textproduct: Portland

SYNOPSIS

An active weather pattern will continue into next week and produce periods of rain and windy conditions, especially along the coast. A large westerly swell will bring high surf today along with an elevated threat of sneaker waves through the weekend. Active weather is expected for the start and latter part of the week, with a few a brief reprieve towards the middle of next week.

DISCUSSION...Today through Saturday

A progressive and active pattern will continue to support repeated chances for rain as system after system affects the Pacific Northwest through the week. There remains strong consensus that the next weather system will move into the region Monday into Tuesday, followed by relatively drier weather Wednesday into early Thursday as upper-level ridging quickly amplifies over the Rockies.

Looking towards Tuesday and Wednesday, IVT values of 250 kg/(ms) are in the forecast which does support moisture via an low end Atmospheric River bringing the next round of precipitation to the Pac NW. Now, there remains a fair amount of uncertainty as to where the AR will be aimed, with most models either pointing towards the Olympic Peninsula or the OR/CA border, with the Olympic Peninsula favored. Either solution would minimize the overall precipitation that would fall within our CWA. Still, chances for 1" or more of rain in 48 hours reaches 40-50% along the coast from Friday morning through next Saturday morning, and 20-40% along the I-5 corridor. As for the weekend, Saturday into Sunday, the chances for 1.50" or more of rain in 48 hours reaches 50-60% along the coast, and 30-40% along the I-5 corridor. Given repeated rounds of rain, increasingly saturated soils could allow for greater runoff into area rivers, and the forecast will continue to be monitored for potential flooding concerns. /42-36

AVIATION...Through 12Z Sunday

Generally VFR conditions across the airspace. However, light precipitation will continue and result a 20-30% chance for intermittent MVFR conditions that will coincide with showers for locations north of the KSLE for both inland and coastal locations through 16Z Sunday. Southerly winds through the TAF period with gusts up to 30 kt along the coast and up to 20 kt inland through around 16Z Sunday. After 16Z-18Z Sunday, VFR conditions expected to persist through the remainder of the TAF period.

KPDX AND APPROACHES...Generally VFR conditions through the TAF period. Light precipitation will continue and result a 20-30% chance for intermittent MVFR conditions through 16Z Sunday. Southerly winds through the TAF period with gusts up to 20 kt through around 16Z Sunday. After 16Z Sunday VFR conditions expected to persist through the remainder of the TAF period. /42

MARINE

An active weather pattern will continue across the waters into next week. Winds will continue to slacken through this morning, with gusts up to 30 kt through the early afternoon. There is a 50-60% chance for another round of gale force wind gusts Monday and Tuesday, therefore have issued another Gale Watch across all waters and the Columbia River Bar starting early Monday morning.

Seas will continue to slowly build today as a fresh, westerly swell will result in seas building towards 20-25 ft. Seas will likely reach 20-22 ft between 0100-0400 on Sunday and not drop below 20 ft until after 2200 Sunday. Seas are forecast to peak around 22-25 ft across the northern waters including the Columbia River Bar, and 19-23 ft across the southern waters. Seas gradually subside late tonight into Monday. However, additional systems on Monday and towards the end of the week will bring additional rounds of Gale Force winds to the waters with seas generally hovering between 12-16 ft for much of next week, with seas building towards the upper teens towards the end of next week. /42

BEACH HAZARDS

A robust westerly swell will result in wave heights peaking somewhere between 20-27 ft with a dominant period of 15-16 seconds. This will result in beach erosion and bring an even higher threat of sneaker waves along the coast on Sunday. High Surf Warnings and Advisories are in effect from 4 AM to 10 PM Sunday along the entire coast.

Extreme caution should be used if you plan to visit beaches today. The large wave runup will dislodge logs on area beaches and result in them rolling up and down area beaches, which have historically killed or seriously injured unsuspecting people, so there will be much more of a threat than just getting wet from a rogue wave. Given the momentum behind these large longer period waves, it's not out of the question that we receive a report or two of damage to infrastructure along the coast, particularly around high tide midday today. -10

PQR WATCHES/WARNINGS/ADVISORIES

OR...High Surf Warning until 10 PM PST this evening for ORZ101-102.

High Surf Advisory until 10 PM PST this evening for ORZ103.

WA...High Surf Warning until 10 PM PST this evening for WAZ201.

PZ...Gale Warning until 4 AM PST early this morning for PZZ210- 251>253-271>273.

Hazardous Seas Warning until 4 AM PST Monday for PZZ210-251>253- 271>273.

Gale Watch from late tonight through Monday evening for PZZ210- 251>253-271>273.