Marine Weather and Tide Forecast for Long Beach, WA

DISCUSSION
Now through Thursday...The weekend storm system is moving closer to the region this morning, with rain expected to reach the coast late this morning and spread inland through the afternoon. Showers will continue tonight and into Sunday as the upper low moves eastward. Confidence is high that most of the forecast area will receive measurable precipitation, with temperatures remaining well below seasonal average through the weekend.

Most locations should see around 0.10-0.40 inch of rain through Sunday, while higher totals are expected in the mountains. The southwest Washington and north Oregon Cascades are favored for 0.50-1.00 inch, with the highest amounts likely in southwest Washington. There is some potential for locally heavier rainfall if a more concentrated band of showers develops on the north and northeast side of the low. A southward shift in this band would increase rainfall totals across the Portland Metro, particularly Saturday night into Sunday morning. At the higher end of the forecast envelope, which is around a 10% chance at this point, rainfall could reach 0.50-0.75 inch in the interior lowlands and 1-2 inches in the Cascades, with the highest amounts again favored in southwest Washington.

As the upper low moves east of the Cascades Sunday, showers should become more scattered and increasingly focused over the higher terrain. The inland valleys and immediate coast should trend mostly dry by late Sunday afternoon, while the Cascades could continue to see showers into the evening.

A 10-20% chance of thunderstorms exists from mid-afternoon through this evening. The main limiting factor is timing, as the period of strongest daytime heating only briefly overlaps with the coldest air aloft. Even so, model soundings show enough instability to support a few thunderstorms. Any storms that develop could produce occasional lightning, brief heavy rain and locally erratic wind gusts. Cold-core funnel clouds are also possible with the stronger showers. These are typically short- lived and remain above the ground, though a funnel reaching the surface cannot be ruled out.

Cool conditions continue Sunday as clouds and showers linger across the region. Interior highs should generally remain in the upper 50s to mid 60s, with cooler readings possible in areas that see heavier showers. The pattern then begins to change Monday as the upper low moves farther east and high pressure starts building over the eastern Pacific. A weak trough may linger near the region into Tuesday, but temperatures should steadily recover, reaching the low to mid 70s across the interior valleys by Tuesday.

The warm-up becomes more pronounced Wednesday and Thursday.
Ensemble guidance now gives about a 75% chance that the offshore ridge shifts closer to the Pacific Northwest, supporting temperatures well into the 80s across the interior lowlands. The remaining guidance keeps some troughing near the region and would favor somewhat cooler temperatures.

Easterly flow is also becoming increasingly likely by midweek as the ridge strengthens and lower pressure develops over northern California. The strongest winds currently appear most likely Wednesday into Thursday morning, with gusts of 25-35 mph and isolated gusts near 40 mph possible in wind-prone areas of the Columbia River Gorge, Cascades and adjacent foothills. The tops of the Coast Range could also become windy, although confidence is lower there. At the higher end of the forecast envelope, around a 10% chance, gusts could reach 30-40 mph with isolated gusts of 45 mph in the most exposed locations. The combination of warmer temperatures, lower humidity and increasing east winds Tuesday through Thursday could increase fire-weather concerns. Increasing winds may also pose a risk for downed trees and branches, particularly where soils remain saturated. This period will be worth monitoring as we get closer. ~12



AVIATION
Through 12Z Sunday...VFR conditions continue throughout most of the airspace ahead of an approaching weather system which will bring increasing rain chances by 18-24Z Sat, earliest at the coast. The only exception as of 10Z Sat is KONP, with marine stratus maintaining MVFR CIGs until 17-18Z Sat (40-50% chance of MVFR CIGs ). The arrival of rain around 18-21Z Sat introduces a 20-40% chance of MVFR CIGs at coastal terminals from 21Z Sat to around 08Z Sun, including a 10-20% chance of IFR CIGs at KONP. While inland terminals will likely stay VFR through the TAF period, there is a 10-20% chance of MVFR CIGs from 03Z to at least 12Z Sun.

Light and variable winds early this morning will increase and become south to southwesterly by Saturday afternoon. South to southwesterly winds rise to 8-12 kt at coastal terminals and to 5-10 kt inland as the weather system approaches. Lastly, there is a 15-20% chance for an isolated thunderstorm across the region Saturday afternoon and evening.

KPDX AND APPROACHES...VFR conditions expected through the period. Rain arrives at the terminal around 00Z Sun, increasing chances of MVFR CIGs to 10-20% through at least 12Z Sun. Light winds this morning will become south to southwesterly at 5-7 kt by Saturday afternoon. ~12

MARINE
An area of weak low pressure near Vancouver Island strengthens slightly as it drops south over the waters today. Winds have begun to shift out of the south and will increase to around 10-15 kt with gusts up to 20 kt through the morning into the afternoon. Heavier showers or thunderstorms that develop with this low pressure system over the waters today could produce stronger wind gusts and lightning. Sunday, onshore southwesterly winds will persist as the low pushes inland. High pressure rebuilds over the waters by Monday, returning northerly winds to the coastal waters early next week. Lastly, seas are expected to subside slightly to around 4-5 ft during the weekend as a northwest swell persists at 9-10 seconds. ~12/DH

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