Marine Weather and Tide Forecast for Corvallis, OR

SYNOPSIS
Inland highs around 90 degrees again this afternoon.
A weak frontal system brings more seasonable temperatures for Wednesday and Thursday, with a chance for some light rain along northern coastal areas early Wednesday. Hotter temperatures return Friday and persist into next week as strong high pressure builds offshore.

SHORT TERM
Now through Thursday Night...
Now through Thursday Night...High pressure remains entrenched over the western CONUS today, promoting clear skies across all of western Oregon and Washington with the exception of some patchy marine stratus along the immediate coast.
Observations from around the area show highs in the upper 80s to low 90s in the interior valleys as of mid afternoon. Visible satellite shows cumulus fields starting to become more agitated near and east of the Cascade crest in central Oregon, and expect this to eventually yield a few thunderstorms this afternoon and evening as cutoff upper level low pressure drifts inland from northern California. Expect most of this activity to remain on the east side of the Cascades, but will maintain a 15-20% chance of thunderstorms along the Lane County Cascades this evening as a few storms could move near the Crest later today.

A brief pattern change will commence tonight as a deep upper level trough over the Gulf of Alaska pushes inland across western Canada. This will send a weak surface cold front across the Pacific northwest early Wednesday, bringing about cloudier weather and more seasonable temps for the area Wednesday into Thursday. Expect any precipitation chances to remain limited to northern coastal areas and parts of southwest Washington on Wednesday. Model QPF suggests parts of Pacific County could see as much as a tenth or two of an inch of rain through early Wednesday afternoon, but other locations along the north Oregon Coast or the Cowlitz Valley will likely be limited to a trace to a few hundredths. Although other locations are expected to remain dry, passage of the front will at least bring some temporary relief from the recent hot temperatures as afternoon highs will run about 10 degrees cooler in the interior valleys, maxing out in the upper 70s to around 80 degrees in most locations. Expect dry weather on Thursday, with a bit less cloud cover and temperatures rebounding by a few degrees into the low 80s in many interior locations. Meanwhile, persistent onshore flow amd marine stratus will keep coastal temperatures in the low to mid 60s going forward. /CB

LONG TERM
Friday through Tuesday...Hotter temperatures return on Friday and look to persist well into next week as ensemble clusters remain in lock step in depicting a strong upper level ridge developing across the NE Pacific in the long term. This will likely correspond to a prolonged stretch of daytime highs in the low 90s across the Willamette Valley and Portland Vancouver Metro, helping to maintain a moderate Heat Risk in these areas from Friday into next week. The probability to reach 95 degrees ranges from 60-80% from Salem to Eugene and 25-40% in the Portland/Vancouver Metro each day from Friday through Monday. The NBM is hinting at the possibility for even hotter temperatures next Tuesday and Wednesday, with NBM 75th percentile guidance depicting highs reaching the low 100s from the Portland/Vancouver Metro to Eugene and pushing Heat Risk into the Major category on Tuesday. It should be said that more modest highs in the low 90s remain well within the range of outcomes on these days, but the potential is there for the first widespread triple digit readings of the summer as we head into Tuesday and the middle of next week.

In terms of precipitation, certainly expect most of the area to remain dry through the end of the long term. However, did note that most deterministic solutions depict a mid level impulse off of northern California this weekend and early next week, which maintains at least a thought for a few thunderstorms in the vicinity of the Lane County Cascades into the long term. Model probabilities are too low to warrant inclusion of thunderstorms in the forecast for now, but will need to monitor this potential as models start to better resolve this feature in the coming days. /CB



AVIATION
Weakening high pressure over the region will give way to a dying front sliding into northwest Oregon and southwest Washington Wednesday morning. Marine clouds are pushing into the Coast Range gaps as a strong southwest to west marine push is underway with the KOTH-KPDX gradient peaking at over 7mb earlier this evening. This suggests marine clouds should deepen substantially overnight and push into the Willamette Valley despite most high resolution model guidance suggesting otherwise. At the moment, high resolution ensemble guidance suggests a 50% chance that marine clouds reach KEUG and stay primarily downriver of KPDX & KTTD along the lowest stretches of the Columbia River. Given the solid 10-20 kt sea breeze observed most of the evening at KEUG, KCVO, KS12 and KMMV, and the aforementioned observed pressure gradients, have hedged towards MVFR ceilings being more likely than not with the latest TAF package for inland taf sites Wednesday morning. The aforementioned dying front will push onto our northern coastal zones around daybreak on Wednesday with a 50-60% chance for drizzle and light rain at KAST between 12-20z Wednesday. The odds the front hangs on enough to produce measurable drizzle or light rain and impact visibilities for the Portland metro taf sites has lowered to ~10% and drops to well below 10% as one goes southward in the Willamette Valley.

PDX AND APPROACHES...Weakening high pressure over the region will give way to a dying front sliding into northwest Oregon and southwest Washington Wednesday. Marine clouds are pushing into the Coast Range gaps this evening as a strong southwest to west marine push is underway with the KOTH-KPDX gradient peaking at over 7mb this evening. This suggests marine clouds should deepen substantially overnight and push into the Willamette Valley despite most high resolution model guidance suggesting otherwise. Given the solid 10-20 kt sea breeze observed most of the evening at KEUG, KCVO, KS12 and KMMV currently, and the aforementioned pressure gradient, have hedged towards MVFR ceilings arriving between 12-15z Wednesday for the Portland taf sites. The aforementioned dying front will push towards the taf sites between 15-20z Wednesday, but the odds the front is strong enough to wring out measurable drizzle or light rain and impact visibilities for the Portland metro taf sites is ~10%.
/Neuman

MARINE
A dense fog advisory has been issued to account for the fact that the widespread low clouds over the waters are most likely lowering to the ocean's surface in the vicinity of the maximum upwelling, which is typically within 20-30NM of the coast.
In addition, a weak front is currently dropping southeastward into the waters. This will turn the winds southerly across the waters overnight. Winds will be strongest within 20 NM of the coast, particularly from Cape Falcon northward, but there is a 75% chance that southerly wind gusts remain below 20 kt. Once the front passes, winds will turn west to northwesterly late in the day on Wednesday.

We will then return a more typical northerly wind pattern Thursday into Friday as high pressure builds across the northeast Pacific and thermally induced lower pressure returns to northern California. This will produce gusty northerly winds and choppier wind driven seas, particularly south of Cape Falcon. Winds and seas will be strongest off the central coast of Oregon and will typically peak in the afternoon and evening hours over the inner waters each day through the weekend. /Neuman

PQR WATCHES/WARNINGS/ADVISORIES
OR...None.
WA...None.
PZ...Dense Fog Advisory until 11 AM PDT Wednesday for PZZ210- 251>253-271>273.