Marine Weather and Tide Forecast for Clatskanie, OR

SHORT TERM
Now through Sunday night...A warming trend is underway this afternoon, with temperatures rising into the upper 50s to low 60s inland and mid to upper 50s along the coast under partly to mostly clear skies. A weak thermal trough remains in place through Saturday, supporting light offshore flow along the east slopes of the Coast Range and Cascades and generally light northerly flow through the Willamette Valley. This pattern will maintain mostly dry conditions aside from the limited late-day shower potential.

Conditions tonight will be more marginal for widespread frost development compared to recent mornings, though localized impacts remain possible in favored valley locations. A Frost Advisory has been issued for the southern Willamette Valley and Upper Hood River Valley for tonight into Saturday morning. While overall conditions are marginal, variability in cloud cover will play a key role in overnight cooling, with more persistent breaks potentially allowing for localized frost development in sheltered areas. While most inland locations are expected to fall into the upper 30s to low 40s, the southern Willamette Valley and Upper Hood River Valley may drop into the mid 30s. Probabilities for temperatures dropping below 37 degrees remain around 40-50% in the southern Willamette Valley, 50- 70% in the Upper Hood River Valley above 1500 ft, and 10-30% elsewhere inland.

On Saturday, weak ridging supports continued mild conditions, with inland highs reaching the low 70s and coastal areas remaining in the upper 50s to low 60s. A weak frontal boundary approaching from the northwest may bring increasing cloud cover and a slight chance of light showers late in the day, though recent trends continue to weaken this system with minimal expected impacts.

An upper-level low develops offshore on Sunday, introducing increasing uncertainty. Current guidance favors the system remaining offshore, though this will support increased cloud cover across the region and limited precipitation chances primarily along the coast.
Most inland areas remain dry, though skies may trend mostly cloudy at times. Despite this, temperatures remain unseasonably warm, with highs in the low to mid 70s expected as a result of southerly flow.


LONG TERM
Monday through Thursday...The primary forecast concern early next week centers on the evolution of a developing upper-level low offshore, which will introduce increasing uncertainty in temperature trends and precipitation chances.

On Monday, a range of outcomes remains possible depending on the position of this low. A farther offshore track would support relatively mild and drier conditions, while a closer or more northerly solution would favor increased cloud cover and a higher likelihood of showers. At this time, low-end precipitation chances increase and become more widespread by late in the day, with temperatures generally above seasonal averages.

Tuesday, attention turns to a more organized Pacific frontal system approaching the region. Confidence increases that this system will bring a return to more widespread precipitation late Tuesday into Wednesday, though some timing differences remain among ensemble members. Specifically, current guidance suggests the start time of precipitation reaching inland will vary from any time between Tuesday evening and Wednesday afternoon. From 5 PM Monday to 5 PM Tuesday, precipitation totals in the lowlands will vary from 0 to 0.6 inches (highest along the coast) under best and worst scenarios, which continues to reflect the poor agreement between models at this time.

The most impactful period looks to be early Wednesday, with widespread rain expected across the region as the front moves through, bringing up to 0.6 to 0.9 inches to the lowlands from 5 PM Tuesday to 5 PM Wednesday in a worst-case scenario. While exact rainfall totals remain somewhat uncertain (a best case scenario could still result in 0 inches of rainfall totals), this system represents a more notable shift back to wetter conditions compared to earlier this week. Into Thursday, the pattern begins to transition once again as the upper-level system shifts inland and heights start to rise. This will support a trend toward decreasing precipitation and a gradual return to drier conditions. ~12

AVIATION
VFR conditions prevail across all terminals through the TAF period. Expect SCT/BKN high clouds across the region tonight. Terminals with the clearest skies tonight will experience more efficient cooling, and thus potential for frost development over metal surfaces. The highest chances (40-50%) for frost development will be across the southern Willamette Valley including KEUG. Threat for frost ends after 15z Sat once daytime heating progresses. High clouds will break out into mostly sunny skies by 18- 21z Sat as high pressure builds overhead. Variable winds around 5 kt or less for most terminals, except slight tightening of KTTD-KDLS pressure gradients will result in easterly winds around 5-10 kt in the far east Portland Metro (KTTD). Along the coast, light offshore winds tonight turn more southwesterly after 18z Sat. This offshore flow along the coast will help prevent low marine stratus from developing.

KPDX AND APPROACHES...VFR conditions through the TAF period with high SCT/BKN clouds tonight. High clouds gradually decrease on Saturday. Variable winds around 5 kt or less. Light easterly winds develops through the Columbia River Gorge after 12z Sat, but not expected to reach KPDX. -10

MARINE
Relatively benign marine conditions continue through this weekend. Northerly winds around 10 kt continue into tonight, then turn southerly ahead of a weakening cold front on Saturday.
Gusts up to 20 kt may continue this afternoon south of Cape Falcon within 20 NM, before easing this evening. Seas will continue to fall to 3-5 ft by tonight, building only slightly to 4-6 ft as the weak front approaches.

There is higher forecast uncertainty for winds and seas early next week as an area of low pressure offshore approaches the coast. The placement of the low will determine the conditions across the waters, with the forecast at this lead time favoring increasing onshore flow through Wednesday, when WNW gusts may reach 20-25 kt beyond 30 NM. Higher winds and a freshly arriving NW swell may push seas to 10-12 ft Wednesday into Thursday.

Very strong ebb currents will continue across the Columbia River Bar each morning through Tuesday. With seas expected to build slightly by early next week, a steep ebb chop may necessitate Small Craft Advisories in the hours around peak flow each day. -36

PQR WATCHES/WARNINGS/ADVISORIES

OR...Frost Advisory from 1 AM to 8 AM PDT Saturday for ORZ116>118- 121.

WA...None.

PZ...None.