textproduct: Portland

SYNOPSIS

Cool onshore flow and persistent cloud cover will maintain below average temperatures over the area through Thursday with little change in the overall weather pattern. Conditions will be mainly dry aside from a few stray sprinkles, mainly over higher terrain. A gradual warming trend develops Friday into the holiday weekend with inland valleys likely warming above 80 degrees for the 4th of July into early next week (60-90% chance).

DISCUSSION...Tuesday afternoon through Monday night

Very little change in weather conditions is expected through Thursday as upper level troughing remains in place over the Western US. Satellite imagery shows cloud cover blanketing NW OR and SW WA with little clearing expected due to increased onshore flow. High temperatures each day are forecast to be in the mid to upper 60s for inland valleys with 50s to low 60s elsewhere. Thursday will likely be slightly warmer with inland valleys into the low to mid 70s as temperatures aloft warm a few degrees, though if cloud cover remains fairly dense, observed high temperatures could end up lower than this. A few light showers or drizzle are possible each day, as well, mainly over the higher terrain.

Confidence increases for a more noticeable warm-up Friday into the upcoming holiday weekend due to the arrival of weak upper level ridging and less cloud cover during peak heating hours. The NBM shows a 60-90% chance for highs above 80 degrees by the 4th of July through Monday for inland valleys south of Vancouver while the coast stays in the 60s. Probabilities for highs above 90 degrees this weekend remain at 1-10%, and the 90th percentile indicates the high end scenario for high temperatures is in the upper 80s for the weekend. This indicates abnormally hot conditions and heat- related impacts are unlikely to occur for the holiday weekend. -03/23

AVIATION

Satellite imagery and terminal observations as of late Tuesday evening depict widespread low-end VFR stratus spreading across northwest Oregon and southwest Washington. High confidence for low-end VFR CIGs across the area (3-5 kft) tonight, with increasing chances for high-end MVFR CIGs (2-3 kft) after 12z Wed. Guidance generally gives a 20-40% chance for MVFR CIGs for Willamette Valley terminals at any given hour between 12-18z Wed, and a 40-60% chance for coastal terminals. By 17-18z Wed, increased mixing will improve conditions back to VFR with CIGs gradually rising throughout the day. Winds light and under 5 kt tonight, turning northwesterly and increasing to 8-11 kt after 21z Wed-00z Thu.

KPDX AND APPROACHES...Low-end VFR CIGs through early Wednesday morning with a 30-40% chance for high-end MVFR CIGs (2-3 kft) at any given hour between 12-18z Wed. Variable winds under 5 kt through the morning. Winds become northwesterly and increase to 6-10 kt after 21z Wed and last through the evening. -10

MARINE

Northwesterly swell through the next several days with steep seas of 8 to 10 ft at 9 seconds through early Wednesday morning. Possible isolated seas to 10 ft in the outer waters of PZZ271-272 past the Small Craft Advisory, however they are not expected to be widespread or long lasting. Winds and seas will ease significantly Wednesday afternoon and evening, with benign conditions expected Thursday and Friday. Seas are expected to range between 4 and 6 ft Wednesday night through the upcoming weekend, with north to northwest winds continuing. Northerly winds do increase in strength over the weekend as a typical summertime ridge sets in. We will see thermally drive winds in the afternoon and evening hours when gusts up to 20-25 kt are expected. -27/23

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...Small Craft Advisory until 11 AM PDT Wednesday for PZZ251- 271>273. Small Craft Advisory until 2 AM PDT Wednesday for PZZ252-253.