Marine Weather and Tide Forecast for Westport, OR

SHORT TERM
Monday afternoon through Thursday night...Satellite and surface weather observations from early Monday afternoon depicted clear skies across all of western WA and western OR with high pressure in place. However, an area of upper level smoke coming from the East Evans Creek Fire burning to the north of Medford, OR was beginning to move into eastern Lane County. This has resulted in slightly hazy skies in the Lane County Cascades.

Otherwise expect mostly clear skies to continue for inland areas tonight through Tuesday with broken low clouds at the coast Tuesday morning. Tuesday will be another warm day with afternoon highs in the upper 80s to near 90 degrees for inland valleys, with highs around 65-70 degrees at the coast due to onshore winds. Temperatures will be nearly the same on Wednesday with plenty of sunshine, aside from some degree of low marine stratus at the coast in the morning. Dry conditions will also continue through Wednesday evening, aside from a 15-30% chance of rain showers over the Oregon Cascades Tuesday evening/night and again Wednesday afternoon/evening. Chances for showers during both of these periods are tied to two upper level impulses ahead of a closed upper level low centered somewhere over the far northeast Pacific. However, dry air entrainment into storm updrafts will likely limit vertical growth of any cells that do develop. In turn, this will limit the potential for lightning and significant rain amounts. The NBM backs this up, producing only a 5-15% chance of thunderstorms on the west slopes of the Cascades with a trace to 0.05 inches of rain near the Cascade crest.

Chances for showers and higher rain amounts increase Wednesday night into Thursday across all of northwest OR and southwest WA, especially over southwest WA and far northwest OR to the north and east of Salem. NBM PoPs have increased to 30-50% in these areas, and 15-30% to the south of Salem through Lane County. This is in response to the aforementioned upper level low over the far northeast Pacific attempting to slowly move inland somewhere over northwest OR and/or western WA. The use of the word "attempting" in the previous sentence was intentional, as roughly half of the ensemble space from the GEFS/GEPS/ENS suggests this low will move near the coast or inland, while the other half keep the low stalled farther offshore while weakening. If this low does move inland, temperatures would trend cooler than the current deterministic forecast with rain showers and isolated thunderstorms becoming more prevalent. If this low stays well offshore, conditions would trend mainly dry and warmer west of the Cascades. This uncertainty is highly evident in total model spread for temperatures, with the NBM 10th-90th percentile suggesting inland valleys could range anywhere from around 80 degrees to near 95 degrees on Wednesday and anywhere from 75-100 degrees on Thursday.
Large model spread is evident for QPF as well, with the NBM min to max 24-QPF values ranging from no rain at all to over 0.25-0.50 inches. If the low does wind up moving directly over northwest OR and southwest WA, some showers and thunderstorms would likely produce locally heavy rainfall given PWAT values around 1", cloud layer winds near 15-20 kt, and deep warm cloud layer depths near 3000-3500 meters. That said, precipitation would be very hit-or-miss given the showery nature, meaning some locations would receive little to no rain while other locations receive 0.25-0.50 inches or more. -23

LONG TERM
Friday through Sunday night...Confidence in the forecast actually increases Friday into the weekend compared to the Wednesday night and Thursday timeframe, despite total model spread for temperatures remaining large. Overall, model ensembles are in good agreement for dry and warm conditions Friday through the upcoming weekend with continued low-level onshore flow and southwest flow aloft. The main uncertainty in the long term forecast is exact high temperatures for inland valleys, which could range anywhere from the lower 80s to near 100 degrees. The most likely outcome is for highs somewhere in the mid 80s to lower 90s.

Chances for highs above 90 degrees peak on Sunday at 40-60% for inland valleys, except 30-40% over the Cowlitz Valley and lower Columbia. Chances for highs of 100 degrees or warmer range between 5-15%. Probabilities for a Major HeatRisk or higher are also low, ranging between 5-20%. This suggests extreme heat with significant heat-related impacts are unlikely to occur. It is also worth noting the coast would remain much cooler than inland areas regardless of the outcome due to light onshore winds. Beyond the seven day forecast, it is possible the warm and dry conditions will persist into early next week as probabilistic guidance is similar on Monday when compared to Sunday. -23

AVIATION
VFR conditions inland through the TAF period, while coastal terminals will experience MVFR to LIFR conditions overnight. Expect at least MVFR CIGs at the coast from now until 19Z Tue, with a 50-70% chance of IFR CIGs and 10-40% chance of LIFR CIGs (highest chances at KONP). Overall, expect MVFR/IFR CIGs at KAST and shallow IFR/LIFR stratus and/or fog at KONP.
After 19Z Tue, coastal terminals will likely improve back to VFR (70-90% chance of VFR). Around 03Z Wed, deteriorated conditions may return to the coast, with a 30-40% chance of MVFR CIGs , 20-30% chance of IFR CIGs , and a 10-20% chance of LIFR CIGs (highest chances at KONP). Otherwise, expect light north to northwesterly winds overnight, then increasing to 5-10 kt inland and 7-12 kt at the coast by 21Z Tue. Coastal terminals may see gusts up to 20 kt.

KPDX AND APPROACHES...VFR with mostly clear skies and northwesterly winds around 5-8 kt. ~12

MARINE
Benign conditions with a typical summertime pattern expected through the week. Northerly winds 10-15 kt expected with afternoon gusts reaching to around 20 kt each day. Seas could be choppy at times with heights mainly in the 4-6 foot range but could see some 7 foot seas at 8-10 seconds. Isolated steep and hazardous seas but not enough to issue a Small Craft Advisory (SCA).

A SCA is in effect from 2AM to 9AM Tuesday morning for the Columbia River Bar for rough seas due to a very strong ebb current leading to seas of 6 to 8 ft. -19/03

PQR WATCHES/WARNINGS/ADVISORIES

OR...None.
WA...None.
PZ...Small Craft Advisory from 2 AM to 9 AM PDT Tuesday for PZZ210.