273.