Marine Weather and Tide Forecast for Clatskanie, OR

SHORT TERM
Now through Wednesday night...Water vapor satellite imagery this afternoon shows an amplified upper level pattern shifting east across the Pacific toward Pacific NW. We see to some extent a baroclinic leaf developing downstream of a PV anomaly at the base of the upper level trough. A weak surface low will likely develop tonight as the weather system approaches the region. This low moves north toward Vancouver Island while a warm front lifts across the area, with light rain through this evening. The main uncertainty comes with the potential of a secondary, compact surface low developing near the Oregon coast Wednesday morning. This would bring the potential for more impactful south to southwesterly winds.
Fortunately, the latest model runs have been trending away from this solution. Still, will likely see winds increasing Wednesday morning. The HRRR shows southerly winds with gusts up to 40-50 mph along the coast becoming westerly by the afternoon. And although there is still potential for a low to spin up quickly near the coast, the probability of exceeding 60 mph is quite low, around 10%. Breezy southerly winds likely through the Willamette Valley as well mid-day Wednesday, with gusts up to 30-40 mph. Those in the Columbia River Gorge and east Portland/Vancouver metro will also notice the easterly winds pick-up Wed morning as the KTTD-KDLS pressure gradient increases to around -7 to -8 mb.

Precipitation rates will likely increase on Wednesday as the upper trough pushes an occluding front across the region. Snow levels above 5000 ft Wednesday morning will gradually fall to around 3500- 4000 ft by Wednesday evening. The higher Cascades are expected to pick up another round of snow, with around 4 to 8 inches of snow likely at pass level, therefore have issued a Winter Weather Advisory for the Cascades. Heaviest snowfall rates expected between 8 AM and 4 PM on Wednesday.

The Upper Hood River Valley will potentially see a mix of wintry weather tonight into early Wed morning. Probabilities have decreased as forecasted temperatures marginally fall to below freezing. But there remains a low chance (10-30%) of areas above 1000 ft to see a freezing rain with ice accumulations up to a tenth an inch or snow up to a half inch. /DH

LONG TERM
Thursday through Tuesday...Models and their ensembles remain in good agreement of upper level ridging building over the region later this week. Expect a mostly dry day on Thursday. But with clouds, temperatures only warm into the lower 50s. Most clusters keep the area dry on Friday, although there is around a 40% chance that a front is able to push rain back into southwest Washington and far NW Oregon by Friday afternoon. Temperatures are likely to continue the gradual warming trend into the mid to upper 50s into the weekend and early next week.

Light rain showers late Friday into Saturday turns to heavier rain later in the weekend as the next weather system will likely be associated with a moderate atmospheric river, potentially persisting through Monday. Both the GEFS and the European Ensemble suggests mean PWAT amounts of around 1.1-1.2 inch now. Uncertainty remains with where the band of heavier moisture sets up. The highest chances of IVT values > 500 kg/m/s (of around 70-90%) have shifted slightly southward, according to the CW3E IVT landfall tool, to much of the central and northern Oregon coast. Although latest HEFS forecasts show a 5-15% chance of local tributary rivers reaching minor flood stage, will need to monitor the flashier rivers as we get closer to Sunday. /DH

AVIATION
Widespread VFR conditions being reported as of 05z Wed as a band of light warm frontal precip lifts north across the area. This band should depart 08-10z, leaving scattered showers as VFR persists through the remainder of the night. Expect LLWS to develop at the coastal terminals overnight as southerly winds increase aloft ahead of approaching cold front while surface winds remain E-SE. Steady rain associated with the cold front will push inland 12-16z Wed, with conditions trending down to MVFR as a result. Expect southerly winds to increase to 10-15 kt at the inland terminals roughly 15-22z, but unidirectional flow should help limit any LLWS concerns in the Willamette valley. Rain tapers to showers behind the front 20-23z Wed as flight conditions gradually improve back towards VFR 00-06z Thu.

PDX AND APPROACHES...Mainly VFR expected through 15-16z Wed, but cigs will continue to straddle FL040 and hamper visual approaches.
Light rain associated with a warm front will depart the terminal 08-10z, leaving showery conditions and 10-15 E-SE winds overnight.
Cold frontal rain band will reach the terminal around 16z Wed and turn winds more southerly as conditions lower to MVFR. Front departs 21-23z Wed, leaving showery weather and cigs improving back to VFR for the rest of the period. /CB

MARINE
Evening update: Gales winds on track per latest buoy observations. Upgraded to a Gale Warning for nearshore waters north of Cape Falcon and moved start time up to 4 AM as 00z hi-res guidance has come into better agreement. Guidance has also continue to back off of solutions depicting a compact surface low moving onto the central coast Wednesday morning. This may allow Gales to end a bit sooner than depicted in current forecast as winds shift to westerly late Wednesday morning. Will evaluate this possibility in the next forecast cycle. /CB

Previous discussion follows...A frontal system moving onshore this evening into Wednesday will bring gusty winds and building seas. Gale Warnings have been expanded to include all inner waters south of Cape Falcon after 4 AM Wednesday, in addition to all outer waters as of 4 PM today. A strong cold front sweeping through the region will produce southerly gusts of 35 to 45 kt, initially beyond 10nm, and subsequently to near-shore zones as winds turn out of the south-southwest. Further gusts of 35 to 45 kt are expected as winds turn out of the west behind the approaching cold front.

A Small Craft Advisory is in effect as of 4 PM today for inner waters north of Cape Falcon and within the Columbia River Bar. A Gale Watch has additionally been issued for inner waters north of Cape Falcon after 7 AM Wednesday, with isolated to scattered gusts of 35 kt possible, most likely behind the cold frontal passage as winds turn out of the west. Within the Columbia River Bar, choppy seas growing to 11 to 13 ft are expected through Wednesday despite modest ebb tides as gusty southerly winds turn westerly Wednesday afternoon. There remains some uncertainty in the strength of winds as well as resultant wave heights beyond Wednesday afternoon due to associated uncertainty in the location of the parent surface low.

Following a quieter Thursday and Friday, additional gales are expected as another surface low and strong cold front track across the northeast Pacific on Saturday. In fact, there appears to be a 40-50% chance in storm-force winds in outer waters on Saturday, though there remains uncertainty given the lead time. -Picard

PQR WATCHES/WARNINGS/ADVISORIES
OR...Winter Weather Advisory from 4 AM Wednesday to 4 AM PST Thursday for ORZ126>128.

WA...Winter Weather Advisory until 4 AM PST Thursday for WAZ211.

PZ...Small Craft Advisory until 4 PM PST Wednesday for PZZ210.

Small Craft Advisory until 4 AM PST Wednesday for PZZ251>253.

Gale Warning from 4 AM to 4 PM PST Wednesday for PZZ251>253.

Gale Warning until 4 PM PST Wednesday for PZZ271>273.