Marine Weather and Tide Forecast for Seaside, OR

SHORT TERM
Today through Friday...A few clouds linger through this morning, mainly along the coast and Cascades, as an upper shortwave trough slides east toward the northern Rockies. A more amplified upper level ridge will begin to slide over the Pacific Northwest, with clearing skies and dry weather expected through at least Thursday. Temperatures remain fairly mild today as northwest onshore flow persists. But, come the first day of May, temperatures are expected to spike as the ridge amplifies over the region, pushing 850 mb temps into the 13-15 C range. Weak offshore flow will also set up early Thursday as a surface thermal trough builds across the coast range. Marine winds push back onshore later in the day, except near the Portland Metro which will likely maintain easterly winds and see temperatures warm into the lower to mid 80s. Marine influences still look to keep coastal locations more mild by comparison, with temperatures topping out in the 60s to near 70.

The upper ridge will continue to shift eastward, and by early Friday, expect a southerly wind reversal ahead of the next weather system. An upper level trough offshore approaches the region later Friday with increasing moisture and low level westerly flow. Expect increasing clouds through the day, with increasing chances for light rain at the coast. Best chance for showers will likely be along the Cascades, increasing Friday afternoon through Friday evening. If skies remain fairly clear allowing surface warming to occur along the western slopes, pattern recognition suggests there is potential for thunderstorms near the crest, but chances remain slight, around 15% or less. Overall, the weather will likely remain fairly pleasant through much of the day, with increasing showers through the evening. Rainfall amounts through Friday night currently forecast to be around a tenth of an inch or less, except in the Cascades and foothills where there is around a 50% chance for wetting rains exceeding 0.25-0.50 inch. /DH

LONG TERM
Saturday through Tuesday...Somewhat cooler temperatures expected on Saturday as the upper level trough slides onto the west coast. Aside from showers along the Cascades and foothills, decreasing through the afternoon, much of the area should remain dry as the upper trough elongates and likely splits. By Sunday, WPC cluster analysis is in good agreement that the base of the tough develops into an upper low over southern California, while more upper ridging begins to nudge back over the Pacific NW into early next week. This will likely bring another warming trend to the area, pushing temperatures back into the 70s by Monday. Potential for more 80 degree days increases to around 20-30% through the middle of next week, while the probability of precipitation remains generally less than 20%. /DH

AVIATION
At 0930z Wednesday, surface weather observations depicted light and variable winds around 5 kt or less across northwest OR and southwest WA. Expect these conditions to continue through 12z Thursday.

In addition to the light winds, a cloud deck was evident along the coast from KAST to KONP with cigs around 3000 ft. Expect this cloud deck to lift to VFR while scattering out by 16z Wednesday.
Clear skies remain in place for inland areas this morning, aside from broken low clouds in the Cascades. These low clouds may briefly backbuild into KTTD and/or KUAO towards 12z Wednesday with cigs around 3000 ft or less, however the probability of this occurring is only at 10-30%. Even if this does occur, cloud cover would likely only last a few hours with clearing after 15-16z.
Given the most likely outcome is for the continuation of clear skies at both terminals, have decided to maintain VFR flight conditions in the 12z TAFs. Will maintain VFR conditions for KHIO, KSLE, KPDX and KEUG as well, as these terminal have even lower probabilities for low clouds to develop.

PDX AND APPROACHES...VFR conditions and mostly clear skies will continue through 12z Thursday with light northwest winds around 5 kt. 10% chance for a brief period of MVFR cigs around 3000 ft from 12-15z Wednesday. Have decided not to include this in the 12z TAF as the most likely outcome is the continuation of clear skies. -TK

MARINE
High pressure will remain in place through Friday, resulting in benign conditions with seas under 10 ft and winds generally under 20 kt. That said, northerly winds should briefly gust up to 20-25 kt late Wednesday afternoon and evening over the southern waters. Therefore, a marginal Small Craft Advisory has been issued for PZZ273 and PZZ253 during that time.

A Small Craft Advisory is also in effect for the Columbia River Bar from 4-10 AM PDT Wednesday. This is when a very strong ebb current will result in steep ebb chop with seas up to 8 ft at 8 to 10 seconds, results in rough bar conditions for small craft. -TK

PQR WATCHES/WARNINGS/ADVISORIES

OR...None.
WA...None.
PZ...Small Craft Advisory until 10 AM PDT this morning for PZZ210.

Small Craft Advisory from 4 PM this afternoon to 10 PM PDT this evening for PZZ253-273.