Marine Weather and Tide Forecast for Philomath, OR

DISCUSSION
Today through Thursday...Satellite imagery and surface observations as of early Friday morning depicts onshore flow supporting a solid marine layer along the coast with stratus clouds pushing through the gaps of the Coast Range and through the Lower Columbia River into the Cowlitz Valley. By 5-7 AM Friday, expect stratus clouds to make it's way into the rest of the I-5 corridor including the Willamette Valley. After 9-11 AM Friday, clouds across interior valleys should begin clearing out as daytime heating progresses and increases mixing.
Meanwhile, there remains uncertainty with how much clearing will occur at the coast. There is about a 50-60% chance at any given hour between 2-7 PM for marine stratus breaking out along the north Oregon coast, but lower confidence for clearing along the central Oregon coast.

Expect dry and warm conditions today and through the weekend for the majority of locations as weak ridging builds over the Pacific Northwest and an upper level trough elongates well- offshore over the northeast Pacific Ocean. An exception would be the Cascades, where there is a 10-25% chance for isolated thunderstorms this afternoon and Saturday afternoon. As shortwaves from the broad parent trough offshore brings more southerly flow aloft over the area, will see increasing instability and monsoonal moisture supporting these thunderstorm chances. Any thunderstorms that develop may bring lightning, brief heavy rain, and erratic winds. Otherwise, the general airmass remains too dry to support any widespread precipitation west of the Cascades. Guidance suggests high confidence for near to slightly above average temperatures for mid-August through the weekend, with afternoon highs warming into the mid to upper 80s across interior valleys.

Early next week, cluster analysis of 500 mb heights continue to suggest dry and seasonably warm conditions as broad upper level troughing remains well-offshore and an upper level ridge axis over the Rockies tilts into the Pacific Northwest. By mid-week, ensembles diverge into various upper level patterns. A little over half of ensemble members are favoring a trough entering the Pacific Northwest and returning cooler temperatures, while the other half favors warmer conditions due to zonal flow or amplified ridging. Either way, no precipitation is forecast as we maintain a dry summertime airmass. -10

AVIATION
Through 18Z Sat...Morning satellite imagery and terminal observations show a mixture of widespread marine stratus and smoke/haze across the airspace. This is resulting in MVFR conditions for inland locations and MVFR to LIFR conditions along the coast.

Guidance is suggesting that the MVFR conditions within the Willamette Valley will improve to VFR around 18Z-20Z Friday, while coastal locations are expected to maintain MVFR conditions through at least 06Z Saturday. Afterwards, conditions along the coast are expected to fall back towards IFR/LIFR for the remainder of the TAF period. As for inland locations, MVFR conditions via marine stratus are expected to return around 10Z-12Z Saturday and will persist through the remainder of the TAF period. Westerly to northwesterly winds generally around 5-10 kt today, strongest in the afternoon.

From 20Z Friday through 06Z Saturday, smoke will likely mix down at times and could impact visibilities. Smoke/haze across the airspace could impact slant range and vertical visibilities anytime through 06Z Saturday for inland locations.

Starting around 10Z Saturday and through at least the end of the TAF period, models are showing around a 10% chance for elevated thunderstorms developing anywhere within the Willamette Valley.
Any thunderstorms that develop could result in frequent lightning, small hail as well as gusty and erratic winds.

KPDX AND APPROACHES.. MVFR conditions through around 20Z Friday, scattering out and improving to VFR afterwards. MVFR conditions expected to return around 12Z-15Z Saturday. Northwesterly winds around 3-7 kt, strongest in the afternoon. From 20Z Friday through 06Z Saturday, smoke will likely mix down at times and could impact visibilities. Smoke/haze across the airspace could impact slant range and vertical visibilities anytime through 06Z Saturday. /42

MARINE
No significant changes in the overall pattern as high pressure offshore will continue to support northerly winds along with benign conditions across all waters through next week. Winds from the north to northwest with gusts less than 21 kts will continue through at least the weekend, with wind driven seas expected to remain around 3-5 ft. -10/42

PQR WATCHES/WARNINGS/ADVISORIES
OR...None.
WA...None.
PZ...None.