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. A gradual warming trend develops Friday into the holiday weekend with most inland valley locations likely warming into the low to mid 80s for high temperatures each day from July 4-7 (70-90% chance, except in the Cowlitz Valley and along the lower Columbia where highs in the mid to upper 70s are the most likely outcome).

DISCUSSION...Wednesday through Tuesday night

The weather pattern observed over the area over the past few days remains unchanged, with conditions on Wednesday expected to be a repeat of what was observed yesterday as moist onshore flow continues and maintains cool and cloudy conditions. Satellite observations from early Wednesday morning depicted overcast skies across all of northwest Oregon and southwest Washington from the coast to the Cascade crest, while surface weather observations depicted light and variable winds around 5 mph or less along with temperatures in the 50s. Similar to yesterday, skies are expected to remain mostly cloudy through the day aside from some limited breaks of sun in the late afternoon and evening, especially to the west of the I-5 corridor in the Willamette Valley. This is also when breezy northwest winds will develop with an incoming sea breeze front, sustained around 8-13 mph with occasional gusts up to 15-20 mph. Gusts up to 25-30 mph are expected in the central Columbia River Gorge and Upper Hood River Valley as westerly winds increase through the Gorge. Given the persistent cloud cover in place, temperatures will remain below average for early July. Forecast highs range from the mid to upper 60s for most locations, except around 70 degrees in Eugene-Springfield.

Model guidance continues to suggest little change to the overall weather pattern on Thursday as well, aside from slightly more sun breaks. As such, temperatures should warm a bit on Thursday with highs in the low to mid 70s, except at the coast where highs will remain in the 60s. Conditions trend sunnier and warmer Friday into the holiday weekend as upper level flow transitions from northwesterly to westerly and 500 mb heights begin to increase a bit. By Friday, widespread highs around 75-80 degrees are expected for inland valleys. Highs will likely warm into the low to mid 80s for July 4-7 (70-90% chance each day, except in the Cowlitz Valley and along the lower Columbia where highs in the mid to upper 70s are the most likely outcome). Despite warmer temperatures inland, the coast will stay stuck in the 60s each day due to persistent onshore flow. Aside from a few stray sprinkles over higher terrain today, no precipitation is expected July 1-7. -23

AVIATION

Widespread cloud cover remains in place across all of northwest Oregon and southwest Washington this morning from the coast to the Cascade crest. Similar to what was observed yesterday, ceilings around 4000-5000 feet are expected to lower close to 3000 feet by 12-14Z Wednesday, except at KEUG where there is a 60-80% chance ceilings will stay around 3500-4000 feet. Ceilings will then lift back to 4000-5000 feet between 17-20Z Wednesday with daytime heating and increased low-level mixing. Winds are expected to follow a diurnal pattern that is similar to yesterday, with light and variable winds around 5 kt or less this morning becoming northwesterly around 7-12 kt by the late afternoon and early evening hours. Occasional wind gusts as high as 15-20 kt are likely to occur at all terminals by 00-02Z Thursday with an incoming sea breeze, except at KTTD and KUAO where the sea breeze front will struggle to reach.

KPDX AND APPROACHES...Low-end VFR ceilings around 4000-5000 feet are expected to lower to around 3000 feet by 12-13Z Wednesday as probabilities for ceilings of 3000 feet or lower have increased to 75-85% during that time. Similar to what was observed yesterday, ceilings will most likely lift to 4000 feet or higher sometime between 16-18Z Wednesday, bringing a quick return to VFR flight conditions. Northwest winds around 5 kt are expected to increase to around 10 kt with occasional gusts up to 15-18 kt around 02Z Thursday with an incoming sea breeze front. Winds should become less gusty after 06Z Thursday. -23

MARINE

Buoy observations early Wednesday morning showed the continuation of steep seas around 7 to 8 feet at 9 seconds due to a persistent fresh northwest swell. Northwest winds continue around 5 to 15 kt, with gusts up to 20 kt over the outer waters. Winds and seas are expected to decrease late Wednesday morning into the afternoon, bringing improving conditions for small craft. Seas fall to 4-6 feet by late Wednesday night and then hold steady through the upcoming weekend.

Meanwhile, predominately northwest winds are expected to continue through Friday with wind speeds becoming even weaker each day. A thermally induced surface trough will build northward up the south Oregon coast over the weekend, bringing increasing northerly winds with gusts up to 20-25 kt. As is often the case during this typical summertime pattern, wind speeds will be strongest during the afternoon and evening hours each day with daytime heating. Although significant wave heights are not expected to increase much, the increasing winds will result in choppier seas. -23

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...Small Craft Advisory until 11 AM PDT this morning for PZZ251- 271>273.